Articles: anesthetics.
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Anesthesia and analgesia · Feb 2002
Randomized Controlled Trial Multicenter Study Clinical TrialThe efficacy and safety of three concentrations of levobupivacaine administered as a continuous epidural infusion in patients undergoing orthopedic surgery.
We evaluated the efficacy and safety of three concentrations of levobupivacaine infused epidurally as analgesia for patients undergoing orthopedic procedures. Patients undergoing elective hip or knee joint replacement were enrolled in the study (n = 105). Sensory blockade was established preoperatively with 10-15 mL of 0.75% levobupivacaine. Patients were then randomized to receive 0.0625%, 0.125%, or 0.25% levobupivacaine as a continuous epidural infusion at 6 mL/h for 24 h. IV morphine patient-controlled analgesia was given as rescue analgesia, and time to first request for analgesia and total dose of morphine consumed were recorded. Sensory blockade, motor blockade, visual analog scale pain score, and cardiovascular variables were also recorded at regular intervals postoperatively. Ninety-one patients were included in the primary intent-to-treat analysis. Total normalized dose of morphine, number of patient-controlled analgesia requests, and overall postoperative visual analog scale pain scores were significantly lower for the 0.25% group compared with the other two groups, and the time to first request for rescue analgesia was longer. There was no significant difference between the 0.125% and 0.25% groups in terms of maximum motor blockade achieved and time to minimal motor blockade. Safety data were equivalent among the three groups. We conclude that levobupivacaine as a continuous epidural infusion provided adequate postoperative analgesia and that the 0.25% concentration provided significantly longer analgesia than 0.125% or 0.0625% levobupivacaine without any significant increase in detectable motor blockade relative to the 0.125% group. ⋯ Postoperative epidural infusion of levobupivacaine can provide safe and effective analgesia for patients having hip or knee joint replacement. Of the three concentrations we infused at a constant rate, 0.25% provided significantly better pain relief.
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Randomized Controlled Trial Multicenter Study Clinical Trial
Fresh gas flow is not the only determinant of volatile agent consumption: a multi-centre study of low-flow anaesthesia.
Seven academic centres studied 302 patients, using desflurane, enflurane, halothane, or isoflurane using circle-systems and Dräger Julian anaesthetic machines, with fresh gas flows (V(F)) of 3, 1, and 0.5 litre min(-1). Volatile agent partial pressures in the breathing system were recorded and agent consumptions measured by weighing. ⋯ At V(F) that involves significant re-breathing, consumption of soluble agents depends only partially on V(F). These results can be explained using Mapleson's hydraulic analogue model.
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Acta Anaesthesiol Belg · Jan 2002
Randomized Controlled Trial Multicenter Study Comparative Study Clinical TrialRemifentanil vs. alfentanil for direct laryngoscopy: a randomized study comparing two total intravenous anaesthesia techniques. TIVA for direct laryngoscopy.
The ideal anaesthesia for direct laryngoscopy is profound and yet brief. The present study sought to determine whether a new anaesthetic technique based on infusion of the ultra short-acting opioid remifentanil was superior to our routine alfentanil multiple-dose technique in terms of haemodynamic stability, stress responses and recovery. A total of 58 patients were randomized to receive propofol and either remifentanil or alfentanil as part of a total intravenous anaesthesia. ⋯ In the remifentanil group, hypotension or bradycardia requiring intervention arose in 5 (18%) and 3 patients (11%); neither response was seen in the alfentanil group. The period from the end of propofol infusion until extubation was 5 min longer in the remifentanil group (P < 0.0001), whereas the time from extubation until discharge was similar in the two groups. Thus, neither technique showed sufficient haemodynamic stability, and further studies are needed to determine optimal dosages of propofol and opioid.
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Anesthesia and analgesia · Dec 2001
Multicenter StudyPharmacokinetics of remifentanil in anesthetized pediatric patients undergoing elective surgery or diagnostic procedures.
