The Child with Disturbance of Oxygen and Carbon Dioxide Exchange

Chest

The chest has a relatively round configuration at birth but changes gradually to one that is more or less flattened in the anteroposterior (front-to-back) diameter in adulthood. In some lung diseases, chronic overinflation causes changes in these measurements. For example, in severe obstructive lung disease (e.g., asthma, cystic fibrosis) the anteroposterior measurement approaches the transverse (side-to-side) measurement to produce the so-called barrel chest. Periodic measurements provide clues to the course of the lung disease or the efficacy of therapy. Increased size indicates progressive obstructive lung disease.

The elliptic shape of the ribs and the angle at which they are attached to the spine allow the thorax to change size during respiration. Contraction of the intercostal muscles lifts the ribs from a downward angle to a more horizontal angle, which increases both the anteroposterior and the lateral dimensions of the chest (Fig. 31-1, A). This also changes the diameter of the bronchi; the diameter increases during inspiration and decreases during expiration, an important factor when the bronchi are narrowed as a result of obstruction or inflammation. Contraction and relaxation of the diaphragm cause the chest cavity to lengthen and shorten, which also increases the volume of the chest cavity during inspiration. Normal expiration is passive, although contraction of the internal intercostal muscles pulls the rib cage downward, and contraction of the abdominal muscles forces the diaphragm upward to actively decrease the chest size. (See Fig. 6-30.)

An adult’s ribs articulate with the vertebrae and sternum from a downward and lateral angle. During inspiration the respiratory muscles contract and the thorax enlarges. In the newborn infant, however, the ribs articulate with the spine at a horizontal rather than a downward slope; consequently, during inspiration the diameter of the chest decreases (Fig. 31-1, B). The infant relies almost entirely on diaphragmatic-abdominal breathing. During inspiration the diaphragm is forced downward, increasing the available space for lung expansion; the intercostal muscles serve primarily as stabilizing forces. Respiration is facilitated by the processes of (1) compliance, the elastic property of lung tissue that allows it to expand and recoil; and (2) resistance, which affects the amount of flow through the airways (see p. 1185).

Variations occur in lung volume relative to posture. In the upright position the evenly distributed weight of the abdominal contents contributes to uniform application of negative intrathoracic pressure. However, in the supine position the abdominal contents apply weight caudally to create a nonuniform distribution of positive pressure to the diaphragm. Consequently, lung volume is increased in the upright position and decreased in the supine position. In addition, the mechanical attachment of the diaphragm to the rib cage is such that contraction elevates the rib cage in the upright position but in the supine position tends to pull in the rib cage (Fig. 31-2).

In the newborn the diaphragm is attached higher in front. Therefore this already stretched diaphragm is unable to contract as far or as forcefully as that of the older infant or child. Young infants are also less able to withstand diaphragmatic fatigue because of fewer energy-producing components. Abdominal distention from gas or fluid can impede diaphragmatic excursion significantly.

Airways

The rigid nasal structures, which are lined with ciliated mucous membranes, serve as passageways for air, warming and moistening air, filtering its impurities, and destroying microorganisms that come in contact with immune defenses in the mucosa. In infancy the nasal passages are narrow, and infants are primarily nose breathers. Any factor that decreases the size of the nasal passages and increases airway resistance, such as nasal mucosal swelling and mucus accumulation, hampers breathing and feeding.

The upper airway (oronasopharynx, pharynx, larynx, and upper part of the trachea) is shared by both the respiratory and the alimentary tracts, and many of the muscles in this area participate in several complex acts. However, the sequence of airway muscle activation is different in breathing and swallowing. The upper airway dilates during inspiration and constricts during exhalation. During some activities these dimensions are modified. For example, inspiration is short during crying, coughing, and sneezing, but with crying the larynx and pharynx dilate. The net result of swallowing is closure of the upper airway with interruption of airflow. Consequently, the timing and magnitude of muscle activation have important implications for airway size and patency.

The pharynx is a passageway for the entry and exit of air, and it plays a role in phonation by helping to produce vowel sounds. The pharynx contains the palatine and lingual tonsils, which are involved in infection control.

The larynx, situated at the upper end of the trachea, is made of a rigid circular framework of cartilage and contains the epiglottis and glottis (vocal cords). These structures prevent solids or liquids from entering the airway during swallowing, and the vibrations of the vocal cords produce voice sounds. In infancy the glottis is located more cephalad (toward the head) than in later childhood, and the laryngeal reflexes are active. The epiglottis is longer and projects farther posteriorly in infants. The narrowest portion of the larynx is at the level of the cricoid cartilage. In the infant and young child the ciliated columnar epithelium below the vocal cords is loosely bound with areolar connective tissue and is therefore more susceptible to edema formation. Swelling of the glottis and epiglottis produces hoarseness and often life-threatening obstruction of this portion of the airway.

The lower airway is made up of the lower trachea, mainstem bronchi, segmental bronchi, subsegmental bronchioles, terminal bronchioles, and alveoli. The trachea, which is composed of smooth muscle supported by C-shaped rings of cartilage, ensures an open airway to the bronchi and lungs. The trachea divides at the carina into two primary bronchi. The right one is situated slightly more vertical than the left, which causes aspirated objects to lodge more frequently in the right bronchus. Each bronchus enters the lung on its respective side, where it divides into secondary bronchi that continue to branch and divide into progressively smaller bronchioles. The entire bronchial tree is lined with mucous membrane and is composed of spiral smooth muscle supported by rings of cartilage. As the bronchioles become smaller, the cartilaginous rings become increasingly irregular and then disappear completely in the smallest bronchioles, the walls of which consist of only a single layer of cells (Fig. 31-3). There is a range of 23 to 26 levels of branches divided into two categories: the conducting airways and the terminal respiratory units. These branch levels are called generations.

Pathophysiology Review

All the structures are subject to obstruction from edema or foreign objects, but the degree of obstruction from constriction of smooth muscle differs. The diameter of the relatively rigid upper airway is less subject to constriction than the lower airway structures, which contain little cartilaginous support. The highly reactive bronchiolar smooth muscle of the lower airway structures can cause life-threatening obstruction during bronchospasm. The airway cartilage in young infants is soft and compressible; therefore the intrathoracic airways are highly reactive to stimuli, such as vagal nerve stimulation.

The airways of the newborn have little smooth muscle, but in children 4 to 5 months of age they contain sufficient muscle to cause narrowing in response to irritating stimuli. By 1 year of age, smooth muscle development and reactivity are comparable to those in the adult. Growth of the respiratory system follows the general growth curve during the early weeks of life, but the airways grow faster than the thoracic and cervical portions of the vertebral column. Consequently, the larynx and trachea descend in relation to the upper spine. For example, the bifurcation of the trachea that lies opposite the third thoracic vertebra in the infant descends to a position opposite the fourth in adulthood (Fig. 31-4). Likewise, the cricoid cartilage descends from a position opposite the fourth cervical vertebra in the infant to opposite the sixth cervical vertebra in the adult. These anatomic changes produce differences in the angle of access to the trachea at various ages, and the nurse must consider this when the infant or child is positioned for resuscitation and airway clearance.

The function of the tracheobronchial tree is to distribute air to the alveoli of the lung. A variety of diseases and conditions, such as mucosal swelling, muscular contraction, and mechanical obstruction by mucus or a foreign body (FB), can cause localized or generalized airway occlusion.

Respiratory Units

The two cone-shaped lungs consist of the bronchi; bronchioles; and innumerable small air sacs, or alveoli. Through these thin-walled sacs, gas exchange occurs by simple diffusion between the inspired air and the bloodstream. The amount of gas exchanged depends on many factors, including the amount and composition of air inhaled, thickness of the alveolar wall, adequacy of circulation to the alveoli, and substances within the alveoli that either prevent their inflation (e.g., surface-active surfactant) or prevent gas exchange (e.g., fluids).

Animation—Bronchi and Bronchioles

With age, changes take place in the air passages that increase the respiratory surface area. The major changes are in the number and size of alveoli and in the increased branching of terminal bronchioles. Although the number of conducting airways is complete early in fetal life, the air sacs are shallow with wide necks and have few shared walls, or septa, at birth. This promotes patency but limits surface area for gas exchange. The alveoli are large with thick septa that have little elastic recoil (not unlike the emphysemic lung). During the first year, bronchioles continue to branch, and the globular alveoli formed earlier in the terminal units rapidly increase in number with each generation. These alveoli partition and divide existing alveoli to form smaller lobular units separated by thinner septa, thus enlarging the area available for gas exchange.

