The heart

The heart is situated in the thorax, within the mediastinum (the space between the two lungs) with its base inclined to the left (Fig. 17.1). It is protected from injury by the bones forming the thoracic cage, the sternum (breastbone) in front, the ribs and the vertebral column behind.

Fig. 17.1 Position of the heart in the thorax

(reproduced with permission from Brooker & Nicol 2006)

The wall of the heart has three layers (Fig. 17.2), as follows:

Fig. 17.2 Heart showing the chambers, valves and blood vessels

(reproduced with permission from Waugh & Grant 2001)

The heart is divided into four chambers (see Fig. 17.2). The two upper chambers or atria are the receiving chambers that pump blood into the ventricles. The two lower chambers are thick-walled ventricles that pump blood to the lungs (pulmonary circulation) and to the tissues and cells (systemic circulation). The right and left sides of the heart are divided by the septum.

Valves situated at the entrance or exit of the chambers ensure that the blood flows in one direction. The two semilunar valves are the pulmonary valve at the junction of the right ventricle and pulmonary artery and the aortic valve at the junction of the left ventricle and the aorta. The atrioventricular (AV) valves between the atria and ventricles prevent any backflow of blood from the ventricles to the atria as the ventricles contract. The right AV valve (tricuspid valve) lies between the right atrium and ventricle and the left AV valve (bicuspid or mitral valve) lies between the left atrium and ventricle.

Coronary circulation

Three major arteries supply the myocardium with oxygen: the right coronary, the left anterior descending and the circumflex. They branch to form a dense network of arterioles and capillaries that extend throughout the myocardium and ensure that it is supplied with oxygen and metabolic waste products are removed. Once the myocardium has been supplied with oxygen, blood returns to the right atrium via the coronary veins and is transported to the lungs for carbon dioxide removal and reoxygenation. The coronary arteries primarily fill with blood during diastole when the heart muscle is relaxed.

Conduction

The electrical conduction system of the heart has four main structures (Fig. 17.3):

Fig. 17.3 Conduction pathways

(reproduced with permission from Brooker & Nicol 2003)

The sinus node is known as the ‘pacemaker’ of the heart because it initiates each heartbeat. It normally fires at a rate between 60 and 100 beats per minute (bpm). From the sinus node, the impulse passes to the AV node causing the atria to contract (atrial systole). From the AV node the impulse passes down the AV bundle in the septum to the right and left bundle branches and the Purkinje fibres. This causes the ventricles to contract (ventricular systole) and eject blood into the aorta and pulmonary artery.

Cardiac cycle

The cardiac cycle is the rhythmic contraction (systole) and relaxation (diastole) of the heart as it fills with blood and pumps it around the body and to the lungs. It comprises a series of stages that occur during a single heartbeat. Normally the whole cycle is completed in less than 1 second. Once one cycle is completed, the next cycle commences to maintain a continuous flow of blood.

The function of the cardiac cycle is to provide an adequate output of blood from the heart. The amount of blood that is ejected with each heartbeat is referred to as the stroke volume (SV), whereas the term cardiac output (CO) refers to the amount of blood ejected from the heart in 1 minute. Hence the equation:

Cardiac Output (CO) 5 Heart Rate (HR) 3 Stroke Volume (SV).

Sinus rhythm

Sinus rhythm is the normal rhythm of the heart. It produces a typical waveform comprising five deflections known universally as P-QRS-T (Fig. 17.4). The deflections depicted on an electrocardiogram (ECG) represent the electrical activity in the heart and correspond to the events of conduction and the stages of the cardiac cycle:

  Page 466 

• P wave – the first small dome-shaped deflection represents electrical activity through the atria and atrial contraction (atrial systole)

• QRS complex – the larger, narrower deflection represents contraction of the ventricles (ventricular systole)

• ST segment – the period during which the coronary arteries fill with blood

• T wave – the gently rounded deflection represents the resting period of the ventricles when they are relaxed (ventricular diastole).

Fig. 17.4 Sinus rhythm

(reproduced with permission from Brooker & Nicol 2003)

At rest the adult heart normally beats in response to the sinus node activity at approximately 70bpm. Sinus rhythm describes any heart rhythm where the complexes described above can be seen and that occurs at a rate between 60 and 100bpm. In adults, a HR rate <60bpm is referred to as sinus bradycardia, while a HR >100bpm is sinus tachycardia.

Systemic and pulmonary circulation

The systemic circulation is the circulation of oxygenated blood from the left ventricle into the aorta, to cells/tissues and deoxygenated blood back to the right atrium of the heart. The pulmonary circulation is the circulation of deoxygenated blood from the right ventricle to the pulmonary artery, to the lungs and oxygenated blood back to the left atrium of the heart.

Thus oxygenated blood returning from the lungs enters the left atrium and passes through the left AV valve into the left ventricle (see Fig. 17.2, p. 465). The left ventricle pumps blood into the systemic circulation through the aorta (large artery) and from there to numerous smaller arteries, arterioles and capillaries, which take blood to the rest of the body (Fig. 17.5). The coronary arteries supplying the myocardium are the first to branch from the aorta. The arterial blood supplies cells with oxygen and nutrients and returns, carrying carbon dioxide and other waste, to the right side of the heart via small veins (venules) and increasingly larger veins. Deoxygenated venous blood returns to the right atrium in two large veins – the superior and inferior venae cavae – and passes through the right AV valve into the right ventricle.

