Anesthesia and analgesia
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Anesthesia and analgesia · Jun 2004
Randomized Controlled Trial Comparative Study Clinical TrialThe impact of heparin-coated cardiopulmonary bypass circuits on pulmonary function and the release of inflammatory mediators.
Reduction of the inflammatory reaction with the use of heparin coating has been found during and after cardiopulmonary bypass (CPB). The question remains whether this reduced reaction also decreases the magnitude of CPB-induced pulmonary dysfunction. We therefore evaluated the effects of a heparin-coated circuit versus a similar uncoated circuit on pulmonary indices as well as on inflammatory markers of complement activation (C3b/c), elastase-alpha(1)-antitrypsin complex, and secretory phospholipase A(2) (sPLA(2)) during and after CPB. Fifty-one patients were randomly assigned into two groups undergoing coronary artery bypass grafting with either a heparin-coated (Group 1) or an uncoated (Group 2) circuit. During CPB, a continuous positive airway pressure of 5 cm H(2)O and a fraction of inspired oxygen (FIO(2)) of 0.21 were maintained. Differences in favor of the coated circuit were found in pulmonary shunt fraction (P < 0.05), pulmonary vascular resistance index (P < 0.05), and PaO(2)/FIO(2) ratio (P < 0.05) after CPB and in the intensive care unit. During and after CPB, the coated group demonstrated lower levels of sPLA(2). After CPB, C3b/c and the elastase-alpha(1)-antitrypsin complex were significantly less in the coated group (P < 0.001). The coated circuit was associated with a reduced inflammatory response, decreased pulmonary vascular resistance index and pulmonary shunt fraction, and increased PaO(2)/FIO(2) ratio, suggesting that the coated circuit may have beneficial effects on pulmonary function. The correlation with sPLA(2), leukocyte activation, and postoperative leukocyte count suggests reduced activation of pulmonary capillary endothelial cells. ⋯ Heparin coating of the extracorporeal circuit reduces the inflammatory response during cardiopulmonary bypass. Analysis of indices of pulmonary function indicates that use of heparin coating may result in less impaired gas exchange.
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Anesthesia and analgesia · Jun 2004
Randomized Controlled Trial Multicenter Study Comparative Study Clinical TrialPosttetanic potentiation and fade in the response to tetanic and train-of-four stimulation during succinylcholine-induced block.
We designed this study to confirm anecdotal observations that neuromuscular block after a single administration of succinylcholine is characterized by fade to train-of-four (TOF) or tetanic stimulation, as well as posttetanic potentiation. This prospective, randomized, 2-center observational study involved 100 patients. Patients were allocated to 1 of 5 groups and received 0.1, 0.3, 0.5, 0.75, or 1.0 mg/kg succinylcholine during propofol/fentanyl/nitrous oxide anesthesia. Neuromuscular function was monitored by TOF using mechanomyography. At 10%-20% spontaneous recovery of the first twitch of TOF, the mode of stimulation was changed from TOF to 1-Hz single-twitch stimulation followed by a tetanic stimulus (50 Hz) for 5 s. Three seconds later, the single twitch (1 Hz) was applied again for approximately 30 s followed by TOF stimulation until full recovery of the TOF response. Succinylcholine-induced neuromuscular block had the following characteristics: 1) twitch augmentation before twitch depression, which was seen more frequently in patients given smaller doses (0.1 and 0.3 mg/kg) than in those given larger doses (0.5-1.0 mg/kg); 2) TOF fade during onset and recovery of the block; 3) tetanic fade; and 4) and posttetanic potentiation. Posttetanic potentiation was related to the pretetanic twitch height but was not related to the dose of succinylcholine administered. Some characteristics of Phase II block were detectable during onset and recovery from doses of succinylcholine as small as 0.30 mg/kg. Posttetanic potentiation and fade in response to train-of-four and tetanic stimuli are characteristics of neuromuscular block after bolus administration of different doses of succinylcholine. ⋯ Posttetanic potentiation and fade in response to train-of-four and tetanic stimuli are characteristics of neuromuscular block after bolus administration of different doses of succinylcholine. We also conclude that some characteristics of a Phase II block are evident from an initial dose (i.e., as small as 0.3 mg/kg) of succinylcholine.
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Anesthesia and analgesia · Jun 2004
Randomized Controlled Trial Comparative Study Clinical TrialThe relative motor blocking potencies of intrathecal ropivacaine: effects of concentration.
