Special Techniques

• Local anesthetics are not general anesthetics. The term general anesthetic is reserved for those drugs such as inhalation anesthetics, propofol, ketamine, or barbiturates that primarily affect neurons in the brain. Like general anesthetics, local anesthetics exert their effect on neurons, but the target is the peripheral nervous system and spinal cord. Because local anesthetics normally do not affect the brain, they have no sedative effect. The patient remains fully conscious unless other agents such as tranquilizers, neuroleptanalgesics, or general anesthetics are used.

• If the appropriate dose and route of administration are used, local anesthetics have relatively few effects on the cardiovascular or respiratory systems. In contrast, preanesthetics and general anesthetics may have significant cardiovascular and respiratory effects. For this reason, local anesthesia may be preferable to general anesthesia in certain high-risk patients. However, local anesthetics are not without risk of toxicity, and the anesthetist should use caution to avoid overdosage, especially in small patients.

• Whereas general anesthetics are widely distributed throughout the body, local anesthetics primarily exert their effects in the area closest to the site of injection. Effective use of local anesthetics requires precise placement of the drug immediately adjacent to the target nerve. The veterinarian or technician performing the procedure must be familiar with the technique involved for each type of nerve block. For example, it is possible to block the sensory nerve of a tooth in a dog to perform a dental procedure; however, accurate and detailed knowledge of the neuroanatomy of the oral cavity is necessary. Local anesthetics are relatively ineffective in areas where drug diffusion is impeded by fat, bone, cartilage, fascia, tendon, and other connective tissues, as well as the presence of inflammation and infection.

• Unlike general anesthetics, local anesthetics are not normally transferred across the placenta to the fetus. For this reason, local anesthesia is used for cesarean sections and obstetric manipulations, particularly in ruminants, and also in small animal patients when general anesthesia is considered high risk.

Topical Use

Local anesthetics such as lidocaine are usually ineffective when applied directly to intact skin because the drug molecules are unable to penetrate the epidermis and reach the dermis, where the peripheral nerves are located. However, local anesthetics can be used for topical analgesia in some clinical situations:

Although topical anesthetics are useful in some situations, they generally offer less pain relief and shorter duration of effect than local anesthetics given by infiltration. Lidocaine patches are available that are applied to the skin and are effective for management of wound or incisional pain.

Infiltration

Local anesthetics may be infiltrated (injected) into tissues, preferably in proximity to the target nerve. The local anesthetic can be given intradermally, subcutaneously, or between muscle planes. Infiltration techniques are used to provide analgesia for surgery involving superficial tissues, including skin biopsies, removal of small skin tumors, and repair of minor lacerations.

The procedure used for infiltration of local anesthetics is relatively simple. The area must be clipped and a skin antiseptic applied in a manner similar to surgical preparation. This prevents inadvertent contamination of the tissues with skin bacteria when the local anesthetic is injected. A small needle (23 or 25 gauge in small animal and equine patients, 20 or 22 gauge in ruminants) is often used to prevent tissue damage and allow for more precise placement of the drug. The amount of the drug to be injected varies with the location and procedure used and may be as little as 0.1 mL or as much as several milliliters in a dog, or several to tens of milliliters in large animal patients. The onset of analgesia is usually 3 to 5 minutes after the injection of lidocaine.

Before surgery commences it is advisable to test the effectiveness of the block by gently pricking the skin with a 22-gauge needle. If sensation is still present, the anesthetist should wait several minutes longer and consider repeating the injection or using another anesthetic protocol if the block does not take effect.

The infiltration of local anesthetics is not universally effective. Deep tissues such as muscles are unlikely to be affected when only superficial neurons are blocked. In addition, obstacles such as scar tissue or fibrous tissue, fat, edema, and hemorrhage impede diffusion of local anesthetic. Local anesthetics are also relatively ineffective when injected into inflamed or infected areas. In areas of active inflammation, tissue pH is acidic, resulting in rapid inactivation of the drug. For this reason and also for the prevention of contamination of other tissue, local anesthetics should not be infiltrated into infected tissues.

