Continued...

Airway and respiratory Support (Ventilation)
The first priority is to secure the airway. Ensure adequate oxygenation and ventilation. High flow oxygen system (e.g. Venturi masks) must be used. Oxygen supply is optimized by maintaining arterial oxygen saturation, by correcting anemia and by increasing cardiac output and systemic blood flow. If airway is unstable and adequate oxygenation and ventilation is not achieved, do endotracheal intubation and provide mechanical ventilation. Because mechanical ventilation abolishes or minimizes work of breathing, reduces oxygen consumption and improves oxygenation, early respiratory support benefits patients with severe shock in addition to those with ARDS/ pulmonary edema.

Cardiovascular Support
Tissue blood flow must be restored by achieving and maintaining an adequate cardiac output and by ensuring that systematic blood pressure is sufficient to maintain perfusion of vital organs. Cardiovascular support involves manipulation of heart rate and rhythm and of three determinants of stroke volume (preload, myocardial contractility and after load).

Rate and Rhythm
Assuring adequate heart rate and rhythm is basic to life support. Monitoring of heart rate is essential in guiding therapy. It is important to keep in mind that heart rate varies according to age and heart rates are acceptable within a wide range of normal for age. That includes correction of hypoxia, acidosis, and electrolyte disturbances.

Preload And Volume Replacement :
Fluid therapy by peripheral, intraosseous or central venous access should be initiated after adequate control of airway and breathing has been accomplished. Preload optimization is most efficient way of increasing cardiac output. Rapid intravascular volume expansion guided by repeated clinical examination and urine output is frequently adequate to restore blood pressure and peripheral perfusion. Pulmonary edema with volume overload is rare in child patients. Volume replacement of 10-20 ml/kg with isotonic solutions such as normal saline or ringers lactate can be safely given and repeated if necessary (typically 40-80 ml /Kg may be required). Controversy continues about whether colloids or crystalloids are preferable (5-8). At present, a judicious mixture of crystalloids, blood products to maintain hemoglobin and clotting factors and colloids to maintain colloid oncotic pressure seems most appropriate and reasonable. As well as being fundamental to the management of hypovolemic shock, replacement of circulating volume is important in managing patients with distributive shock.

The absolute contraindication of preload augmentation in children is a persistent elevation in ventricular filling pressures without an increase in cardiac output. Further preload augmentation does not improve peripheral perfusion and by increasing venous pressure may increase vascular leak leading to increased tissue edema, most notably pulmonary edema. Chest X-RAY (showing enlarged heart shadow and pulmonary edema) or bedside echocardiography, are useful adjuncts to clinical examination to identify cardiac decompensation.

Choice Of Fluid For Volume Replacement
Blood : to maintain hemoglobin at around 10 gm.

Crystalloids : Cheap, convenient to use, free of side-effects. Rapidly distributed across intravascular and interstitial spaces. Volume 2-4 times of colloid required for same volume expansion, transient volume expansion.

Colloids: (starch, gelatins) produce greater and more sustained increase in plasma volume. Fresh frozen plasma supplies clotting factors.

Albumin : Should be used only in special circumstances e.g. burns and septic shock. Cost of therapy is an issue while considering colloid solutions for expansion of plasma volume.