Fig. 17.5 The systemic and pulmonary circulation.

The right ventricle pumps blood into the pulmonary circulation through the pulmonary artery (see Fig. 17.5). The pulmonary artery divides to send a branch to each lung where further subdivisions occur and the blood moves through smaller and smaller arteries and arte-rioles until they reach the pulmonary capillaries. Gas exchange occurs between the blood in the capillaries and the air in the alveoli of the lungs (see p. 470); carbon dioxide moves from blood to the alveoli and oxygen from the alveoli to the blood.

The oxygenated blood is returned to the left atrium of the heart through venules and larger and larger veins that form four pulmonary veins (two from each lung).

An efficient pulmonary and systemic circulation ensures that the body tissues and organs are perfused with oxygenated blood and waste products are removed.

Plasma

Plasma is the straw-coloured fluid found when blood separates. In the vascular system, plasma provides a medium to carry blood cells. Plasma is between 90 and 92% water and dissolved nutrients, gases, electrolytes, hormones, drugs, waste products and proteins such as albumin, globulins and fibrinogen.

Blood cells

There are three types of blood cell: erythrocytes (red cells), leucocytes (white cells) and thrombocytes (platelets).

Haemostasis

Normally blood flows freely within the vascular system but when there is significant bleeding from a damaged blood vessel, the process of haemostasis normally prevents major blood loss.

Haemostasis involves four overlapping stages:

Blood groups

There are two major blood group classifications: the ABO system and the rhesus system.

The ABO system has four main blood groups – A, B, AB and O – which are defined by the presence of antigens (specific proteins) on the surface of the erythrocyte. People with antigen A are blood group A, those with antigen B are group B. People who have both A and B antigens are blood group AB and those without either antigen are group O.

Someone with blood group A will have anti-B antibodies in their plasma, someone with blood group B will have anti-A antibodies, people with blood group O will have both anti-A and B antibodies while someone with blood group AB will have no antibodies. These antibodies will bind to a foreign antigen and initiate a reaction that destroys the cell such as occurs if incompatible blood is transfused (Bywater & Rawlings 2003) (see p. 498).

It is important to be aware of the different blood groups in order to ensure that when blood is transfused, blood from the correct group is given to the correct person. Table 17.1 outlines the ABO blood group compatibility.

Table 17.1 ABO blood group compatibility (reproduced with permission from Brooker & Nicol 2003)

The rhesus group is determined by a further set of antigens on the erythrocyte. People who have the antigens are rhesus positive (Rh[D]-positive) and those without are rhesus negative (Rh[D]-negative). Unlike the ABO system there are no preformed anti-rhesus (anti-D) antibodies. However, if a rhesus negative person receives rhesus positive blood they will develop anti-D. Although this will not cause a transfusion reaction at the time, any future transfusion will initiate a reaction and the donor erythrocytes will be attacked.

During pregnancy a rhesus negative woman who has a rhesus positive fetus may become sensitized and develop anti-D antibodies. During a subsequent pregnancy with a rhesus positive fetus the anti-D antibodies can cross the placenta and cause haemolysis (breakdown) of the fetal erythrocytes. This is a serious condition and can lead to fetal death or the baby may suffer brain damage or die after birth. Women are tested for rhesus group during antenatal care. Anti-D is given to rhesus negative women to prevent the sensitization of the immune system. It is given by injection following events that may lead to sensitization such as bleeding during pregnancy, miscarriage, termination and labour.

Respiratory structures

The respiratory structures (Fig. 17.6) include:

Fig. 17.6 The respiratory structures

(reproduced with permission from Brooker and Nicol 2003)

Bronchi, bronchioles and alveoli

The processes of humidification and warming in the upper respiratory tract are complete, air is saturated with water and warmed to 37°C and most foreign particles have been removed before it enters the bronchi.

  Page 470 

Once the right and left main bronchi enter the lungs they divide into smaller and smaller bronchi, bronchioles and finally the tiny alveolar ducts that lead into the alveoli. The larger bronchi are lined with respiratory mucosa and the walls are supported by rings of cartilage and so remain open throughout the respiratory cycle (inspiration and expiration). As the bronchi become smaller they lose the cartilage and the lining gradually changes to non-ciliated epithelium. Further changes occur as the walls become thinner until a single layer of simple epithelium remains in the alveolar ducts and alveoli. This structural adaptation facilitates gaseous exchange.

The alveoli are very small air sacs clustered together and surrounded by a network of pulmonary capillaries. Special cells in the walls of the alveoli secrete surfactant (phospholipid fluid) which ensures a moist membrane needed for gaseous exchange. Surfactant also reduces surface tension and prevents alveolar collapse between breaths. Surfactant starts to be secreted by about 22 weeks’ gestation and there is a rapid increase around 35 weeks’ gestation (MacGregor 2000). Hence in the preterm infant, surfactant production may be insufficient to maintain patency of the alveoli and lead to respiratory distress (see p. 483).

