Anesthesia and analgesia
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Anesthesia and analgesia · Jan 1998
Randomized Controlled Trial Clinical TrialTracheal intubation in ambulatory surgery patients: using remifentanil and propofol without muscle relaxants.
Using alfentanil followed by an anesthetic induction dose of propofol provides adequate conditions for tracheal intubation without neuromuscular relaxants. Remifentanil, which has a clinical onset similar to that of alfentanil, has not been investigated for this indication. Accordingly, 80 ASA physical status I and II premedicated outpatients were randomly assigned to one of four groups (n = 20/group). Remifentanil 1, 2, 3, or 4 micrograms/kg (Groups I-IV, respectively) was infused intravenously over 90 s. Sixty seconds after beginning the remifentanil infusion, propofol 2 mg/kg was infused over 5 s. Ninety seconds after the administration of propofol, laryngoscopy and tracheal intubation were attempted and graded. Clinically acceptable intubating conditions (i.e., jaw relaxed, vocal cords open, and fewer than two coughs in response to intubation) were observed in 35%, 75%, 100%, and 95% of patients in Groups I-IV, respectively. Clinically acceptable intubating conditions were significantly (P < 0.05) less likely to occur in Group I compared with all other groups. Excellent intubating conditions (i.e., vocal cords open, no movement in response to intubation) were observed in 30%, 50%, 80%, 80% of patients in Groups I-IV, respectively. Overall conditions at intubation were significantly (P < 0.05) better in Groups III and IV compared with Groups I and II. The mean time to resumption of spontaneous ventilation after induction was < 5 min in all groups. No patient manifested clinically significant muscle rigidity. The mean arterial pressure decreased 16%, 20%, 28%, 26% immediately before tracheal intubation in Groups I-IV, respectively. No patient was treated for hypotension or bradycardia. In conclusion, healthy, premedicated patients with favorable airway anatomy can be reliably intubated with good or excellent conditions 90 s after the administration of remifentanil 3-4 micrograms/kg and propofol 2 mg/kg. ⋯ Remifentanil 3 micrograms/kg and propofol 2 mg/kg co-administered intravenously may reliably provide adequate conditions for tracheal intubation in healthy patients without neuromuscular relaxants. This combination of drugs may allow the rapid return of spontaneous ventilation.
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Anesthesia and analgesia · Jan 1998
Randomized Controlled Trial Clinical TrialRecovery from opioid anesthesia: the clinical implication of context-sensitive half-times.
The context-sensitive half-time, the time required for a 50% decrease in drug concentration, has been proposed to predict the speed of recovery after infusions of i.v. anesthetics. We studied 40 patients to compare the clinical recovery characteristics of alfentanil and sufentanil. Patients were randomly allocated to receive either sufentanil/propofol (Group 1) or alfentanil/propofol (Group 2) total i.v. anesthesia by target-controlled infusions (TCI), assuming an equipotency ratio of 500:1. After discontinuation, times to tracheal extubation and to discharge from the postanesthesia care unit were measured, as were drug concentrations up to 24 h. The TCI bias was -17.1% for sufentanil and -16.9% for alfentanil. We found no difference in mean extubation times between the groups (48.7 min in Group 1 versus 46.4 min in Group 2), whereas discharge criteria were fulfilled significantly (P = 0.039) earlier after alfentanil (99.5 min) compared with sufentanil (131.3 min). The relative decrement values to tracheal extubation were 62.1% for sufentanil and 48.0% for alfentanil, compared with 75.7% and 65.0% for discharge, respectively. Based on a difference in propofol requirements, we suggest an actual sufentanil to alfentanil equipotency ratio of 1:300. We conclude that the decay in pharmacodynamic effect is not only the result of pharmacokinetics. ⋯ Computer simulations may help to anticipate the clinical behavior of anesthetic drugs. In a clinical setting, we tested whether the recovery characteristics after i.v. anesthesia could be explained by a pharmaco-kinetic value, which describes the decline of drug concentrations in the body. This was not fully achieved.
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Anesthesia and analgesia · Jan 1998
Randomized Controlled Trial Clinical TrialThe effect of adenosine triphosphate on sevoflurane requirements for minimum alveolar anesthetic concentration and minimum alveolar anesthetic concentration-awake.
