Anesthesia and analgesia
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Anesthesia and analgesia · May 2001
Randomized Controlled Trial Comparative Study Clinical TrialThe intubating laryngeal mask airway after induction of general anesthesia versus awake fiberoptic intubation in patients with difficult airways.
We performed the current study to compare tracheal intubation (TI) using awake fiberoptic intubation (AFOI) and TI using the intubating laryngeal mask airway (ILMA) in patients with difficult airway. Our hypothesis was that patients with difficult airways could be safely intubated after induction of anesthesia using the ILMA. After ethics approval and informed consent, 38 patients who were identified to have difficult airways were randomly assigned to AFOI or TI using the ILMA. Patients in the AFOI group had the usual sedation and airway topicalization. Patients in the ILMA group were induced with propofol for ILMA insertion and succinylcholine for TI. The first TI attempt was done blindly via the ILMA and all subsequent attempts were performed with fiberoptic guidance. All patients in the ILMA group were successfully ventilated. Successful TI was achieved in all patients in both groups. However, in 10% of the patients in the ILMA group, TI was achieved by a second anesthesiologist who was more experienced with the use of the ILMA. In a postoperative questionnaire, patients in the ILMA group were more satisfied with their method of TI (P < 0.01). The ILMA is a useful device in the management of patients with difficult airways and may be a valuable alternative to AFOI when AFOI is contraindicated or in the patient with the unanticipated difficult airway. ⋯ The intubating laryngeal mask airway is a useful device in the management of patients with difficult airways and may be a valuable alternative to awake fiberoptic intubation (AFOI) when AFOI is contraindicated or in the patient with the unanticipated difficult airway.
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Anesthesia and analgesia · May 2001
Modulation of NMDA receptor function by ketamine and magnesium. Part II: interactions with volatile anesthetics.
Mg2+ and ketamine interact superadditively at N- methyl-D-aspartate (NMDA) receptors, which may explain the clinical efficacy of the combination. Because patients are usually exposed concomitantly to volatile anesthetics, we tested the hypothesis that volatile anesthetics interact with ketamine and/or Mg2+ at recombinantly expressed NMDA receptors. NR1/NR2A or NR1/NR2B receptors were expressed in Xenopus oocytes. We determined the effects of isoflurane, sevoflurane, and desflurane on NMDA receptor signaling, alone and in combination with S(+)-ketamine (4.1 microM on NR1/NR2A, 3.0 microM on NR2/NR2B) and/or Mg2+ (416 microM on NR1/NR2A, 629 microM on NR1/NR2B). Volatile anesthetics inhibited NR1/NR2A and NR1/NR2B glutamate receptor function in a reversible, concentration-dependent, voltage-insensitive and noncompetitive manner (half-maximal inhibitory concentration at NR1/NR2A receptors: 1.30 +/- 0.02 minimum alveolar anesthetic concentration [MAC] for isoflurane, 1.18 +/- 0.03 MAC for desflurane, 1.24 +/- 0.06 MAC for sevoflurane; at NR1/NR2B receptors: 1.33 +/- 0.12 MAC for isoflurane, 1.22 +/- 0.08 MAC for desflurane, and 1.28 +/- 0.08 MAC for sevoflurane). On both NR1/NR2A and NR1/NR2B receptors, 50% inhibitory concentration for volatile anesthetics was reduced approximately 20% by Mg2+, approximately 30% by S(+)-ketamine, and approximately 50% by the compounds in combination. Volatile anesthetic effects on NMDA receptors can be potentiated significantly by Mg2+, S(+)-ketamine, or-most profoundly-both. Therefore, the analgesic effects of ketamine and Mg2+, are likely to be enhanced in the presence of volatile anesthetics. ⋯ Clinically relevant concentrations of volatile anesthetics inhibit functioning of N-methyl-D-aspartate receptors expressed recombinantly in Xenopus oocytes. This inhibition is reversible, concentration-dependent and voltage-insensitive, and results from noncompetitive antagonism of glutamate/glycine signaling. In addition, these effects can be potentiated significantly by co-application of either Mg2+, S(+)-ketamine, or--most profoundly--both.
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Anesthesia and analgesia · May 2001
Randomized Controlled Trial Multicenter Study Comparative Study Clinical TrialA randomized double-blinded multicenter comparison of remifentanil versus fentanyl when combined with isoflurane/propofol for early extubation in coronary artery bypass graft surgery.