Oxygen diffuses from the alveolar air, across the very thin layer of cells, the respiratory and capillary membranes into capillary blood (Fig. 17.7). Carbon dioxide leaves the blood and diffuses across the two membranes into the alveoli. The carbon dioxide is excreted during expiration.

Fig. 17.7 Gas exchange between alveolus and pulmonary capillary

(reproduced with permission from Brooker and Nicol 2003)

For efficient gaseous exchange to occur there must be both adequate ventilation of the lungs and good perfusion with blood. In other words, if the lungs expand and fill with air, this will only lead to effective breathing; there also needs to be good supply of blood to the alveoli for the exchange of oxygen and carbon dioxide.

Breathing (ventilation)

Breathing is the mechanical process by which air moves in and out of the lungs. There are two processes: inspiration, which requires energy and is active, and expiration, which is passive. Expiration is followed by a short pause before the next inspiration. In a normal respiratory cycle (at rest), the amount of air inhaled and exhaled is normally around 500 mL in an adult. This is known as the tidal volume (TV).

During inspiration the capacity of the thoracic cavity is increased as the diaphragm (muscle between the thorax and the abdomen) and intercostal muscles (between the ribs) contract. The lungs are stretched, the pressure within the lungs falls and air moves into the lungs in order to equalize the atmospheric and alveolar air pressures.

During expiration, the relaxation of the diaphragm and intercostal muscles leads to an inward and downward movement of the thoracic cage and elastic recoil of the lungs. The pressure in the lungs is greater than atmospheric air and air moves out.

Normal, unlaboured breathing depends on several factors. These include:

Adult basic life support

An adult is defined as a person who has reached puberty for the purpose of providing BLS. If the casualty is outside hospital an emergency ambulance must be summoned by dialling 999 (see below). If the cardiopulmonary arrest has occurred in hospital the nurse should know the internal ‘crash call’ telephone number for summoning the cardiac arrest team. The National Patient Safety Agency (NPSA) (2004) advised all NHS Trusts in England and Wales to standardize the internal crash call telephone number to 2222. At the time of writing the vast majority of acute Trusts now use 2222 but until all Trusts have converted, individual hospitals may have a different number and all staff should be aware of it.

When initially faced with an adult whom you suspect has experienced a cardiopulmonary arrest, the following procedure should be started immediately:

Fig. 17.8 Opening the airway: A. Head tilt/chin lift – adult. B. Jaw thrust – adult. C. Head tilt/chin lift – child

(reproduced from Mallik et al 1998 and Huband & Trigg 2000)

Fig. 17.17 Oxygen delivery systems: A. Fixed performance, high-flow Venturi system mask. B. Variable flow – Hudson-type mask. C. Nasal cannulae/prongs. D. Delivery of humidified oxygen via a head box

(reproduced with permission from Brooker & Nicol 2003; Nicol et al 2004; Huband & Trigg 2000)

Fig. 17.9 Chest compression: A. Adult. B. Child. C. Infant

Fig. 17.10 Rescue breaths: A. Adult. B. Child. C. Infant

Fig. 17.11 Recording peak expiratory flow rate

(reproduced with permission from Brooker & Nicol 2003)

(Resuscitation Council (UK) 2005).

Basic life support for infants and children

A child is defined as a person aged 1 year and up to the age of puberty and an infant as being less than 12 months old for the provision of BLS. The differences between BLS for children and infants and that for adults (see above) are outlined in Box 17.8 (p. 478).

Skin – general assessment

Assessment of the skin is quick and easy yet provides useful information about both breathing and circulation. Nurses should take every opportunity to assess a person’s skin, e.g. while helping them with personal hygiene. More information about skin condition and assessment is provided in Chapters 16 and 25.

In health the skin should be warm, dry, intact and normal colour for racial group. However, with normal ageing the skin becomes drier and loses its natural elasticity. In people with either very pale or dark skin it may be difficult to notice abnormalities such as pallor or a bluish hue (cyanosis). This explains why it is important to also look at the mucosae, e.g. inside the mouth or the conjunctiva inside the lower eyelid, which in health should be pink and moist.

Changes in skin colour

The colour of the skin including the nail beds and the lips and the mucosae can provide valuable information:

Skin turgor and oedema

Assessment of the skin should include turgor and the presence of oedema. Turgor indicates the elasticity of the skin and although this decreases with age, skin turgor may be useful in a holistic assessment of hydration status. Reduced turgor may be an early sign of dehydration (see Ch. 19).

To assess skin turgor, a fold of skin, usually on the back of the hand, is lifted. Once released, it should quickly return to its original position. However, because skin loses its elasticity with age it will not return to its original position so quickly in older people.

