Prevention of hypertension during trans-sphenoidal surgery--the effect of bilateral maxillary nerve block with local anaesthetics.

Background: Severe cardiovascular responses are known to occur during trans-sphenoidal excision of the pituitary gland despite adequate depth of anaesthesia. This study was undertaken to evaluate the effects of bilateral maxillary nerve block with local anaesthetics on the cardiovascular responses to various stimuli during this procedure.

Methods: In a group of 32 patients, 5-10 ml of a mixture of bupivacaine 0.5% and lignocaine 2% (1:1) was injected in the pterygopalatine fossa after induction of general anaesthesia. Seven control group patients did not receive any nerve block. In all the patients, general anaesthesia was induced with thiopentone and maintained with nitrous oxide-oxygen, pentazocine, boluses of thiopentone and halothane. Pancuronium was used for neuromuscular blockade.

Results: In both the groups, maximum hypertension occurred on opening the blades of the bivalve nasal speculum. In the study group, hypertensive response was significantly less following nasal infiltration with adrenaline containing solution (10.26% increase vs. 23.08% in the control group, P < 0.05), nasal dissection (2.82% vs. 9.45%, P < 0.01) and on application of the nasal speculum (14.93% vs. 35.16%, P < 0.01). The effect on heart rate response was not significant.

Conclusion: The described technique is a useful adjunct to general anaesthesia for suppressing the haemodynamic responses during trans-sphenoidal surgery.