摘要:

BackgroundThis study compared the administration of 0.1% ropivacaine and 0.5 &mgr;g/ml sufentanil with that of 0.1% bupivacaine and 0.5 &mgr;g/ml sufentanil via patient-controlled epidural analgesia route during labor.MethodsTwo hundred healthy pregnant women at term with a single fetus with a vertex fetal presentation were randomized in a double-blind fashion to receive either 0.1% ropivacaine and 0.5 &mgr;g/ml sufentanil or 0.1% bupivacaine and 0.5 &mgr;g/ml sufentanil using a patient-controlled epidural analgesia pump (5-ml bolus dose, 10-min locked-out period, no basal infusion). Pain score on a visual analog scale, Bromage score (0–3), level of sensory block, patient-controlled epidural analgesia ratio, drug use, supplemental boluses, and side effects were recorded at 30 min and then hourly. Mode of delivery, duration of first and second stages of labor, umbilical cord pH, Apgar scores of the newborn, and a measure of maternal satisfaction were recorded after delivery.ResultsNo differences were seen between the two groups for pain scores on a visual analog scale during labor, volume of anesthetic solution used, mode of delivery, or side effects. Motor block during the first stage of labor was significantly less in the ropivacaine group than in the bupivacaine group (no motor block in 97.8 of patientsvs.88.3%, respectively;P< 0.01). Duration of the second stage of labor was shorter in the ropivacaine group (1.3 ± 1.0vs.1.5 ± 1.2 h [mean ± SD];P< 0.05). Maternal satisfaction was greater in the bupivacaine group (91 ± 13 mm for contraction, 89 ± 19 mm for delivery on a visual scale: 0 = not satisfied at all, 100 = fully satisfied) than in the ropivacaine group (84 ± 21 and 80 ± 25 mm;P< 0.0001). Patients in the ropivacaine group requested more supplemental boluses to achieve analgesia during the second stage of labor than those in the bupivacaine group (29.7vs.19.8%, respectively, requested one or more supplemental boluses;P< 0.05).ConclusionsDelivered as patient-controlled epidural analgesia, 0.1% ropivacaine and 0.5 &mgr;g/ml sufentanil produce less motor block but are clinically less potent than 0.1% bupivacaine and 0.5 &mgr;g/ml sufentanil.

ISSN:0003-3022    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

BackgroundThe authors assessed the heparin management testin vitroin volunteers andin vivoduring cardiopulmonary bypass.MethodsIn vitro, the heparin management test was analyzed for heparin levels between 0 and 6 IU/ml using variations in hematocrit, platelets, procoagulants, and storage time. Thein vivostudies consisted of two groups: In group I (cardiopulmonary bypass ≤ 90 min, n = 40), anticoagulation was performed according to the activated clotting time (with or without aprotinin); in group II (cardiopulmonary bypass ≥ 180 min, with aprotinin) included use (n = 10) and nonuse of coumadin (n = 10) and anticoagulation according to the automated heparin dose–response assay. Tests were performed in duplicate (whole blood, two heparin management test analyzers) and compared with anti-Xa activity (plasma).ResultsIn vitro, the results of the heparin management test (n = 1,070) correlated well with heparin concentration (r2= 0.98). Dilution and storage time did not affect the heparin management test; a hematocrit of 60% and reduced procoagulants (10%) prolonged clotting time.In vivo,the correlation (heparin management testvs.anti-Xa) was strong in group I (r2= 0.97 [with aprotinin] and 0.96 [without aprotinin]; n = 960) and group II without coumadin (r2= 0.89, n = 516). In group II with coumadin, the overall correlation was r2= 0.87 and 0.79 (n = 484), although the range varied widely (0.57–0.94, between-analyzer differences 0–47%).ConclusionsThe results of the heparin management test were influenced by hematocrit, plasma coagulation factors, and the heparin level, but not by use of aprotinin. The heparin management test provided reliable valuesin vitroin group I, and in group II without coumadin but was less reliable in group II with coumadin.

