Role of gabapentin in controlled hypotension for nasal surgeries: a randomized controlled study

Background
Providing bleeding control is critically important when microsurgical techniques are used. A mild bleeding can complicate the working in surgical field in nasal surgery so, a bloodless surgical field should be provided. For that purpose, the anesthesiologists should use controlled hypotension anesthetic technique. The aim of this study was to investigate the hypotensive and analgesic effects of gabapentin if combined with nitroglycerin infusion for conduction of hypotensive anesthesia in nasal surgeries.
Patients and methods
The present study was carried out at El-Zahraa hospital, Al Azhar University on 40 patients ASA I and II were randomly assigned into two equal groups (=20). Gabapentin nitroglycerin (GN) group: patients received 1200 mg gabapentin orally 2 h preoperatively. Nitroglycerin placebo group (N): patients received placebo tablet orally 2 h preoperatively. Intravenous nitroglycerin infusion started and titrated for all 40 patients according to the target hypotensive condition (mean arterial pressure range between 55–65 mmHg and heart rate between 60–75 b/min). Intraoperative hemodynamic changes in the form of heart rate (HR) and mean arterial pressure (MAP) were recorded; the total nitroglycerin dose required was recorded; blood loss and quality of surgical field were assessed. Also, visual analog scale (VAS) for pain assessment and total amount of morphine used within 12 postoperative hours were detected for each group.
Results
The results showed that the heart rate and the mean arterial pressure were significantly lower in the GN group compared to N group. The total dose of intraoperative nitroglycerin was significantly lower in the GN group compared to N group. GN group provides the lower amount of blood loss and better surgical field exposure compared to N group. The visual analog scale (VAS) values was significantly lower at 30 min and 4 h post-operative while non-significant difference at 1 and 6 h postoperative in the GN group compared with N group. There was a significantly lower in the total morphine consumption for GN group compared to N group.
Conclusion
Preoperative oral gabapentin (1200 mg) augments the hypotensive effect of nitroglycerin as it provides dryness of surgical field associated with lower infusion rate of nitroglycerin. Also, it has better analgesic effect with lower narcotic consumption during controlled hypotensive anesthesia for nasal surgeries when compared to the administration of nitroglycerin alone.