Anesthesia and analgesia
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Anesthesia and analgesia · Dec 1997
Randomized Controlled Trial Comparative Study Clinical TrialSevoflurane or halothane anesthesia: can we tell the difference?
This study was performed to evaluate the ability of anesthesiologists to differentiate between sevoflurane, a newer, more expensive anesthetic, and halothane. A total of 113 assessments were made by 36 anesthesiologists on 58 children, aged 6 mo to 6 yr, scheduled for bilateral myringotomy and tube placement. All patients received midazolam (0.5 mg/kg per os) approximately 30 min before the induction of anesthesia. Sevoflurane or halothane was randomly selected for anesthetic induction and maintenance. The anesthesiologists, who were unaware of the anesthetic being used, were asked to identify the anesthetic based on clinical signs and to assess the quality of induction, speed of induction, and speed of emergence using a visual analog scale (VAS; minimum score = 0, maximum score = 100). The anesthesiologists correctly identified the anesthetic only 56.6% of the time. This was not significantly different from the 50% that would result from random guessing (P = 0.08). Further, there were no significant differences in VAS scores between the two groups. This study suggests that in premedicated pediatric patients undergoing brief surgical procedures, anesthesiologists cannot correctly differentiate between sevoflurane and halothane. The lack of significant differences in VAS scores suggests that the speed of induction, the speed of emergence, and the quality of induction are similar under these clinical conditions. Any purported benefits of sevoflurane seem to be of minor consequence under the circumstances studied. ⋯ When the anesthetic halothane or sevoflurane is administered in a blind, randomized fashion, anesthesiologists could not reliably identify which drug was being used to anesthetize children for a brief surgical procedure. These results suggest that the differences between the two drugs in clinical practice are small and may not justify the additional cost of sevoflurane.
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Anesthesia and analgesia · Dec 1997
Randomized Controlled Trial Clinical TrialLate-onset preemptive analgesia associated with preincisional large-dose alfentanil.
Few studies using systemic opioids have been adequately designed to demonstrate a preemptive effect. We investigated the preemptive effect of intraoperative large-dose intravenous (I.V.) opioids over a 72-h period after lower abdominal surgery. Thirty-eight ASA physical status I or II patients undergoing abdominal hysterectomy were studied in a prospective, randomized, double-blind design. Group PRE received alfentanil 70 microg/kg over 10 min before surgical incision; Group POST received alfentanil 70 microg/kg over 10 min after incision. Patients received no other intraoperative opioid. Pain was treated in the recovery room with 2-mg I.V. boluses of morphine and was subsequently managed via patient-controlled analgesia (PCA) using morphine sulfate. Visual analog scale pain scores at rest (VAS-R) and on movement (VAS-M) and PCA morphine consumption were recorded for 72 hours. VAS-M and VAS-R scores did not differ at any point, and morphine consumption was similar in both groups over the initial 48 h. Group PRE used significantly less morphine from 48 to 72 h postoperatively (P < 0.02). We conclude that presurgical incisional (i.e., compared with postincisional) large-dose opioid exposure results in a modest, late decrease in postoperative morphine consumption, with no clinical impact on early postoperative pain. Timing of the observed reduction coincides with maximal output of substances implicated in experimental hyperalgesia. ⋯ When given before surgical incision, alfentanil, a short-acting narcotic, was associated with a reduction in morphine requirements 48-72 h after surgery. Brief interventions may have a delayed and sustained impact on pain perception, possibly by reducing mechanisms of sensitization.
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Anesthesia and analgesia · Dec 1997
Randomized Controlled Trial Clinical TrialOptimal dose of nicardipine for maintenance of hemodynamic stability after tracheal intubation and skin incision.
