Effect of oral gabapentin on haemodynamic variables during microlaryngoscopic surgery

Background: Manipulation of the larynx, such as laryngoscopy and tracheal intubation, is associated with haemodynamic and cardiovascular responses. In microlaryngoscopic procedures, these responses are more severe than laryngoscopy for endotracheal intubation because in microlaryngoscopic surgeries laryngoscope fixes for a longer time (15–20 minutes compared to 15–30 seconds in tracheal intubation). This study was performed to evaluate the effect of 800 mg oral gabapentin on the haemodynamic variables during microlaryngoscopic surgery. Methods: 30 patients aged 30–70 years, ASA physical status I or II, who underwent microlaryngeal surgery were included to the study. The night before surgery, 15 patients (group G) received 100 mg gabapentin and 15 patients (group P) received a placebo. Ninety minutes before the operation, they either received 800 mg gabapentin (group G), or received a placebo (group P). Results: Heart rate, systolic, diastolic and mean arterial blood pressure were measured on the night before the procedure, the morning before the procedure, at arrival to the operating room as baseline, before and after induction, 1, 3 min after tracheal intubation, 1, 5, 15, 25 min after fixing laryngoscope, before laryngoscope removal, and 1 min after that. Analyses revealed that the systolic blood pressure was lower in group G after induction, 1 and 5 min after fixing laryngoscope and before removing the laryngoscope. Diastolic blood pressure in group G was lower at the time of arriving in the operating room, after induction, 1 min after fixing surgical laryngoscope and before removing the laryngoscope. Mean arterial pressure behaved similarly, and additionally it was lower at 5 min after fixing the laryngoscope. Heart rate was reduced at the time after induction, 1, 3 min after intubation, 5 min after fixing the laryngoscope and before laryngoscope removal in group G. Overall, in the group G, diastolic blood pressure and mean arterial pressure were lower in the first 15 min after microlaryngoscopy compared to group P but there was no difference in mean systolic blood pressure and mean heart rate. Conclusion: 800 mg oral gabapentin given 90 min before a procedure attenuates the rise of diastolic blood pressure and mean arterial blood pressure in the first 15 min after microlaryngoscopy surgery, but has no effect on systolic blood pressure or heart rate.