Anesthesia and analgesia
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Anesthesia and analgesia · Apr 2002
Comment Letter Randomized Controlled Trial Comparative Study Clinical TrialReduction of pain on injection of propofol: a comparison of fentanyl with remifentanil.
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Anesthesia and analgesia · Apr 2002
Meta AnalysisA quantitative, systematic review of randomized controlled trials of ephedrine versus phenylephrine for the management of hypotension during spinal anesthesia for cesarean delivery.
This quantitative systematic review compared the efficacy and safety of ephedrine with phenylephrine for the prevention and treatment of hypotension during spinal anesthesia for cesarean delivery. Seven randomized controlled trials (n = 292) were identified after a systematic search of electronic databases (MEDLINE, EMBASE, The Cochrane Controlled Trials Registry), published articles, and contact with authors. Outcomes assessed were maternal hypotension, hypertension and bradycardia, and neonatal umbilical cord blood pH values and Apgar scores. For the management (prevention and treatment) of maternal hypotension, there was no difference between phenylephrine and ephedrine (relative risk [RR] of 1.00; 95% confidence interval [CI], 0.96-1.06). Maternal bradycardia was more likely to occur with phenylephrine than with ephedrine (RR of 4.79; 95% CI, 1.47-15.60). Women given phenylephrine had neonates with higher umbilical arterial pH values than those given ephedrine (weighted mean difference of 0.03; 95% CI, 0.02-0.04). There was no difference between the two vasopressors in the incidence of true fetal acidosis (umbilical arterial pH value of <7.2; RR of 0.78; 95% CI, 0.16-3.92) or Apgar score of <7 at 1 and 5 min. This systematic review does not support the traditional idea that ephedrine is the preferred choice for the management of maternal hypotension during spinal anesthesia for elective cesarean delivery in healthy, nonlaboring women. ⋯ Phenylephrine and ephedrine to manage hypotension during spinal anesthesia for elective cesarean delivery were compared in this systematic review. Women given ephedrine had neonates with lower umbilical cord blood pH values compared with those given phenylephrine. However, no differences in the incidence of fetal acidosis (pH value of <7.2) or neonatal Apgar scores were found.
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Anesthesia and analgesia · Apr 2002
Randomized Controlled Trial Comparative Study Clinical TrialA comparison of epidural infusions in the combined spinal/epidural technique for labor analgesia.
We compared the clinical effects of three epidural infusions initiated after subarachnoid medication was administered as part of the combined spinal/epidural technique for labor analgesia. Fifteen minutes after administering subarachnoid fentanyl 25 microg and 1 mL of bupivacaine 0.25%, and 5 min after an epidural test dose of 3 mL of bupivacaine 0.25%, women were randomized to receive an epidural infusion of saline, bupivacaine 0.125%, bupivacaine 0.0625%, or bupivacaine 0.04% with epinephrine 1:600,000. All epidural infusions were started at 10 mL/h, and all except the Saline Group also received fentanyl 2 microg/mL. The end point of the study was delivery or request for additional medication for analgesia. We found that time until request for additional analgesia was longest in women who received bupivacaine 0.125% (median duration, 300 min) versus saline (median duration, 118 min) (P = 0.0001) and was intermediate for bupivacaine 0.0625% and bupivacaine 0.04% (median duration, 162 and 180 min, respectively) (P = 0.0001 versus saline). Women who received bupivacaine 0.125% had the most motor block. We conclude that all the bupivacaine-based infusions we tested maintained the analgesia from subarachnoid medication longer than saline, with the longest duration, but the most motor block, from bupivacaine 0.125%. ⋯ In this prospective, randomized, and double-blinded study we found that initiating an epidural infusion of bupivacaine 0.125% with fentanyl 2 microg/mL at 10 mL/h 15 min after subarachnoid fentanyl 25 microg with 1 mL of bupivacaine 0.25%, followed by an epidural test dose of 3 mL of bupivacaine 0.25%, maintained the analgesia for longer but with more motor block than with either bupivacaine 0.04% or bupivacaine 0.0625%.
