Anesthesiology
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Perioperative administration of the alpha 2 agonist clonidine has been shown to increase plasma alfentanil concentrations; however, the mechanism for this pharmacokinetic drug interaction is unknown. Because alfentanil undergoes extensive hepatic biotransformation, clonidine inhibition of alfentanil metabolism may alter alfentanil disposition. The first purpose of this investigation was to test the hypothesis that clonidine impairs human liver alfentanil metabolism. ⋯ Preincubation of D-medetomidine with microsomes did not enhance the inhibition of alfentanil metabolism. These results suggest that the increased alfentanil plasma concentrations and potentiation of alfentanil anesthesia associated with clonidine do not result from clonidine inhibition of alfentanil metabolism. D-medetomidine impairment of alfentanil metabolism, however,if present at therapeutic concentrations, may influence alfentanil disposition.(ABSTRACT TRUNCATED AT 250 WORDS)
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Randomized Controlled Trial Clinical Trial Retracted Publication
Blood conservation techniques and platelet function in cardiac surgery.
Postoperative alterations in platelet function induced by cardiopulmonary bypass (CPB) are of importance. The effect on platelet aggregation of three different techniques for reducing blood consumption was studied in 30 patients undergoing elective aortocoronary bypass grafting from the beginning of anesthesia until the 1st postoperative day. The patients were randomly divided into three groups, in which 1) a cell separator was used during and after CPB; 2) a hemofiltration device was used; and 3) high-dose aprotinin was used in order to reduce the need of homologous blood. ⋯ On the 1st postoperative day, platelet aggregation in the hemofiltration patients and the patients treated with aprotinin had normalized. Aggregation of patients pretreated with high-dose aprotinin was not different from that of the hemofiltration patients throughout the investigation. Blood loss was significantly highest in the cell-separator group (770 +/- 400 ml on the 1st postoperative day) but was not different between the hemofiltration (390 +/- 230 ml) and the aprotinin-treated patients (260 +/- 160 ml).(ABSTRACT TRUNCATED AT 250 WORDS)
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Randomized Controlled Trial Clinical Trial
Fetal heart rate after epidural lidocaine and bupivacaine for elective cesarean section.
This prospective double-blind study was designed to determine whether the fetal heart rate (FHR) changes that have been reported after epidural administration of bupivacaine and lidocaine during labor are present when larger doses of these drugs are given during elective cesarean section. Prior to inserting an epidural catheter, FHR and maternal vital signs were monitored during a control period in 60 healthy term parturients. Patients were randomly assigned to receive either 0.5% bupivacaine with 0.1 mEq sodium bicarbonate added to each 20 ml (n = 30) or 2% lidocaine with 1:300,000 epinephrine (n = 30). ⋯ The groups were similar with respect to maternal characteristics, onset of surgical anesthesia, time to delivery, and uterine incision-delivery interval. Maternal blood pressure decreased from control values in both groups (P less than 0.05), but there was no difference between the groups in either the incidence of hypotension or ephedrine requirements. Analysis of FHR tracings by a perinatologist blinded to the study group revealed no changes after anesthesia and no significant differences between the groups at any time in basal FHR, short- or long-term variability, or the incidence of accelerations or decelerations.(ABSTRACT TRUNCATED AT 250 WORDS)
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Clinical Trial Controlled Clinical Trial
Measurement of pulmonary blood flow with transesophageal two-dimensional and Doppler echocardiography.
Transesophageal echocardiography permits measurement of the pulmonary artery diameter (two-dimensional echocardiography) and pulmonary artery blood flow velocity (pulsed-wave Doppler). These measurements considered with the heart rate allow for the determination of pulmonary artery blood flow, which is equivalent to cardiac output. This study compared the precision of transesophageal Doppler-derived cardiac output (DdCO) with the precision of thermodilution cardiac output (TdCO) and examined the agreement between DdCO and TdCO in 33 cardiac surgical patients. ⋯ A total of 45 sets of triplicate measurements were made. The range of cardiac outputs encountered was 1.7-6.6 l.min-1 by TdCO and 1.5-6.9 l.min-1 by DdCO. The 95% confidence limits for the difference between the two methods (agreement) was 0.030 +/- 0.987 l.min-1.(ABSTRACT TRUNCATED AT 250 WORDS)