Prevention of hypotension during spinal anesthesia for cesarean delivery - An effective technique using combination phenylephrine infusion and crystalloid cohydration

Background: Many methods for preventing hypotension during spinal anesthesia for cesarean delivery have been investigated, but no single technique has proven to be effective and reliable. This randomized study studied the efficacy of combining simultaneous rapid crystalloid infusion (cohydration) with a high-dose phenylephrine infusion. Methods: Nonlaboring patients scheduled to undergo elective cesarean delivery received an intravenous infusion of 100 mu g/ min phenylephrine that was started immediately after spinal injection and titrated to maintain systolic blood pressure near baseline values until uterine incision. In addition, patients received infusion of lactated Ringer's solution that was given either rapidly (group 1, n = 57) or at a minimal maintenance rate (group 0, n = 55). Maternal hemodynamic changes and neonatal condition were compared. Results: Six patients were excluded from analysis. Only 1 of 53 patients (1.9% [95% confidence interval, 0.3-9.9%]) in group 1 experienced hypotension versus 15 of 53 patients (28.3% [95% confidence interval, 18.0-41.6%]) in group 0 (P = 0.0001). Compared with group 0, patients in group 1 had greater values for the following: serial measurements of systolic blood pressure (P = 0.02), minimum recorded systolic blood pressure (P = 0.0002), and minimum recorded heart rate (P = 0.013). Total phenylephrine consumption was smaller in group 1 compared with group 0 (P = 0.008). Neonatal outcome and maternal side effects were similar between groups. Conclusions: Combination of a high-dose phenylephrine infusion and rapid crystalloid cohydration is the first technique to be described that is effective for preventing hypotension during spinal anesthesia for cesarean delivery.