N Hirose1, Y Kondo2, T Maeda3, M Matsui1, M Matsuda1, T Suzuki1. 1. Department of Anesthesiology, Nihon University School of Medicine, 30-1 Oyaguchi-Kamicho, Itabashi-ku, Tokyo 173-8610, Japan. 2. Department of Anesthesiology, Nihon University School of Medicine, 30-1 Oyaguchi-Kamicho, Itabashi-ku, Tokyo 173-8610, Japan; Department of Neurological Surgery, Nihon University School of Medicine, 30-1 Oyaguchi-Kamicho, Itabashi-ku, Tokyo 173-8610, Japan. Electronic address: kondo.yuko@nihon-u.ac.jp. 3. Department of Anesthesiology, Nihon University School of Medicine, 30-1 Oyaguchi-Kamicho, Itabashi-ku, Tokyo 173-8610, Japan; Department of Neurological Surgery, Nihon University School of Medicine, 30-1 Oyaguchi-Kamicho, Itabashi-ku, Tokyo 173-8610, Japan.
Abstract
BACKGROUND: Hypotension induced by spinal anesthesia for cesarean section causes a decrease in maternal regional cerebral blood volume and oxygenation. We used near-infrared spectroscopy to determine whether prophylactic infusion of phenylephrine attenuates these decreases. METHODS:Sixty patients undergoingbupivacaine spinal anesthesiafor cesarean section were randomly divided into one of three intravenous infusion groups: saline (P0), phenylephrine 25 (P25) or 50 µg/min (P50). Mean arterial pressure, heart rate and near-infrared spectroscopy measurements were made at one-minute intervals for 20 minutes, and oxyhemoglobin, deoxy-hemoglobin and total-hemoglobin concentrations and tissue oxygenation index were determined. Mean changes in the values between baseline and each measurement time after intrathecal injection were compared. RESULTS: Significant decreases in mean arterial pressure were seen in group P0 compared to P25 and P50 (P <0.01). Heart rate decreased in a dose-dependent manner during phenylephrine infusion (P0 vs. P25 and P50, P25 vs. P50; P <0.05). Significantly higher total-hemoglobin levels were observed in the phenylephrine groups versus the P0 group (P <0.01). The largest decrease in tissue oxygenation index was found in the P50, followed by P0 and P25 groups (P0 vs. P25 and P50, P25 vs. P50; P <0.05). CONCLUSION: Prophylactic infusion of phenylephrine, especially at 25 µg/min, can effectively suppress decreases in regional cerebral blood volume and regional cerebral blood oxygenation after induction of spinal anesthesia for cesarean section.
RCT Entities:
BACKGROUND:Hypotension induced by spinal anesthesia for cesarean section causes a decrease in maternal regional cerebral blood volume and oxygenation. We used near-infrared spectroscopy to determine whether prophylactic infusion of phenylephrine attenuates these decreases. METHODS: Sixty patients undergoing bupivacaine spinal anesthesia for cesarean section were randomly divided into one of three intravenous infusion groups: saline (P0), phenylephrine 25 (P25) or 50 µg/min (P50). Mean arterial pressure, heart rate and near-infrared spectroscopy measurements were made at one-minute intervals for 20 minutes, and oxyhemoglobin, deoxy-hemoglobin and total-hemoglobin concentrations and tissue oxygenation index were determined. Mean changes in the values between baseline and each measurement time after intrathecal injection were compared. RESULTS: Significant decreases in mean arterial pressure were seen in group P0 compared to P25 and P50 (P <0.01). Heart rate decreased in a dose-dependent manner during phenylephrine infusion (P0 vs. P25 and P50, P25 vs. P50; P <0.05). Significantly higher total-hemoglobin levels were observed in the phenylephrine groups versus the P0 group (P <0.01). The largest decrease in tissue oxygenation index was found in the P50, followed by P0 and P25 groups (P0 vs. P25 and P50, P25 vs. P50; P <0.05). CONCLUSION: Prophylactic infusion of phenylephrine, especially at 25 µg/min, can effectively suppress decreases in regional cerebral blood volume and regional cerebral blood oxygenation after induction of spinal anesthesia for cesarean section.