**5.3 Hypoxaemia**

Inadequate pulmonary blood flow and/or admixture of deoxygenated with oxygenated blood in systemic circulation are usually responsible for ischaemia. In addition pulmonary congestion with inadequate exchange of gases can also leads to hypoxaemia.

Persistent hypoxaemia leads to following changes

	- a. Growth retardation

The anaesthetic management includes adequate hydration, maintenance of systemic blood pressure, minimizing additional resistance to pulmonary blood flow and avoids sudden increase in oxygen demand (crying, struggling, and inadequate level of anaesthesia).

#### **5.4 Pulmonary hypertension (HTN)**

During early stages, the pulmonary HTN is reactive and responds to hypothermia, stress, pain, acidosis, hypercarbia, hypoxia and elevated intrathoracic pressure but later pulmonary HTN becomes fixed. This last stage, where pulmonary vascular resistance exceeds SVR and symptoms appear due to R L shunt, is the Eisenmenger syndrome13.

Anaesthetic risk is quite high including right ventricular failure, bronchospasm, pulmonary hypertensive crisis and cardiac arrest. Anaesthetic management focus on preventing further increase in R-L shunt by keeping SVR high and PVR low, maintaining myocardial contractility and prevention of arrhythmia and hypovolemia.