Once the local anesthetic reaches the neuron, the duration of effect depends on the type of drug being used and the rate of absorption by local blood vessels (see Table 6-1). This in turn depends on whether epinephrine is used with the local anesthetic. Lidocaine, the drug most commonly used for local injection, may be purchased with or without epinephrine. The concentration of epinephrine used is 0.01 mg/mL of lidocaine.

Epinephrine is added to lidocaine for the following two reasons:

Lidocaine without epinephrine may be preferred to lidocaine with epinephrine in some situations. A solution containing epinephrine should not be used at an incision site because it may impair tissue perfusion and healing. Lidocaine with epinephrine should not be used on the ears, tail, or digits, because circulation to these areas may be compromised. Epinephrine also increases the risk of ventricular arrhythmias (particularly in animals anesthetized with halothane) and should be used with caution in animals with known cardiac disease. Lidocaine without epinephrine is used for intravenous techniques.

Local anesthetic injections may be painful in the awake patient. Some anesthetists add sodium bicarbonate (one tenth the volume of local anesthetic) to decrease pain on injection.

Two techniques are commonly used for infiltration of local anesthetics: nerve blocks and line blocks.

Intraarticular Administration

In certain circumstances, local anesthetics can be injected directly into a joint. For example, bupivacaine has been shown to provide significant analgesia when injected into the stifle joint at the conclusion of stifle arthroscopy and surgery. A dose of 0.4 mL of 0.5% bupivacaine per kilogram, diluted with sterile saline (not water) to a volume sufficient to fill the joint, has been recommended. The drug is injected immediately after closure of the joint capsule.

Regional Anesthesia

Regional anesthesia is a technique whereby a local anesthetic is injected into a major nerve plexus or in proximity to the spinal cord. This results in the blockage of nervous impulses to and from a relatively large area, such as an entire limb or the caudal portion of the body. Examples of regional anesthesia in veterinary medicine include paravertebral, epidural, spinal (intrathecal), and brachial plexus blocks.

Systemic Administration

Lidocaine can also be administered by constant rate infusion to healthy anesthetized animals to reduce the dose of general anesthetic or analgesic required for painful operations and to prevent cardiac arrhythmias. The dose used is 50 to 75 mcg/kg/min in dogs and horses, and 25 mcg/kg/min in cats.

1. Motor neurons may also be affected, and the patient may lose voluntary motor control of the affected body part. The loss of motor function to the limbs typically results in recumbency. This may be inconvenient (e.g., for a standing procedure in a cow) or undesirable and dangerous (e.g., a horse that falls and thrashes as it repeatedly tries unsuccessfully to stand).

2. If local anesthetic is injected into a nerve, temporary or permanent loss of function may result. Direct injection into a nerve should be avoided, except for animals undergoing an amputation.

3. Tissue irritation may occur after the injection of some local anesthetics. Some veterinarians prefer mepivacaine instead of other local anesthetics because it appears to cause less tissue irritation.

4. Paresthesia, an abnormal sensation of tingling, pain, or irritation, may be apparent during recovery from local anesthesia. (Human patients also experience this tingling sensation—for example, during recovery from “numbing” of the oral cavity with Novocain.) Animals should be monitored during recovery because they may chew or otherwise traumatize affected areas and may require chemical or physical restraint or the use of E-collars (cats and dogs).

5. Human and animal patients may exhibit allergic reactions to local anesthetics, usually in the form of a skin rash or hives. Anaphylaxis is also occasionally seen. Local anesthetics should not be used in patients in which an allergic reaction to these drugs has been previously observed.