Alveoli increase steadily in number, but it is unclear when septal division ceases and an increase in size begins. It appears to occur sometime during middle childhood, although evidence indicates that an increase in the number of alveoli for each terminal airway takes place at puberty. Approximately nine times more alveoli are present at age 12 years than at birth. In later stages of growth the structures lengthen and enlarge. In addition, collateral pathways of ventilation develop, including pores through alveolar walls and possibly pathways between bronchioles.

All these factors have significant implications for respiratory disorders in children. Infants and young children have less alveolar surface area for gas exchange, the narrowly branching peripheral airways become easily obstructed, and lack of collateral pathways inhibits ventilation beyond obstructed units. Consequently, young children are subject to obstruction and atelectasis, especially as a result of repeated infection.

A variety of pathologic conditions affect lung growth. A postural defect such as kyphoscoliosis reduces the number of alveoli. Infections of the respiratory tract (e.g., coxsackievirus) can permanently alter lung development, resulting in decreased numbers of small airways. Replication of alveoli is inhibited, so the remaining alveoli are large but decreased in number. Changes in hormone levels influence lung growth. Glucocorticosteroids, thyroxine, and prolactin enhance lung development, but lack of thyroid hormone results in immature lungs. Biochemical substances that enhance lung growth are theophylline, estrogen, isoxsuprine, epidermal growth factor, and heroin injected during pregnancy. Some medications such as phenobarbital or excess insulin inhibit lung growth.

Gas Exchange

Gases in the blood are measured by the partial pressures (tensions) of the individual gases and are expressed in millimeters of mercury. With oxygen therapy it is important to understand the relationship between the concentration of the inspired gas and the partial pressure of that gas in the arteries (Pao₂). Inspired oxygen is expressed as the fraction of inspired oxygen (Fio₂), with 1.0 indicating 100% oxygen, 0.5 indicating 50% oxygen, and so on. Patients breathing room air have an Fio₂ of 0.21 because ambient air contains 21% oxygen.

Ambient air is composed of 21% oxygen, trace amounts of carbon dioxide, and 79% nitrogen (N). Water vapor (H₂O) also exerts pressure. The water vapor does not change with the barometric pressure (Pb) but exerts a constant pressure of 47 mm Hg when the gas is fully saturated at body temperature. Each gas contributes to the total barometric pressure as follows:

At sea level, the total pressure of gases in the atmosphere and the blood (Pb) is always equal to 760 mm Hg.

The significance of inspired gases lies in the Fio₂ and the pressure it exerts (Pio₂). At sea level this can be calculated as follows:

When the Fio₂ increases (e.g., to 50%), the pressure exerted also increases:

As the inspired gas travels down the airway and reaches the alveoli, the pressure drops as carbon dioxide is added to the mixture. Ambient air contains only traces of carbon dioxide. As the gas diffuses from the capillary blood to the alveoli, however, the amount and pressure of carbon dioxide in the alveoli increase to the carbon dioxide levels in the venous blood (approximately 40 mm Hg). By subtracting the Pco₂ from the Pio₂, one can determine the alveolar oxygen pressure (PAo₂). The PAco₂ is first divided by 0.8. This correlation factor, or respiratory quotient (RQ), is used to calculate the ratio of oxygen absorbed to carbon dioxide eliminated. The alveolar pressure can then be expressed as:

Because normal venous Po₂ is approximately 40 mm Hg, a gradient is created when the PAo₂ is 100 mm Hg and diffusion occurs between the alveoli and capillary blood. When the patient’s PAo₂ decreases, the Fio₂ can be raised to increase the PAo₂, thereby increasing the gradient for diffusion. Because carbon dioxide is more soluble than oxygen, it diffuses 21 times faster; therefore diffusion of carbon dioxide from the blood to the alveoli is not impaired. The amount of oxygen that diffuses into the blood and the amount of carbon dioxide removed by the lungs depend on several factors (Box 31-2).

Defenses of the Respiratory Tract

The respiratory tract has several anatomic and biochemical characteristics that provide natural defenses against the many biologic and inanimate agents that can damage respiratory tissues. Intact defenses help repel and resist the impact of injurious agents; factors that reduce the integrity of these mechanisms increase the vulnerability of these tissues to invasion and disease. Respiratory tract defenses include:

Some children have conditions (e.g., chronic asthma, cystic fibrosis, and the various immunodeficiency disorders) that predispose them to infection as a result of interference with the efficiency of these mechanisms. Frequent, intense exposure to organisms that accompany conditions of crowding or continual exposure to irritating substances in the air results in breakdown of healthy defenses. Concurrent illness, malnutrition, or fatigue reduces the efficiency of natural defenses. Drying of the mucous membranes also inhibits the activity of humoral defenses, such as immunoglobulins.

Respiration

Assess the configuration of the chest and the pattern of respiratory movement, including rate, regularity, symmetry of movements, depth, effort expended in respiration, and use of accessory muscles of respiration. To determine deviations, the nurse must know the normal type and rate of respiration in relation to the child’s size and age. (See inside back cover.) Respirations (ventilations) are best determined when the child is sleeping or quietly awake.

Tachypnea (rapid respirations) often occurs with anxiety, elevated temperature, severe anemia, and metabolic acidosis. It may also be associated with respiratory alkalosis caused by psychoneurosis and with central nervous system (CNS) disturbances. By observing changes in respiratory rate, the nurse can follow and evaluate the progress of disorders that contribute to low compliance, such as the pneumonias, pulmonary edema, and pleural effusion.

Alterations in the depth of respirations—too deep (hyperpnea) or too shallow (hypopnea)—are recognized as abnormal only in the extremes. Hyperpnea is noted with fever, severe anemia, respiratory alkalosis associated with psychosis, CNS disturbances, and respiratory acidosis that accompanies disorders such as diabetic ketoacidosis or diarrhea. Hypoventilation may occur with metabolic alkalosis in conditions such as hypertrophic pyloric stenosis and respiratory acidosis that accompanies diaphragmatic paralysis or CNS depression. Hypoventilation in preterm infants may occur as a result of pulmonary immaturity, absence of adequate substrate to support respiratory muscle activity, neurologic insult, and neurologic immaturity. Children with neuromuscular diseases such as spinal muscular atrophy may also exhibit hypoventilation. Congenital central hypoventilation syndrome, or Ondine curse, is a rare CNS defect in which respiratory failure occurs as a result of the respiratory system’s failure to respond to increasing carbon dioxide levels; this condition has been known to occur in children with Hirschsprung disease and is often manifested on the first day of life (Haddad, 2007).

Associated Observations

Retractions, or a sinking in of soft tissues relative to the cartilaginous and bony thorax, may occur in some pulmonary disorders. In disease states (particularly in severe airway obstruction), retractions become extreme. Subcostal retraction, observed anteriorly at the lower costal margins, indicates a flattened diaphragm because it not only lowers the floor of the thorax, but also pulls on the rib cage in response to a greater than normal decrease in intrathoracic pressure. In severe airway obstruction, retractions extend to the supraclavicular areas and the suprasternal notch (Fig. 31-6).

Anatomy Review—Location of Retractions

Nasal flaring is a sign of respiratory distress and a significant finding in an infant. The enlargement of the nostrils helps reduce nasal resistance and maintains airway patency. Nasal flaring may be intermittent or continuous and should be described as minimum or marked.

Head bobbing in a sleeping or exhausted infant is a sign of dyspnea. The head, supported on the caregiver’s arm only at the suboccipital area, bobs forward with each inspiration. This is caused by neck flexion resulting from contraction of the scalene and sternocleidomastoid muscles. Noisy breathing such as “snoring” is frequently associated with hypertrophied adenoidal tissue, choanal obstruction, polyps, or an FB in the nasal passages.

Stridor, which is a high-pitched, noisy respiration, is usually an indication of narrowing of the upper airway, either as a result of edema and inflammation, or in association with an upper airway obstruction, often from mucus secretions or possibly from a foreign object. Stridor may be inspiratory or expiratory. Common causes in children include croup, epiglottitis, FB, or tracheitis (Boat and Green, 2007).

Grunting is frequently a sign of pain in older children, suggesting acute pneumonia or pleural involvement. It is also observed in pulmonary edema and is a characteristic of respiratory distress in newborns and infants. It is the body’s attempt at more efficient respirations. Grunting serves to increase end-respiratory pressure and thus prolong the period of oxygen and carbon dioxide exchange across the alveolocapillary membrane.