This study established the median effective dose (ED(50)) for motor block of intrathecal 1% and 0.1% ropivacaine and determined the effects of the concentration of the solution injected on the motor block obtained. We enrolled into this prospective, randomized, double-blind, sequential allocation study 54 parturients undergoing elective Cesarean delivery under combined spinal-epidural technique. Parturients were randomized to receive intrathecal ropivacaine either 1% or 0.1%. The initial dose was chosen to be 4 mg, with subsequent doses being determined by the response of the previous patient (testing interval, 1 mg). The occurrence of any motor block in either lower limb within 5 min from the intrathecal injection of the study solution was considered effective. The motor block at 5 min was 6.1 mg for 1% ropivacaine (95% confidence interval [CI], 5.1-7.1) and was 9.1 mg (95% CI, 7.8-10.3) for 0.1% ropivacaine (P = 0.0013; 95% CI difference, 1.3-4.7). The relative efficacy ratio of the 2 concentrations was 1.5 (95% CI difference, 1.2-1.9) in favor of the larger concentration. The ED(50) of spinal ropivacaine to produce motor block in pregnant patients was significantly influenced by the concentration of the local anesthetic, with dose requirements being increased by 50% for the smaller concentration. ⋯ The minimum local anesthetic dose for motor block with 0.1% ropivacaine is 50% larger than the 1% concentration with a relative efficacy ratio of 1.5. Our findings suggest that more diluted local anesthetic solutions determine less motor block, and this may be considered in ambulant laboring parturients.
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Anesthesia and analgesia · Jun 2004
Randomized Controlled Trial Comparative Study Clinical TrialProphylaxis of postoperative nausea and vomiting with oral, long-acting dimenhydrinate in gynecologic outpatient laparoscopy.
Dimenhydrinate is an inexpensive antiemetic with few side effects available as an oral, long-acting (LA) formulation (Gravol L/A) containing 25 mg of immediate and 50 mg of sustained release drug. We designed this double-blind comparison trial to assess the efficacy of dimenhydrinate LA versus droperidol alone and the combination for prophylaxis of nausea, vomiting, and retching in outpatient gynecologic laparoscopy. One-hundred-forty-one women were randomized into 3 groups: 1) droperidol (placebo capsule preoperatively and IV droperidol 0.625 mg before induction), 2) dimenhydrinate LA preoperatively and IV placebo before induction, or 3) combination. Information regarding nausea, vomiting, retching, pain, and sedation was recorded in the postanesthesia care unit (PACU) and collected by telephone for the presence of symptoms: on arrival home; at bedtime; upon arising, and at lunchtime the following day. The overall incidence of complete treatment failure (rescue medication in PACU or nausea, vomiting, or retching at any time point) was 28 of 46 (61%), 28 of 48 (58%), and 22 of 47 (47%); and for treatment failure vomiting (rescue medication in PACU or vomiting or retching at any time point) was 16 of 46 (35%), 11 of 48 (23%), and 5 of 47 (11%), for the droperidol, dimenhydrinate, and combination groups, respectively (P = 0.007 for droperidol versus combination). There were no differences in sedation or pain. Preoperative administration of an oral dose of LA dimenhydrinate in combination with droperidol when compared with droperidol alone effectively reduced the incidence of vomiting but not nausea in women undergoing elective outpatient gynecologic laparoscopy. ⋯ Dimenhydrinate is an inexpensive antiemetic with few side effects available as a long-acting oral formulation. Women undergoing outpatient gynecologic laparoscopy were given droperidol, an effective antiemetic, dimenhydrinate alone, or the combination of the two drugs. Dimenhydrinate plus droperidol significantly reduced the overall incidence of vomiting, but not nausea, when compared with droperidol alone.
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Factor V Leiden (FVL) is the most common known inherited cause of thrombophilia; it is present in approximately 5% of the Caucasian population. Although the risk of venous thrombosis associated with this polymorphism in various medical settings is well described, its effect on perioperative risk is only beginning to be explored. ⋯ This review will describe the physiology of the FVL mutation, briefly clarify its risk in the nonsurgical setting, and assess current data regarding FVL in noncardiac and cardiac surgery. Finally, a summary of current clinical evidence and a plan for more detailed investigation of this potentially significant risk factor will be proposed.