Oedema is an abnormal accumulation of tissue fluid between the cells (see Ch. 19). It usually collects in dependent regions such as the legs, ankles/feet or sacral area. For example, if someone spends much of the day sitting in a chair, fluid will collect in the sacral area and ankles. This is partly due to immobility and lack of normal contraction of the calf muscles. Normally muscle contraction squeezes the veins and helps to maintain the return of venous blood to the heart (see Ch. 25). However, dependent oedema is also compounded by gravity, which allows fluid to collect in these areas. Oedema may be seen in people with the following conditions:

However, swollen ankles with some oedema may be found when standing still in hot weather or during pregnancy and are not necessarily a sign of ill health.

The term ‘pitting’ is used to describe oedema that remains indented or pitted when lightly pressed. This is frequently a sign of more severe oedema.

Oedema is not usually visible until the body has retained at least 4L of fluid, which is equivalent to approximately 4 kg of weight gain. An accurate way to record fluid balance is through daily weighing and people with heart failure who are prone to fluid retention, for example, are frequently asked to record their weight daily.

Capillary refill time

Capillary refill time is useful for assessing skin perfusion (amount of blood passing through the skin) and cardiac output. Although peripheral areas such as the nail bed may be used, central areas such as the sternum are more useful in people with a poor cardiac output and poor peripheral circulation. To test capillary refill time, two fingers are lightly pressed into the area for a period of 5 seconds. On release, the skin colour should return to normal within 2 seconds. If it takes longer for the skin colour to return, capillary refill time is prolonged and it is likely that the person has a low cardiac output.

Heart/pulse rate

When blood is pumped from the heart there is rhythmic expansion and recoil of the arteries in the vascular system. Wherever an artery is near the skin surface this ejection of blood will cause a pulse, which can be felt when the artery is gently pressed against a bony prominence. In adults and older children this is commonly felt at the wrist where the radial artery crosses the forearm bone, the radius (see Ch. 14). In babies aged less than 6 months HR is determined by using a stethoscope to count the apex beat of the heart (see Ch. 14).

The pulse rate should be easily palpated and is a useful measure of the function of the cardiovascular system. The pulse should reflect the HR and varies with age. It is normally between 60 and 80bpm in adolescents and adults at rest, although up to 100bpm is considered normal. In the neonate the HR is faster and is usually between 120 and 160bpm depending on whether the baby is active, crying, resting or asleep. The HR slows during infancy and childhood to reach adult levels during adolescence (see Ch. 14).

Box 17.9 outlines some situations and disorders in which HR is faster or slower than normal.

A weak and thready pulse is frequently faster than normal and is found in dehydration (see Ch. 19), hypovolaemia or heart failure. A pulse that feels strong and bounding is also frequently fast and may indicate pyrexia, anxiety or hypervolaemia (high blood volume).

When a pulse is noted to be irregular, it should be reported and documented in the nursing notes and on the appropriate charts. Many heart diseases, such as atrial fibrillation (AF), cause an irregular pulse rate and commonly occur in older people. Further investigations should be undertaken an apex–radial pulse should be recorded and an ECG performed.

Apex and radial

Sometimes the radial pulse rate is not the same as the HR (pulse deficit). This can happen if the heart rhythm is abnormal. A disturbance in heart rhythm is called an arrhythmia, e.g. AF where the atria beat very rapidly but only some of the beats lead to a pulse. In these situations the pulse is likely to be irregular and a simultaneous recording of the apex beat and the radial pulse rate is useful (Box 17.10).

Peripheral pulses

Pulses are found wherever a blood vessel lies close to the skin surface. The radial pulse has been described above (see p. 479). Other peripheral pulses (see Fig. 14.10, p. 378) are assessed in a variety of specific situations. Peripheral pulses indicate the flow of blood to the peripheries and how well the heart is functioning. Additionally, they provide information on the state of the individual blood vessels, e.g. checking for the presence of the pedal pulse (dorsalis pedis) in the foot when a person has a sus-pected blockage in the arteries supplying the leg, or following surgery to clear a blockage (see Ch. 14 for further information).

The electrocardiogram

The ECG waveform depicts the electrical activity of the heart (see p. 466 and Fig. 17.4). It is used to detect arrhythmias and heart diseases such as myocardial infarction. Readers requiring more information about ECG should consult Further reading suggestions.

Blood pressure

Blood pressure (BP) is the pressure exerted upon the wall of the arteries by the circulating blood. It is a useful, non-invasive measurement, widely used in patient assessment (see Ch. 14). BP is usually measured indirectly using a sphygmomanometer (usually aneroid) or an electronic device. Mercury sphygmomanometers are being replaced as a safety measure because of the toxicity of mercury. BP is a routine aspect of health assessment in adults and at prescribed intervals for monitoring condition, e.g. after surgery or for hypertension. BP is less frequently recorded as part of assessment in children; however, in some cases BP can indicate the presence of congenital heart disease or kidney disease.

BP has two measurements and is measured in millimetres of mercury pressure (mmHg). The two measurements reflect different stages of the cardiac cycle (see p. 465): the upper reading, the systolic pressure, when the heart contracts (systole) and the lower reading, the diastolic pressure, when the heart is relaxed (diastole). As the heart contracts, blood is pumped from the left ventricle into the aorta and systemic arteries and this is recorded as the systolic BP. Following ventricular ejection, blood moves along the arteries, and the elastic vessel walls start to recoil. This is then recorded as the diastolic BP (see Ch. 14 for details of measuring BP).