Wheezing is a continuous musical sound originating from vibrations in narrowed airways (Watts and Goodman, 2007). Wheezing is primarily heard on expiration and may be either polyphonic (with widespread narrowing of the airways [e.g., asthma]), or monophonic (single-pitched sound produced in the larger airways [e.g., tracheomalacia]). Infants may have wheezing as a result of increased airway resistance and a compliant chest wall; there is evidence that inflammatory mediators such as histamines, leukotrienes, and interleukins may also contribute to wheezing in infants (Watts and Goodman, 2007). Older children often have wheezing with a lower respiratory tract infection as a result of inflammation, bronchospasm, and accumulated secretions, all of which serve to narrow the airways and produce the characteristic wheezing sound.

Color changes of the skin, especially mottling, pallor, and cyanosis, are important. Except for the peripheral bluish discoloration (acrocyanosis) resulting from circulatory stasis in the newborn or the mottling or peripheral cyanosis resulting from a cool environment, mottling and cyanosis are significant and usually indicate cardiopulmonary disease.

Chest pain may be a complaint of older children and may have a variety of causes, both pulmonary and nonpulmonary. It may be caused by disease of any of the chest structures—esophagus, pericardium, diaphragm, pleura, or chest wall. Parietal pleural pain is usually localized over the affected area and is aggravated by respiratory movements. The pain of diaphragmatic pleural irritation may be referred to the base of the neck posteriorly and anteriorly or to the abdomen. Most pleural pain is related to respiration; therefore respiratory movements are shallow and rapid and may be accompanied by grunting, especially in the younger patient.

Clubbing, or proliferation of tissue about the terminal phalanges, accompanies a variety of conditions, frequently those associated with chronic hypoxia, primarily cardiac defects, and chronic pulmonary disease (e.g., cystic fibrosis). Although clubbing often worsens with lung disease, it does not accurately reflect disease progression. The degree of clubbing depends on the extent to which the nail base is lifted on the dorsal surface of the phalanx by the tissue proliferation. The greater the angle formed above the finger or toe at the skin-nail junction, the more pronounced the clubbing, especially when there is a decided curvature to the nail (Fig. 31-7).

Cough is often associated with respiratory disease, although it may suggest other disorders (Box 31-3). It serves as a protective mechanism and an indicator of irritation. A cough can be initiated voluntarily but is usually a result of a complex reflex consisting of three components: afferent nerve fibers, the cough center, and efferent nerve fibers. The respiratory epithelium contains afferent receptors that are sensitive to mechanical or chemical stimuli. These receptors are concentrated in the areas of the larynx, the carina, and the bifurcations of the large and medium-sized bronchi. When a stimulus is applied to these areas, impulses are transmitted via the vagus nerve to the cough center in the brainstem. Efferent impulses travel via the vagus, phrenic, and spinal motor nerves to the larynx, intercostal muscles, diaphragm, abdominal muscles, and pelvic floor. An inspiratory gasp and closure of the glottis are followed by contraction of muscles in the chest wall, diaphragm, abdomen, and pelvic floor. The resulting compression and increase in pleural, alveolar, and subglottic pressure cause a sudden opening of the glottis and immediate release of trapped air at extremely rapid expiratory flow rates, which forces undesirable material from the respiratory tract.

Inflammation or infection in the upper or lower respiratory tract may produce coughing. Some types of cough are characteristic of specific diseases. For example, a severe cough is associated with measles and cystic fibrosis, and the paroxysmal cough accompanied by an inspiratory “whoop” is typical of pertussis in small children. A brassy, nonproductive cough is part of the symptomatology of croup and FB aspiration. Because there are no cough receptors in the alveoli, a cough may be absent in a child with pneumonia in the early stages of the disease but is a common feature during active pneumonia and recovery. The nurse assesses a cough according to the features listed in Box 31-4.

Pulmonary Function Tests

Noninvasive pulmonary mechanics are often measured at the bedside of infants and children with the use of pneumotachography or spirometry. However, information obtained limits diagnosis because the same functional abnormality may occur in different diseases. These tests are useful to evaluate the severity and course of a disease and to study the effects of treatment (Table 31-1 and Fig. 31-8).

Radiology and Other Diagnostic Procedures

Radiography is used frequently in diagnostic evaluation of children (Table 31-2). Although no definitive information exists on the effects of low-dose radiation, providers take action to protect vulnerable areas from possible damage. When possible, technicians and others try to prevent unnecessary exposure of the child (and nursing personnel), and they protect the more radiosensitive areas. Careful protection of the patient’s immature gonads with lead shields is essential. Other sensitive areas are the thyroid gland, ocular lens, and bone marrow.

Although nurses have limited control over the length, frequency, and correct application of the x-ray beam, they can make certain that the infant or child receives proper protection from possible hazards. Lead shields, correctly placed and consistently applied to areas not needed for diagnostic purposes, are essential. Play and modification of methodology effectively reduce the trauma sometimes associated with the procedure and gain the child’s cooperation. Nurses, regardless of age and pregnancy status, should use protective equipment to guard against unnecessary radiation exposure during diagnostic examinations.

Several other procedures are used to diagnose lung disorders (Table 31-3). Most require specialized equipment and skills. All require preparation of the child.

Blood Gas Determination

Blood gas measurements are sensitive indicators of change in respiratory status in acutely ill patients (Table 31-4). They provide valuable information regarding lung function, lung adequacy, and tissue perfusion and are essential for monitoring conditions involving hypoxemia, carbon dioxide retention, and pH. For the acutely ill patient, this information also guides decisions regarding therapeutic interventions, such as adjusting mechanical ventilator settings, modifying chest physiotherapy (CPT), administering oxygen, or positioning the child for maximum ventilation. Both invasive and noninvasive methods are available (see Atraumatic Care box).

Pulse oximetry provides a continuous or intermittent noninvasive method of determining oxygen saturation (Sao₂). A sensor composed of a light-emitting diode (LED) and a photodetector is placed in opposition around a foot, hand, finger, toe, or earlobe, with the LED placed on top of the nail when digits are used (Fig. 31-9). The diode emits red and infrared lights that pass through the skin to the photodetector. The photodetector measures the amount of each type of light absorbed by functional hemoglobins (those capable of carrying oxygen). Hemoglobin saturated with oxygen (oxyhemoglobin) absorbs more infrared light than does hemoglobin not saturated with oxygen (deoxyhemoglobin). A microprocessor determines the difference between absorption of the red and infrared light. The percentage of the total normal hemoglobin that is oxygenated is displayed on a monitor.

Pulsatile blood flow is the primary physiologic factor that influences accuracy of the pulse oximeter. In most infants with continuous pulse oximetry monitoring, the nurse must change the electrode site at least every 3 to 4 hours to prevent pressure necrosis (in infants with poor perfusion or disrupted skin integrity). In infants with poor perfusion and temperature problems such as hypothermia or sensitive skin, the probe may need more frequent changing. In an active or crying infant motion artifact may make the reading more difficult to obtain.

Another noninvasive method is transcutaneous monitoring (TCM), which provides continuous monitoring of transcutaneous partial pressure of oxygen in arterial blood (tcPao₂) and, with some devices, of carbon dioxide in arterial blood (tcPaco₂). An electrode is attached to the warmed skin to facilitate arterialization of cutaneous capillaries. The site of the electrode must be changed every 3 to 4 hours (or more frequently according to skin status) to avoid burning the skin, and the machine must be calibrated with every site change. This monitoring is used frequently in neonatal intensive care units, but it may not reflect an accurate Pao₂ in infants with impaired local circulation.

The Pao₂ can be correlated with the Sao₂ by means of the oxyhemoglobin dissociation curve (Fig. 31-10), although changes in Pao₂ do not cause identical (linear) changes in Sao₂. The curve represents the relationship between Pao₂ (measured in the blood) and Sao₂ (measured by the pulse oximeter). As seen on the graph, when the Pao₂ is 60 mm Hg, the Sao₂ is 90%. Increasing the Pao₂ above this point does not significantly increase Sao₂ or greatly improve oxygen delivery to the tissues. At this point, further increases in the Pao₂ will only increase the dissolved oxygen in the blood and will not, under normal conditions, contribute significantly to the arterial oxygen content. On the lower part of the curve, however, even small changes in the Pao₂ produce large changes in saturation. This is an advantage at the tissue level, especially in low oxygen states (hypoxia) because a small decrease in Pao₂ will cause a relatively large unloading of oxygen to the tissues.