6. Systemic toxicity may occur, particularly if a local anesthetic is inadvertently given intravenously without the use of a tourniquet. Systemic toxicity may be seen even if the drug is placed in the subcutaneous tissues, if a large amount of local anesthetic is injected. The most common signs of systemic toxicity originate in the central nervous system. The first sign of systemic toxicity is usually sedation, followed by nausea, restlessness, muscle twitching, hyperexcitability, seizures, respiratory depression, and, eventually, coma. Treatment of central nervous system signs may include intravenous or intrarectal diazepam (0.2 to 0.4 mg/kg) and administration of oxygen. Cardiovascular effects may also be observed, because of the direct effect of local anesthetics on the heart. Intravenous injection of lidocaine may inhibit the conduction of electrical impulses within the heart muscle and decrease the force of cardiac contractions. This is undesirable when local anesthesia is performed but makes this drug useful in the treatment of some types of ventricular arrhythmias. Bupivacaine is more cardiotoxic than lidocaine. The dose of lidocaine given subcutaneously to dogs, cows, and horses should not exceed 10 mg/kg and in cats should not exceed 4 mg/kg to avoid systemic toxicity. The smallest possible dose should be used. If the drug is given intravenously, the dose of lidocaine should not exceed 4 mg/kg in dogs, 2 mg/kg in large animals, and 0.5 mg/kg in cats. The dose of bupivacaine given subcutaneously should not exceed 2 mg/kg in dogs and 1 mg/kg in cats. For the average (4-kg) cat, the maximum dose of 2% (20 mg/mL) lidocaine is 0.8 mL (16 mg) if given subcutaneously and 0.1 mL (2 mg) if given intravenously. For 0.5% (5 mg/mL) bupivacaine, the maximum subcutaneous dose for a 4-kg cat is 4 mg (0.8 mL). Bupivacaine should not be given by intravenous injection. Dilution of the calculated dose of lidocaine or bupivacaine with sterile saline is helpful in small patients because it increases the volume and decreases the concentration of the solution to be injected.

7. Epidural or spinal injection may rarely traumatize the spinal cord or cauda equina, particularly if the animal is struggling during placement of the needle. Inflammation and fibrosis have been reported after epidural infiltration of local anesthetics containing preservatives. In addition, myelitis (spinal cord inflammation) and meningitis (inflammation of the pia mater, arachnoid, or dura mater) may occur if asepsis is not maintained.

8. If local anesthetics are permitted to infiltrate into the cranial portion of the spinal cord, serious toxicity and even death may occur. If the local anesthetic reaches the midthoracic vertebrae, innervation of the intercostal muscles may be blocked, interfering with normal respiration. If local anesthetic diffuses as far forward as the cervical spinal cord, the phrenic nerve may be affected. This nerve innervates the diaphragm, and loss of function may result in respiratory paralysis. When epidural anesthesia is performed, care should be taken to keep the patient’s head elevated to avoid gravitational flow of the anesthetic into the anterior spinal canal around the thoracic and cervical spinal cord. The anesthetist should be prepared to intubate and artificially ventilate the lungs of any patient undergoing epidural anesthesia, because this may be necessary if intercostal and phrenic nerve function is impaired.

9. Diffusion of local anesthetic into the cervical and thoracic spinal cord may also affect sympathetic nerves supplying the heart and blood vessels, resulting in a sympathetic blockade with symptoms of bradycardia, decreased cardiac output, and hypotension. If blood pressure measurement is unavailable, careful monitoring of the capillary refill time, heart rate, and pulse strength will alert the anesthetist to a fall in blood pressure. Treatment consists of intravenous fluid administration at a rate of 20 mL/kg over a 15- to 20-minute period.

• Tranquilizers and general anesthetics may decrease the responsiveness of the respiratory center in the brain to carbon dioxide. This means that inspiration does not occur as often in the anesthetized animal as in the healthy awake animal, despite the fact that the carbon dioxide level may be significantly elevated. This explains the observation that a respiratory rate of 8 to 20 breaths per minute is normal in cats and dogs under inhalation anesthesia, whereas the same animal would be expected to have a respiratory rate of 15 to 30 breaths per minute when awake.

