CARDIOPULMONARY RESUSCITATION (also see Chapter 78 )

Pediatric cardiopulmonary arrest differ from adult arrest in a number of ways. Adults usually experience cardiac arrest secondary to coronary artery disease with severe ischemia and precipitation of malignant arrhythmia. Children, on the other hand, have relatively normal coronary arteries, and it is uncommon for them to experience a primary arrhythmia. The more usual situation in pediatrics is initial respiratory compromise or arrest followed by secondary cardiac arrest. Another difference is the character of the terminal arrhythmia. Adults generally display ventricular arrhythmias, whereas children are more likely to have a bradyarrhythmia that degenerates into asystole.

In any PICU there are patients who were victims of cardiopulmonary arrest and successful resuscitation; treatment of these patients is described in the section on asphyxiated patients. In addition to caring for successfully resuscitated patients, the PICU staff must be prepared to provide CPR for their own patients. Identifying patients at risk before they have a full cardiopulmonary arrest is as important as providing good CPR. Such identification requires constant clinical surveillance and identification of risk factors. Critically ill patients are frequently placed at risk at various times during the day. Problems can be avoided by increasing everyone's attentiveness to these high-risk periods—during airway manipulation, during any change in therapy, during manipulation of the patient or bed, and at the change in doctor and nursing shifts.

The basic ABCs of resuscitation are a sequence that must be so familiar that little or no thought is required to begin the initial resuscitative efforts. Despite the evolving literature regarding new CPR, the standard American Heart Association CPR is still advocated as the appropriate method.^[371]

Once ventilation has begun, if no evidence of a pulse can be found, external cardiac compressions should be started. (Establishment and maintenance of an airway are discussed elsewhere.) A rhythm is very important: five sternal compressions are given for each breath. A pause is made after each five compressions to allow for adequate lung inflation unless the trachea has been intubated. The rate of compressions should be at least 100 per minute in infants and 80 to 100 per minute in children and adults. Hand positioning can be accomplished in a number of ways. For CPR in an infant, there are two correct hand placements: (1) both thumbs can be placed over the sternum while the fingers are curved around the back over the spine, or (2) one hand can be placed behind the back for support while sternal compressions are performed with two fingers of the other hand. This second procedure can also be used in toddlers. The adult-style two-handed massage is preferable in older children, with the patient placed on a cardiac board. Pressure should always be completely released between forceful compressions to permit filling of the heart chambers, and a pulse should be palpated to assess the adequacy of compressions.

Vascular access is important, but in a child, attaining it may be difficult or impossible. Although a number of medications (atropine, epinephrine, lidocaine) can be given through the ETT, bicarbonate, calcium, fluid, and pressors require vascular access. CPR guidelines include IO lines (18-gauge spinal or IO needle inserted in the tibia 2 to 3 cm below the tibial tuberosity). Common drugs used for CPR include the following:

1. Atropine is used for treatment of bradycardia; the dose in children is 0.02 mg/kg with a minimum dose of 0.1 mg and a maximum of 1.0 mg.
2. Sodium bicarbonate corrects the metabolic component of the acidosis. The recommended dose is 1 mEq/kg, followed by 0.5 mEq/kg. The usual acidosis is primarily respiratory, and in the event of inadequate ventilation, administration of bicarbonate may increase PaCO₂ and thereby decrease pH. In addition, overzealous use of bicarbonate has complications: lowered threshold for ventricular fibrillation and left shift of the oxygen dissociation curve. The present guidelines suggest that bicarbonate administration be tailored to ABG values.
3. Calcium is a positive inotrope and peripheral vasoconstrictor. Caution should be exercised during the administration of calcium in an adult with cardiopulmonary