Oximetry is insensitive to hyperoxia because hemoglobin approaches 100% saturation for all Pao₂ readings above approximately 100 mm Hg, which is a potentially dangerous situation for the preterm infant at risk for developing oxidative stress. Oxidative stress may lead to complications such as bronchopulmonary dysplasia and retinopathy of prematurity. (See Chapter 10.) Therefore the preterm infant being monitored with oximetry should have a range of upper limits identified, such as 89% to 93%, and a protocol should be established for decreasing oxygen when saturations are high.

Several factors affect the degree to which oxygen combines with hemoglobin. A shift of the curve to the left causes an increased affinity of hemoglobin for oxygen, but the oxygen is not easily released to the tissues. This represents an increase in the Sao₂ if it is measured against the same Pao₂ of the normal oxyhemoglobin dissociation curve. This left shift can be caused by an increase in blood pH or a decrease in Paco₂ or body temperature.

A shift of the curve to the right causes a decreased affinity of hemoglobin for oxygen but improved oxygen release to the tissues. This represents a lower Sao₂ if measured against the same Pao₂ of the normal oxyhemoglobin dissociation curve. This rightward shift can be caused by a decrease in blood pH or an increase in Paco₂ or body temperature.

Oximetry offers several advantages over TCM. Oximetry (1) does not require heating the skin, thus reducing the risk of burns; (2) eliminates a delay period for transducer equilibration; and (3) maintains an accurate measurement regardless of the patient’s age or skin characteristics or the presence of lung disease.

Applying the sensor correctly is essential for accurate Sao₂ measurements. Because the sensor must identify every pulse beat to calculate the Sao₂, movement can interfere with sensing. Some devices synchronize the oxygen saturation reading with the heartbeat, thereby reducing the interference caused by motion. Sensors are not placed on extremities used for blood pressure monitoring or with indwelling arterial catheters, since pulsatile blood flow can be affected. It is recommended that the probe site be changed according to manufacturer guidelines.

It is important to make certain that sensory connectors and oximeters are compatible. Wiring that is incompatible can generate considerable heat at the tip of the sensor, causing second- and third-degree burns under the sensors. Pressure necrosis can also occur from sensors attached too tightly. Therefore inspect the skin under the sensor frequently.

Ambient light from ceiling lights and phototherapy or high-intensity heat and light from radiant warmers can interfere with readings. Therefore cover the sensor to block these light sources. Intravenous dyes; green, purple, or black nail polish; nonopaque synthetic nails; and possibly ink used for footprinting can also cause inaccurate Sao₂ measurements. The nurse should remove the dyes or, in the case of porcelain nails, use a different area used for the sensor. Skin color, thickness, and edema do not affect the readings. Elevated levels of carboxyhemoglobin, methemoglobin, and fetal hemoglobin affect the accuracy of the device because it can only distinguish between oxyhemoglobin and deoxyhemoglobin; therefore the child with carbon monoxide poisoning may have a normal Sao₂ reading but an abnormal (low) Pao₂.

Arterial blood gas (ABG) sampling helps to evaluate gas exchange and oxygenation and may be performed on blood from an artery or a capillary. Historically, some controversy surrounds the collection of “arterialized” capillary blood for blood gas measurements. However, many believe it to be a safe, convenient, and relatively accurate method, and that capillary blood gas (CBG) can accurately reflect the arterial pH and Pco₂ in most pediatric disease states (Yildizdas, Yapicioglu, Yilmaz, et al, 2004; Bilan, Behbahan, and Khosroshahi, 2008). The blood samples are obtained by a heel stick after dilation of the vascular bed by warming. The first drop of blood is discarded, and subsequent blood is collected directly into heparinized capillary tubes held in a horizontal position.

ABG samples may also be obtained through an indwelling arterial catheter or by arterial puncture. The sites most commonly used for arterial puncture include the radial, dorsalis pedis, posterior tibial, and femoral arteries. A catheter may also be placed in the neonate’s umbilical artery for ABG sampling. The femoral artery is the last choice because hemorrhage and hematomas are difficult to control in this area and the risk for limb ischemia is high if the femoral artery is damaged (Curley and Moloney-Harmon, 2001). Risks of arterial puncture include pain, artery damage, decreased perfusion to the extremity distal to the puncture site, thrombosis, and hemorrhage (see Atraumatic Care box). Before a radial artery puncture, perform the Allen test to assess adequacy of the collateral circulation. To perform the test, elevate the extremity distal to the puncture site and blanch it by squeezing gently (such as making a fist). The two arteries supplying blood flow to the extremity (such as the radial and ulnar arteries in the wrist) are then occluded. Lower the extremity, and remove pressure from one artery (such as the ulnar). If color returns to the blanched extremity in less than 5 seconds, this indicates collateral circulation.

An accurate ABG or CBG requires unclotted whole or capillary blood; therefore use a heparinized syringe or capillary tube to draw blood samples. Do not allow air bubbles to enter the sample, since air alters the blood gas concentration. Many institutions use prepackaged ABG sampling kits, which allow air-free samples to be drawn without the need for heparin dilutions. The amount collected depends on the child’s size. Depending on the laboratory facilities, as little as 0.1 ml may be sufficient in small infants. After obtaining the blood sample, pack it in ice to reduce blood cell metabolism and have it taken to the laboratory immediately for analysis. Table 31-4 lists normal ABG and pH measurements on room air at sea level for adults and children 7 to 19 years of age.

Although ABG values are similar for children and adults, newborns can have slightly lower values and still be considered normal. For example, normal pH values for a newborn range from 7.26 to 7.29, the average Pao₂ is 70 mm Hg, the average Paco₂ is 33 mm Hg, and the average bicarbonate is 20 mEq/L.

ABG values also depend on the concentration of oxygen the child is breathing. The arterial Po₂ should rise in proportion to the oxygen concentration being inhaled. Therefore, when evaluating ABG values, consider the following: the percentage of oxygen administered (if any), the child’s body temperature (as little as 1° F can alter the blood gas values 5% to 8%), and the presence of anxiety (if children hyperventilate, carbon dioxide is exhaled) or crying (can cause breath holding, resulting in decreased Pao₂).

The significance of ABG determination is related primarily to the relationships among the following three parameters: pH, Po₂, and Pco₂. (See Acid-Base Imbalance, Chapter 28.) Any change in a blood gas value must be compared with the other values and with previous readings, as well as with the child’s clinical appearance and behavior, medical history, and associated physiologic factors.

Clinical indications for blood gas analysis include changes in pulse oximetry, color (e.g., mottling, pallor, cyanosis, or duskiness), depth or rate of respirations (e.g., shallow and rapid), behavior or sensorium, and vital signs. Blood gas analysis is also used to determine adequacy of treatment and optimal ventilator settings in infants and children on supplemental oxygen and noninvasive and invasive mechanical ventilation. The nurse may or may not obtain the blood sample by arterial puncture, depending on the institution’s policies. In any event, nurses must understand the results of blood gas analyses because these results provide essential information to guide nursing interventions (e.g., changing the position, performing suction, administering prescribed drugs, or notifying the practitioner).

One approach to determine a simple acid-base disturbance:

In a patient with a mixed acid-base disorder, compensatory factors (renal, pulmonary, or both) have been set in motion to equilibrate the blood pH. (See Acid-Base Imbalance, Chapter 28.)

Oxygen Administration

Oxygen delivered to infants is well tolerated by using a plastic hood (Fig. 31-11). Low and high concentrations of oxygen can be easily maintained in this head hood, and most nursing procedures can continue without interrupting the oxygen delivery. At least 4 to 5 L/min of flow is necessary to maintain oxygen concentrations and remove the exhaled carbon dioxide.

The humidified oxygen should not be blown directly into the face of an infant in a hood. Cold fluid or air applied to the face stimulates receptors that trigger the diving reflex, which causes bradycardia and shunting of blood from peripheral to central circulation. The oxygen hood should not rub against the infant’s neck, chin, or shoulder.

Older infants and children can use a nasal cannula or prongs. Nasal cannula may also be used for lower concentrations of oxygen for infants and children who do not require high oxygen concentrations; the cannula has two soft prongs, which are inserted into the nares, providing flow into the nasopharynx. Skin care of the nasal alae is important to prevent breakdown.

