Shock

Hypovolaemic shock is the most common form of shock seen in children population globally. Hemorrhagic shock (trauma) is a form of hypovolaemic shock.

There is usually a history of volume loss (vomiting, diarrhoea, or blood loss) and the child may demonstrate signs of dehydration (oliguria, poor skin turgor, dry mucous membranes).

Treatment includes monitoring of ABCs according to paediatric ALS guidelines and aggressive fluid replacement with isotonic crystalloid (Plasmalite or 0.9% normal saline) fluid given in 20 mL/kg increments (up to 60 mL/kg given in the first 15–20 minutes).

After 60–80 ml/kg of isotonic fluid is administered, colloid fluids (starch or gelatin) should be considered (particularly blood products if hypovolaemia is secondary to haemorrhage).

Hypoglycaemia may be present in children, especially infants in all forms of shock.

Distributive shock is characterised by low systemic vascular resistance due to vasodilatation, accompanied by increased cardiac output and a redistribution of blood flow, resulting in abnormal peripheral vasodilatation with warm extremities. This category of shock includes: 

• Anaphylactic shock: Characterised by increased vascular permeability and vasodilatation due to systemic release of histamine. This can produce cutaneous manifestations (rash), potential upper airway obstruction (angioedema), bronchiolar constriction (asthma-like symptoms) and profound hypotension. 

The anaphylactic shock should be treated with the support of the airway, breathing and circulation, including administration of adrenaline and fluids to counteract histamine release and hypotension.

• Neurogenic shock: can occur from brainstem injury or compression or transection of the spinal cord with the loss of sympathetic cardiovascular tone. This is characterised by hypotension associated with bradycardia. 

Drug poisonings can also result in peripheral vasodilatation leading to distributive shock. 

• Septic shock occurs with some frequency in the paediatric patients. It

may initially present as a compensated shock with a hyperdynamic/vasodilated state resulting in warm extremities, bounding pulses, tachypnea, tachycardia and a widened pulse pressure.

If not managed adequately, this state can progress to an uncompensated stage with progression to cool extremities from hypoperfusion. Septicaemia in children may present with either hyperthermia or hypothermia.

The septic shock should be treated by considering the  ABCs according to paediatric ALS guidelines and aggressive fluid replacement with isotonic crystalloid fluid given in 20 mL/kg increments (up to 60 mL/kg given in the first 15–20 minutes). Vasopressors may also be used.

Hypoglycaemia may be present in children, especially infants in all forms of shock.

Cardiogenic shock can result from several aetiologies:

• congenital heart disease, 
• certain dysrhythmia, 
• infection, 
• metabolic derangements, 
• obstructive lesions in the heart (congenital or acquired), 
• trauma (myocardial contusion)
• drug poisoning. 

Signs:

• low cardiac output, 
• cardiomegaly
• pulmonary venous congestion 
• hepatomegaly. 

Management:

Vasopressor support should be considered early in this form of shock because fluid administration must proceed with caution. Isotonic fluids should be given in increments of 10 mL/kg in cardiogenic shock, with a continuous reassessment of the perfusion status, perfusion, liver size and lung sounds after each administration.

The underlying cause of the shock must be considered. Infants with some forms of congenital heart disease who are previously asymptomatic may present acutely in cardiogenic shock due to the closure of the ductus arteriosus in the first few weeks of life. 

Obstructive shock is caused by the inability to produce adequate cardiac output despite normal intravascular volume and myocardial function.

Examples include:

• acute pericardial tamponade,
• tension pneumothorax,
• pulmonary systemic hypertension,
• congenital or acquired outflow obstructions.

Early diagnosis of these conditions is essential, as most of these causes can be treated.