Effects of nitroglycerin versus labetalol on peripheral perfusion during deliberate hypotension for sinus endoscopic surgery: a randomized, controlled, double-blinded trial

Background

Deliberate hypotension is used to provide a bloodless field during functional endoscopic sinus surgery; however, the impact of controlled hypotension during anesthesia on peripheral tissue perfusion has not been extensively evaluated. The aim of this study was to compare the impact of nitroglycerin- versus labetalol-induced hypotension on peripheral perfusion.

Methods

The present randomized, double-blinded, controlled trial included adult patients undergoing endoscopic sinus surgery. Patients were allocated to one of two groups according to the drug received for induction of deliberate hypotension: nitroglycerin (n = 20) or labetalol (n = 20). Mean arterial pressure was maintained at 55–65 mmHg in both groups. Both study groups were compared according to pulse oximeter-derived peripheral perfusion index (primary outcome), serum lactate level, mean arterial pressure, heart rate, surgical field score, and intraoperative blood loss.

Results

Forty patients were included in the final analysis. The nitroglycerin group exhibited a higher peripheral perfusion index at nearly all records (p < 0.0001) and lower postoperative serum lactate levels (1.3 ± 0.2 mmol/L vs. 1.7 ± 0.4 mmol/L; p = 0.001) than the labetalol group. The peripheral perfusion index was higher in the nitroglycerin group than at baseline at most intraoperative readings. The median surgical field score was modestly lower in the labetalol group than in the nitroglycerin group in the first 20 min (2 [interquartile range (IQR) 2–2.5] versus 1.5 [IQR 1–2]; p = 0.001). Both groups demonstrated comparable and acceptable surgical field scores in all subsequent readings.

Conclusion

Nitroglycerin-induced deliberate hypotension was accompanied by higher peripheral perfusion index and lower serum lactate levels than labetalol-induced deliberate hypotension during sinus endoscopic surgery.

Trial registration

The study was registered at clinicaltrials registry system with trial number: NCT03809065. Registered at 19 January 2019. This study adheres to CONSORT guidelines.

Transfer of labetalol into amniotic fluid and breast milk in lactating women

The transfer of labetalol into human breast milk and amniotic fluid was studied in women with pregnancy hypertension. The women were treated with labetalol 600-1200 mg daily. The ratio between the areas under the milk and plasma concentration versus time curves varied between 0.8 and 2.6. No consistent relation between milk and plasma concentration in the mother was observed either within the individuals during a dose interval or between different individuals. One of the nursed infants at the end of the dose interval had a plasma labetalol in the same range as the mother, and in another infant the level was below the detection limit. Amniotic fluid concentrations 2-3 h after dosing were generally lower than in plasma.

Clinical evaluation of labetalol alone and combined with chlorthalidone in essential hypertension: a double-blind multicentre controlled study

In a multicentre, double-blind, crossover, placebo-controlled study, the antihypertensive effect of labetalol 100 mg and chlorthalidone 10 mg, given alone or in combination, has been assessed in 32 hypertensive patients. The combination had a greater effect in reducing blood pressure than did its separate components. This was particularly evident after exercise. Heart rate increased during chlorthalidone therapy, decreased during labetalol therapy, and a summation effect was observed during treatment with the combination. In most cases additivity was observed, as no interaction between the single components was observed, except for heart rate after exercise, and for diastolic blood pressure in the upright position. No interaction was observed either in the biochemical indices or in the clinical side-effects.