Oxygen masks are available in pediatric sizes. The simple oxygen mask fits over the patient’s nose and oxygen is delivered as the child breathes. The simple oxygen mask is used for short-term oxygen therapy, and it should be used at oxygen flow rates greater than 5 to 6 L/min to minimize carbon dioxide rebreathing. The simple mask has side holes to permit room air to enter into the mask to be mixed with oxygen. Signs of carbon dioxide rebreathing include somnolence, dizziness, headache, tingling, and eventually unconsciousness. A partial rebreathing mask is similar to the simple mask in that the plastic reservoir fits over the child’s face; the partial rebreather has a reservoir at the base of the mask that receives expired air and fresh gas so lower oxygen flow rates (<4 L/min) can be used. The nonrebreathing mask is similar to the partial rebreathing mask, but the former has a one-way valve that limits rebreathing carbon dioxide. Another valve on the nonrebreathing mask’s reservoir ensures that room air is not mixed with oxygen, thus providing higher oxygen concentrations (provided the mask fits correctly).

At times the child or infant may become quite agitated with the use of a mask, and a blow-by method may be used to provide low oxygen concentrations (<30%), humidification, or aerosolized medication. The blow by can be made with any oxygen tubing, corrugated tubing, or a mask held approximately 2 to 3 inches from the child’s nose and mouth. It is recognized that this method is not the optimal choice of oxygen delivery.

Face masks may not be well tolerated by children, since the fit must be snug to the face to ensure adequate oxygen delivery. A face tent or bucket is often better tolerated, since this soft piece of plastic sits beneath the child’s chin and allows for the direction of oxygen up to the area of the mouth and nose without having the mouth and nose enclosed by plastic (Curley and Moloney-Harmon, 2001).

Historically the oxygen tent (often referred to as a croup tent) was used as a satisfactory means for oxygen administration in older infants and some small children; however, these are rarely used in developed countries. A tent does not require any device to come into direct contact with the face, but the concentration of oxygen within the tent is difficult to control and to maintain above 30% to 50%. A major difficulty with the use of the tent is keeping the tent closed so that oxygen concentration is maintained; the humidification also presents a problem as the linens and child’s clothing becomes saturated quite easily and must be changed often. Closely monitor the child’s temperature in an oxygen tent.

Oxygen Toxicity

Oxygen is essential to life and a valuable therapeutic aid. Prolonged exposure to high oxygen tensions, however, can damage lung tissue. Although the exact pathogenesis of the pulmonary changes is unclear, evidence indicates damage to lung capillaries, which causes diffuse microhemorrhagic changes, diminished mucus flow, inactivation of surfactant, and altered ciliary function. The result of these changes is a gradual impairment of alveolar ventilation.

Atelectasis may occur as a result of the “washing out” of nitrogen from the alveoli by the high concentrations of oxygen. This is more likely to occur in persons with low tidal volume and retention of mucus or other secretions.

Oxygen-induced carbon dioxide narcosis is a physiologic hazard of oxygen therapy that may occur in persons with chronic pulmonary disease. It is rare in children, except those with cystic fibrosis. These children have chronic alveolar hypoventilation with a concomitant chronic carbon dioxide retention and hypoxemia. The respiratory center has adapted to the continuously higher Paco₂ levels, and therefore hypoxia becomes the more powerful stimulus to respiration. When the Pao₂ is elevated during oxygen administration, the hypoxic drive is removed, causing progressive hypoventilation and increased Paco₂ levels, and the child rapidly becomes unconscious. Carbon dioxide narcosis can also be induced by the administration of sedation in these patients.

Other suspected toxic effects of oxygen include changes in the renal tubules, sympathoadrenal medullary stimulation precipitating neurogenic seizures, and an increased rate of destruction of red blood cells. In extremely preterm infants the risk of retinopathy of prematurity is a major concern in oxygen administration, although the exact correlation between the two is unclear. (See Chapter 10.)

Chest Physiotherapy

CPT usually refers to the use of postural drainage in combination with adjunctive techniques that are thought to enhance the clearance of mucus from the airway. These are often referred to as airway clearance techniques. These techniques include manual or mechanical percussion, vibration, and squeezing of the chest; cough; forceful expiration (exhalation) or huffing; and breathing exercises. Special mechanical devices (e.g., vest-type percussors) are also currently used to perform CPT in children with chronic pulmonary illness such as cystic fibrosis (see p. 1280). Additional methods include the flutter device (see p. 1284), Acapella, and intrapulmonary percussive ventilation (Marks, 2008). Postural drainage in combination with forced expiration has been beneficial.

Common techniques used in association with postural drainage include manual percussion of the chest wall and percussion with mechanical devices such as a high-frequency hand-held chest compression device. Nurses may be responsible for this procedure, and they should become skilled in the technique. The patient is dressed in a light shirt and placed in a postural drainage position. The practitioner then gently but firmly strikes the chest wall with a cupped hand (Fig. 31-14, A). For infants and small children, special devices are available for percussing small areas (Fig. 31-14, B). A “popping,” hollow sound, not a slapping sound, should be the result. The procedure should be done only over the rib cage and should be painless. Percussion can be performed with a soft, circular mask (adapted to maintain air trapping) or a percussion cup marketed to aid in loosening secretions (see Fig. 31-14, B).

Vibration can be used to help move secretions cephalad during exhalations. Larger children may benefit from a more powerful vibrator such as a high-frequency chest compression device. This therapy is subject to patient tolerance, and pulse oximetry is an excellent monitoring tool for therapy tolerance.

CPT is contraindicated when patients have pulmonary hemorrhage, pulmonary embolism, end-stage renal disease, increased intracranial pressure, osteogenesis imperfecta, or minimum cardiac reserves. Avoid the head-down positions in children with gastroesophageal reflux (Marks, 2008). McIlwaine (2007) notes that the head-down position is detrimental and should not be used; Naylor, McLean, Chow, and colleagues (2006) also recommend that the head-down position be used infrequently because of an increase in cardiovascular adverse effects. Guidelines for performing CPT are given in the Nursing Care Guidelines box.

Squeezing is sometimes useful while the child is in the drainage position. Direct the child to take a deep breath and then exhale through the mouth rapidly and as completely as possible. The depth of the expiratory effort is increased by brief, firm pressure from the practitioner’s hands compressing the sides of the chest. This decreases the volume of the tracheobronchial tree and facilitates the expression of secretions. Inspiration after the activity often stimulates a deep, productive cough. Another technique to force exhalation is to use abdominal thrusts in conjunction with a MAC device (see discussion below).

Encourage deep breathing when the child is relaxed and in the desired position for drainage. Direct the child to take several deep breaths using diaphragmatic breathing. The use of deep breathing enlarges the tracheobronchial tree, enabling air to circulate around and through secretions that are not affected by usual tidal volumes. Exhalations after these deep breaths often carry secretions and may stimulate a cough. Other methods that can be employed to stimulate deep breathing are the use of incentive spirometers and incorporation of play that extends the expiratory time and increases expiratory pressure. For example, play may include blowing pinwheel toys, moving small items by blowing through a straw, blowing cotton balls or a Ping-Pong ball on a table, preventing a tissue from falling by blowing it against a wall, blowing up balloons (under supervision), singing loudly (especially songs with a lot of words between breaths), or blowing soap bubbles.

With or without stimulation, encourage children to cough, not to suppress a cough, and not to waste strength and energy with repeated weak and ineffective coughs. One or two hard coughs after a deep breath are more efficient. Because many children have difficulty coughing when in a dependent position, have them sit up while they cough. Having the child hug a stuffed toy or a small pillow offers comfort, as well as physical support, during coughing. As an alternative, reinforce the child’s efforts by encircling the chest with your hands and compressing the sides of the lower chest in synchrony with the cough. This is less fatiguing and increases the effectiveness of the cough efforts.

Mechanical-assisted cough (MAC) devices are available for children with acute or chronic pulmonary disease and neuromuscular disease to assist in clearing the airway when the cough reflex is ineffective or diminished. These devices may be used with CPT to enhance the removal of mucus from the airways. The mechanical cough insufflator-exsufflator (MIE) has been evaluated and found to be safe and effective in the daily management of respiratory function (Fauroux, Guillemot, Aubertin, et al, 2008; Homnick, 2007). The MIE delivers positive inspiratory pressures at a set rate, followed by negative pressure exsufflation coordinated with the patient’s own breathing rhythm. The exsufflation is designed to mimic a cough reflex so mucus can be effectively cleared. Airway suctioning after exsufflation is accomplished as necessary to clear the airways. In children the MIE may be connected directly to a tracheostomy or used with a mouthpiece or face mask.