ISSN:0003-3022    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

BackgroundAnesthetic drug interactions traditionally have been characterized using isobolographic analysis or multiple logistic regression. Both approaches have significant limitations. The authors propose a model based on response-surface methodology. This model can characterize the entire dose–response relation between combinations of anesthetic drugs and is mathematically consistent with models of the concentration–response relation of single drugs.MethodsThe authors defined a parameter, &thgr;, that describes the concentration ratio of two potentially interacting drugs. The classic sigmoid Emaxmodel was extended by making the model parameters dependent on &thgr;. A computer program was used to estimate response surfaces for the hypnotic interaction between midazolam, propofol, and alfentanil, based on previously published data. The predicted time course of effect was simulated after maximally synergistic bolus dose combinations.ResultsThe parameters of the response surface were identifiable. With the test data, each of the paired combinations showed significant synergy. Computer simulations based on interactions at the effect site predicted that the maximally synergistic three-drug combination tripled the duration of effect compared with propofol alone.ConclusionsResponse surfaces can describe anesthetic interactions, even those between agonists, partial agonists, competitive antagonists, and inverse agonists. Application of response-surface methodology permits characterization of the full concentration–response relation and therefore can be used to develop practical guidelines for optimal drug dosing.

ISSN:0003-3022    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

BackgroundMultiport epidural catheters are popular; however, the reliability of the air test has not been evaluated with this catheter design. The authors determined the effectiveness of aspirating for blood and the air test in detecting intravascular multiorifice epidural catheters.MethodsThree hundred women in labor underwent placement of a blunt-tip, three-hole, 20-gauge, lumbar epidural catheter. If there were no signs of spinal anesthesia, 3 ml lidocaine or bupivacaine was injected and the patient was observed for signs of spinal anesthesia. If there were no signs of spinal anesthesia, the authors injected 1 ml air through the epidural catheter while listening to the maternal precordium using a Doppler fetal heart rate monitor. Catheters through which blood was aspirated were air-tested and replaced. Patients with air–test-positive, blood–aspiration-negative catheters received 100 mg lidocaine through the catheter and were questioned about toxicity symptoms. The authors injected bupivacaine–fentanyl through aspiration-negative,air–test-negative catheters and recorded the sensory analgesic level 20 min later.ResultsThe authors aspirated cerebrospinal fluid through one catheter and documented intravascular placement in 11 catheters. Results of the air test and blood aspiration were positive for eight catheters. Blood could not be aspirated from one air–test-positive catheter; perioral numbness developed in the patient after lidocaine injection. Blood was freely aspirated from two air–test-negative catheters. In the remaining 288 catheters, bupivacaine–fentanyl injection produced epidural analgesia in 279 patients and no effect in 9 patients.ConclusionsThe authors obtained false-negative results with both catheter aspiration and the air test. Fractionating the local anesthetic dose is important when using multiorifice epidural catheters.

ISSN:0003-3022    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

BackgroundThe authors tested the hypothesis that pressure support ventilation (PSV) provides more effective gas exchange than does unassisted ventilation with continuous positive airway pressure (CPAP) in anesthetized adult patients treated using the laryngeal mask airway.MethodsForty patients were randomized to two equal-sized crossover groups, and data were collected before surgery. In group 1, patients underwent CPAP, PSV, and CPAP in sequence. In group 2, patients underwent PSV, CPAP, and PSV in sequence. PSV comprised positive end expiratory pressure set at 5 cm H2O and inspiratory pressure support set at 5 cm H2O above positive end expiratory pressure. CPAP was set at 5 cm H2O. Each ventilatory mode was maintained for 10 min. The following data were recorded every minute for the last 5 min of each ventilatory mode and the average reading taken: end tidal carbon dioxide, oxygen saturation, expired tidal volume, leak fraction, respiratory rate, noninvasive mean arterial pressure, and heart rate.ResultsIn both groups, PSV showed lower end tidal carbon dioxide (P < 0.001), higher oxygen saturation, (P< 0.001), and higher expired tidal volume (P< 0.001) compared with CPAP. In both groups, PSV had similar leak fraction, respiratory rate, mean arterial pressure, and heart rate compared with CPAP. In group 1, measurements for CPAP were similar before and after PSV. In group 2, measurements for PSV were similar before and after CPAP.ConclusionThe authors concluded that PSV provides more effective gas exchange than does unassisted ventilation with CPAP during LMA anesthesia while preserving leak fraction and hemodynamic homeostasis.

