Bupivacaine cardiotoxicity is related to increased brain sensitivity.
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Animals↗
Biomedical subjects
M C Norris
Publications and source records attributed to M C Norris.
Preoxygenation for cesarean section: a comparison of two techniques.
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Adult↗
Intrathecal sufentanil (5 vs. 10 microg) for labor analgesia: efficacy and side effects.
BACKGROUND AND OBJECTIVES: Despite growing popularity, there are few studies examining the relative efficacy of different doses of intrathecal sufentanil for labor analgesia. This prospective, randomized, double-blind study compared the efficacy and side effects of 5 and 10 microg intrathecal sufentanil. METHODS: Sixty-three healthy, laboring, term parturients < or =5 cm cervical dilation participated in this study. In a randomized, double-blind fashion, patients received 5 or 10 microg intrathecal sufentanil as part of a combined spinal epidural technique. Patients rated pain, itching, nausea, and sedation on verbal analog scales before and every 10 minutes after drug injection. We also recorded maternal blood pressure and peripheral oxygen saturation before and every 10 minutes after drug injection. Before and 30 and 60 minutes after drug injection, we measured maternal end-tidal CO2. RESULTS: Both doses of sufentanil provided adequate analgesia. Although 10 microg sufentanil produced slightly more profound analgesia, the duration of pain relief did not differ between the two groups. Both drug doses were associated with significant increases in itching and end-tidal CO2. The 10-microg dose was associated with more sedation and a greater decrease in SaO2. CONCLUSIONS: Both 5 and 10 microg intrathecal sufentanil provided adequate labor analgesia. Both doses were associated with measurable spinal (itching) and supraspinal (sedation, respiratory depression) side effects.
Adult↗
Continuous spinal anesthesia after unintentional dural puncture in parturients.
Headache after unintentional dural puncture with 17- or 18-gauge needles represents a significant source of anesthetic-induced maternal morbidity. We performed this study to determine whether inserting a catheter into the subarachnoid space after dural puncture can significantly alter the incidence of headache. Thirty-five women, requesting labor analgesia, suffered a dural puncture during attempts to identify the epidural space using an 18-gauge Hustead needle (bevel oriented parallel to the longitudinal axis of the back). Subsequently, the anesthesiologist inserted a 20-gauge polyamide catheter into the CSF and provided continuous spinal anesthesia throughout labor and delivery. A second group of 21 women suffered dural puncture with the same epidural technique but without subarachnoid catheter insertion. These women subsequently received lumbar epidural anesthesia. After delivery, we visited all women daily until discharge and questioned them about the presence and severity of headache. Neither the incidence of headache nor the need for therapeutic blood patch differed significantly between the two groups of women. No other anesthetic related complications ensued. Continuous spinal anesthesia after unintentional dural puncture does not decrease the incidence of headache in parturients.
Analgesia, Obstetrical↗
Does continuous intravenous infusion of low-concentration epinephrine impair uterine blood flow in pregnant ewes?
BACKGROUND AND OBJECTIVES: Bolus intravenous injection of epinephrine can decrease uterine blood flow. This study examined the effects of intravenous infusion of epinephrine on uterine blood flow in the gravid ewe. METHODS: Maternal and fetal vascular catheters and a maternal electromagnetic uterine artery flow probe were implanted in 10 near-term gravid ewes. After recovery, saline, 0.125% bupivacaine, 0.125% bupivacaine with 1:200,000 epinephrine, 0.125% bupivacaine with 1:400,000 epinephrine, and 0.125% bupivacaine with 1:800,000 epinephrine were infused into the maternal superior vena cava. Drugs were infused at 10 mL/h for 30 minutes and then at 20 mL/h for an additional 30 minutes. Animals also received an intravenous bolus of epinephrine 15 micrograms. Throughout all infusions, maternal heart rate, systemic and pulmonary blood pressures, uterine blood flow, cardiac output, and acid-base balance were measured, as well as fetal heart rate, blood pressure, and acid-base balance. RESULTS: Epinephrine 15 micrograms decreased uterine blood flow to 68 +/- 14% of baseline (mean +/- SD). Infusion of all solutions had no effect on any measured hemodynamic variable. CONCLUSIONS: In gravid ewes, intravenous infusion of < or = 1.67 micrograms/min epinephrine altered neither maternal hemodynamics nor uterine blood flow. To the extent that sheep data can be extrapolated to humans, these results suggest that continuous intravenous infusion of epinephrine in local anesthetic solutions is safe if the epidural catheter should enter a blood vessel during the infusion.
Anesthesia, Obstetrical↗
Spinal anesthesia for cesarean delivery. A comparison of two doses of hyperbaric bupivacaine.