Breathing and postural exercises are useful techniques with motivated children and children with kyphoscoliosis, cystic fibrosis, asthma, and bronchiectasis. Breathing exercises are part of a total therapy program and are more convenient when performed in association with bronchial drainage.

The goals of breathing exercises are to (1) develop more effective diaphragmatic and lower intercostal breathing; (2) relax all muscles, especially those of the upper chest, shoulder girdle, and neck; and (3) attain correct posture. The number and type of exercises depend on the child’s age, motivation, and strength and the type and extent of the physiologic disturbance. Select breathing exercises to meet the specific child’s needs. The most important exercises are diaphragmatic breathing and side bending, with emphasis on abdominal expansion and lateral expansion.

Nursing Care Management

The regulation and maintenance of mechanical ventilators are often the responsibility of respiratory care practitioners. However, the nurse should understand the function of the ventilator and how to detect signs of malfunction and deviations from the desired settings. The nursing process in the care of the pediatric patient on mechanical ventilation involves baseline and continuous respiratory assessment and provision of optimum ventilation through interventions such as preventing accidental or unplanned extubation; positioning for optimum ventilation and comfort; suctioning the airway only as necessary; monitoring for potential side effects of mechanical ventilation (e.g., pneumothorax); preventing infection; ensuring that adequate humidification is provided; and providing support, comfort, and reassurance to the child and the family. It is important to help the family understand why the intubated child cannot speak when an ET tube is in place. The nurse can enhance the family’s role in providing emotional support to the child by allowing family involvement in the child’s care. With mechanical ventilation, nutrition and hydration needs must be met with either gastrostomy feedings or parenteral nutrition. (See Chapter 10 for assisted and controlled ventilation in the neonate.)

Nursing assessment of the child requiring mechanical ventilation focuses on physical examination, vital signs, response to treatment, pulmonary status, oxygenation, comfort, airway patency (e.g., obstruction or unplanned extubation and dislodgment), laboratory analysis (ABGs), and pulse oximetry. All infants and children who are intubated and on mechanical ventilation should be placed on a cardiorespiratory monitor.

When an infant or child is intubated, medications are usually administered for achieving a successful, atraumatic intubation and decreasing the child’s anxiety. Because pain and agitation are often difficult to distinguish in children, it is important that nurses assess and treat agitation in the ventilated infant and child to decrease the potential for self-harm, maximize the effects of the therapy (oxygenation of tissues), and prevent self-extubation (Brinker, 2004). Rapid sequence intubation (RSI) is commonly performed in pediatric (and some neonatal) patients to induce an unconscious, neuromuscular blocked condition to avoid the use of positive pressure ventilation and the risk of possible aspiration (Bottor, 2009). Atropine, fentanyl, and vecuronium or rocuronium are drugs commonly used during RSI. In neonates endotracheal intubation is often a stressful event, and hypoxia and pain are commonly associated with routine intubation; RSI in neonates may serve to prevent such adverse events (Bottor, 2009).

Animation—Intubation

Animation—Intubation in Infant

Objective assessment tools to measure anxiety in intubated children should guide medication administration; the Comfort scale has been used in critically ill ventilated patients (Brinker, 2004). Medications used for sedation in children on mechanical ventilation include opioids (fentanyl and morphine), benzodiazepines (midazolam [Versed] and lorazepam [Ativan]), and neuromuscular blockade agents (pancuronium, vecuronium, and rocuronium). Propofol may be used short term in intubated children. Prolonged use of sedating agents may cause withdrawal, physical dependence, and tolerance, and plans should be implemented to counteract untoward effects, especially during the weaning process (Brinker, 2004).

Other important criteria to assess include nutritional status, intake and output (urinary output should be at least 2 ml/kg/hr for the infant and younger child and 1 ml/kg/hr for the older child), and skin integrity (especially around the face and lips for the child with an ET tube, and around the neck and stoma for the child with a tracheostomy). In some cases there is an increase in the amount of oral or nasal secretions, which requires appropriate perioral skin care. The child’s lips and mouth may be dry and uncomfortable; therefore provision of oral care and moisture is important to decrease discomfort.

Weaning the patient from a ventilator involves gradual physical and psychologic withdrawal from dependence on the mechanical device. Criteria for beginning the weaning process vary with the primary disease.

If the intubated child is receiving nasogastric feedings and is at risk for aspiration, feedings are usually stopped a few hours before extubation. Steroids may be administered before the extubation to control laryngeal edema. The child should remain on a cardiorespiratory monitor, and resuscitation and reintubation equipment must be available at the bedside.

CPT and suctioning are ordinarily performed just before tube removal, and cool mist or a noninvasive form of oxygen delivery (nasal cannula, face mask) is initiated immediately after extubation. The nurse monitors the child for respiratory distress and observes adequacy of oxygenation through ABG measurements or pulse oximetry. The most common complications after extubation are airway edema and pain, fatigue, and atelectasis. Stridor results from airway edema and often responds to nebulized racemic epinephrine. This can be given several times to reduce airway swelling and avoid reintubation.

Endotracheal Airways

An artificial airway is commonly used in association with artificial ventilation and in children with upper airway obstruction (Box 31-7). ET intubation can be accomplished by the nasal (nasotracheal), oral (orotracheal), or direct tracheal (tracheostomy) routes. Oral intubation is usually the method of choice for emergency situations, but for prolonged intubation a nasotracheal tube is often used. Nasotracheal intubation facilitates oral hygiene and provides more stable fixation, which reduces the complication of tracheal erosion and the danger of accidental extubation. Nasotracheal intubation also allows for age-appropriate oral development such as learning to suck on a pacifier. This normal development decreases the possibility that the patient will develop oral aversions and perhaps even later feeding difficulties as a result of being intubated. One potential disadvantage of nasal intubation is erosion of the nasal septum; therefore meticulous skin care and monitoring for skin breakdown are essential.

Animation—Intubation, Incorrect Placement

Use only uncuffed ET tubes in children less than 8 years of age (Curley and Moloney-Harmon, 2001). Although infants have been successfully maintained on ET tubes for longer periods, tracheostomy is usually considered in some infants and older children who require intubation for an extended period. However, infants may experience complications as a result of prolonged intubation, including tracheomalacia. Therefore it is not uncommon to attempt early weaning. Prolonged mechanical ventilation in infants has also been associated with the development of bronchopulmonary dysplasia, or chronic lung disease.

The decision to change from an ET tube to a tracheostomy is made on an individual basis. The tracheostomy allows the child to speak (by temporarily occluding the opening with a special speaking device) and eat and also facilitates clearing of secretions. Suctioning an ET tube is carried out with the same care as suctioning a tracheostomy.

The practice of instilling sterile saline in the ET tube or tracheostomy before suctioning is still common in many intensive care units. However, the routine use of saline is not recommend because of increased incidence of oxygen desaturation, increased intracranial pressure, increased arterial blood pressure, and nosocomial infection (Ridling, Martin, Bratton, et al, 2003; Celik and Kanan, 2006; Morrow and Argent, 2008; Gardner and Shirland, 2009). The conclusions drawn from neonatal and adult studies are that routinely instilling saline is not supported by research. A review of 14 studies contends that normal saline (NS) does not liquefy or thin out thick secretions in the endotracheal tube; the researchers pointed out that sputum recovery with NS instillation was minimal and did not outweigh the adverse effects of routine NS instillation (Halm and Krisko-Hagel, 2008). Policies about instillation of sterile saline while suctioning vary among institutions (see Evidence-Based Practice box). Evidence-based guidelines for ET suctioning in neonates and infants have been published elsewhere (Gardner and Shirland, 2009).

Tracheostomy Care

Before the tracheotomy is performed, it is important to prepare the child and family. Teaching before the procedure should include the child (if age appropriate), family, and other primary caregivers. It should address the child’s appearance with a tracheostomy, the communication method to be used after the procedure, and postoperative procedures. If time permits, medical play or hands-on experience with tracheostomy supplies and a tour of the pediatric intensive care unit are helpful to decrease anxiety.

The child returns from the operating room with the tracheostomy tube in place and long sutures (stay sutures) taped to the chest. These sutures are attached to the tracheal rings and can be used to hold the stoma open in the event of accidental decannulation. In approximately 5 days a tract is formed in the trachea, subcutaneous tissue, and skin, at which time the stay sutures are no longer required. The nurse should tell the child that removal of the stay sutures is not painful.

