drugs and stimuli that have profound cardiovascular and respiratory effects. These need to be managed carefully in order to avoid adverse effects on intracranial dynamics; therefore good monitoring and venous access must be present from the outset. The aim is to prevent large swings in blood pressure and heart rate, to maintain good oxygenation at all times and to avoid hypercapnia.
The airway must be secured with an endotra-cheal tube for all intracranial and major spinal surgery. For some non-invasive investigations performed under anesthesia or for minor procedures, a laryngeal mask airway may be used. The endotracheal tube must be carefully positioned and very well secured, as access is difficult once surgery has started. Intubation is carried out after induction of anesthesia when relaxation has been achieved by muscle relaxants, except where there is an indication for awake intubation.
While the induction agents are generally cardiovascular depressants, and the blood pressure often falls on induction, laryngoscopy and intubation are stimulating and cause a rise in heart rate and blood pressure. It is essential to monitor the blood pressure closely throughout the whole period of induction and for the anesthesiologist to be prepared to intervene to treat hyper- or hypotension. A number of drugs have been recommended to obtund the hypertensive response. Commonly used drugs include a small increment of the induction agent, a short-acting opioid such as alfentanil or sufentanil, a short-acting beta-blocker, or lignocaine. There should be no attempts to intubate until muscle relaxation has been achieved in order to avoid coughing, with its attendant effect on ICP.
Some patients are difficult to intubate for anatomical or pathological reasons and special techniques may be needed. Awake fiberoptic intubation may be the preferred approach in such patients as well as for those with an unstable cervical spine.
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