Anesthesia and analgesia
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Anesthesia and analgesia · Aug 1999
Randomized Controlled Trial Comparative Study Clinical TrialA cost comparison of methohexital and propofol for ambulatory anesthesia.
Methohexital is eliminated more rapidly than thiopental, and early recovery compares favorably with propofol. We designed this study to evaluate the recovery profile when methohexital was used as an alternative to propofol for the induction of anesthesia before either sevoflurane or desflurane in combination with nitrous oxide. One hundred twenty patients were assigned randomly to one of four anesthetic groups: (I) methohexital-desflurane, (II) methohexital-sevoflurane, (III) propofol-desflurane, or (IV) propofol-sevoflurane. Recovery times after the anesthetic drugs, as well as the perioperative side effect profiles, were similar in all four groups. A cost-minimization analysis revealed that methohexital was less costly for the induction of anesthesia. At the fresh gas flow rates used during this study, the costs of the volatile anesthetics for maintenance of anesthesia did not differ among the four groups. However, at low flow rates (< or = 1 L/min), the methohexital-desflurane group would have been the least expensive anesthetic technique. In conclusion, methohexital is a cost-effective alternative to propofol for the induction of anesthesia in the ambulatory setting. At low fresh gas flow rates, the methohexital-desflurane combination was the most cost-effective for the induction and maintenance of general anesthesia. ⋯ Using methohexital as an alternative to propofol for the induction of anesthesia for ambulatory surgery seems to reduce drug costs. When fresh gas flow rates < or = 1 L/min are used, the combination of methohexital for the induction and desflurane for maintenance may be the most cost-effective general anesthetic technique for ambulatory surgery.
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Anesthesia and analgesia · Aug 1999
Randomized Controlled Trial Clinical TrialJugular bulb oxygen saturation during propofol and isoflurane/nitrous oxide anesthesia in patients undergoing brain tumor surgery.
We investigated, in brain tumor patients, the jugular bulb venous oxygen partial pressure (PjO2) and hemoglobin saturation (SjO2), the arterial to jugular bulb venous oxygen content difference (AJDO2), and middle cerebral artery blood flow velocity (Vmca) during anesthesia, and the effect of hyperventilation on these variables. Twenty patients were randomized to receive either isoflurane/ nitrous oxide/fentanyl (Group 1) or propofol/fentanyl (Group 2). At normoventilation (PacO2 35 +/- 2 mm Hg in Group 1 and 33 +/- 3 mm Hg in Group 2), SjO2 and PjO2 were significantly higher in Group 1 than in Group 2 (SjO2 60% +/- 6% and 49% +/- 13%, respectively; P = 0.019) (PjO2 32 +/- 3 and 27 +/- 5 mm Hg, respectively; P = 0.027). In Group 2, 5 of 10 patients had SjO2 < 50%, and 3 of these patients had SjO2 < 40% and AJDO2 > 9 mL/dL. All patients in Group 1 had SjO2 > 50%. During hyperventilation, there were no differences in SjO2, PjO2, or AJDO2 between the two groups. On hyperventilation, there was no correlation between the relative decreases of Vmca and 1/AJDO2 (r = 0.21, P = 0.41). The results indicate during propofol anesthesia, half of the brain tumor patients showed signs of cerebral hypoperfusion, but not during isoflurane/nitrous oxide anesthesia. Furthermore, during PacO2 manipulations, shifts in Vmca are inadequate to evaluate brian oxygen delivery in these patients. ⋯ During propofol anesthesia at normoventilation, 50% of brain tumor patients showed signs suggesting cerebral hypoperfusion, but this could not be demonstrated during isoflurane/nitrous oxide anesthesia. During PacO2 manipulations, consecutive measurements of the cerebral blood flow velocity may be inadequate to assess cerebral oxygenation.
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Anesthesia and analgesia · Aug 1999
Randomized Controlled Trial Clinical TrialPreoperative small-dose ketamine has no preemptive analgesic effect in patients undergoing total mastectomy.
