Anesthesia and analgesia
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Anesthesia and analgesia · Dec 1997
Randomized Controlled Trial Comparative Study Clinical TrialContribution of the spinal cord to arousal from inhaled anesthesia: comparison of epidural and intravenous fentanyl on awakening concentration of isoflurane.
To investigate the contribution of modulation of afferent nociceptive inputs by an opioid in the spinal cord to arousal from inhaled anesthesia, we determined the awakening concentration of isoflurane in 50 unpremedicated patients scheduled for abdominal hysterectomy. Patients were assigned randomly to three groups. Group I received bolus injections of both epidural and intravenous (I.V.) saline, followed by both epidural and I.V. infusions at the rate of 0.2 mL x kg(-1) h(-1). Group II received an I.V. injection of fentanyl 2 microg/kg, followed by an infusion at the rate of 25 ng x kg(-1) x min(-1), and Group III received an epidural injection and infusion in the same administration regimen as Group II. Anesthesia was induced with and maintained by isoflurane in an air/oxygen mixture (fraction of inspired oxygen = 0.5) with no adjuvant drugs. The study drug was administered at the start of retroperitoneal suturing. The awakening concentrations of isoflurane in Groups I, II, and III (mean +/- SD) were 0.32% +/- 0.07%, 0.31% +/- 0.06%, and 0.24% +/- 0.06%, respectively. At that time, plasma fentanyl concentrations in Groups II and III were 1.12 +/- 0.09 ng/mL and 0.65 +/- 0.04 ng/mL, respectively. Epidural fentanyl infusion reduced the awakening concentration of isoflurane more (P < 0.01) than I.V. fentanyl infusion, despite the lower plasma concentration (P < 0.01) in the epidural group. These findings suggest that epidural fentanyl delays arousal from inhaled anesthesia by modulating the afferent nociceptive inputs in the spinal cord. The spinal cord may contribute to arousal from inhaled anesthesia through the regulation of afferent inputs by opioids along with the supraspinal region of the central nervous system (CNS), even if the effects of subarachnoid fentanyl on the higher CNS via the cephalad migration is taken into consideration. ⋯ The present study revealed that the spinal cord, the lower level of central nervous system, contributed to arousal from general anesthesia, along with the higher central nervous system, by comparing the concentrations of an inhaled anesthetic, isoflurane, in the expiration of patients receiving systemic or regional administration of an opioid, fentanyl.
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Anesthesia and analgesia · Dec 1997
Meta AnalysisDrugs to minimize perioperative blood loss in cardiac surgery: meta-analyses using perioperative blood transfusion as the outcome. The International Study of Peri-operative Transfusion (ISPOT) Investigators.
Concern about the side effects of allogeneic red blood cell transfusion has increased interest in methods of minimizing perioperative transfusion. We performed meta-analyses of randomized trials evaluating the efficacy and safety of aprotinin, desmopressin, tranexamic acid, and epsilon-aminocaproic acid in cardiac surgery. All identified randomized trials in cardiac surgery were included in the meta-analyses. The primary outcome was the proportion of patients who received at least one perioperative allogeneic red cell transfusion. Sixty studies were included in the meta-analyses. The largest number of patients (5808) was available for the meta-analysis of aprotinin, which significantly decreased exposure to allogeneic blood (odds ratio [OR] 0.31, 95% confidence interval [CI] 0.25-0.39; P < 0.0001). The efficacy of aprotinin was not significantly different regardless of the type of surgery (primary or reoperation), aspirin use, or reported transfusion threshold. The use of aprotinin was associated with a significant decrease in the need for reoperation because of bleeding (OR 0.44, 95% CI 0.27-0.73; P = 0.001). Desmopressin was not effective, with an OR of 0.98 (95% CI 0.64-1.50; P = 0.92). Tranexamic acid significantly decreased the proportion of patients transfused (OR 0.50, 95% CI 0.34-0.76; P = 0.0009). Epsilon-aminocaproic acid did not have a statistically significant effect on the proportion of patients transfused (OR 0.20, 95% CI 0.04-1.12; P = 0.07). There were not enough patients to exclude a small but clinically important increase in myocardial infarction or other side effects for any of the medications. We conclude that aprotinin and tranexamic acid, but not desmopressin, decrease the number of patients exposed to perioperative allogeneic transfusions in association with cardiac surgery. ⋯ Aprotinin, desmopressin, tranexamic acid, and epsilon-aminocaproic acid are used in cardiac surgery in an attempt to decrease the proportion of patients requiring blood transfusion. This meta-analysis of all published randomized trials provides a good estimate of the efficacy of these medications and is useful in guiding clinical practice. We conclude that aprotinin and tranexamic acid, but not desmopressin, decrease the exposure of patients to allogeneic blood transfusion perioperatively in relationship to cardiac surgery.
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Anesthesia and analgesia · Dec 1997
Randomized Controlled Trial Comparative Study Clinical TrialPostoperative analgesic requirement after cesarean section: a comparison of anesthetic induction with ketamine or thiopental.