We evaluated the effects of i.v. adenosine triphosphate (ATP) on sevoflurane minimum alveolar anesthetic concentration (MAC) and MAC-Awake. The study group included healthy patients 20-60 yr of age. The study groups for MAC-Awake determination included 49 patients who were scheduled for elective surgery. The study groups for MAC determination included 53 patients scheduled for elective surgery involving a skin incision. These patients were randomly assigned to two groups, an ATP group and a control group. The ATP group received 100 micrograms.kg-1.min-1 ATP i.v., and the control group received no medication. The ATP group and the control group were compared with regard to MAC-Awake (anesthetic concentration achieving 50% probability of eye opening in response to a verbal command) and MAC (anesthetic concentration achieving 50% probability of no movement in response to skin incision). The MAC-Awake was 0.7% +/- 0.1% in the control group (mean +/- SD) and 0.7% +/- 0.1% in the ATP group. MAC was 1.9% +/- 0.1% in the control group and 2.1% +/- 0.2% in the ATP group. The differences in MAC and MAC-Awake between the two groups were not statistically significant. We conclude that ATP infusion (100 micrograms.kg-1.min-1) has no effect on sevoflurane MAC and MAC-Awake. ⋯ We found that an i.v. adenosine triphosphate infusion (100 micrograms.kg-1.min-1) has no effect on sevoflurane minimum alveolar anesthetic concentration (anesthetic concentration achieving 50% probability of no movement in response to skin incision) and minimum alveolar anesthetic concentration-Awake (anesthetic concentration achieving 50% probability of eye opening in response to a verbal command) in humans.
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Anesthesia and analgesia · Jan 1998
Randomized Controlled Trial Clinical TrialThe pharmacodynamics of mivacurium preceded by atracurium or cisatracurium in children.
We evaluated whether mivacurium maintains its short duration of effect when preceded by atracurium or cisatracurium in 45 children during propofol/alfentanil/N2O/O2 anesthesia. Neuromuscular response was recorded by using an adductor pollicis electromyogram (EMG). Children were randomized to receive two doses of atracurium (350 micrograms/kg and 70 micrograms/kg in Group AM), cisatracurium (64 micrograms/kg and 10 micrograms/kg in Group CM), or mivacurium (200 micrograms/kg and 100 micrograms/kg in Group MM), followed by a final dose of mivacurium 100 micrograms/kg. The second and third doses of the muscle relaxants were administered at 25% EMG recovery. After the final dose of mivacurium, the times to 95% of EMG recovery in groups AM, CM, and MM were (median with 10-90 percentile range) 33.0 (28.0-40.0) min, 30.7 (26.0-40.3) min, and 10.3 (8.0-14.0) min, respectively (P < 0.0001). The recovery times to a train-of-four ratio of 0.70 were 30.3 (24.7-37.0) min, 28.0 (24.7-37.7) min, and 10.3 (8.0-13.7) min for groups AM, CM, and MM, respectively (P < 0.0001). Thus, the duration of effect of mivacurium was prolonged by 200% if preceded by either atracurium or cisatracurium. ⋯ We compared the pharmacodynamics of mivacurium given alone or preceded by atracurium or cisatracurium in children. The duration of effects of mivacurium was prolonged by 200% if preceded by either atracurium or cisatracurium. This implies that mivacurium has a short duration of effect only when given as a single relaxant.
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Anesthesia and analgesia · Jan 1998
Factors that influence parents' decisions to consent to their child's participation in clinical anesthesia research.
There is concern that the environment in which consent for anesthesia research is sought may be coercive. We therefore designed this study to determine the factors that parents consider in consenting to their child's participation in clinical anesthesia research. The study sample consisted of 246 parents who had been approached for permission to allow their child to participate in a clinical anesthesia study. Parents were asked to complete a questionnaire detailing the reasons for their decision to consent or decline their child's participation. There were no differences in the demographics of the consenters (n = 168) and nonconsenters (n = 78). Perceived risk and the importance of the study were the primary factors in the parents' decisions to consent or decline. Only 2.8% of nonconsenters strongly considered a lack of privacy as a deciding factor; 15.3% stated that they had insufficient time in which to make a decision, and 0% reported having felt pressured. Furthermore, only 3.1% of consenters strongly considered an obligation to consent. Results of this survey highlight factors that influence parents' decisions to consent to their child's participation in clinical anesthesia research. We hope that this information will be important to researchers in providing an appropriate environment for obtaining consent for clinical anesthesia research studies. ⋯ Parents who are approached for permission for their child to participate in a research study must be fully informed and under no pressure to consent. This study describes factors that influence parents' decisions to consent to their child's participation in clinical anesthesia research.