Airway and breathing
The resuscitation mantra of Airway, Breathing, Circulation or ‘ABC’ remains the management priority in the shocked child as in any other. Before assessment of the nature or severity of shock can be made, the clinician must ensure that the airway is patent and that the patient is breathing adequately without assistance. If this is not so then appropriate steps should be taken to stabilise the airway and ensure adequate breathing.
Intubation and judicious positive pressure ventilation can benefit the shocked child when significant myocardial dysfunction exists and will reduce oxygen consumption caused by increased work of breathing. High flow oxygen should be administered via a facemask with a reservoir bag to maximise oxygen concentration. The shocked child must not be allowed to become hypoxic by the omission of a simple treatment such as oxygen therapy.
As the airway and breathing are being managed, the following monitoring should take place:
• Pulse oximetry
• 3 lead electrocardiogram monitoring
• Blood pressure
Circulation
The clinician should pay particular attention to:
• Pulse rate, rhythm and volume
• Peripheral skin color, temperature, capillary refill time, rashes
• Respiratory rate and work of breathing
• Signs of cardiac failure
• Neurological state
• Signs of injury that might have caused hemorrhage (limb fracture, abdominal trauma, head trauma)
• Urine output
Whilst relatively uncommon in children, the presence of cardiac dysrhythmia associated with shock will require immediate management. Vascular access should be achieved as quickly as possible. At least one, but preferably two, large-bore venous cannule should be sited. If poor perfusion makes this impossible then intraosseous, central venous (femoral or internal jugular vein) or peripheral venous cutdown are acceptable alternatives. At the time of vascular access appropriate blood samples should be taken:
• Full blood count and film
• Blood cross-match—in hemorrhage; most children with septic shock will require transfusion
• Coagulation screen—particularly in septic shock
• Plasma urea, creatinine and electrolytes
• Serum calcium
• Plasma glucose and lactate
• Blood gas estimation—arterial or central venous gases are most useful
• Blood culture and microbial sensitivities
A bedside blood glucose test should also be performed and hypoglycemia corrected promptly. Once assessment and monitoring have been completed (in the acutely sick child this should take no more than 1–2 minutes), the clinician then moves on to definitive management of the shock state. With reference to the three factors involved in the shocked heart there are three objectives of treatment:
1. Correction of hypovolemia (preload)
2. Optimising the cardiac pump (contractility)
3. Ensuring peripheral distribution of blood (afterload)
Following restoration of circulation, a secondary survey for organ specific signs should be carried out.
Correction of hypovolemia
The objective of volume replacement in shock is to optimise preload. The hypovolemic child should be managed initially with a rapid intravenous infusion of warmed fluid of 20 ml/kg. The approximate weight of a child can be calculated by using the formula:
WEIGH of CHILD (Kg) = 2 (Age in years + 4)
The selection of fluid is a matter of departmental policy and no little controversy in the literature. The author recommends 0.9% saline as the fluid of choice in volume resuscitation except in suspected meningococcemia and septic shock when 4.5% human albumin solution is preferred. This is because albumin offers a more logical approach and a theoretically longer duration of action in the presence of the profound capillary leak that occurs, particularly in meningococcal sepsis. Close attention should be made to the effect of the fluid bolus on heart rate, pulse volume and, to a lesser extent, blood pressure. A lack of or very transient fall in heart rate should be followed by a second similar fluid bolus. Further boluses of 10–20 ml/kg may be required depending on clinical response.
Prompt consideration of definitive airway support and intensive care unit admission will be required for these patients as the risk of pulmonary edema is very high. If available, reference to serial blood gas and plasma lactate measurements may aid assessment of progress and invasive monitoring of central venous pressure (CVP) is a marker of preload in the unobstructed heart. A CVP higher than that usually acceptable (i.e. >10mmHg) will be required to optimise cardiac performance in myocardial dysfunction which is universal in septic shock.
Important management notes
• When hemorrhage is suspected, no more than 40 ml/kg of crystalloid should be given before blood is used as the replacement fluid
• In meningococcemia and septic shock, 4.5% albumin is preferred to crystalloid
• In infants with gastroenteritis, 4.5% albumin should be used after 40 ml/kg crystalloid, and other diagnoses considered, e.g. volvulus, peritonitis
• Children with meningococcal sepsis often require up to and over 100 ml/kg fluid in resuscitation
Optimising the cardiac pump
Inotropic support may be required when shock persists despite significant fluid replacement. This may not apply when hemorrhage is the cause of hypovolemia. In this case surgical management of the bleed will be required whilst the child continues to receive blood as volume replacement. Patients in septic shock commonly demonstrate poor myocardial contractility and concurrent low SVR in the presence of metabolic acidosis and endothelial injury. These children benefit from agents producing strong inotropy and peripheral vasoconstriction. Table below lists commonly used inotropes, their principal actions and therapeutic dose ranges.
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| Inotropic drugs in pediatric shock treatment |
Choice of inotropic agent is not without controversy and is an issue for departmental consideration. Dopamine is widely used as the first line inotrope in the shocked child, followed by epinephrine (adrenaline) if response to dopamine is inadequate. In cases of septic shock, where low SVR is likely, there is logic in choosing first an agent that produces vasoconstriction. Epinephrine (adrenaline) (often in conjunction with norepinephrine (noradrenaline) offers positive inotropy and peripheral vasoconstriction, and its early use in the septic shocked child can be very valuable. The dose of inotrope should be titrated according to clinical response. Once this level of cardiac support has been instituted, the patient is likely to have been intubated and ventilated and requires invasive blood pressure monitoring and definitive intensive care management.
Ensuring peripheral distribution of blood
Afterload can be too great or too low to allow normal delivery of blood to the tissues. In the vasodilated child, such as in sepsis, norepinephrine (noradrenaline) and epinephrine (adrenaline) provide vasoconstriction to improve SVR and reduce maldistribution. In the child with cardiogenic shock, such as in those following cardiac surgery, the afterload is relatively high as the injured heart struggles to pump efficiently. Vasodilators such as sodium nitroprusside can ‘off-load’ ventricular work improving cardiac output. More recently phosphodiesterase inhibitors, such as enoximone and milrinone, are increasingly used, as they provide low-level inotropy in conjunction with vasodilatation to enhance cardiac output.
Specific therapies
Individual problems require action in addition to the general principles of management employed in most cases of shock. The following are for consideration:
• Antimicrobial drugs as clinically indicated, e.g. in meningococcemia or the immunocompromised
• Coagulopathy—correct with fresh frozen plasma or cryoprecipitate
• Metabolic acidosis—can improve with volume replacement or might require alkalising agents
• Electrolyte disturbances—correct as necessary
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