Prevention of hypotension induced by combined spinal epidural anesthesia using continuous infusion of vasopressin: A randomized trial.

BACKGROUND: Central neuraxial blockade (CNB) is an established technique of providing anesthesia for surgeries of the lower limb and abdomen. Hypotension is the most common side effect of CNB. It was hypothesized that by supplementing the initial burst of vasopressin following hypovolemia, hypotension following combined spinal epidural anesthesia (CSEA) could be avoided.

MATERIALS AND METHODS: A total of 122 patients undergoing lower limb and abdomen surgeries were included in the study, with 61 patients randomized into two groups - I and II. Patients in Group I received infusion of normal saline as soon as CSEA was applied. When systolic blood pressure (SBP) decreased to <90 mmHg, they received a 6 mg bolus of mephentermine to counteract hypotension. Patients in Group II received a continuous infusion of vasopressin as soon as CSEA was applied. If despite maximum dose of vasopressin, SBP dropped to < 90 mmHg, then intravenous mephentermine was administered to counteract hypotension. Hemodynamic parameters and side effects were noted.

RESULTS: Level of block attained in both groups was comparable in terms of dermatomal height. The mean SBP and mean arterial pressure values of Group I were significantly lower than in Group II in the initial 14 min. Diastolic BP was also significantly lower in Group I. Heart rate was found to be lower in Group II, especially after 30 min ( P < 0.05).

CONCLUSION: Maintaining plasma levels of the physiological burst of vasopressin helps to avoid hypotension following neuraxial blockade. Continuous infusion of vasopressin at 1-3 U/h can prevent hypotension following neuraxial blockade.