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   arrest because calcium has been implicated in decreasing the threshold for ventricular arrhythmias. In pediatrics, because ventricular arrhythmias are rarely a problem, calcium administration is relatively safer. The dose of calcium is 10 mg elemental calcium per kilogram. The present recommendation is to use calcium only to treat hypocalcemia, hyperkalemia, and calcium channel blocker overdose.
4. Dextrose is given to correct hypoglycemia, which may be a precipitating or a complicating feature of the arrest. The dose of dextrose is 0.5 to 1.0 g/kg. It is available as D₅₀ W (dose, 1 to 2 mL/kg) and D₂₅ W (dose, 2 to 4 mL/kg). In cardiovascular arrest, D₅₀ W and D₂₅ W act as osmotic diuretics as well. Dextrose (0.5 g/kg) is also used in combination with insulin (0.1 U/kg) to treat hyperkalemia. Hyperglycemia should be avoided during resuscitation for fear of increasing CNS damage.
5. Epinephrine, an adrenergic agonist, is usually given by the intravenous or IO route, but it can also be administered through the ETT (0.1 mL/kg of a 1:1000 solution). Epinephrine is supplied as a 1:10,000 solution (0.1 mg/mL); the dose is 0.1 mL/kg repeated every 3 to 5 minutes as needed. High-dose epinephrine (0.1 to 0.2 mg/kg or 0.1 to 0.2 mL/kg of a 1:1000 solution) has not been shown to improve outcome, but it may improve myocardial and cerebral blood flow. High-dose epinephrine should be reserved for catecholamine-resistant circumstances such as anaphylaxis, α- or β-blocker overdose, and severe sepsis unresponsive to regular-dose epinephrine.
6. Lidocaine is used to decrease ventricular irritability and help maintain a normal rhythm after defibrillation. It is also a myocardial depressant that decreases myocardial contractility and should therefore be given only when absolutely necessary (i.e., a stable rhythm cannot otherwise be maintained). The dose is 1 mg/kg as a single dose; it may be repeated several times or can be given as an infusion of 1 to 2 mg/kg/hr.

During resuscitation, constant infusion of an inotrope or chronotrope is common practice. Countershock therapy (cardioversion) is indicated if ventricular fibrillation or ventricular tachycardia is present or develops. The dose used in pediatrics is 1 to 3 W-sec/kg or 10 to 15 W-sec/yr of life. The synchronized mode is selected for ventricular tachycardia, and the nonsynchronized mode is used for fibrillation. If small paddles are not immediately available for small children, the adult paddles are most easily used in an anteroposterior placement. If resuscitation efforts prove unsuccessful, the primary event that precipitated the arrest should be evaluated for correctable mechanical or metabolic insults (or both). Possible reasons for unsuccessful resuscitation include tension pneumothorax/hemothorax, disruption of the major vessels, cardiac tamponade, profound hypovolemia, profound metabolic imbalance, toxin ingestion, and hypothermia. Hypothermia presents a considerable problem: a patient with a core temperature of less than 30°C may appear dead or unresponsive to pharmacologic management, and it is important to rewarm the patient as part of the resuscitation. A hypothermic patient can be pronounced dead only if the patient has no electrical activity on the ECG and a core temperature of at least 30°C or if the person cannot be warmed to 30°C with aggressive methods (including peritoneal dialysis for rewarming).

Iatrogenic complications may also occur and may make resuscitation unsuccessful. Such complications include traumatic pneumothorax from attempted vascular cannulation, pericardial tamponade from intracardiac injections, splenic or hepatic rupture from closed-chest compressions, pneumothorax from overzealous positive-pressure ventilation, and placement of the ETT into the esophagus. A patient in cardiorespiratory distress or arrest has an excellent chance of full recovery with adequate resuscitation. Speed, orderly direction, cooperation of all personnel, and continuous assessment of the effectiveness of resuscitation are key to successful restoration of an adequate heart rate, blood pressure, ventilation, and most important, brain function. Keeping the brain alive must be the objective of every resuscitative effort, and with rapid institution and maintenance of ventilation and cardiac massage, patients can be neurologically normal after periods of cardiac arrest.