• Tranquilizers and general anesthetics relax the intercostal muscles and diaphragm, causing them to expand less than they normally do during the inspiratory phase. Because the chest does not expand fully, the V_T is reduced. The anesthetist may become aware of the reduced V_T by noting that the reservoir bag does not collapse significantly during the inhalation phase (i.e., the volume of gas inhaled is relatively small). Because V_T and respiratory rate are decreased, respiratory minute volume is also decreased.

• Hypercarbia. Paco₂ may rise in the anesthetized patient, because carbon dioxide produced by the body is not eliminated as rapidly as in the awake animal. As the blood carbon dioxide level rises, carbon dioxide combines with water molecules in the bloodstream to form bicarbonate ions (HCO₃⁻) and hydrogen ions (H⁺). The accumulation of hydrogen ions causes the pH of circulating blood to fall, leading to respiratory acidosis. Blood pH in the healthy awake animal is 7.38 to 7.42, whereas in the anesthetized animal, blood pH may be as low as 7.20.

• Hypoxemia. If the anesthetized animal is breathing room air, Pao₂ may fall below normal values as a result of the decreased respiratory minute volume. Less oxygen enters the lungs, and therefore less is available to be absorbed into the blood.

• Atelectasis. Because V_T is reduced, the alveoli do not expand as fully as normal on inspiration. The alveoli in some sections of the lung, particularly those that are lower in the animal’s body, may partially collapse (a condition called atelectasis).

• Prolonged anesthesia (more than 90 minutes).

• Obesity.

• Administration of neuromuscular blocking agents (see following section).

• Preexisting lung disease such as pneumonia.

• Recent head trauma.

• Surgical procedures involving the chest or diaphragm. These animals may have preexisting cardiovascular or pulmonary disease and are at significant risk for cardiovascular collapse or respiratory arrest if conventional anesthesia with unassisted ventilation is attempted.

• Species differences. Horses in particular are prone to the problems listed previously, regardless of physical status. Adult ruminants also tend to hypoventilate and become hypercarbic.

1. The patient’s lungs are ventilated by the anesthetist using the anesthetic breathing system; this technique is referred to as manual ventilation. A common term that is also used to indicate manual ventilation is bagging. In this type of PPV, the lungs are filled with oxygen by the pressure of gas entering the airways as the anesthetist squeezes the reservoir bag with the pop-off valve fully or partially closed. Exhalation is passive and occurs when the positive pressure is discontinued and the pop-off valve is opened fully, allowing the lungs to empty. For most patients, periodic bagging (one or two breaths every 2 to 5 minutes) is adequate to expand the lungs and reduce atelectasis. However, some patients require bagging throughout the anesthetic period, which is referred to as intermittent mandatory ventilation.

2. The patient’s lungs are ventilated by a ventilator; this technique is called mechanical ventilation. In this type of PPV, the lungs are filled with oxygen by the pressure of gas from a special apparatus called a ventilator. As with manual ventilation, exhalation is passive and occurs when the positive pressure is discontinued. Ventilators used in anesthesia are not usually used to periodically ventilate patients, but are most commonly used to provide intermittent mandatory ventilation.

Manual Ventilation

Manual ventilation can be performed on a periodic basis (one or two breaths every 2 to 5 minutes) on any anesthetized patient. These periodic breaths, also called “sighs,” help expand collapsed alveoli and reverse atelectasis. For the patient’s lungs to be manually ventilated, the pop-off valve is closed and the reservoir bag is compressed until the lungs are inflated. When pressure on the reservoir bag is released, exhalation can occur. The anesthetist must use caution to ensure that the pressure used is not excessive: the patient’s chest should rise only to the same extent as with normal awake respiration. When normal lungs are ventilated, the pressure manometer reading should not exceed 20 cm H₂O in small animal patients and 40 cm H₂O in large animal patients. The bag should be squeezed for 1 to 1.5 seconds. Excessive or prolonged pressure may damage lung tissue and impede venous return to the heart.

