Anesthesia and analgesia
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Anesthesia and analgesia · May 2004
ReviewA qualitative systematic review of the role of N-methyl-D-aspartate receptor antagonists in preventive analgesia.
We evaluated in a qualitative systematic review the effect of N-methyl-D-aspartate (NMDA) receptor antagonists on reducing postoperative pain and analgesic consumption beyond the clinical duration of action of the target drug (preventive analgesia). Randomized trials examining the use of an NMDA antagonist in the perioperative period were sought by using a MEDLINE (1966-2003) and EMBASE (1985-2003) search. Reference sections of relevant articles were reviewed, and additional articles were obtained if they evaluated postoperative analgesia after the administration of NMDA antagonists. The primary outcome was a reduction in pain, analgesic consumption, or both in a time period beyond five half-lives of the drug under examination. Secondary outcomes included time to first analgesic request and adverse effects. Forty articles met the inclusion criteria (24 ketamine, 12 dextromethorphan, and 4 magnesium). The evidence in favor of preventive analgesia was strongest in the case of dextromethorphan and ketamine, with 67% and 58%, respectively, of studies demonstrating a reduction in pain, analgesic consumption, or both beyond the clinical duration of action of the drug concerned. None of the four studies examining magnesium demonstrated preventive analgesia. ⋯ We evaluated, in a qualitative systematic review, the effect of N-methyl D-aspartate antagonists on reducing postoperative pain and analgesic consumption beyond the clinical duration of action of the target drug (preventive analgesia). Dextromethorphan and ketamine were found to have significant immediate and preventive analgesic benefit in 67% and 58% of studies, respectively.
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Anesthesia and analgesia · May 2004
Randomized Controlled Trial Clinical TrialThe analgesic effects of gabapentin after total abdominal hysterectomy.
We investigated, in a randomized, placebo-controlled, double-blind study, the efficacy and safety of gabapentin on pain after abdominal hysterectomy and on tramadol consumption in patients. The 50 patients were randomized to receive either oral placebo or gabapentin 1200 mg 1 h before surgery. Anesthesia was induced with propofol and maintained with sevoflurane in 50% N(2)O/O(2) with a fresh gas flow of 2 L/min (50% N(2)O in O(2)) and fentanyl (2 microg/kg). All patients received patient-controlled analgesia with tramadol with a 50 mg initial loading dose, 20 mg incremental dose, 10-min lockout interval, and 4-h limit of 300 mg. The incremental dose was increased to 30 mg if analgesia was inadequate after 1 h. Patients were studied at 4, 8, 12, 16, 20, and 24 h for visual analog (VAS) pain scores, heart rate, peripheral oxygen saturation, mean arterial blood pressure, respiratory rate, sedation, and tramadol consumption. The VAS scores in the sitting and supine position at 1, 4, 8, 12, 16, and 20 h were significantly lower in the gabapentin group when compared with the placebo group up to 20 h after surgery. The tramadol consumption at 12, 16, 20, and 24 h and total tramadol consumption were significantly less in the gabapentin group when compared with placebo group. Sedation scores were similar at all the measured times. There were no differences between groups in adverse effects. Preoperative oral gabapentin decreased pain scores and postoperative tramadol consumption in patients after abdominal hysterectomy. ⋯ This randomized, controlled trial examined the effects of preoperative oral gabapentin 1200 mg on postoperative pain and tramadol consumptions. We conclude that preoperative oral gabapentin is effective in reducing postoperative pain scores and tramadol consumption in patients after abdominal hysterectomy.
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Anesthesia and analgesia · May 2004
Comparative StudyComparative evaluation of Narcotrend, Bispectral Index, and classical electroencephalographic variables during induction, maintenance, and emergence of a propofol/remifentanil anesthesia.
In the present study, we sought to compare the abilities of Narcotrend (NT) with the Bispectral Index (BIS) electroencephalographic system to monitor depth of consciousness immediately before induction of anesthesia until extubation during a standardized anesthetic. We investigated 26 patients undergoing laminectomy. Investigated states of anesthesia were: awake, loss of response, loss of eyelash reflex, steady-state anesthesia, first reaction, and extubation during emergence. NT, BIS, spectral edge frequency, median frequency, relative power in delta, theta, alpha, beta, and hemodynamics were recorded simultaneously. The ability of all variables to distinguish between awake versus loss of response, awake versus loss of eyelash reflex, awake versus steady-state anesthesia, steady-state anesthesia versus first reaction and extubation were analyzed with the prediction probability. Effects of remifentanil during propofol infusion were investigated with Friedman's and post hoc with Wilcoxon's test. Only NT and BIS were able to distinguish all investigated states accurately with a prediction probability >0.95. After start of remifentanil infusion, only hemodynamics changed statistically significantly (P < 0.05). NT and BIS are more reliable indicators for the assessment of anesthetic states than classical electroencephalographic variables and hemodynamics, whereas the analgesic potency of depth of anesthesia could not be detected by NT and BIS. ⋯ The modern electroencephalographic monitoring systems Narcotrend and Bispectral Index are more reliable indicators for the assessment of anesthetic states than classical electroencephalographic and hemodynamic variables to predict anesthetic conditions from before induction of anesthesia until extubation during a standardized anesthetic regime with propofol and remifentanil. The analgesic potency of depth of anesthesia could not be detected by Narcotrend and Bispectral Index.
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Anesthesia and analgesia · May 2004
Randomized Controlled Trial Clinical TrialPrevention of atelectasis formation during the induction of general anesthesia in morbidly obese patients.
Atelectasis caused by general anesthesia is increased in morbidly obese patients. We have shown that application of positive end-expiratory pressure (PEEP) during the induction of anesthesia prevents atelectasis formation in nonobese patients. We therefore studied the efficacy of PEEP in morbidly obese patients to prevent atelectasis. Twenty-three adult morbidly obese patients (body mass index >35 kg/m(2)) were randomly assigned to one of two groups. In the PEEP group, patients breathed 100% oxygen (5 min) with a continuous positive airway pressure of 10 cm H(2)O and, after the induction, mechanical ventilation via a face mask with a PEEP of 10 cm H(2)O. In the control group, the same induction was applied but without continuous positive airway pressure or PEEP. Atelectasis, determined by computed tomography, and blood gas analysis were measured twice: before the induction and directly after intubation. After endotracheal intubation, patients of the control group showed an increase in the amount of atelectasis, which was much larger than in the PEEP group (10.4% +/- 4.8% in control group versus 1.7% +/- 1.3% in PEEP group; P < 0.001). After intubation with a fraction of inspired oxygen of 1.0, PaO(2) was significantly higher in the PEEP group compared with the control group (457 +/- 130 mm Hg versus 315 +/- 100 mm Hg, respectively; P = 0.035) We conclude that in morbidly obese patients, atelectasis formation is largely prevented by PEEP applied during the anesthetic induction and is associated with a better oxygenation. ⋯ Application of positive end-expiratory pressure during induction of general anesthesia in morbidly obese patients prevents atelectasis formation and improves oxygenation. Therefore, this technique should be considered for anesthesia induction in morbidly obese patients.
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Anesthesia and analgesia · May 2004
Randomized Controlled Trial Clinical TrialImprovement of pain treatment after major abdominal surgery by intravenous S+-ketamine.
The use of intraoperative racemic ketamine for pain prevention after abdominal surgery is controversial. We compared one preincisional i.v. injection of S(+)-ketamine with its preincisional and repeated intraoperative use in 45 patients undergoing surgery with epidural and general anesthesia. S(+)-ketamine is a new drug formulation that contains the more potent S(+)-stereoisomer of ketamine. Patients were randomized to receive placebo, 0.5 mg/kg preincisional S(+)ketamine, or 0.5 mg/kg preincisional and 0.2 mg/kg intraoperative S(+)-ketamine repeated at 20-min intervals. In the postoperative period, epidural ropivacaine (2 mg/mL; 0.12 mL.kg(-1).h(-1)) was infused for pain therapy. Patients who received repeated S(+)-ketamine reported smaller pain scores than those who received placebo after awakening and 3 and 6 h later (P < or = 0.05). Fewer patients with repeated S(+)-ketamine required additional analgesics than those with placebo (P < or = 0.05). Cumulative consumption of additional diclofenac and dextropropoxyphene at 24 h was less after single (P < 0.05) and repeated (P < 0.05) S(+)-ketamine versus placebo. After awakening, patients who received repeated S(+)-ketamine reported being in a better mood than those in the other groups (P < 0.05). No psychotomimetic side effects were noted. In conclusion, preincisional and repeated intraoperative small-dose S(+)-ketamine added to general and epidural anesthesia causes better postoperative pain relief than general and epidural anesthesia alone. ⋯ After major visceral surgery, preincisional and repeated intraoperative small-dose S(+)-ketamine added to general and epidural anesthesia causes better postoperative pain relief than general and epidural anesthesia alone.