BACKGROUND AND OBJECTIVES: Hyperbaric local anesthetic pools in the thoracic spinal curvature in supine patients. The authors hypothesized that patients receiving 12 or 15 mg of hyperbaric bupivacaine would achieve similar levels of sensory block but the spinal anesthetic would be denser and longer lasting in patients receiving the 15 mg dose. METHODS: Twenty eight healthy term parturients scheduled for elective cesarean delivery randomly received 12 or 15 mg hyperbaric 0.75% bupivacaine in 8.25% dextrose. Patients were in the right lateral position during drug injection and were then positioned supine with left uterine displacement on a horizontal operating table. A blinded anesthesiologist assessed the dermatome level of sensory analgesia to pinprick every 2 minutes for 20 minutes, then every 15 minutes until the sensory level regressed to T10. RESULTS: The mean level of sensory anesthesia was 2.2 spinal segments higher in patients receiving 15 mg versus 12 mg hyperbaric bupivacaine (24.8 +/- 3.7 versus 22.6 +/- 1.4 spinal segments; P = .031). Regression to T10 occurred more quickly in the 12 mg than in the 15 mg group (140.0 +/- 16.5 versus 162.1 +/- 33.8 minutes, P = .046). Patient height did not correlate with the maximum number of spinal segments blocked in either group. All patients had adequate surgical anesthesia. CONCLUSIONS: Parturients receiving 15 mg of hyperbaric bupivacaine developed a higher mean level and longer duration of sensory analgesia than those receiving 12 mg.
Adult↗
Do patient variables influence the subarachnoid spread of hyperbaric lidocaine in the postpartum patient?
BACKGROUND AND OBJECTIVES: Age, height, weight, body mass index (weight/height2), and vertebral column length may affect the subarachnoid spread of local anesthetics. Little information exists concerning the relationship between these variables and the spread of hyperbaric lidocaine. The authors studied the influence of patient demographics on the block produced by hyperbaric lidocaine in women undergoing postpartum tubal ligation. METHODS: Within 48 hours of vaginal delivery, the authors studied 44 ASA class 1-2 women agreeing to spinal anesthesia for postpartum tubal ligation. Before induction of anesthesia, the authors weighed each patient, measured her height and vertebral column length, and calculated body mass index. In a standardized manner, the authors induced spinal anesthesia with 5% lidocaine 75 mg. An observer, blinded to the measured variables, evaluated loss-of-temperature sensation and loss-of-sensation of sharpness to pinprick bilaterally every 5 minutes for 30 minutes and again at 45 and 60 minutes. RESULTS: There was no correlation between age, weight, body mass index, vertebral column length, or time from delivery to placement of the block, and the spread of sensory block after subarachnoid injection of hyperbaric lidocaine. Only height weakly correlated with the spread of block (r2 = 0.15). CONCLUSIONS: While height may have some small influence on the spread of sensory block, the variation in spread of block within patients of the same height is large. The data suggest that adjusting the dose of local anesthetic injected based on differences in patient height would provide no clinically significant benefit.
Adult↗
Subarachnoid labor analgesia. Fentanyl and morphine versus sufentanil and morphine.
BACKGROUND AND OBJECTIVES: To compare the duration of pain relief and incidence of side effects using two subarachnoid administered drug combinations for labor analgesia: fentanyl 25 micrograms with morphine 0.25 mg or sufentanil 10 micrograms with morphine 0.25 mg. METHODS: Thirty healthy term primagravid patients with cervical dilation < or = 5 cm consented to participate in this prospective, randomized, double-blind study. Patients received the assigned drug combination subarachnoid with simultaneous epidural catheter placement using a double needle technique. The authors recorded blood pressure and patient's rated pain, nausea, and pruritus using 10-cm visual analog scales at 0, 5, 10, 15, 20, 25, 30, and every 30 minutes until the patient requested additional analgesia. RESULTS: The onset of analgesia was rapid in both groups. The mean duration of analgesia was similar; 114 +/- 55 minutes in the fentanyl and morphine group and 134 +/- 79 minutes in the sufentanil and morphine group. The sufentanil and morphine group experienced more severe pruritus (P = .015). CONCLUSIONS: Both fentanyl and morphine and sufentanil and morphine provide adequate labor analgesia for about 2 hours. Patients who receive sufentanil experience more severe pruritus.
Adult↗
A comparison of meperidine and lidocaine for spinal anesthesia for postpartum tubal ligation.
BACKGROUND AND OBJECTIVES: This study compares the anesthetic potency, duration, and side effects of subarachnoid meperidine and lidocaine for postpartum tubal ligation. METHOD: Twenty healthy, unpremedicated postpartum women gave written informed consent to participate in this randomized double-blind study. After intravenous infusion of 200 mL physiologic salt solution, patients received subarachnoid injections from either lidocaine 70 mg in 7.5% glucose or meperidine 60 mg in saline while lying in the right lateral position. Heart rate, blood pressure, sensory and motor block, pain, nausea, and pruritus were recorded at intervals for up to 12 hours after injection. The time to first postoperative analgesic was also recorded. RESULTS: There were no differences between the groups in demographics, heart rate, or blood pressure at any time. Sensory or motor block developed slightly faster in the lidocaine group. One patient in each group required general anesthesia owing to inadequate sensory block. Beginning at 60 minutes, meperidine patients experienced more pruritus (P < .05). Lidocaine patients had more postoperative pain (P < .01) and required supplemental analgesia 83.3 +/- 32.7 minutes after induction versus 447.6 +/- 184.0 minutes in the meperidine group. No patient's oxygen saturation fell below 95%. Patients expressed equal satisfaction with both agents. CONCLUSION: Subarachnoid meperidine and lidocaine both provide adequate anesthesia for postpartum tubal ligation. Meperidine provided longer postoperative analgesia.
Adult↗