For some patients, respiratory depression is so severe that periodic bagging does not provide the necessary level of ventilation, placing increased demand on the anesthetist’s time and attention. Animals with preexisting heart or lung disease or diaphragmatic hernias may go into respiratory arrest immediately after induction. Other patients continue to breathe under anesthesia, but their V_T is small (shallow breaths) and/or the respiratory rate is less than 6 breaths/min. These patients require intermittent mandatory ventilation. Ventilation can be assisted starting immediately after intubation, at which point the anesthetist should use the reservoir bag to superimpose positive pressure on the animal’s own spontaneous breathing efforts. For many patients it is adequate to give a few larger than normal breaths manually then to connect the patient to a ventilator or to initiate manual ventilation. The initial large V_T depresses the animal’s urge to breathe by lowering blood carbon dioxide levels. Once the patient is connected to a ventilator or is undergoing appropriate manual ventilation, the patient usually stops spontaneous breathing efforts within 1 minute. Initially, the assisted ventilation rate should be 8 to 20 respirations per minute, depending on patient size. If after 3 to 5 minutes the patient still makes spontaneous breathing efforts, it may be necessary to use a neuromuscular blocking agent, which paralyzes the muscles of respiration (see the following section).

Once control has been established, a ventilation rate of 6 to 12 breaths/min is usually adequate. A pressure of 15 to 20 cm H₂O is recommended in small animals (30 to 40 cm H₂O in large animals), unless the chest is open, in which case higher pressures may be required depending on the degree to which the lungs are packed off by the surgeon to better expose the surgical field. When the reservoir bag is squeezed, the inspiratory time should be 1 to 1.5 seconds. Expiratory time should be at least twice as long as inspiratory time. The pop-off valve must be closed when the reservoir bag is squeezed; however, it should be opened briefly every two to three breaths to allow gas to escape from the circuit. The anesthetist must allow the airway pressure to return to zero during expiration so that cardiopulmonary function can normalize (improving venous return of blood to the heart and increasing stroke volume).

When assisting or controlling ventilation, the anesthetist may find it difficult to evaluate the adequacy of the ventilation efforts. Pulse oximetry and end-tidal capnography are valuable aids (see Chapter 5). For example, if the pulse oximeter reading is 95% or less in a patient undergoing manual ventilation, the patient may need more frequent ventilation or ventilation at a greater pressure or volume.

When the surgical procedure is nearing completion, the anesthetist must transition the patient from the intermittent mandatory breaths given by the ventilator, to spontaneous breathing. This is known as “weaning” the animal off the ventilator and is accomplished by turning off the anesthetic (and nitrous oxide if it is being used) while continuing to ventilate the patient’s lungs with oxygen. If a neuromuscular blocking agent has been used, it should be reversed, if necessary. The anesthetist should gradually reduce the rate of inspirations to approximately two to four per minute while observing the animal for evidence of spontaneous breathing. When this is seen, the patient’s ventilation can then be assisted by squeezing a small amount of air from the reservoir bag with each inspiration. Eventually, the animal will regain the ability to maintain a normal rate and V_T, and ventilation assistance can be discontinued. This may take several minutes to reestablish, particularly in older, hypothermic, or debilitated patients and in patients in which ventilation has been controlled for a long time. Warming the patient or stimulating the patient by pinching the toe pads or gently rubbing the thorax and abdomen (small animal), or twisting an ear (large animal), may help the patient regain spontaneous respiratory movements.

Mechanical Ventilation

Mechanical ventilation is similar to intermittent mandatory manual ventilation in many respects. In mechanical ventilation, however, the patient’s breathing is controlled by a ventilator, rather than by hand compression of the reservoir bag. When a ventilator is connected to the breathing circuit, it functionally replaces the reservoir bag and becomes a part of the breathing circuit. The ventilator automatically compresses a bellows, which forces oxygen and anesthetic gas into the patient’s airways via an endotracheal tube.