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Anesthesia and analgesia · Apr 2002
Randomized Controlled Trial Clinical TrialThe effects of intravenous almitrine on oxygenation and hemodynamics during one-lung ventilation.
One-lung ventilation (OLV) induces an increase in pulmonary shunt sometimes associated with a decrease in PaO2 despite ventilation with 100% oxygen. PaO2 improvement has been reported in one-lung ventilated animals receiving IV almitrine, a pulmonary vasoconstrictor. We evaluated the ability of almitrine to prevent a decrease in PaO2 during OLV. Patients without pulmonary hypertension undergoing OLV for lung surgery were randomly assigned to receive either placebo (Group P, n = 8) or almitrine infusion at a rate of 8 microg x kg(-1) x min(-1) (Group A, n = 8) from the start of OLV. Gasometric and hemodynamic values were recorded with the patient in the lateral decubitus position during two-lung ventilation and at 10-min intervals during OLV over a 30-min period (OLV-10, OLV-20, OLV-30). Compared with the values found during two-lung ventilation (434 +/- 22 mm Hg in Group P and 426 +/- 23 mm Hg in Group A), PaO2 decreased at OLV-10 (305 +/- 46 mm Hg), OLV-20 (203 +/- 20 mm Hg), and OLV-30 (178 +/- 18 mm Hg) in Group P (P < 0.05) and at OLV-20 (354 +/- 25 mm Hg) and OLV-30 (325 +/- 17 mm Hg) in Group A (P < 0.05). PaO2 values differed between the groups at OLV-20 and OLV-30 (P < 0.05). Pulmonary artery pressure and cardiac output did not change. In conclusion, 8 microg x kg(-1) x min(-1) IV almitrine prevents and limits the OLV-induced decrease in PaO2 without causing any hemodynamic modification. ⋯ Eight microg x kg(-1) x min(-1) IV almitrine limits one-lung ventilation-induced decrease in PaO2 without causing any hemodynamic modification in patients without pulmonary hypertension.
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Anesthesia and analgesia · Apr 2002
The differential effect of halothane and 1,2-dichlorohexafluorocyclobutane on in vitro muscle contractures of patients susceptible to malignant hyperthermia.
Malignant hyperthermia (MH) is an autosomal dominant, potentially fatal pharmacogenetic disorder of skeletal muscle. Approximately half of all known MH families show a linkage to the ryanodine receptor type 1 (RY1) gene. Although our knowledge of the diagnosis, genetics, and therapy of MH has improved, the exact pathogenesis and the role of volatile anesthetics as trigger substances for an MH crisis remain unknown. Compounds that do not obey the Meyer-Overton hypothesis (i.e., nonimmobilizers) are today an important part of research on anesthetic mechanisms. We designed this study to test the hypothesis that the nonimmobilizer 1,2-dichlorohexafluorocyclobutane (2N) compared with halothane has different effects on in vitro muscle contractures of muscle bundles from MH-susceptible (MHS) individuals. In vitro muscle contracture tests were performed with either halothane (approximately 660 microM, equivalent to approximately 4 minimum alveolar anesthetic concentration [MAC]) or 2N ( approximately 100 microM, equivalent to approximately 5 times predicted MAC). MAC is defined as the anesthetic concentration that prevents nocifensive movements after a surgical stimulus in 50% of subjects. In contrast to halothane, 2N caused only minimal muscle contractures in muscle bundles from six MHS patients (0.13 g [0.04-0.31 g] vs 1.95 g [1.60-4.70 g], median values and ranges; P = 0.004). Halothane and 2N differ in their effects on muscle contractures of MHS individuals, possibly because of a differing action on MH RY1. ⋯ Using in vitro contracture tests, we showed that halothane and the nonimmobilizer 1,2-dichlorohexafluorocyclobutane differ in their effects on contractures of muscle bundles from individuals susceptible to malignant hyperthermia (MH) as a result of their differing action on MH ryanodine receptors. These findings render this receptor a possible molecular target for volatile anesthetic action.