The normal BP range varies with age: in adults the optimum BP is <120 systolic and <80 diastolic, and a normal BP is described as <130/,85 mmHg (Williams et al 2004). In the neonate, BP is normally between 60 and 85 systolic/20 and 60 diastolic mmHg (see Ch. 14).

In addition, there are many factors that normally influence BP throughout a 24-hour period (see Ch. 14). These include:

A sustained increase in BP is termed hypertension and in adults this is defined as a BP over 140/90 mmHg. For example, Grade 1 (mild) hypertension is systolic pressure between 140 and 159 mmHg and diastolic pressure between 90 and 99 mmHg (Williams et al 2004). BP tends to increase with age in developed countries. Lifestyle factors contributing to hypertension are outlined in Box 17.11.

Hypertension is a serious condition and leads to many problems, e.g. CHD, heart failure, strokes, kidney damage and retinal changes. The BP is recorded on three separate occasions before treatment is commenced for hypertension. This is because there are several factors that may lead to inaccuracies in blood pressure readings in addition to ‘white coat’ hypertension where the anticipation of having BP recorded causes it to increase. Box 17.12 outlines some interventions to ensure the accuracy of BP measurement and recording.

A low blood pressure that is insufficient to maintain tissue blood flow and oxygenation is termed hypotension. It may be caused by:

Hypotension may lead to feelings of dizziness or even fainting (syncope) because insufficient blood and hence oxygen reaches the brain. Fainting can also be caused by other factors. These include:

The first aid for fainting is outlined in Box 17.14.

Central venous pressure

Central venous pressure (CVP) records the pressure in the central venous system or the right atrium of the heart and is a useful measurement to assess fluid status. A catheter is inserted into a large central vein, usually the internal jugular or subclavian vein, and attached to a monitoring device. Frequently a pressure transducer monitors and records the pressure in mm of mercury (mmHg). Occasionally a water column is used, in which case the measurement is recorded in centimetres of water (cmH₂O). Central venous pressure is measured in the acutely ill and as such is frequently seen in intensive care or high dependency units. However, central venous pressures may also be measured in the patient on the general ward and so it is useful to have some idea of the importance of this measurement.

Breathing – general assessment

The assessment of breathing includes respiratory rate, depth and rhythm and assessment of the function of the lungs. Normal breathing at rest is silent, even and regular and is the unconscious active inspiration of air followed by passive expiration. However, both inspiration and expiration may become active with the person forcing air in or out of the lungs. Active breathing usually uses accessory muscles of breathing, the abdominal muscles and the muscles of the neck and shoulders. The use of the accessory muscles occurs in normal deep breathing and is also frequently seen in a person with breathing difficulties (see p. 483).

Respiratory rate

The respiratory rate should be recorded as one of the first observations in all general assessments and is referred to in greater depth in Chapter 14. In addition, the respiratory rate should be recorded as part of ongoing monitoring of vital signs, as ‘respiratory rate is a significant predictor of critical illness’ (Butler-Williams et al 2005, p. 35). When counting the respiratory rate, breathing should be observed for a 60-second period, with the person at rest. It is also a useful idea to count the respiratory rate without the person being aware and inadvertently altering their breathing rate.

The normal respiratory rate varies with age. The normal adult respiratory rate at rest is usually between 12 and 15 breaths per minute, while it is normal for a neonate to breathe at 30–60 breaths per minute (see Ch. 14).

A respiratory rate that is faster than that expected for age (tachypnoea) is normal when caused by:

Disorders of breathing and circulation that cause tachypnoea may include:

A respiratory rate that is slower then expected for age (bradypnoea) is normal when the person is sleeping; however, it is abnormal when caused by:

Breathing patterns – depth and rhythm

The breathing pattern should be assessed while counting the respiratory rate. When assessing breathing patterns the nurse should observe features that include:

Abnormal breath sounds

Normal breathing is silent. Any noise that occurs during breathing is therefore abnormal. The noise may occur either during inspiration or expiration. Abnormal sounds include:

Cough and sputum

In health, regular deep breathing and ciliary action remove normal secretions and inhaled foreign particles. Secretions are generally swallowed but may be coughed up (expectorated). However, when these mechanisms are ineffective or there is an increase in mucus secretion or foreign particles, the cough becomes essential (Jones & Moffat 2002). A cough is the sudden and rapid expulsion of air from the lungs. Coughing may be voluntary or it may be an involuntary cough reflex. The cough reflex is part of the protective mechanisms that protect the airway from foreign bodies that either irritate or may obstruct the airway. The cough reflex occurs, for example, when food or fluid goes the ‘wrong way’.