ISSN:0003-3022    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

BackgroundMorphine and ketamine may prevent central sensitization during surgery and result in preemptive analgesia. The reliability of preemptive analgesia, however, is controversial.MethodsGastrectomy patients were given preemptive analgesia consisting of epidural morphine, intravenous low-dose ketamine, and combinations of these in a randomized, double-blind manner. Postsurgical pain intensity was rated by a visual analog scale, a categoric pain evaluation, and cumulative morphine consumption.ResultsPreemptive analgesia by epidural morphine and by intravenous low-dose ketamine were significantly effective but not definitive. With epidural morphine, a significant reduction in visual analog scale scores at rest was observed at 24 and 48 h, and morphine consumption was significantly lower at 6 and 12 h, compared with control values. With intravenous ketamine, visual analog scale scores at rest and morphine consumption were significantly lower at 6, 12, 24, and 48 h than those in control subjects. The combination of epidural morphine and intravenous ketamine provided definitive preemptive analgesia: Visual analog scale scores at rest and morphine consumption were significantly the lowest at 6, 12, 24, and 48 h, and the visual analog scale score during movement and the categoric pain score also were significantly the lowest among the groups.ConclusionThe results suggest that for definitive preemptive analgesia, blockade of opioid and N-methyl-d-aspartate receptors is necessary for upper abdominal surgery such as gastrectomy; singly, either treatment provided significant, but not definitive, postsurgical pain relief. Epidural morphine may affect the spinal cord segmentally, whereas intravenous ketamine may block brain stem sensitizationviathe vagus nerve during upper abdominal surgery.

ISSN:0003-3022    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

BackgroundThe spread of epidural analgesia is facilitated by pregnancy. Changes in the epidural structure during pregnancy may affect the spread of analgesia in pregnant women. To investigate the changes in the epidural space produced by pregnancy, the authors performed epiduroscopy in pregnant women.MethodsUsing a flexible fiberscope, the authors evaluated the epidural space in 73 women undergoing lumbar epidural anesthesia. Patients were classified into three groups: a nonpregnant group (n = 21), a first trimester pregnant group (8–13 weeks, n = 23), and a third-trimester pregnant group (27–39 weeks, n = 29). A 17-gauge Tuohy needle was inserted using the paramedian technique and the loss-of-resistance method with 5 ml air. The epiduroscope was introduced into the lumbar epidural space via the Tuohy needle and was advanced approximately 10 cm in a cephalad direction from the needle tip within the epidural space. The differences in the epidural space among the three groups then was evaluated.ResultsThe epiduroscopy showed that the epidural pneumatic space, after injection of a given amount of air, was narrower and the density of the vascular network greater in the third-trimester group than in the other two groups. The amount of engorged blood vessels was greater in the third and first trimester groups than in the nonpregnant group. The amount of bleeding at the needle tip and the amount of fatty and fibrous connective tissue did not differ among the three groups.ConclusionsEpidural blood vessels become engorged in the first trimester; the density of the vascular networks increase in the third trimester. These changes in the epidural space during pregnancy may affect the spread of epidural analgesia in pregnant women.

ISSN:0003-3022    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

BackgroundProposed advantages of port-access cardiac surgery have yet to be substantiated. The authors retrospectively compared patients undergoing port-access cardiac surgery with a matched group undergoing conventional cardiac surgery.MethodsForty-six patients who underwent port-access cardiac surgery were matched with 46 who underwent conventional cardiac surgery. Absolute criteria for matching included morning-of-surgery admission, procedure undergone, and care being delivered by one of two surgeons. If possible, matching included care delivered by one of two anesthesiologists. Patients were matched as closely as possible for preoperative demographic and clinical characteristics.ResultsAll 46 pairs of patients were matched for procedure and admitted the morning of surgery. All 92 operations were performed by one of two surgeons, and 89% were performed by one of two anesthesiologists. Preoperative demographic and clinical characteristics were equivalent between groups. Compared with conventional cardiac surgery, port-access cardiac surgery increased surgical complexity (it almost tripled cardiopulmonary bypass time during coronary artery bypass grafting and increased it almost 40% during mitral valve procedures) and increased total operating room time (P < 0.0001). Port-access cardiac surgery had no beneficial effect on earlier postoperative extubation, decreased incidence of atrial fibrillation, or intensive care unit time, yet it decreased postoperative duration of stay (P= 0.029, all patients), a benefit observed primarily in patients undergoing coronary artery bypass grafting (P= 0.002).ConclusionsThis retrospective analysis revealed that port-access cardiac surgery increases surgical complexity, increases operating room time, has no effect on earlier postoperative extubation or decreased incidence of atrial fibrillation or intensive care unit time, and may facilitate postoperative hospital discharge (primarily in patients undergoing coronary artery bypass grafting). Properly designed prospective investigation is necessary to ascertain whether port-access cardiac surgery truly offers any benefits over conventional cardiac surgery.

