Insight into the emerging technique of awake surgery

Dr Jayashree S Simha

Anaesthesiology, a vital ingredient in the recipe for a safe and successful surgery, has advanced in leaps and bounds.

With a better understanding of the pathophysiology of disease, the advent of newer and better drugs, excellent monitoring aides which measure every necessary physiological parameter of the patient and an understanding surgical team, it has been possible to tread into newer avenues of treatment like awake craniotomy and awake heart surgery.

It has always been a challenge for the neurosurgeon when handling pathology that involves the motor strip of the brain or important areas like the speech centre. Minor transgressions will lead to unmitigated disaster, leaving a much incapacitated patient, unable to speak or paralysed. This unacceptable morbidity was a major constraint.

How wonderful would it be if one could have an awake patient, thereby making it possible for the neurosurgeon to check every move of his. One could make the patient talk or move his limbs, ensuring that vital areas of the brain are preserved.

It is a wrong notion that for awake surgery, the anaesthesiologist has no role to play. In fact, in such situations, the responsibility of the anaesthesiologist increases significantly. A vigilant anaesthesiologist keeping an eagle’s eye on all the parameters of the patient, ensures necessary sedation and anxiolytics are administered in carefully titrated doses and maintaining the vital functions of circulation and respiration. He or she should be prepared to plunge into action, resuscitate the patient and prevent the occurrence of catastrophes like sudden neurological deterioration, bleeding, intracranial hypertension, vasospasm, seizures or respiratory/cardiac arrest.

The principle of awake surgery is to keep the patient pain free, without anxiety, yet being able to respond to commands. This happy situation is achieved by the intelligent use of drugs. Pre-operative evaluation and counseling, stressing the importance of the patient’s active cooperation helps in ensuring a successful outcome. Adequate sedation, analgesia and anxiolysis are achieved by meticulous dosing. Drugs commonly used include hypnotics like propofol, midozolam or droperidol, opioids like fentanyl, alfentanyl or sufantanyl.

Using monitoring devices which include pulse oxymeter, cardiac rhythm, and respiration monitor and blood pressure device, helps in maintaining a safe environment for the patient.

The surgical procedure includes creating a small opening in the skull under local anaesthesia with precise localisation of the lesion with the help of steriotactic frame and computerised calculation of the depth of the lesion with the help of computerised tomography. Then, a thin needle is passed through this opening, to the calculated depth and a biopsy is taken or the lesion is excised.

Difficulties posed include an unco-operative patient and the use of the stereotactic frame during surgery which hinders emergency airway management. Proper planning and having the expertise to perform intubation by using a fibreoptic intubating scope are essential.

Thus, with an excellent co-ordinated team work, an anaesthesiologist can contribute effectively and significantly to the performance of complex operations on vital areas of the brain safely, leaving a happy surgeon and a healthy patient!

The writer is head of department of anaesthesiology at Manipal Hospital, Bangalore.

Email: simha@vsnl.com