Many types of ventilators can be used with a veterinary anesthesia machine, and they vary in the number and complexity of the controls (Figure 6-2). The basic design is a bellows inside a housing, which is attached to the reservoir bag port of a circle breathing system. The bellows is compressed at a specified rate and a specified volume by a driving gas. Most ventilators have a double gas circuit pattern, with one circuit providing oxygen and anesthetic for the patient, and the other circuit containing a separate gas (oxygen or air) to drive the bellows. Ventilators are available for either large animal or small animal use. In both cases the scavenger should be attached to the exhaust port of the ventilator.

Depending on the type of ventilator used, the anesthetist may choose to deliver gases on inspiration according to a pressure cycle, volume cycle, or time cycle. A pressure-cycled ventilator (such as the Bird Mark 7 Respirator) will supply air until the pressure reaches a preset level. A time-cycled ventilator (such as the Small Animal Ventilator by Drager) supplies air according to a set inspiratory time. A volume-cycled type (such as the Ohio Metomatic) delivers a preset V_T regardless of the pressure required. In volume-cycled ventilators, the anesthetist must adjust the volume of gas to be delivered on inspiration (usually 10 to 15 mL/kg, less if respiration is to be assisted rather than controlled).

After connecting the ventilator to the breathing circuit, the anesthetist should closely observe the patient to ensure that the chest rises with each inspiration. Respiratory rate is usually 6 to 12 breaths/min. Duration of inspiration is set at 1 to 1.5 seconds, and duration of expiration should be 2 to 6 seconds with an inspiratory/expiratory ratio of 1:2 to 1:3. If a pressure-cycled ventilator is used, a pressure setting of 12 cm to 20 cm is normally selected. These settings may be varied to adapt to the special needs of selected patients. For example, a dog with gastric dilation–volvulus or a horse with colon torsion may need higher airway pressures to deliver a minimal effective V_T. Obese cats and dogs often require normal rates but higher airway pressures to overcome the thoracic effects of obesity.

Like manual ventilation, mechanical ventilation is particularly indicated for patients with compromised respiration. It is not normally necessary in healthy anesthetized patients, in which periodic manual bagging (once every 5 minutes) is usually sufficient. Mechanical ventilation is particularly helpful in animals undergoing a thoracotomy or other lengthy operation, in which manually providing intermittent mandatory ventilation would be difficult for the anesthetist.

Rebreathing versus Non-rebreathing Systems

Intermittent mandatory manual ventilation can be performed using either a rebreathing or a non-rebreathing system. Non-rebreathing systems usually lack a manometer, and the anesthetist must use sight and touch to determine the optimal V_T.

In-Circle versus Out-of-Circle Vaporizers

Patients connected to a circle system with an in-circle nonprecision vaporizer can be bagged every 5 minutes to assist ventilation. However, it is advisable to turn the vaporizer setting to zero before bagging the patient, to prevent sudden vaporization of large amounts of anesthetic as a result of the increased flow of carrier gas through the vaporizer. Mandatory controlled ventilation with an in-circle vaporizer is difficult and may be dangerous, unless the vaporizer is turned down or off or end-tidal anesthetic agent monitoring is available. Because of the increased gas flow associated with controlled ventilation and the lack of back pressure compensation in these vaporizers, the patient may receive excessive amounts of vaporized anesthetic.

In contrast, it is feasible to use mandatory manual or mechanical ventilation on patients connected to a circle system with an out-of-circle precision vaporizer. If the vaporizer is compensated for gas flow and back pressure, it is not necessary to turn the concentration setting to zero during controlled ventilation. However, if mandatory manual ventilation is used, it may be advisable to reduce the precision vaporizer setting, or the patient’s level of anesthesia may become too deep because of increased delivery of anesthetic to the lungs. The anesthetist should closely monitor the patient and adjust the vaporizer setting according to the patient’s anesthetic depth.