ISSN:0003-3022    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

BackgroundErythrocytes are transfused to prevent or treat inadequate oxygen delivery resulting from insufficient hemoglobin concentration. Previous studies failed to find evidence of inadequate systemic oxygen delivery at a hemoglobin concentration of 5 g/dl. However, in those studies, sensitive, specific measures of critical organ function were not used. This study tested the hypothesis that acute severe decreases of hemoglobin concentration alters human cognitive function.MethodsNine healthy volunteers, age 29 ± 5 yr (mean ± SD), were tested with verbal memory and standard, computerized neuropsychologic tests before and after acute isovolemic reduction of their hemoglobin to 7, 6, and 5 g/dl and again after transfusion of their autologous erythrocytes to return their hemoglobin concentration to 7 g/dl. To control for duration of the experiment, each volunteer also completed the same tests on a separate day, without alteration of hemoglobin, at times of the day approximately equivalent to those on the experimental day.ResultsNo test showed any change in reaction time or error rate at hemoglobin concentration of 7 g/dl compared with the data at the baseline hemoglobin concentration of 14 g/dl. Reaction time, but not error rate, for horizontal addition and digit–symbol substitution test (DSST) increased at hemoglobin 6 g/dl (mean horizontal addition, 19%; 95% confidence interval [CI], 4–34%; mean DSST, 10%; 95% CI, 4–17%) and further at 5 g/dl (mean horizontal addition, 43%; 95% CI, 6–79%; mean DSST, 18%; 95% CI, 4–31%). Immediate and delayed memory was degraded at hemoglobin 5 g/dl but not at 6 g/dl. Return of hemoglobin to 7 g/dl returned all tests to baseline, except for the DSST, which significantly improved, and returned to baseline the following morning after transfusion of all autologous erythrocytes.ConclusionAcute reduction of hemoglobin concentration to 7 g/dl does not produce detectable changes in human cognitive function. Further reduction of hemoglobin level to 6 and 5 g/dl produces subtle, reversible increases in reaction time and impaired immediate and delayed memory. These are the first prospective data to demonstrate subtle degraded human function with acute anemia of hemoglobin concentrations of 6 and 5 g/dl. This reversibility of these decrements with erythrocyte transfusion suggests that our model can be used to test the efficacy of erythrocytes, oxygen therapeutics, or other treatments for acute anemia.

ISSN:0003-3022    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

BackgroundSpinal cord stimulation (SCS) is known to relieve pain in patients with complex regional pain syndrome (CRPS) and, in general, to cause vasodilation. The vasodilatory effect of SCS is hypothesized to be secondary to inhibition of sympathetically mediated vasoconstriction, or through antidromic impulses resulting in release of vasoactive substances. The aim of the present study was to assess whether pain relief in CRPS after SCS is, in fact, dependent on vasodilation. In addition, we tried to determine which of the potential mechanisms may cause the vasodilatory effect that is generally found after SCS.MethodsTwenty-four of 36 patients with unilateral CRPS responded to the test of SCS. Twenty-two of these 24 responders (hand, n = 14; foot, n = 8) who had undergone previous sympathectomy were enrolled for the study. In addition, 20 control subjects (10 controls for each extremity) were studied. By means of laser Doppler flowmetry, the skin microcirculation of the patients was measured bilaterally while the SCS system was switched off and while it was activated. Control subjects (n = 20) were tested once only. The ratio of the rest flow at heart level and the dependent position was defined as the vasoconstriction index.ResultsBoth in affected hands and feet, patients were found to have lower vasoconstriction indices (P < 0.01) as compared with controls, indicating a decreased sympathetic tone. Applying SCS did not result in any microcirculatory change as compared with baseline or the contralateral clinically unaffected side.ConclusionsThe current study failed to show that SCS influences skin microcirculation in patients with CRPS and a low sympathetic tone. Therefore, we may conclude that pain relief in CRPS due to SCS is possible without vasodilation. Because sympathetic activity was greatly decreased in our patients, these results support the hypothesis that the vasodilation that is normally found with SCS is due to an inhibitory effect on sympathetically maintained vasoconstriction.

ISSN:0003-3022    

出版商:OVID    

年代:2000

数据来源: OVID