Combined Spinal-Epidural Anesthesia for Cesarean Delivery: The Dose-Dependent Effects of Hyperbaric Bupivacaine on Maternal Hemodynamics

In Response: Dr. Balestrieri (1) wonders whether we are better off using the low doses of intrathecal bupivacaine found effective in our study (2). The aim of our study was to demonstrate the hemodynamic benefits of low-dose spinal anesthesia for cesarean delivery. The hemodynamic benefits were convincing. Unfortunately, this technique is associated with a shorter duration of anesthesia. In 10%–20% of patients in the low dose group, additional anesthesia was required through an epidural catheter. We therefore recommended low-dose spinal anesthesia only as part of a combined spinal epidural (CSE) technique. Some patients in the high- dose group also needed epidural supplementation, and so the utility of the CSE was not limited to patients receiving low doses. Dr. Balestrieri correctly points out that the onset of anesthetic block was delayed with the low-dose technique. However, the difference was a mere 2.5 min, and did not affect the total duration of the procedure. The argument that the technique is more time consuming to place may be valid, but we question the importance. In experienced hands, a CSE does not take more then a few minutes to perform. Dr. Balestrieri argues that with the low-dose technique there are increased postoperative analgesic requirements. Our study did not evaluate the need for postoperative analgesia. We know of no evidence that supports this statement. Dr. Balestrieri ends his letter with the important question: Is a low-dose spinal technique better then a high-dose technique combined with judicious titration of vasopressors to maintain arterial blood pressure? Spinal anesthesia results in a worse neonatal acid–base status as compared withboth general and epidural anesthesia (3,4). This may be due to the anesthetic technique (more hypotension) or to the treatment of hypotension using ephedrine. Phenylephrine is a better vasopressor than ephedrine for use during cesarean delivery, resulting in less fetal acidosis (5–7). If maternal arterial blood pressure can be maintained using phenylephrine, most likely there will be no adverse consequences to the fetus or the mother. However, in our view it is better to prevent hypotension than to treat it. Marc Van de Velde, MD, PhD Dominique Van Schoubroeck, MD Jacques Jani, MD An Teunkens, MD Carlo Missant, MD Jan Deprest, MD, PhD Departments of Anesthesiology and Obstetrics and Gynaecology University Hospitals Gasthuisberg Katholieke Universiteit Leuven Leuven, Belgium [email protected]