Choking occurs when there is a partial blockage to the upper airway. The person will be anxious, have difficulty breathing and may start coughing. This may dislodge the foreign body but, if not, urgent treatment may be necessary to prevent asphyxia. This is characterized by severe hypoxia leading to hypoxaemia (reduced oxygen content in arterial blood) and hypercapnia (increased carbon dioxide in arterial blood). Unconsciousness occurs and eventually death without effective treatment. Choking has a number of causes but usually occurs when a foreign body, e.g. food such as peanuts, small toys or pieces of toys, loose tooth, pen top, etc., is inhaled.

The first aid treatment for an adult who is choking is outlined in Box 17.17. The first aid procedures for choking in infants and children differ from those in adults and readers are advised to consult Further reading (e.g. Mohun et al 2002). Obviously it is preferable to prevent choking in the first place by identifying the risks and excluding them whenever possible, such as by choosing toys suitable for a child’s age (Box 17.18).

A cough may be described as dry or productive. Coughing may be associated with pain in some chest conditions and following chest or abdominal surgery (see Ch. 24). Prolonged coughing can cause muscle pain and may deter patients from coughing. The nurse should assess levels of pain and ensure that effective pain relief is provided (see Ch. 23).

A dry cough is one that develops without the presence of excess secretions. The cough could result from an irritant in the upper airway such as smoke or cold air and sometimes develops into a ‘tickly’ cough. Some forms of medication cause a dry cough, e.g. some heart medication such as angiotensin-converting enzyme (ACE) inhibitors. A constant dry cough is frequently a nuisance to the person and may result in them stopping their medication if they think this is the likely cause. For this reason it is important to listen to the patient’s complaints and inform the prescriber so that medication can be reviewed.

A productive cough is one where excess mucus or sputum (‘phlegm’) is present in the respiratory tract. When the airways are inflamed, as occurs during an infection, there is an excessive secretion of mucus, which then accumulates in the airways. The mucus is usually expectorated by coughing. A productive cough may also be found where ciliary action is ineffective. Smoking is known to damage the cilia, and is responsible for the so called ‘smokers cough’.

The nurse should observe the colour, consistency, quantity and odour of any sputum produced during coughing and record this information in the nursing notes and charts (Box 17.19). Any changes should be reported to the person in charge.

A specimen of sputum will be sent to the laboratory for microscopy, culture and sensitivity if infection is suspected (see Ch. 15). Box 17.20 (p. 486) outlines the safe and effective collection of a sputum specimen. If the patient is unable to expectorate a specimen may be obtained during nasopharyngeal/tracheal suctioning (see pp. 490–491) by using a sputum trap.

Peak expiratory flow rate

The peak expiratory flow rate (PEFR) is the greatest rate of airflow out of the lungs and is measured in litres per minute (L/min) during a forced expiration. The normal range for PEFR depends on age, height and gender. It is an important measure of lung function and is frequently used as a guide to monitor the progress of a condition such as asthma or the person’s response to their medication. A Wright or mini-Wright peak flow meter is used to measure PEFR (Box 17.21).

Pulse oximetry

Pulse oximetry is used to measure the percentage of saturated haemoglobin in the arterial blood and gives a useful indication of the amount of oxygen in the peripheral blood. Oxygen saturation monitoring is frequently undertaken, either continuously or as a periodic measurement. The normal oxygen saturation range is 94–98%.

The measurement is performed with a non-invasive pulse oximeter, a device comprising a probe connected to a monitor (Fig. 17.12). The probe should be placed where it is in close contact with the blood such as the nail bed or ear lobe. The pulse oximeter measures and displays the peripheral capillary saturation of haemoglobin (SpO₂) (Allen 2004). Pulse oximetry has limitations and results must be interpreted carefully (Box 17.22).

Fig. 17.12 Pulse oximeter and probe

(reproduced with permission from Nicol et al 2004)

Arterial blood gas analysis, an invasive procedure, may be used in critically ill people to directly measure the amount of oxygen and carbon dioxide in the blood and other parameters that include blood pH (see Ch. 19).

Pain associated with breathing or circulation problems

Pain is abnormal and, if present, may indicate circulatory or breathing problems. It can be caused by a variety of conditions and may be either cardiac or non-cardiac in origin. As with any pain, it is important for the care team to identify the cause so that appropriate pain relief and management can be planned (see Ch. 23).

The following points should be considered when assessing the person with pain associated with breathing or circulation problems:

It is important, however, to remember that it is not always easy to ascertain answers to questions about levels and sites of pain. People with a learning difficulty or speech problems can find it difficult to describe pain or its location, while a child’s response to pain is linked to their developmental stage (see Ch. 23).

Breathing exercises and coughing

Secretions can be moved and expectorated by deep breathing exercises and coughing. The patient should be encouraged to increase their fluid intake so that they can more easily expectorate the secretions. It is important to provide the patient with clean sputum cartons with lids as required and mouth washes/teeth cleaning facilities after expectoration. A specimen of sputum may be requested (see Box 17.20, p. 486). The nurse should advise the patient to avoid swallowing secretions, as this can lead to nausea.

