Anesthesia and analgesia
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Anesthesia and analgesia · Oct 1999
Randomized Controlled Trial Clinical TrialThe impact of saline flush of the epidural catheter on resolution of epidural anesthesia in volunteers: a dose-response study.
We evaluated the effect of 1, 20, and 40 mL of epidural saline flush on recovery from lidocaine epidural anesthesia. Eight volunteers were studied for three study periods, each separated by 72 h. The volume of saline was randomized, and a new catheter was inserted for each study period. A standardized dose of 20 mL of 2% plain lidocaine was injected for 10 min, followed by an epidural saline flush 30 min later. Sensory block was assessed by pinprick and transcutaneous electrical stimulation and motor block by a modified Bromage scale and isometric maximal force contraction. Times to void and ambulate independently before discharge were recorded. Peak plasma lidocaine concentrations and time to peak concentration were determined. Results from six volunteers showed that epidural saline, 40 mL, significantly altered anesthetic resolution, accelerating the time of complete sensory and motor block regression (P < 0.05). Median peak levels of sensory and motor block and times to void and ambulate were similar among treatment groups. Peak plasma lidocaine concentrations were similar in all treatment groups. Our data suggest that a 40-mL epidural saline injection 30 min after the induction facilitates regression of epidural lidocaine anesthesia, but a 20-mL bolus does not. Epidural saline injection does not affect vascular absorption of epidural lidocaine. ⋯ Epidural catheter flushing with 40 mL of saline, after establishment of epidural lidocaine anesthesia, can facilitate sensory and motor block recovery. However, this does not affect vascular absorption of epidural lidocaine.
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Anesthesia and analgesia · Oct 1999
Practice Guideline GuidelineASE/SCA guidelines for performing a comprehensive intraoperative multiplane transesophageal echocardiography examination: recommendations of the American Society of Echocardiography Council for Intraoperative Echocardiography and the Society of Cardiovascular Anesthesiologists Task Force for Certification in Perioperative Transesophageal Echocardiography.
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Anesthesia and analgesia · Oct 1999
Low-flow anesthesia and reduced animal size increase carboxyhemoglobin levels in swine during desflurane and isoflurane breakdown in dried soda lime.
After institutional approval, we studied the effect of animal size, anesthetic concentration, and fresh gas flow (FGF) rate on inspired carbon monoxide (CO) and carboxyhemoglobin (COHb) during anesthesia in swine, using soda lime previously dried to 1 +/- 0.1% water content. To ascertain the effect of anesthesia, eight adult pigs were anesthetized with either 1 minimum alveolar anesthetic concentration (MAC) desflurane or isoflurane and, to characterize the effect of the FGF rate, it was doubled in four pigs. To determine the effect of animal size, four small and four large pigs received 1 MAC desflurane or isoflurane, and to determine the effect of the anesthetic concentration, a group of four swine was exposed to 0.5 MAC. CO and COHb concentrations were larger with desflurane (5500 +/- 980 ppm and 57.90% +/- 0.50%, respectively) than with isoflurane (800 ppm and 17.8% +/- 2.14%, respectively), especially in the small animals. Increasing the FGF rate significantly reduced peak CO and COHb concentrations resulting from both anesthetics; however, when each anesthetic was reduced to 0.5 MAC, the concentrations obtained were similar. We conclude that CO intoxication is more severe with desflurane than with isoflurane, that small animals are at higher risk for CO poisoning, and that low FGF can increase COHb concentrations. ⋯ The present study shows that the use of desflurane with desiccated carbon dioxide absorbents in pediatric anesthesia can produce a dangerous carbon dioxide intoxication, especially with low-flow anesthesia.
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Anesthesia and analgesia · Oct 1999
Comparative StudyA strategy for deciding operating room assignments for second-shift anesthetists.
We developed a relief strategy for assigning second-shift anesthetists to late-running operating rooms. The strategy relies on a statistical method which analyzes historical case durations available from surgical services information systems to estimate the expected (mean) remaining hours in cases after they have begun. We tested our relief strategy by comparing the number of hours that first-shift anesthetists would work overtime if second-shift anesthetists were assigned using our strategy versus if the anesthesia coordinator knew in advance the exact amount of time remaining in each case. Our relief strategy resulted in 3.4% to 4.9% more overtime hours for first-shift anesthetists than the theoretical minimum, as would have been obtained had perfect retrospective knowledge been available. Few additional staff hours would have been saved by supplementing our relief strategy with other methods to monitor case durations (e.g., real-time patient tracking systems or closed circuit cameras in operating rooms). ⋯ A relief strategy that relies only on analyzing historical case durations from an operating room information system to predict the time remaining in cases performs well at minimizing anesthetist staffing costs.
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Anesthesia and analgesia · Oct 1999
Meta AnalysisA meta-analysis of the effectiveness of cell salvage to minimize perioperative allogeneic blood transfusion in cardiac and orthopedic surgery. International Study of Perioperative Transfusion (ISPOT) Investigators.
Concern about risks of allogeneic transfusion has led to an interest in methods for decreasing perioperative transfusion. To determine whether cell salvage reduces patient exposure to allogeneic blood, we performed meta-analyses of randomized trials, evaluating the effectiveness and safety of cell salvage in cardiac or orthopedic elective surgery. The primary outcome was the proportion of patients who received at least one perioperative allogeneic red cell transfusion. Twenty-seven studies were included in the meta-analyses. Cell salvage devices that do not wash salvaged blood were marginally effective in cardiac surgery patients when used postoperatively (relative risk [RR] = 0.85, 95% confidence interval [CI] = 0.79-0.92). Devices that wash or do not wash salvaged blood considerably decreased the proportion of orthopedic surgery patients who received allogeneic transfusion (RR = 0.39, 95% CI = 0.30-0.51 and RR = 0.35, 95% CI 0.26-0.46, respectively). No studies of cell savers that wash salvaged blood during cardiac surgery were included. Cell salvage did not appear to increase the frequency of adverse events. We conclude that cell salvage in orthopedic surgery decreases the risk of patients' exposure to allogeneic blood transfusion perioperatively. Postoperative cell salvage in cardiac surgery, with devices that do not wash the salvaged blood, is only marginally effective. ⋯ This meta-analysis of all published randomized trials provides the best current estimate of the effectiveness of cell salvage and is useful in guiding clinical practice. We conclude that cell salvage in orthopedic surgery decreases the proportion of patients requiring allogeneic blood transfusion perioperatively, but postoperative cell salvage is only marginally effective in cardiac surgery.