• Excessive airway pressure may rupture alveoli, causing pneumothorax and/or pneumomediastinum.

• Cardiac output may be decreased if positive pressure is maintained throughout the respiratory cycle (during expiration and inspiration).

• If the ventilation rate is too high, excessive amounts of carbon dioxide may be exhaled, leading to respiratory alkalosis, which (if severe) can cause cerebral vasoconstriction and decreased cerebral blood flow.

• Controlled ventilation is generally more efficient at delivering anesthetic gas, even from a precision out-of-circle vaporizer. A ventilator will thus deliver more inhalant anesthetic to the patient, which may lead to exacerbation of side effects such as hypotension and increased central nervous system depression. Conversely, ventilators are often used in large animal patients as anesthetic delivery devices to maintain a smoother plane of anesthesia than sometimes occurs with spontaneous breathing.

• Mechanical ventilation is not intended to relieve the anesthetist of the necessity for patient monitoring. The anesthetist must closely monitor all animals in which ventilation is controlled or assisted to ensure that patient anesthetic depth and vital signs are maintained within acceptable limits.

a. Excess oxygen concentration in the blood

b. Excess carbon dioxide concentration in the blood

c. Insufficient oxygen in the blood

d. Insufficient carbon dioxide in the blood

a. ½

b. 2

c. 3

d. 4

a. 5 to 10

b. 10 to 15

c. 16 to 20

d. 20 to 25

a. An increase in the Paco₂ and a decrease in the Pao₂

b. A decrease in the Paco₂ and an increase in the Pao₂

c. A decrease in the Paco₂ and a decrease in the Pao₂

d. An increase in the Paco₂ and an increase in the Pao₂

a. Peripheral nervous system

b. Central nervous system

c. Peripheral and central nervous systems

d. Autonomic nervous system

a. Sensory neurons only

b. Motor neurons only

c. Sensory and motor neurons only

d. Sensory, motor, and autonomic neurons

a. They mechanically block nerve impulse transmission

b. They interfere with the movement of sodium ions

c. They block all impulses at the spinal cord level

d. They affect neurotransmission within the brain

a. Line block

b. Epidural block

c. Infiltration nerve block

d. Intravenous anesthesia

TrueFalse

a. T13

b. L6

c. L7

d. S1

e. The coccygeal vertebrae

a. 1

b. 4

c. 10

d. 15

a. With epinephrine

b. Without epinephrine

c. Either with or without epinephrine

d. Lidocaine should not be used for this technique.

a. Excess fluid in the respiratory system

b. The absence of breathing

c. Collapse of the alveoli

d. Bronchial constriction

a. Respiratory alkalosis

b. Metabolic alkalosis

c. Respiratory acidosis

d. Metabolic acidosis

a. Increase the vaporizer setting

b. Decrease the vaporizer setting

c. Disconnect the patient from the circle system before starting manual ventilation

d. The lungs of patients that are connected to a circle system should not be manually ventilated.

a. Heart rate

b. Jaw tone

c. Palpebral reflex

d. Pedal reflex

True False

a. Depolarizing

b. Nondepolarizing

a. Cardiac

b. Smooth muscle

c. Skeletal muscle

d. All types are equally affected.

TrueFalse

a. A decreased cardiac output

b. Muscle twitching

c. A state of respiratory alkalosis

d. Ruptured alveoli

a. Topically on the epidermis

b. Topically on mucous membranes

c. Topically on the cornea

d. Through injection

a. Fat

b. Scar tissue

c. Rapid heart rate

d. Hemorrhage

a. Sedation

b. Convulsions

c. Muscle twitching

d. Respiratory depression

a. Sympathetic blockade

b. Paralysis of intercostal muscles

c. Paralysis of diaphragm

d. Hypertension