To determine the optimal dose of nicardipine (N) for maintenance of hemodynamic stability during the postinduction period, we designed a randomized, double-blind, placebo-controlled, dose-ranging study using four different doses of N administered after a standardized anesthetic induction sequence. A total of 106 patients were assigned to one of the following treatment groups: saline (control), N 0.5 mg (N0.5), N 1 mg (N1), N 2 mg (N2), and N 4 mg (N4). The study medication was administered intravenously (I.V.) in 2.5 mL of saline over 30 s 2 min before laryngoscopy. Mean arterial pressure (MAP) and heart rate (HR) were recorded at 1-min intervals for 15 min after tracheal intubation and for 5 min after skin incision. After intubation, the peak MAP values differed from the preinduction baseline MAP values by 21% +/- 20%, 9% +/- 12%, 1% +/- 13%, -10% +/- 12%, and -15% +/- 13% (mean +/- SD) in the control, N0.5, N1, N2, and N4 groups, respectively. However, the percent change in the pre- to postintubation MAP values (37% to 47%) was similar in all five groups. The highest postintubation HR values were recorded in the N4 group (P < 0.05 versus the other groups). However, the increases in MAP values after skin incision were the least in the N4 group. In conclusion, N1 I.V., administered 2 min before laryngoscopy provides optimal control of arterial blood pressure during the postinduction period. ⋯ Acute increases in blood pressure during anesthesia are undesirable in patients with preexisting cardiovascular diseases. This double-blind study found that the calcium-channel blocker, nicardipine, 1 mg intravenously 2 min before tracheal intubation maintained hemodynamic stability during the intraoperative period.
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Anesthesia and analgesia · Dec 1997
Randomized Controlled Trial Comparative Study Clinical TrialPharmacokinetics and pharmacodynamics of propofol in a new solvent.
Pain on injection is the most commonly reported adverse event after propofol injection. In a randomized, cross-over study in two groups of 12 healthy male volunteers (24-42 yr), we compared the pharmacokinetics and pharmacodynamics of two new propofol formulations (1% and 2% concentrations) in a fat emulsion consisting of medium- and long-chain triglycerides with the standard propofol formulation. After a single intravenous bolus injection of 2 mg/kg, propofol blood levels were measured for 24 h and evaluated according to an open three-compartment model. The derived pharmacokinetic variables were not different among formulations. Additionally, electroencephalographic recordings of the onset and duration of hypnotic action were comparable with all formulations. After propofol 1% in the new formulation, fewer volunteers reported severe or moderate pain on injection (9%) than after the standard formulation (59%) (P < 0.05). We attribute this result to a lower concentration of free propofol in the aqueous phase of the new formulation. ⋯ Changing the composition of the carrier fat emulsion for propofol does not have an impact on the pharmacokinetics and efficacy of propofol, but it promises to provide better patient acceptance by lowering the incidence of moderate and severe pain on injection.
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Anesthesia and analgesia · Dec 1997
Randomized Controlled Trial Comparative Study Clinical TrialThe UpsherScope in routine and difficult airway management: a randomized, controlled clinical trial.
The UpsherScope, a rigid fiberoptic laryngoscope, may facilitate tracheal intubation. We performed a randomized, controlled trial of tracheal intubation using the UpsherScope and compared the success rate with that of direct laryngoscopy. Three hundred patients were randomly assigned to either fiberoptic oral intubation using the UpsherScope (Group US, n = 148) or to direct laryngoscopy (Group DL, n = 152). No significant differences in airway variables were observed between the groups. US intubation was successful in 129 of 148 patients (87%). A second or third attempt was required in 15% and 3%, respectively, of the patients successfully intubated with US. The remaining patients were intubated using DL (n = 17) or the flexible fiberoptic bronchoscope (n = 2). The success rate of DL was significantly higher (97%; P < 0.05), with a second or third attempt required in only seven patients. Time needed to perform successful intubation was 50 +/- 41 s for the US group compared with 23 +/- 13 s for the DL group (P < 0.05). We found no advantage of the UpsherScope over direct laryngoscopy during routine and difficult airway management. Time needed, number of attempts required to perform intubation, and incidence of failure were significantly longer and higher in group US. ⋯ We studied tracheal intubation using the fiberoptic UpsherScope and compared the success rate with that of a control group of patients intubated using conventional laryngoscopy. No advantages of the new device were found. On the contrary, time needed, number of attempts required, and incidence of failure were even longer and higher.