We compared a fentanyl/isoflurane/propofol regimen with a remifentanil/isoflurane/propofol regimen for fast-track cardiac anesthesia in a prospective, randomized, double-blinded study on patients undergoing elective coronary artery bypass graft surgery. Anesthesia was induced with a 1-min infusion of 0.5 mg/kg propofol followed by 10-mg boluses of propofol every 30 s until loss of consciousness. After 0.2 mg/kg cisatracurium, a blinded continuous infusion of remifentanil at 1 microg. kg(-1). min(-1) or the equivalent volume rate of normal saline was then started. In addition, a blinded bolus syringe of 1 microg/kg remifentanil or 10 microg/kg fentanyl, respectively, was given over 3 min. Blinded remifentanil, 1 microg. kg(-1). min(-1) (or the equivalent volume rate of normal saline), together with 0.5% isoflurane, were used to maintain anesthesia. Significantly more patients (P < 0.01) in the fentanyl regimen experienced hypertension during skin incision and maximum sternal spread compared with patients in the remifentanil regimen. There were no differences between the groups in time until extubation, discharge from the surgical intensive care unit, ST segment and other electrocardiogram changes, catecholamine levels, or cardiac enzymes. The remifentanil-based anesthetic (consisting of a bolus followed by a continuous infusion) resulted in significantly less response to surgical stimulation and less need for anesthetic interventions compared with the fentanyl regimen (consisting of an initial bolus, and followed by subsequent boluses only to treat hemodynamic responses) with both drug regimens allowing early extubation. ⋯ Both fentanyl and the newer opioid remifentanil, when each is combined with isoflurane and propofol, allowed for fast-track cardiac anesthesia. The remifentanil regimen used in this study resulted in significantly less hemodynamic response to surgical stimulation.
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Anesthesia and analgesia · May 2001
Randomized Controlled Trial Multicenter Study Clinical TrialThe efficacy and resource utilization of remifentanil and fentanyl in fast-track coronary artery bypass graft surgery: a prospective randomized, double-blinded controlled, multi-center trial.
We compared (a) the perioperative complications; (b) times to eligibility for, and actual time of the following: extubation, less intense monitoring, intensive care unit (ICU), and hospital discharge; and (c) resource utilization of nursing ratio for patients receiving either a typical fentanyl/isoflurane/propofol regimen or a remifentanil/isoflurane/propofol regimen for fast-track cardiac anesthesia in 304 adults by using a prospective randomized, double-blinded, double-dummy trial. There were no differences in demographic data, or perioperative mortality and morbidity between the two study groups. The mini-mental status examination at postoperative Days 1 to 3 were similar between the two groups. The eligible and actual times for extubation, less intense monitoring, ICU discharge, and hospital discharge were not significantly different. Further analyses revealed no differences in times for extubation and resource utilization after stratification by preoperative risk scores, age, and country. The nurse/patient ratio was similar between the remifentanil/isoflurane/propofol and fentanyl/isoflu-rane/propofol groups during the initial ICU phase and less intense monitoring phase. Increasing preoperative risk scores and older age (>70 yr) were associated with longer times until extubation (eligible), ICU discharge (eligible and actual), and hospital discharge (eligible and actual). Times until extubation (eligible and actual) and less intense monitoring (eligible) were significantly shorter in Canadian patients than United States' patients. However, there was no difference in hospital length of stay in Canadian and United States' patients. We conclude that both anesthesia techniques permit early and similar times until tracheal extubation, less intense monitoring, ICU and hospital discharge, and reduced resource utilization after coronary artery bypass graft surgery. ⋯ An ultra-short opioid technique was compared with a standard fast-track small-dose opioid technique in coronary artery bypass graft patients in a prospective randomized, double-blinded controlled study. The postoperative recovery and resource utilization, including stratification of preoperative risk score, age, and country, were analyzed.
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Anesthesia and analgesia · May 2001
Clinical TrialContinuous fascia iliaca compartment block in children: a prospective evaluation of plasma bupivacaine concentrations, pain scores, and side effects.
We sought to determine the plasma concentrations of bupivacaine and its main metabolite after continuous fascia iliaca compartment (FIC) block in children. Twenty children (9.9 +/- 4 yr, 38 +/- 19 kg) received a continuous FIC block for either postoperative analgesia (n = 16) or femoral shaft fracture (n = 4). A bolus dose of 0.25% bupivacaine (1.56 +/- 0.3 mg/kg) with epinephrine was followed by a continuous administration of 0.1% bupivacaine (0.135 +/- 0.03 mg. kg(-)(1). h(-)(1)) for 48 h. Plasma bupivacaine levels were determined at 24 h and 48 h by using gas liquid chromatography. Heart rate, arterial blood pressure, respiratory rate, side effects, and pain scores were recorded at 4-h intervals during 48 h. No significant differences were found between mean plasma bupivacaine levels at 24 h (0.71 +/- 0.4 microg/mL) and at 48 h (0.84 +/- 0.4 microg/mL) (P = 0.33). FIC block provided adequate analgesia in most cases. No severe adverse effects were noted. We conclude that the bupivacaine plasma concentrations during continuous FIC block in children are within the safety margins. FIC block is well tolerated, and provides satisfactory pain relief in most cases. ⋯ In this study, we have shown that, in children, continuous fascia iliaca compartment block, a technique providing neural blockade of the thigh and the anterior part of the knee, was associated with safe plasma bupivacaine concentrations, was well tolerated, and provided satisfactory pain scores in most cases.