Remifentanil hydrochloride is an ultra-short-acting opioid that undergoes rapid metabolism by tissue and plasma esterases. We aimed to characterize the pharmacokinetics and determine the hemodynamic profile of remifentanil after a single-bolus dose in children aged 0 to 18 yr. Forty-two children undergoing elective surgical procedures received remifentanil 5 microg/kg infused over 1 min. Patients were divided into age groups as follows: young infants (< or =2 mo), older infants (> 2 mo to < 2 yr), young children (2 to < 7 yr), older children (7 to < 13 yr), adolescents (13 to < 16 yr), and young adults (16 to < 18 yr). Arterial blood samples were collected and analyzed by mass spectroscopy to determine remifentanil pharmacokinetic profiles. Hemodynamic measurements for remifentanil's effect were made after the infusion. Methods of statistical analysis included analysis of variance and linear regression, with significance at P < or = 0.05. Complete remifentanil pharmacokinetic data were obtained from 34 patients. The volume of distribution was largest in the infants < 2 mo (mean, 452 mL/kg) and decreased to means of 223 to 308 mL/kg in the older patients. There was a more rapid clearance in the infants < 2 mo of age (90 mL. kg(-1). min(-1)) and infants 2 mo to 2 yr (92 mL. kg(-1). min(-1)) than in the other groups (means, 46 to 76 mL. kg(-1). min(-1)). The half-life was similar in all age groups, with means of 3.4 to 5.7 min. Seven subjects (17%) developed hypotension related to the remifentanil bolus. Remifentanil showed an extremely rapid elimination similar to that in adults. The fast clearance rates observed in neonates and infants, as well as the lack of age-related changes in half-life, are in sharp contrast to the pharmacokinetic profile of other opioids. Remifentanil in a bolus dose of 5 microg/kg may cause hypotension in anesthetized children. ⋯ The pharmacokinetics of remifentanil were studied in children from birth to 18 yr. Remifentanil was found to have age-related changes in clearance and volume of distribution, but not half-life. The increased clearance observed in young infants is in contrast to other opioids.
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Anesthesia and analgesia · Dec 2001
Randomized Controlled Trial Multicenter Study Comparative Study Clinical TrialLong-duration low-flow sevoflurane and isoflurane effects on postoperative renal and hepatic function.
Sevoflurane degradation by carbon dioxide absorbents during low-flow anesthesia forms the haloalkene Compound A, which causes nephrotoxicity in rats. Numerous studies have shown no effects of Compound A formation on postoperative renal function after moderate-duration (3-4 h) low-flow sevoflurane; however, effects of longer exposures remain unresolved. We compared renal function after long-duration low-flow (<1 L/min) sevoflurane and isoflurane anesthesia in consenting surgical patients with normal renal function. To maximize degradant exposure, Baralyme was used, and anesthetic concentrations were maximized (no nitrous oxide and minimal opioids). Inspired and expired Compound A concentrations were quantified. Blood and urine were obtained for laboratory evaluation. Sevoflurane (n = 28) and isoflurane (n = 27) groups were similar with respect to age, sex, weight, ASA status, and anesthetic duration (9.1 +/- 3.0 and 8.2 +/- 3.0 h, mean +/- SD) and exposure (9.2 +/- 3.6 and 9.1 +/- 3.7 minimum alveolar anesthetic concentration hours). Maximum inspired Compound A was 25 +/- 9 ppm (range, 6-49 ppm), and exposure (area under the concentration-time curve) was 165 +/- 95 (35-428) ppm. h. There was no significant difference between anesthetic groups in 24- or 72-h serum creatinine, blood urea nitrogen, creatinine clearance, or 0- to 24-h or 48- to 72-h urinary protein or glucose excretion. Proteinuria and glucosuria were common in both groups. There was no correlation between Compound A exposure and any renal function measure. There was no difference between anesthetic groups in 24- or 72-h aspartate aminotransferase or alanine aminotransferase. These results show that the renal and hepatic effects of long-duration low-flow sevoflurane and isoflurane were similar. No evidence for low-flow sevoflurane nephrotoxicity was observed, even at high Compound A exposures as long as 17 h. Proteinuria and glucosuria were common and nonspecific postoperative findings. Long-duration low-flow sevoflurane seems as safe as long-duration low-flow isoflurane anesthesia. ⋯ Postoperative renal function after long-duration low-flow sevoflurane (with Compound A exposures greater than those typically reported) and isoflurane anesthesia were not different, as assessed by serum creatinine, blood urea nitrogen, and urinary excretion of protein and glucose. This suggests that low-flow sevoflurane is as safe as low-flow isoflurane, even at long exposures.