Anesthesia and analgesia
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Anesthesia and analgesia · Mar 2000
Randomized Controlled Trial Comparative Study Clinical TrialA comparison of epidural analgesia with 0.125% ropivacaine with fentanyl versus 0.125% bupivacaine with fentanyl during labor.
We previously found that the extent of an epidural motor block produced by 0.125% ropivacaine was clinically indistinguishable from 0.125% bupivacaine in laboring patients. By adding fentanyl to the 0. 125% ropivacaine and bupivacaine solutions in an attempt to reduce hourly local anesthetic requirements, we hypothesized that differences in motor block produced by the two drugs may become apparent. Fifty laboring women were randomized to receive either 0. 125% ropivacaine with fentanyl 2 microg/mL or an equivalent concentration of bupivacaine/fentanyl using patient-controlled epidural analgesia (PCEA) with settings of: 6-mL/hr basal rate, 5-mL bolus, 10-min lockout, 30-mL/h dose limit. Analgesia, local anesthetic use, motor block, patient satisfaction, and side effects were assessed until the time of delivery. No differences in verbal pain scores, local anesthetic use, patient satisfaction, or side effects between groups were observed; however, patients administered ropivacaine/fentanyl developed significantly less motor block than patients administered bupivacaine/fentanyl. Ropivacaine 0.125% with fentanyl 2 microg/mL produces similar labor analgesia with significantly less motor block than an equivalent concentration of bupivacaine/fentanyl. Whether this statistical reduction in motor block improves clinical outcome or is applicable to anesthesia practices which do not use the PCEA technique remains to be determined. ⋯ By using a patient-controlled epidural analgesia technique, ropivacaine 0.125% with fentanyl 2 microg/mL produces similar analgesia with significantly less motor block than a similar concentration of bupivacaine with fentanyl during labor. Whether this statistical reduction in motor block improves clinical outcome or is applicable to anesthesia practices which do not use the patient-controlled epidural analgesia technique remains to be determined.
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Anesthesia and analgesia · Mar 2000
Age-related thermoregulatory differences in a warm operating room environment (approximately 26 degrees C).
Inadvertent hypothermia occurs frequently at typical ambient operating room (OR) temperatures, especially in elderly patients receiving general anesthesia. The aims of the current study were to 1) determine the incidence and magnitude of core hypothermia in an unusually warm OR environment, and 2) to assess age-related differences in perioperative thermoregulatory responses under these circumstances. Forty patients receiving general anesthesia for orthopedic surgical procedures (20 younger patients, 20-40 yr old) and (20 older patients, 60-75 yr old) were enrolled. Mean ambient temperature in the ORs was 25.8 degrees +/- 0.2 degrees C. Core temperature, vasoconstriction, and shivering were compared in the younger and older age groups. Mean core temperature on admission to the postanesthesia care unit was not significantly different in the younger (36.7 degrees +/- 0.1 degrees C) and older (36.4 degrees +/- 0.1 degrees C) age groups. Only 10% of patients (n = 4, 1 younger, 3 older) were admitted with a core temperature <36.0 degrees C. Only 2% of patients (n = 1, older group) had a core temperature <35.5 degrees C. This very mild degree of hypothermia was associated with postoperative vasoconstriction in 80% of the younger and 55% of the older patients (P = 0.18). Postoperative shivering occurred in 40% of the younger patients and in 10% of the older patients (P = 0.06). In summary, an ambient OR temperature near 26 degrees C (79 degrees F) is effective in preventing core hypothermia during general anesthesia regardless of patient age. Even very mild postoperative hypothermia may initiate thermoregulatory responses. ⋯ By increasing ambient temperature in the operating room to 26 degrees C (79 degrees F), the incidence of core hypothermia can be dramatically reduced in both younger and older patients.
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Anesthesia and analgesia · Mar 2000
Randomized Controlled Trial Clinical TrialWhat concentration of sufentanil should be combined with ropivacaine 0.2% wt/vol for postoperative patient-controlled epidural analgesia?
In this randomized double-blinded study, we sought to determine an optimal dose-combination of sufentanil with ropivacaine 0.2% wt/vol as postoperative epidural analgesics. One hundred twenty patients undergoing major abdominal surgery under general and thoracic epidural anesthesia (T9-11) were assigned to groups receiving patient-controlled epidural analgesia with ropivacaine 0.2% wt/vol (R), ropivacaine 0.2% wt/vol + sufentanil 0.5 microg/mL (R+S0.5), 0. 75 microg/mL (R+S0.75), 1.0 microg/mL (R+S1). A visual analog score of less than 40 was considered effective, and all side effects were recorded. In randomized subgroups (10 patients per group), plasma pharmacokinetic data were obtained for both epidural drugs. Four patients in Group R and two in Group R+S0.5 were excluded because of inadequate analgesia. The drug infusion rates (range of means: 5.4-5. 9 mL/h) were similar in all patients. Analgesia was superior for sufentanil 0.75 microg/mL with no further enhancement by the larger sufentanil concentration of 1 microg/mL. Sufentanil plasma levels were within the range of the minimal effective concentrations (highest in R+S1), and there was no covariation between plasma levels and pain relief. Free ropivacaine plasma concentrations remained stable for 96 h. No severe side effects were detected, although pruritus correlated with an increasing dose of sufentanil. We conclude that the combination of ropivacaine 0.2% wt/vol and 0.75 microg/mL sufentanil provided the best analgesia with the fewest side effects of the three combinations tested. ⋯ Sufentanil is added to epidural infusions of ropivacaine 0.2% wt/vol to improve the effectiveness of postoperative pain management. Regarding the risk of side effects, however, it is still unclear what concentration of sufentanil should be added to the local anesthetic. For postoperative thoracic epidural analgesia after major abdominal surgery, the combination of ropivacaine 0.2% wt/vol and 0.75 microg/mL sufentanil resulted in an appropriate cost:benefit ratio between good analgesia and side effects.
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Anesthesia and analgesia · Mar 2000
Multicenter Study Comparative Study Clinical TrialThe effects of sevoflurane on serum creatinine and blood urea nitrogen concentrations: a retrospective, twenty-two-center, comparative evaluation of renal function in adult surgical patients.
Despite mounting clinical evidence that supports its safety, the question of the potential adverse effects of sevoflurane on renal function continues to generate some controversy. This study retrospectively evaluated pooled renal laboratory data from 22 different clinical trials that compared sevoflurane with three widely used anesthetics. The trials examined postoperative changes in serum creatinine and blood urea nitrogen levels from a total of 3, 436 ASA physical status I-IV adult surgical patients administered either sevoflurane (n = 1941) or a control drug (isoflurane, enflurane, or propofol; n = 1495) as the maintenance anesthetic. The incidences of increased serum creatinine and blood urea nitrogen concentrations were similar among patients administered sevoflurane and those administered control drugs. Additionally, no trends specific to sevoflurane were observed with respect to postoperative serum creatinine concentration and fresh gas flow rate, concurrent treatment with nephrotoxic antibiotics, or type of carbon dioxide absorbent. ⋯ Our data for changes in serum creatinine and blood urea nitrogen indicate that, for exposures of less than 4 minimum alveolar anesthetic concentration/h, sevoflurane is not associated with an increased risk of renal toxicity compared with other commonly used anesthetics. For clinical purposes, the pre- to postoperative changes in serum creatinine and blood urea nitrogen are appropriate measures of renal function in surgical patients.