Patients with chest infections or those who are susceptible to an infection, e.g. postoperatively or with rib fractures, should be encouraged to breathe deeply at intervals. The nurse must ensure that effective analgesics are administered to allow this without pain. Deep breathing with expansion of both lung bases is easiest with the spine straight. This is either in the upright sitting position or with the back straight when lying flat. This will expand the lung bases and facilitate gaseous exchange and clearance of basal secretions.

Breathlessness is extremely frightening and breathing exercises may control and help the person restore their normal breathing pattern during an attack of breathlessness or following a bout of coughing. Usually the patient will find these exercises easier if they are in a half side-lying position. They should be encouraged to breathe out gently while relaxing their shoulders and upper chest. When breathing in, this should also be gentle, and they should feel their lower ribs and upper abdomen expand. They should be encouraged to breathe gently, with minimal effort. Patients prone to panic attacks and attacks of breathlessness should be encouraged to practise this technique.

‘Huffing’ and coughing are useful techniques to help expectorate secretions. Huffing is thought to be less tiring than coughing and so it is useful to teach this to someone with chronic respiratory disease (Box 17.26).

Postural drainage

Sometimes postural drainage is needed to remove secretions, particularly in patients with chronic respiratory disease. In these circumstances the person lies in bed with the foot of the bed elevated. Gravity then assists the movement of secretions from areas of the lungs. Alternatively, the patient can lie on their side with pillows placed under their waist to gently tip their head down. The physiotherapist will modify the patient’s position to drain secretions from particular lobes or lung segments.

In small children with bronchiectasis or cystic fibrosis, a parent or carer may perform postural drainage.

Suctioning

In some circumstances it may be necessary to use suction to remove secretions from the airway. This is more likely when there is an artificial airway such as an endotracheal tube (a plastic tube introduced through the mouth or nose into the trachea to secure or maintain the airway) or tracheostomy tube (Fig. 17.14 and Box 17.27), the person is sedated or unconscious, when there is a poor cough reflex as may occur following a stroke or head injury, or when the patient is too weak to expectorate.

Fig. 17.14 Tracheostomy tube

(adapted with permission from Brooker & Nicol 2003)

Suctioning should only be undertaken by someone who is competent to do so. The nurse should therefore have been taught how to undertake the procedure and observed in order to confirm competence. Patients and parents can also be taught how to perform suctioning when long-term assistance with clearing of secretions is required, e.g. a child or adult discharged home on home ventilation (see pp. 495–496).

Suctioning should be performed as a clean procedure. The nurse should wash their hands and protect themselves from infection by wearing a clean (not necessarily sterile) glove on both hands, plastic apron and eye protection if necessary.

Readers can find more information about suctioning in Further reading suggestions (e.g. Nicol et al 2004, Higgins 2005).

Nebulizers (Fig. 17.15A, p. 492)

A nebulizer can be used to administer medication or to liquefy secretions with 0.9% saline solution. The drug is inhaled and is rapidly absorbed through the alveolar blood supply. It therefore acts quickly and side-effects associated with oral intake are avoided. Most nebulizers require a flow of gas and will be administered either with compressed air or oxygen. The nebulizer breaks up the solution so that it is inhaled as small droplets suspended in a gas. The use of a nebulizer is outlined in Box 17.28 (p. 492).

Fig. 17.15 A. Nebulizer

(reproduced with permission from Nicol et al 2004). B. Metered-dose inhaler. C. Inhaler with spacer attached

Dry powder inhalers

A dry powder inhaler releases medication as the person breathes in. The patient places their mouth around the device and breathes in. The flow generated by their breath releases the medication into particles that can be inhaled. These inhalers are easy to carry around and are therefore convenient to use at work, at home, in the car or at school.

The nurse should ensure that patients are able to use their inhaler effectively. Inhaler technique should always be checked by the practice nurse or general practitioner or before hospital discharge and on a regular basis in clinic.

Metered-dose inhalers (Fig. 17.15B, p. 492)

These are also available for inhaled medication and are frequently used by people with asthma. The inhaler is designed to deliver a dry powder and the medication, which is forced into the lungs.

Before use the inhaler is shaken to distribute the powder evenly within the gas. The cap is removed and the inhaler is held upright. To be effective, the patient should breathe out gently and then place their mouth around the mouthpiece of the inhaler. As they start to breathe in, the canister top should be pressed to release the medication. The breath should be slow and deep, and held for approximately 10 seconds. Usually the prescribed dose is for more than one ‘puff’ in which case the subsequent doses should be taken after approximately 30 seconds.

Using the inhaler requires a degree of coordination and may therefore not be suitable for children, some people with learning disabilities, some older people or those with poor dexterity (Box 17.29, p. 493). Spacer devices are available which are easier to use (Fig. 17.15C, p. 492). They comprise a large and, usually, cone-shaped device, onto which the inhaler is fitted and are thought to be effective when used with regular breathing.

Problems associated with oxygen therapy

There are various physical, psychological and social problems associated with oxygen therapy, many of which are similar to those experienced by patients who are breath-less (see pp. 488–490) (Box 17.30). The problems include:

Oxygen administration systems

Oxygen is supplied via a piped system in hospitals or in standard colour-coded cylinders (black with a white top) in the community and occasionally in hospital (Fig. 17.16, p. 494).

