AWAKE INTUBATION INCREASES INTRACRANIAL-PRESSURE WITHOUT AFFECTING CEREBRAL BLOOD-FLOW VELOCITY IN INFANTS

Tracheal intubation is frequently required in neonatal anaesthetic pra ctice. Awake intubation is one method of securing the air way and in c ertain circumstances, for many anaesthetists, can be preferable to int ubation following induction of anaesthesia. Previous studies have infe rred that the elevation in anterior fontanelle pressure observed durin g tracheal intubation in neonates was caused by an increase in cerebra l blood flow although it was never measured. In this study, direct met hods were used to observe changes in the cerebral circulation. Thirtee n neonates, ASA I to III (E), aged from 1 to 34 days of age were studi ed. Patients were randomized to receive either tracheal intubation awa ke or following induction of anaesthesia with thiopentone 5 mg . kg-1 and succinylcholine 2 mg . kg-1. Heart rate, systolic arterial blood p ressure, anterior fontanelle pressure, cerebral blood flow velocity (u sing transcranial Doppler sonography) and oxygen saturation were recor ded at the following intervals: baseline (not crying), after intraveno us atropine 0.02 mg . kg-1, during laryngoscopy, immediately after ins ertion of the endotracheal tube, one and five minutes later. The use o f atropine masked the cardiovascular responses to intubation. Whereas the change in anterior fontanelle pressure from baseline was different between the groups (P < 0.05), the cerebral blood flow velocity varia bles were not. The rise in anterior fontanelle pressure seen in the aw ake group may be attributed to a reduction of the venous outflow from the cranium thereby increasing cerebral blood volume and subsequently the intracranial pressure.