Children who have undergone a tracheotomy must be closely monitored for complications such as hemorrhage, edema, aspiration, accidental decannulation, tube obstruction, and the entrance of free air into the pleural cavity. Nursing care focuses on maintaining a patent airway, facilitating the removal of secretions, providing humidified air or oxygen, offering comfort care, cleansing the stoma, monitoring the child’s ability to swallow, and teaching while simultaneously preventing complications.

Because the child may be unable to signal for help, direct observation of the child and the use of respiratory and cardiac monitors are essential. Perform respiratory assessments (including breath sounds and work of breathing, vital signs, pulse oximetry, tightness of the tracheostomy ties, and the type and amount of secretions) every 15 minutes until the patient is stable and then every 1 to 2 hours for the first 24 hours. Perform assessments thereafter every 2 to 4 hours or more frequently if needed.

Position the child with the head of the bed raised, or in the position most comfortable to the child. Suction catheters, the suction source, gloves, sterile saline, sterile gauze for wiping away secretions, scissors, an extra tracheostomy tube of the same size with ties already attached, another tracheostomy tube one size smaller, and the obturator are kept at the bedside. Provide a source of humidification, since the normal humidification and filtering functions of the airway have been bypassed. Intravenous fluids ensure adequate hydration until the child is able to swallow sufficient amounts of fluids.

Decannulation

The tracheostomy tube is removed as soon as it is no longer needed. Airway problems of short duration (e.g., FB obstruction) usually allow early removal, but some conditions (e.g., tracheomalacia, tracheostenosis, vocal cord paralysis) may require that the tracheostomy tube remain in place indefinitely.

Opinions differ regarding the best means for removing the tube, especially after lengthy intubation. The usual procedure may take up to several months to wean or “downsize” the child to the smallest possible tracheostomy tube. Once this has been accomplished and the child’s respiratory status is unimpaired for 24 hours, the tube is occluded, and then removed within the next 24 hours. A small bandage is usually placed over the open stoma, which will close within a short time. The procedure is carried out in a clinical setting where continuous observation is available and emergency reintubation can be accomplished without delay, if necessary. After successful decannulation, the child remains under close observation for an additional period.

Home Care of the Child with a Tracheostomy

The early return of the infant or child with a tracheostomy to a home setting can reduce developmental delays or social handicaps related to prolonged hospitalization. Placement in the home also allows for reestablishment of routines and a regular schedule of normal activities. Physical, occupational, and speech therapy continues in the home setting. Nursing care may also be continued in the home through private-duty care or by routine, frequent nursing visits.

Preparing the family to care for the child with a tracheostomy at home is multifaceted (see Family-Centered Care box). Teaching sessions should be short, and written material must accompany instructions to reinforce what is taught. The family must be able to demonstrate tracheostomy care before the child is discharged from the hospital. Home-based care of a tracheostomy includes suctioning the tracheostomy; cleaning the stoma; changing the tracheostomy ties; changing the tracheostomy tube; adapting the home environment; and recognizing warning signs of obstruction, infection, or a worsening condition.

To prepare for any emergency, the family must learn infant or child cardiopulmonary resuscitation (CPR). The local utility company and local emergency medical service (EMS) should be notified of the child’s condition and the equipment used in the home. Prior notification allows for a quick response if help is needed.

The home should have all the necessary equipment before the child arrives. Supplies include sterile saline; a portable suction machine (and a DeLee suction trap); connecting tubing for suction; suction catheters; tracheostomy dressings; twill tape or self-adhering tracheostomy ties; pipe cleaners or a tracheostomy brush; an extra tracheostomy tube; a BVM; and a cool mist humidifier. Many children receive oxygen at home, so this too must be in place. Finally, an apnea monitor or pulse oximeter may be needed in some situations.

Encourage the family to take the child out of the home for routine outings. Two people should always be present when traveling because the child may need attention while riding in the car or at the destination. In addition to routine child care supplies, the family should always bring the portable suction machine, suction catheters, gloves, and an extra tracheostomy tube.

1. Presence or history of a condition that might predispose to respiratory failure

2. Observation of respiratory failure

3. Measurement of ABGs

Conditions That Predispose to Respiratory Failure

Respiratory disorders are classified according to three dominant functional abnormalities, although all three types may be present in the disease. In obstructive lung disease there is increased resistance to airflow in either the upper or the lower respiratory tract. Obstruction can result from anomalies (tracheomalacia, choanal atresia, vocal paralysis), aspiration (meconium, mucus, vomitus, FB), infection (epiglottitis, pneumonia, pertussis, severe tonsillitis), tumors (hemangioma, cystic hygroma), anaphylaxis, and laryngospasm from local irritation (intubation, drowning, aspiration).

In restrictive lung disease, impaired lung expansion results from loss of lung volume, decreased distensibility, or chest wall disturbance. Causes of pulmonary restriction include respiratory distress syndrome, pneumonia, cystic fibrosis, pneumothorax, pulmonary edema, pleural effusion, near drowning, congenital diaphragmatic hernia, abdominal distention, muscular dystrophy, paralytic conditions (poliomyelitis, botulism), and severe structural obstructions such as severe scoliosis.

In primary inefficient gas transfer there is insufficient alveolar ventilation for carbon dioxide removal or impaired oxygenation of pulmonary capillary blood as a result of dysfunction of the respiratory control mechanism or a diffusion defect. Causes of respiratory center depression include cerebral trauma (birth injuries); intracranial tumors; CNS infection (meningitis, encephalitis, sepsis); overdose with barbiturates, opioids, or benzodiazepines (diazepam [Valium] or midazolam); severe asphyxia (hypercapnia, hypoxemia); and tetanus. Pulmonary diffusion defects include pulmonary edema, fibrosis, embolism, or hypertension; collagen disorders; Pneumocystis carinii pneumonia; anemia; and hemorrhage.

Recognition of Respiratory Failure

Respiratory failure that occurs as a result of acute obstruction of a major airway or cardiac arrest is sudden and readily apparent. Gradual and more covert development of signs and symptoms is less easily recognized. Insufficient alveolar ventilation from any cause ultimately leads to hypoxemia and hypercapnia. However, in some situations severe respiratory distress may be present without significant carbon dioxide retention, and hypoxemia may occur without clinically detectable cyanosis. Therefore evaluation of respiratory adequacy is based on both clinical assessment and laboratory studies. Nursing observation and judgment are vital to successful management of respiratory failure. Nurses must be able to assess a situation and initiate appropriate action within moments.

Unless respiratory arrest occurs suddenly, signs of hypoxemia and hypercapnia are usually subtle in their development, becoming more obvious as respiratory failure progresses. The unknowing observer may attribute early signs such as mood changes and restlessness to other causes, and some signs can be altered by other factors. Clinical manifestations of respiratory failure are listed in Box 31-8.

In clinical situations in which impaired ventilation can be anticipated or clinical manifestations indicate impending hypoxemia, serial measurements of blood gases should be obtained and monitored to detect impending respiratory failure, and therapy should be implemented before respiratory acidosis becomes extreme.

Observation and Monitoring

The nurse monitors the child to anticipate respiratory failure, determine a course of action, and assess the patient’s response to treatment. If close, continuous monitoring is required, the child is transferred to a pediatric intensive care unit. The child is kept as comfortable as possible, and observation is geared toward general appearance, responsiveness, pulse oximetry, and vital signs. The child is positioned to allow maximum lung expansion and comfort, such as sitting upright or leaning forward (depending on respiratory status).

Animation—Inefficient Bag Ventilation

Prone positioning improves oxygenation and lung mechanics in adult patients with acute lung injury and acute respiratory distress syndrome. A multicenter pediatric trial for prone positioning showed it to be ineffective in improving oxygenation in acute lung injury or acute respiratory distress syndrome (Curley, Hibberd, Fineman, et al, 2005). At this point, the only indications for its use are in the case of bronchial compression by the heart or the need to augment secretion clearance. The nurse monitors the child’s cardiac and respiratory status by observation and by electronic means. However, no monitoring equipment can replace conscientious nursing observations (Box 31-9), which should focus primarily on the child’s airway, oxygenation, ventilation, and tissue perfusion.

Because one goal of therapy is to control the body’s oxygen demands, assessments of fever and pain should be frequent. Both conditions (as well as cold stress) can dramatically increase oxygen requirements, especially in younger children, and therefore increase respiratory effort. Measure oxygenation by the use of pulse oximetry or blood gas monitoring.

