Anesthesia and analgesia
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Anesthesia and analgesia · Apr 1999
Randomized Controlled Trial Comparative Study Clinical TrialOnset time, recovery duration, and drug cost with four different methods of inducing general anesthesia.
We compared two conventional induction techniques (thiopental and propofol), an inhaled induction with sevoflurane using a circle system, and a rebreathing method. Fentanyl 1 microg/kg was given to women undergoing 10- to 20-min procedures. Anesthesia was induced (n = 20 each) with one of the following: 1) sevoflurane and N2O from a rebreathing bag (Sevo/Bag). A 5-L bag was prefilled with a mixture of sevoflurane 7% and N2O 60% in oxygen. The bag was connected between the normal circle system, separated by a spring-loaded valve; 2) sevoflurane 8% and N2O 60% from a circle system on a conventional anesthesia machine with a total fresh gas flow of 6 L/min (Sevo/Circle); 3) propofol 3 mg/kg as an i.v. bolus; 4) thiopental sodium 5 mg/kg as an i.v. bolus. Postoperative nausea and vomiting was treated with ondansetron. Induction times were comparable with each method. Recovery duration was shortest with sevoflurane, intermediate with propofol, and longest with thiopental. Induction drug costs were lowest with Sevo/Bag and thiopental, intermediate with Sevo/Circle, and highest with propofol. However, sevoflurane (by either method) caused considerable nausea and vomiting that required treatment. Consequently, total drug cost was least with thiopental, intermediate with Sevo/Bag and propofol, and greatest with Sevo/Circle. Thus, no single technique was clearly superior. ⋯ Anesthetic induction techniques influence awakening time, recovery duration, and drug costs. We tested two i.v. methods and two inhaled techniques. However, none of the four tested methods was clearly superior to the others.
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Anesthesia and analgesia · Apr 1999
Randomized Controlled Trial Comparative Study Clinical TrialLess core hypothermia when anesthesia is induced with inhaled sevoflurane than with intravenous propofol.
Hypothermia after the induction of anesthesia results initially from core-to-peripheral redistribution of body heat. Sevoflurane and propofol both inhibit central thermoregulatory control, thus causing vasodilation. Propofol differs from sevoflurane in producing substantial peripheral vasodilation. This vasodilation is likely to facilitate core-to-peripheral redistribution of heat. Once heat is dissipated from the core, it cannot be recovered. We therefore tested the hypothesis that the induction of anesthesia with i.v. propofol causes more core hypothermia than induction with inhaled sevoflurane. We studied patients undergoing minor oral surgery randomly assigned to anesthetic induction with either 2.5 mg/kg propofol (n = 10) or inhalation of 5% sevoflurane (n = 10). Anesthesia in both groups was subsequently maintained with sevoflurane and 60% nitrous oxide in oxygen. Calf minus toe skin temperature gradients <0 degrees C were considered indicative of significant vasodilation. Ambient temperature and end-tidal concentrations of maintenance sevoflurane were comparable in each group. Patients in both groups were vasodilated throughout most of the surgery. Nonetheless, core temperatures in patients who received propofol were significantly lower than those in patients who received inhaled sevoflurane. These data support our hypothesis that even a brief period of vasodilation causes substantial redistribution hypothermia that persists throughout surgery. ⋯ Core temperatures in patients who received i.v. propofol were consistently lower than those in patients who received inhaled sevoflurane, although anesthesia was subsequently maintained with sevoflurane in nitrous oxide in both groups. This suggests that even a brief period of propofol-induced vasodilation during anesthetic induction causes substantial redistribution hypothermia that persists throughout surgery.
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Anesthesia and analgesia · Apr 1999
Randomized Controlled Trial Clinical TrialOptimization of the dose of intrathecal morphine in total hip surgery: a dose-finding study.
We designed this study to determine the optimal intrathecal dose of morphine in total hip surgery. The optimal intrathecal dose was defined as that providing effective analgesia and minimal side effects 24 h after total hip surgery. Patients (n = 143) scheduled for total hip surgery were randomized to four double-blinded groups with a standardized bupivacaine dose but different doses of intrathecal morphine (Group I = 0.025 mg, Group II = 0.05 mg, Group III = 0.1 mg, and Group IV = 0.2 mg). Pain scores, i.v. morphine intake (patient-controlled analgesia), and morphine-related side effects (respiratory depression, postoperative nausea and vomiting, itching, urinary retention) were recorded for 24 h after surgery. Excellent postoperative pain relief was present in all groups. The highest pain scores were found in Group I. The mean use of systemic morphine administered by patient-controlled analgesia infusion pump was 23.7, 17.8, 10.9, and 9.9 mg in Groups I-IV, respectively (P < 0.01 for Groups III and IV versus Group I). We conclude that 0.1 mg of intrathecal morphine is the optimal dose for pain relief after hip surgery with minimal side effects. ⋯ Earlier studies showed excellent postoperative pain relief after intrathecal morphine. However, the severity of side effects resulted in decreased enthusiasm for this anesthesia technique. In the present study, we show that an intrathecal dose of 0.1 mg of morphine can be used safely in total hip surgery with excellent postoperative pain relief.
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Anesthesia and analgesia · Apr 1999
Randomized Controlled Trial Comparative Study Clinical TrialThe effect of stimulus frequency on the analgesic response to percutaneous electrical nerve stimulation in patients with chronic low back pain.
Low back pain (LBP) is one of the most common medical problems in our society. Increasingly, patients are turning to nonpharmacologic analgesic therapies such as percutaneous electrical nerve stimulation (PENS). We designed this sham-controlled study to compare the effect of three different frequencies of electrical stimulation on the analgesic response to PENS therapy. Sixty-eight consenting patients with LBP secondary to degenerative lumbar disc disease were treated with PENS therapy at 4 Hz, alternating 15 Hz and 30 Hz (15/30 Hz), and 100 Hz, as well as sham-PENS (0 Hz), according to a randomized, cross-over study design. Each treatment was administered for a period of 30 min three times per week for 2 wk. The pre- and posttreatment assessments included the health status survey short form and visual analog scales for pain, physical activity, and quality of sleep. After receiving all four treatments, patients completed a global assessment questionnaire. The sham-PENS treatments failed to produce changes in the degree of pain, physical activity, sleep quality, or daily intake of oral analgesic medications. In contrast, 4-Hz, 15/30-Hz, and 100-Hz stimulation all produced significant decreases in the severity of pain, increases in physical activity, improvements in the quality of sleep, and decreases in oral analgesic requirements (P < 0.01). Of the three frequencies, 15/30 Hz was the most effective in decreasing pain, increasing physical activity, and improving the quality of sleep (P < 0.05). In the global assessment, 40% of the patients reported that 15/30 Hz was the most desirable therapy, and it was also more effective in improving the patient's sense of well-being. We conclude that the frequency of electrical stimulation is an important determinant of the analgesic response to PENS therapy. Alternating stimulation at 15-Hz and 30-Hz frequencies was more effective than either 4 Hz or 100 Hz in improving outcome measures in patients with LBP. ⋯ The frequency of electrical stimulation seems to be an important determinant of the analgesic efficacy of percutaneous electrical nerve stimulation. Mixed low- and high-frequency stimulation was more effective than either low or high frequencies alone in the treatment of patients with low back pain.