Fig. 17.16 Oxygen cylinder

(reproduced with permission from Nicol et al 2004)

Oxygen can be administered in a variety of ways (Fig. 17.17, p. 494), including:

The administration method chosen will depend upon age, the reason for administration, whether it is short or long term and where possible the patient’s preferences. For example, a young child or baby may not tolerate an oxygen mask and so a headbox or incubator may be used.

Oxygen may be given as a short-term treatment, e.g. postoperatively. However, long-term oxygen therapy (LTOT) may be needed for a patient with COPD, and arrangements must be made for oxygen therapy to be supplied at home (Box 17.31, p. 494).

Humidification

Water vapour is present in atmospheric air to a greater or lesser extent and so when breathing atmospheric air humidification is dependent upon the environmental humidity. Normal air humidity is between 40 and 60% and depends on temperature. Further water vapour is normally added to inspired air as it passes through the upper airways (see pp. 468–469). However, humidification of inspired air is impaired in situations that include:

Various hot- and cold-water devices are available for the humidification of inspired air and one such device is shown in Figure 17.18 (p. 496).

Fig. 17.18 Humidification of oxygen

(reproduced with permission from Brooker & Nicol 2003)

Non-invasive intermittent positive pressure ventilation

Artificial ventilation can also be delivered using non-invasive intermittent positive pressure ventilation (NIPPV), also known as non-invasive ventilation (NIV). A mask is used to avoid the need for an endotracheal tube or tracheostomy.

A mask covers the mouth and/or nose and is attached to a mechanical ventilator that pushes oxygen into the lungs. It is useful in nocturnal hypoventilation, a syndrome related to sleep apnoea (see Ch. 10). It is also used in severe muscle fatigue, neuromuscular weakness, COPD and in severe heart failure. NIPPV may be used almost continuously or on a sporadic basis for someone who only requires support at night. It is therefore increasingly used at home for both adults and children who require longer-term assistance with breathing while living at home. However, if this is to be effective it is essential that not only do the family receive accurate information beforehand, but they also receive adequate support. People on home ventilation understandably worry that they may suffer equipment failure and back-up systems and emergency plans should be decided upon in advance.

Although NIPPV can enable the person to live at home, travel and stay with friends, the device is heavy and awkward to move. It is frequently noisy to use and this may be a significant problem when cohabiting couples share a bed.

Monitoring during blood transfusion

Prior to commencing a blood transfusion it is important to obtain baseline recordings of temperature, pulse rate, blood pressure and respiration rate. These should then be repeated according to local policy during the transfusion, e.g. recorded every 15 minutes for the first hour and thereafter recorded hourly if the person is well and shows no adverse effects until the unit of blood is transfused. However, when more than one unit of blood is given, the observations should be recommenced at 15 minute intervals with each new unit of blood. The early signs of a transfusion reaction, including fever and rigors, should be observed. If a severe reaction occurs, BLS (see pp. 473–478) may be required.

Fluid balance is monitored and recorded and this includes recording the volume of blood transfused. It is generally assumed that a unit of whole blood is 500 mL and a unit of packed red cells is 300 mL. For more accurate recording of fluid volume, the unit of blood should be weighed. Grams of weight approximate to millilitres of volume, i.e. a unit of blood weighing 490 g is recorded as 490 mL.

When monitoring fluid balance (see Ch. 19) it is also important to record urine output. If a transfusion reaction occurs the donor erythrocytes agglutinate and can cause kidney damage. If the patient complains of loin or back pain, a sample of urine should be observed and tested for haematuria (blood in the urine).

Fluid balance is of particular importance in older people, the very young or those with cardiac or respiratory failure, when circulatory overload may lead to hypertension and pulmonary oedema. This is characterized by increasing respiratory rate, dyspnoea and agitation.

Documentation is important. All observations should be clearly recorded. In addition, the start and finish times of each unit of blood should be documented.

Ensuring transfusion safety

Due to the danger associated with the transfusion of incorrect or incompatible blood and other complications, hospitals and community settings have their own strict blood transfusion policy that must be observed. Although blood should be administered at room temperature it should be removed from the blood bank fridge no more than 30 min/1 hour before transfusion, and, preferably, only 15 minutes prior. The local policy regarding the checking procedure on removal from the blood bank and prior to commencing the transfusion, including patient identification, must be undertaken and a qualified nurse should always take responsibility for this procedure.

The safe disposal of equipment is essential. Gloves should be worn when handling blood or intravenous administration sets to protect staff from blood-borne diseases (see Ch. 15).

When completed, the transfused blood packs should be returned to the laboratory if a transfusion reaction is suspected. Otherwise, the disposal of blood bags should be in accordance with the local policy. Due to concerns over vCJD, any blood products or blood waste must be incinerated.

Transfusion complications

Complications associated with blood transfusion include:

Readers requiring more information about complications should consult Further reading (e.g. Bywater & Rawlings 2003).

Alternatives to donated blood transfusion

Apart from blood conservation through minimizing loss, the alternatives to the transfusion of donor blood include: