Anesthesia and analgesia
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Anesthesia and analgesia · Oct 2001
Meta AnalysisEpidural analgesia reduces postoperative myocardial infarction: a meta-analysis.
Postoperative cardiac morbidity and mortality continue to pose considerable risks to surgical patients. Postoperative epidural analgesia is considered to have beneficial effects on cardiac outcomes. The use in high-risk cardiac patients remains controversial. No study has shown that postoperative epidural analgesia decreases postoperative myocardial infarction (PMI) or death. All studies are underpowered to show such a result, and the cost of conducting a large trial is prohibitive. We performed a metaanalysis to determine whether postoperative epidural analgesia continued for more than 24 h after surgery reduces PMI or in-hospital death. The available databases were searched for randomized controlled trials of epidural analgesia that was extended at least 24 h into the postoperative period. The search yielded 17 studies, of which 11 were randomized controlled trials comprising 1173 patients. Metaanalysis was conducted by using the fixed-effects model, calculating both an odds ratio and a rate difference. Postoperative epidural analgesia resulted in better analgesia for the first 24 h after surgery. The rate of PMI was 6.3%, with lower rates in the Epidural group (rate difference, -3.8%; 95% confidence interval [CI] -7.4%, -0.2%; P = 0.049). The frequency of in-hospital death was 3.3%, with no significant difference between Epidural and Nonepidural groups (rate difference, -1.3%; 95% CI, -3.8%, 1.2%, P = 0.091). Subgroup analysis of postoperative thoracic epidural analgesia showed a significant reduction in PMI in the Epidural group (rate difference, -5.3%; 95% CI, -9.9%, -0.7%; P = 0.04). ⋯ Postoperative epidural analgesia, especially thoracic epidural analgesia, continued for more than 24 h reduces postoperative myocardial infarctions.
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Anesthesia and analgesia · Oct 2001
Randomized Controlled Trial Comparative Study Clinical TrialA new posterior approach to the sciatic nerve block: a prospective, randomized comparison with the classic posterior approach.
To evaluate the efficacy and acceptance of a new posterior subgluteus approach to the sciatic nerve, as compared with the classic posterior approach, 128 patients undergoing foot orthopedic procedures were randomly allocated to receive either the classic posterior sciatic nerve block (Group Labat, n = 64) or a modified subgluteus posterior approach (Group subgluteus, n = 64). All blocks were performed with the use of a nerve stimulator (stimulation frequency, 2 Hz; intensity, 1-0.5 mA). In Group subgluteus, a line was drawn from the greater trochanter to the ischial tuberosity; then, from the midpoint of this line, a second line was drawn perpendicularly and extended caudally for 4 cm. The end of this line represented the needle entry. In both groups, a proper sciatic stimulation was elicited at 0.5 mA; then 20 mL of 0.75% ropivacaine was injected. The time from needle insertion to successful sciatic nerve stimulation was 60 s (range, 10-180 s) with the Labat's approach and 32 s (range, 5-120 s) with the new subgluteus approach (P = 0.0005). The depth of appropriate sciatic stimulation was 45 +/- 13 mm (mean +/- SD) after 2 (range, 1-7) needle redirections in Group subgluteus and 67 +/- 12 mm after 4 (range, 1-10) needle redirections in Group Labat (P = 0.0001 and P = 0.00001, respectively). The failure rate was similar in both groups. Severe discomfort during the procedure was less frequent and acceptance better in Group subgluteus (5 patients [8%] and 60 patients [94%], respectively) than in Group Labat (20 patients [31%] and 49 patients [77%], respectively) (P = 0.0005 and P = 0.005, respectively). We conclude that this new subgluteus posterior approach to the sciatic nerve is an easy and reliable technique and can be considered an effective alternative to the more traditional Labat's approach. ⋯ Evaluating the efficacy and acceptance of a new approach to the sciatic nerve block, this prospective, randomized study demonstrated that the new subgluteus posterior approach is an easy and reliable technique and can be considered an useful alternative to the more traditional Labat's approach in patients undergoing foot surgery, facilitating the performance of the sciatic nerve blocks.
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Anesthesia and analgesia · Oct 2001
Randomized Controlled Trial Clinical TrialThe concentration-effect relationship of the respiratory depressant effects of alfentanil and fentanyl.
The relative potencies of fentanyl and alfentanil for respiratory depression were determined in eight healthy male volunteers in a double-blinded, randomized study with a cross-over design. The drugs were delivered by computer-driven infusion with logarithmically ascending plasma concentrations until the respiratory rate reached 2/min and/or oxygen saturation decreased below 85% with subjects breathing room air. Ventilation was measured with respiratory inductive plethysmography, indirect calorimetry, and arterial blood gas analysis, and plasma drug concentrations were determined. Pharmacodynamic modeling was performed using a fractional E(max) model for minute volume and respiratory rate and the concentrations producing 50% depression (i.e., apparent 50% effective concentration [EC(50)] values) were determined. Both drugs decreased ventilation in a similar manner, and drug infusions were terminated at mean +/- SD measured plasma concentrations of 254 +/- 88 ng/mL and 5.1 +/- 1.7 ng/mL for alfentanil and fentanyl, respectively. Alfentanil decreased minute volume from baseline by 54% +/- 19% and respiratory rate by 40% +/- 11% with EC(50) values of 234 +/- 57 ng/mL and 195 +/- 101 ng/mL. The respective decreases for fentanyl were 50% +/- 11%, 41% +/- 15%, and the estimated EC(50) values were 6.1 +/- 1.4 ng/mL and 3.5 +/- 1.4 ng/mL, respectively. Using the apparent EC(50) values, the calculated potency ratio for alfentanil:fentanyl was (mean and 95% confidence interval) 1:39 (1:31-1:46) for minute volume and 1:51 (1:34-1:68) for respiratory rate. This is analogous to the analgesic effect studied earlier. The findings support the notion of parallel analgesic and respiratory depressant effects of alfentanil and fentanyl. Therefore equianalgesic concentrations of both drugs will lead to equally pronounced respiratory depression. ⋯ This double-blinded, randomized study evaluated the potency ratio of alfentanil and fentanyl-induced respiratory depression. The findings support the notion of parallel analgesic and respiratory depressant effects of alfentanil and fentanyl. Therefore equianalgesic concentrations of both drugs will lead to equally pronounced respiratory depression.
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Anesthesia and analgesia · Oct 2001
Randomized Controlled Trial Clinical TrialSalbutamol prevents the increase of respiratory resistance caused by tracheal intubation during sevoflurane anesthesia in asthmatic children.
Asthmatic children having their tracheas intubated with sevoflurane often have an increase in respiratory system resistance (Rrs). In this randomized, placebo-controlled, double-blinded study, we investigated the protective effect of an inhaled beta2-adrenergic agonist. Either salbutamol or placebo was administered 30 to 60 min before anesthesia to 30 mildly to moderately asthmatic children scheduled for elective surgery. Induction was performed with sevoflurane in a mixture of 50% nitrous oxide in oxygen and maintained at 3%, with children breathing spontaneously via a face mask and Jackson-Rees modification of the T-piece. Airway opening pressure and flow were measured before and after insertion of an oral endotracheal tube. Rrs and respiratory system compliance were calculated with multilinear regression analysis. The groups were comparable with respect to age, weight, asthma history, and breathing pattern. Intubation induced a different Rrs response in the two groups: children treated with salbutamol showed a 6.0% (-25.2% to +13.2%) decrease (mean, 95% confidence interval), whereas in the Placebo group there was a 17.7% (+4.4% to +30.9%) increase (P = 0.04). Neither asthma history nor the serum inflammation marker eosinophilic cationic protein was predictive for this response. We conclude that when using sevoflurane in mildly to moderately asthmatic children, a preanesthetic treatment with inhaled salbutamol is protective of an increase in Rrs. ⋯ Tracheal intubation with sevoflurane as the sole anesthetic is now often performed in children. It can induce an increase in respiratory system resistance in children with asthma. This study shows that in children with mild to moderate asthma, a preanesthetic treatment with inhaled salbutamol can prevent the increase of respiratory system resistance.
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Anesthesia and analgesia · Oct 2001
Randomized Controlled Trial Clinical TrialThe effect of timing of dolasetron administration on its efficacy as a prophylactic antiemetic in the ambulatory setting.
Dolasetron (12.5 mg IV) is effective in both preventing and treating postoperative nausea and vomiting (PONV) after ambulatory surgery. However, the optimal timing of dolasetron administration and its effect on the patient's quality of life after discharge have not been established. One-hundred-five healthy, consenting women undergoing gynecologic laparoscopic procedures with a standardized general anesthetic technique were enrolled in this randomized, double-blinded study. Group 1 received dolasetron 12.5 mg IV 10-15 min before the induction of anesthesia; Group 2 received dolasetron 12.5 mg IV at the end of the laparoscopy (79 +/- 48 min later than Group 1); and Group 3 received dolasetron 12.5 mg IV at the end of anesthesia (93 +/- 52 min later than Group 1). The incidence of PONV, complete responses (defined as no emetic episodes and no rescue medication within the 24-h period after anesthesia), recovery profiles, and patient satisfaction were recorded. In the postanesthesia care unit and during the 24-h follow-up period, the incidence of nausea and vomiting, as well as the need for rescue antiemetics, did not differ significantly among the three groups. The percentages of patients with complete responses to the study drug within the first postoperative 24 h were also similar in all three groups (55%, 59%, and 52% for Groups 1, 2, and 3, respectively). The early and intermediate recovery profiles, including resumption of a normal diet and patient satisfaction with the control of PONV, were not different among the three study groups. Dolasetron 12.5 mg IV administered before the induction of anesthesia is as effective as dolasetron given at the end of laparoscopy or at the end of anesthesia in preventing PONV after outpatient laparoscopy. ⋯ The timing of dolasetron administration appears to have little effect on its efficacy when administered as a prophylactic antiemetic in the ambulatory setting.