Family Support

Children who are in respiratory distress often relax after an airway is established and their respiratory effort is assisted. However, they are anxious and frightened when they are unable to communicate; therefore it is important to effectively manage the child’s anxiety. This may be accomplished initially with mild sedation until the child’s ventilatory status has improved.

It is often frightening for young children to discover they are unable to make vocal sounds, including crying. It is also stressful to parents to watch their child’s inability to vocalize and helplessness. It is important to talk to children and reassure them that their voices will return when the breathing tube (ET tube or tracheostomy) is removed.

Parents have many concerns relative to ET tubes and ventilators. Before intubation, the nurse should discuss with them the reasons for the decision to implement the therapy, the expected results, and the approximate length of time it will remain in place. Parents are often concerned about the (often) life-threatening implications generated by the need for the procedure and the possible long-term effects on the child, both physiologic and psychologic. They are also concerned about the long-term residual effects on the brain and on the child’s psychologic status. Parents who must face the possibility of caring for the child with a tracheostomy or a home ventilator have additional worries regarding their ability to assume this responsibility (see p. 1206).

For families whose child has had a respiratory arrest, support focuses on keeping the family informed of the child’s status and helping them cope with a near-death experience or an actual death. (See Chapter 23.) Knowing that their child requires CPR is a frightening and often overwhelming experience for parents. Uncertainty regarding outcome—both mortality and morbidity—is a primary concern. Traditionally family members have not been allowed to be present during resuscitation efforts (see Evidence-Based Practice box).

Nurses can serve as the family’s advocate by either being present with them or making certain a support person, such as a clergy member, is present. After the child’s recovery or death, the family needs continued support and thorough medical information regarding lifesaving measures, the prognosis if the child survives, and the cause of death if the child dies.

Resuscitation Procedure

The American Heart Association (2005) implemented several changes in CPR guidelines that incorporate the use of the automatic external defibrillator (AED) as part of the treatment of cardiorespiratory arrest in children 1 year of age and older. The 2005 guidelines state that AEDs can be safely and effectively used in children ages 1 to 8 years; however, there are insufficient data to support or refute the use of AEDs in children younger than 1 year old. Appropriate-sized pediatric pads must be used for small children. Health care providers are advised to give children 1 year and older a defibrillatory shock after providing approximately five cycles of CPR (approximately 2 minutes of cycles of 30 compressions and two ventilations by the lone rescuer), provided the AED is sensitive to pediatric rhythms, the device is capable of delivering a pediatric dosage of 2 joules/kg, and a shockable rhythm (usually ventricular fibrillation) is present. In a hospital situation, where weight-based defibrillation dosing is possible, manual defibrillation is the mode of choice instead of AED. When using an AED, health care providers are advised to give adults and children older than 8 years a defibrillatory shock within 5 minutes of collapse outside the hospital and within 3 minutes in the hospital.

Pediatric CPR

Changes in resuscitation procedure for the lay rescuer are discussed in the following section. The sequence of CPR steps for the health care provider is discussed in both the text and Fig. 31-20.

If two rescuers are present, one rescuer should begin CPR while the second rescuer activates the EMS system by calling 911 and obtaining an AED. Pediatric rescuers provide five cycles of basic life support (approximately 2 minutes) before activating EMS; each cycle consists of 30 chest compressions and two ventilations. Because pediatric arrests are most commonly caused by respiratory arrest, maintaining ventilation is primary.

• The child is unable to make any sounds.

• The cough becomes ineffective.

• There is increasing respiratory difficulty with stridor.

Infants

A combination of back blows (over the spine between the shoulder blades) and chest thrusts (on the sternum, in the same location as for chest compressions) is recommended to relieve the FB obstruction in infants (Fig. 31-26). Place a choking infant face down over the rescuer’s arm with the head supported and lower than the trunk. For additional support the rescuer should support the arm firmly against the thigh. Deliver up to five quick, sharp, back blows between the infant’s shoulder blades with the heel of the rescuer’s hand. Use less force than would be applied to an adult. After delivery of the back blows, place the free hand flat on the infant’s back so that the infant is “sandwiched” between the two hands, making certain the neck and chin are well supported. While maintaining support with the infant’s head lower than the trunk, turn the infant and place the infant supine on the rescuer’s thigh, and apply up to five quick downward chest thrusts in rapid succession in the same location as external chest compressions described for CPR. Continue back blows and chest thrusts until the object is removed or the infant becomes unconscious.

Children

A series of subdiaphragmatic abdominal thrusts (Heimlich maneuver) is recommended for children older than 1 year of age. The maneuver creates an artificial cough that forces air, and with it the FB, out of the airway. The procedure is carried out with the child in a standing, sitting, or lying position (Fig. 31-27). In the conscious choking child, upward thrusts are delivered to the upper abdomen with the fisted hand at a point just below the rib cage. To prevent damage to the internal organs, the rescuer’s hands should not touch the xiphoid process of the sternum or the lower margins of the ribs. Repeat up to five thrusts in rapid succession until the FB is expelled.

It is neither necessary nor desirable to squeeze or compress the arms during the procedure. It is not a punch or a bear hug. The child may vomit after relief of the obstruction and should be positioned to prevent aspiration. After breathing is restored, the child should receive medical attention and be assessed for complications.

The success of the technique is primarily a result of the obstruction occurring at the end of a maximum respiration. The victim is most likely to choke on food during inspiration; therefore the tidal volume plus expiratory reserve volume is present in the lungs. When pressure is exerted on the diaphragm by the maneuver, the food bolus is ejected with considerable force by this trapped air.

If the victim is breathing or resumes effective breathing after emergency interventions, place in the recovery position: move the head, shoulders, and torso simultaneously and turn onto the side. The leg not in contact with the ground may be bent and the knee moved forward to stabilize the victim (Fig. 31-28). Do not move the victim in any way if trauma is suspected, and do not place the child in the recovery position if rescue breathing or CPR is required.

• The major functions of the respiratory tract are to distribute air and exchange gases to supply cells with oxygen and to remove carbon dioxide.

• Several anatomic features predispose infants and young children to airway obstruction and atelectasis: they have less alveolar surface for gas exchange, narrowly branching peripheral airways become easily obstructed, and lack of collateral pathways inhibits ventilation beyond obstructed units.

• Gas exchange depends on the amount and composition of gases inhaled, thickness of the alveolar wall, adequacy of circulation to the alveoli, and substances within the alveoli that prevent their inflation or gas exchange.

• The amount of oxygen that diffuses into the blood depends on a pressure gradient between alveolar air and capillary blood, the total functional surface area of the alveolocapillary membrane, minute volume, and alveolar ventilation.

• Defense mechanisms of the respiratory tract include the lymphatic system, mucus secretions, ciliary action, epiglottis, cough reflex, tracheobronchial dynamics, body position changes, and humoral defenses.

• Complete assessment of respiratory function involves a detailed history, physical examination, pulmonary function tests, radiography, and blood gas determination.

• Pulse oximetry is a noninvasive method of determining the oxygen saturation in the blood. One limitation of the technology is that it does not identify dangerously high oxygen levels.

• Improvement in respiratory function may be accomplished with measures such as oxygen therapy, positioning, humidification, aerosol therapy, and artificial ventilation.

• Always humidify oxygen when administering it to children.

• CPT is useful for patients with increased sputum production but is contraindicated for some.

• Implications for possible intubation include airway obstruction, respiratory arrest, neuromuscular compromise or paralysis, and hypoxemia.

• Respiratory failure is the inability of the respiratory system to maintain adequate oxygenation of the blood, with or without carbon dioxide retention.

• Management of respiratory failure is to provide oxygen, maintain ventilation, apply appropriate therapy, and anticipate complications.

• ET and tracheostomy suctioning involves premeasured insertion of the catheter, application of suction for 3 or 4 seconds when withdrawing the catheter, and supplemental oxygen before and after suctioning.

• Occlusion of the ET and tracheostomy tube is life threatening; therefore equipment for replacing a tube must always be available.

• Pediatric CPR includes five cycles (about 2 minutes) of ventilations (two) and compressions (30) before summoning emergency help.

• Automatic external defibrillators are safe to use in children 1 year and older in an arrest situation where there is no pulse.

• Choking and respiratory failure are respiratory emergencies that require immediate intervention.

• Use abdominal thrusts in children in whom FB obstruction is witnessed or strongly suspected. Use a combination of back blows and chest thrusts for infants with FB obstruction.

• In a conscious choking child, make attempts to relieve the obstruction only if the child is unable to make any sounds, the cough becomes ineffective, or the child has increasing respiratory difficulty with stridor.