We evaluated the preemptive analgesic effect of a small dose of ketamine given before or immediately after surgery in a randomized, double-blinded study performed in 128 women undergoing total mastectomy. Group 1 patients received ketamine 0.15 mg/kg as a 5-mL i.v. injection 5 min before surgery and isotonic saline 5 mL i.v. at the time of skin closure. Group 2 received 5 mL i.v. of isotonic saline, then 0.15 mg/kg i.v. ketamine. A standard general anesthesia procedure including sufentanil was used. In the recovery room, patient-controlled analgesia i.v. morphine was used for postoperative analgesia. Postoperative pain was assessed by measuring morphine consumption and visual analog scale pain scores. No significant intergroup differences were seen in the pain scores. Patient-controlled analgesia morphine consumption was lower during the first 2 h after surgery in patients given ketamine at the time of skin closure. No patient complained of hallucinations or nightmares. The incidence of adverse effects was not different between the two groups. In conclusion, administering ketamine at the end of surgery is more effective in reducing morphine consumption than it is when given before surgery. ⋯ We administered the same small dose of ketamine before or after surgery. The preoperative administration of 0.15 mg/kg ketamine in patients undergoing total mastectomy did not elicit a preemptive analgesic effect. Ketamine given at closure reduced the patient-controlled analgesia morphine requirement in the first 2 h after surgery.
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Anesthesia and analgesia · Aug 1999
Randomized Controlled Trial Clinical TrialPleural bupivacaine for pain treatment after nephrectomy.
The efficacy of pleural analgesia after nephrectomy is controversial. We therefore evaluated i.v. opioid requirements in patients with and without pleural bupivacaine. Patients undergoing elective nephrectomy were randomly assigned to receive postoperative i.v. piritramid alone (n = 18) or piritramid combined with pleural bupivacaine (n = 19). In the patients assigned to receive pleural analgesia, boluses of 20 mL of 0.25% bupivacaine were given at 6-h intervals via an pleural catheter that was inserted in the medial axillary line at the sixth intercostal space. Pain scores (10-cm visual analog scale) and opioid requirements were recorded over the first 2 postoperative days. One hour after pleural puncture, a chest radiograph was performed. The catheter was removed 48 h after insertion. Patient characteristics were similar in each group, as was the duration of surgery. Pain scores were similar in each group: 3.0 +/- 2.5 in those given pleural bupivacaine and 3.1 +/- 2.7 in those given piritramid alone. However, the piritramid requirement was significantly less in those given pleural bupivacaine (23 +/- 3 mg) than in those given piritramid alone (45 +/- 6 mg). Furthermore, the time from completion of surgery until the first opioid request was significantly longer in the patients who received bupivacaine (4.7 +/- 1.0 vs 2.8 +/- 1.0 h). One patient had a small pneumothorax that resolved without treatment. These data indicate that pleural analgesia is effective and provides a significant opioid-sparing effect. ⋯ We conclude that pleural analgesia significantly prolongs the time until postoperative opioid was first requested and halves the total required dose. These data indicate that pleural analgesia is effective and provides a significant opioid-sparing effect.
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Anesthesia and analgesia · Aug 1999
Randomized Controlled Trial Clinical TrialIntraoperative phenylephrine infusion decreases the magnitude of redistribution hypothermia.
Core hypothermia during the first hour after induction of general anesthesia results largely from an internal core-to-peripheral redistribution of body heat. This redistribution results from both central inhibition of tonic thermoregulatory vasoconstriction in the arteriovenous shunt and anesthetic-induced vasodilation. We therefore tested the hypothesis that acute administration of phenylephrine, a pure alpha-adrenergic agonist, reduces the magnitude of anesthetic-induced core-to-peripheral redistribution of body heat. Patients undergoing minor oral surgery were randomly assigned to an infusion of 0.5 microgram.kg-1.min-1 phenylephrine i.v. or no treatment (control). The phenylephrine infusion was started immediately before anesthesia was induced with 2.5 mg/kg propofol i.v. Subsequently, anesthesia was maintained with sevoflurane and 60% nitrous oxide in oxygen. Calf minus toe, skin-temperature gradients < 0 degree C were considered indicative of significant arteriovenous shunt vasodilation. Ambient temperature and end-tidal concentrations of maintenance sevoflurane were comparable in each group. Although there were no significant differences in skin-temperature gradients, core temperatures in the untreated patients decreased significantly more (1.2 +/- 0.4 degrees C) than in those given phenylephrine (0.5 +/- 0.2 degree C, P < 0.001). These data suggest that maintaining precapillary vasoconstriction of blood vessels, not in the arteriovenous shunt reduces the magnitude of redistribution hypothermia. ⋯ Core hypothermia immediately after induction of general anesthesia results largely from core-to-peripheral redistribution of body heat. Core temperature reduction during the first hour of anesthesia decreased less in patients given phenylephrine than in untreated controls. These data suggest that maintaining precapillary vasoconstriction possibly reduces the magnitude of redistribution hypothermia.