In a randomized, double-blind study, we compared postoperative pain and analgesic requirement in patients who underwent elective cesarean section under general anesthesia induced with thiopental 4 mg/kg (n = 20) or ketamine 1 mg/kg (n = 20). Anesthesia was maintained with nitrous oxide and isoflurane. Postoperative analgesia was provided by patient-controlled analgesia (PCA) using morphine. Median (range) time to first PCA demand was greater in the ketamine group (28 [3-134] min) compared with the thiopental group (20.5 [3-60] min; P = 0.04). Median (range) morphine consumption over 24 h was less in the ketamine group (24.3 [3-41] mg) compared with the thiopental group (35 [4-67] mg; P = 0.017). Visual analog scale pain scores were similar between groups. No patients had recall of intraoperative events or unpleasant dreams. Two patients in the thiopental group and one patient in the ketamine group had pleasant intraoperative dreams. Apgar scores were similar between groups. Median umbilical venous pH was higher (7.33 vs 7.31; P = 0.04) and attributable to lower median umbilical venous Pco2 (5.72 vs 6.14 kPa; P = 0.02) in the ketamine group compared with the thiopental group. Induction of anesthesia for cesarean section using ketamine is associated with a lower postoperative analgesic requirement compared with thiopental. ⋯ Patients who had anesthesia for cesarean section induced with ketamine required less analgesic drugs in the first 24 h compared with patients who received thiopental. Ketamine, unlike thiopental, has analgesic properties that may reduce sensitization of pain pathways and extend into the postoperative period.
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Anesthesia and analgesia · Dec 1997
Randomized Controlled Trial Clinical TrialThe effects of epsilon-aminocaproic acid on fibrinolysis and thrombin generation during cardiac surgery.
Despite the efficacy of antifibrinolytic drugs in reducing bleeding after cardiac surgery, concerns remain regarding their potential to promote thrombosis. We examined the effect of the antifibrinolytic drug, epsilon-aminocaproic acid (EACA) on fibrinolysis and thrombin generation during cardiac surgery. Forty-one adults undergoing primary coronary artery bypass graft surgery requiring cardiopulmonary bypass (CPB) were prospectively randomized in a double-blind trial to receive either saline or EACA. A loading dose of 150 mg/kg EACA was given before anesthetic induction, followed by a 15 mg x kg(-1) x h(-1) infusion, which continued until 3 h after CPB. Plasma samples for the measurement of D-dimer, thrombin-antithrombin III, and soluble fibrin were obtained before surgery, 1 h on CPB, and 3 and 20 h after CPB. In the EACA group, fibrinolytic activity, as measured by D-dimer, was significantly decreased 3 h after CPB, (0.51 +/- 0.15 mg/L vs 1.13 +/- 0.14 mg/L, P < 0.005). Decreased fibrinolytic activity was accompanied by decreased bleeding in the EACA group (660 +/- 127 mL vs 931 +/- 113 mL, P < 0.05). No differences in the generation of thrombin or soluble fibrin were apparent between the two groups. Suppression of fibrinolytic activity in the absence of concomitant reductions in thrombin generation suggests that EACA could potentiate a hypercoagulable prethrombotic state in the perioperative setting. ⋯ In a randomized, prospective trial of primary cardiac surgery, we demonstrated that the synthetic antifibrinolytic drug epsilon-aminocaproic acid suppresses fibrinolysis with no effects on thrombin generation. These results suggest the potential for synthetic antifibrinolytic drugs to induce a hypercoagulable prethrombotic state in the perioperative setting.
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Anesthesia and analgesia · Dec 1997
Randomized Controlled Trial Clinical TrialReversal of neuromuscular blockade with neostigmine has no effect on the incidence or severity of postoperative nausea and vomiting.
We performed this randomized, double-blind, placebo-controlled study to determine whether reversal of neuromuscular block with neostigmine increases the incidence and severity of postoperative nausea and vomiting (PONV). We studied 162 women undergoing abdominal hysterectomy and randomly allocated them into two groups. In Group A, neuromuscular block produced with mivacurium was antagonized with neostigmine 2.0 mg and glycopyrrolate 0.4 mg intravenously, whereas Group B received no drugs to facilitate antagonism of blockade. The incidence and severity of PONV was assessed up to 27 h after the operation. There was no difference in PONV between the groups (in Group A 35% had nausea and 33% vomited; in Group B 28% nauseated and 40% vomited) or in the amount of antiemetics given. We had a 75% chance to find a 30% difference in PONV. We conclude that the administration of neostigmine and glycopyrrolate at the end of anesthesia to reverse neuromuscular block does not increase the incidence or severity of PONV. ⋯ Neostigmine may increase postoperative nausea and vomiting. In this study, omission of reversal of neuromuscular block with neostigmine failed to decrease the incidence or severity of postoperative nausea and vomiting.