Anesthesia and analgesia
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Anesthesia and analgesia · Sep 1998
Randomized Controlled Trial Clinical TrialEpidural fentanyl reduces the shivering threshold during epidural lidocaine anesthesia.
Epidural local anesthetics and IV opioids both decrease the core temperature that triggers shivering. However, the effect of epidural opioids on shivering thresholds has not been assessed. In this study, we tested the hypothesis that adding epidural fentanyl to epidural lidocaine decreases the shivering threshold compared with epidural lidocaine alone. Fourteen healthy male patients undergoing extracorporeal shockwave lithotripsy under epidural anesthesia were randomly assigned to receive either epidural lidocaine or epidural lidocaine plus epidural fentanyl. Ice-cold lactated Ringer's solution was given IV before epidural blockade, and the core temperature that triggers shivering was established. Then epidural anesthesia was induced, and the shivering threshold was established again after lithotripsy. Results were analyzed using paired or unpaired t-tests. Reduction in the shivering threshold by epidural anesthesia was significantly greater when fentanyl was added to lidocaine than when lidocaine was used alone (mean +/- SD: -0.6+/-0.4 degrees C versus -0.1+/-0.4 degrees C; P < 0.02). We conclude that patients are at increased risk of hypothermia when fentanyl is added to epidural lidocaine. ⋯ Fentanyl is often added to lidocaine to improve the quality of epidural blockade and to reduce side effects. However, this study shows that patients are at increased risk of hypothermia when fentanyl is added to lidocaine.
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Anesthesia and analgesia · Sep 1998
Clinical TrialThe laryngeal mask airway reliably provides rescue ventilation in cases of unanticipated difficult tracheal intubation along with difficult mask ventilation.
In 1995, our department of anesthesiology established an airway team to assist in treating unanticipated difficult endotracheal intubations and an airway quality improvement (QI) form to document the use of emergency airway techniques in airway crises (laryngeal mask airway [LMA], flexible fiberoptic bronchoscopy, retrograde intubation [RI], transtracheal jet ventilation [TTJV], and cricothyrotomy). Over a 2-yr period, team members and staff anesthesiologists completed airway QI forms to document the smallest peripheral SpO2 during an airway crisis, the number of direct laryngoscopies (DL) performed before using an emergency airway technique, and the emergency airway technique that succeeded in rescue ventilation. Team members agreed to use the LMA as the first emergency airway technique to treat the difficult ventilation/difficult intubation scenario. A SpO2 value < or =90% during mask ventilation defined difficult ventilation. Inability to perform tracheal intubation by DL defined difficult intubation. An increase in the SpO2 value >90% defined rescue ventilation. Review of airway QI forms from October 1, 1995 until October 1, 1997 revealed 25 cases of difficult ventilation/difficult intubation. Before airway rescue, the median SpO2 was 80% (range 50%-90%), and there were four median attempts at DL (range one to nine). The LMA had a success rate of 94% (95% confidence interval [CI] 77-100). Flexible fiberoptic bronchoscopy, TTJV, RI, and surgical cricothyrotomy had success rates of 50% (95% CI 0-100), 33% (95% CI 0-100), 100% (95% CI 37-100), and 100% (95% CI 37-100), respectively. LMA insertion as the first alternative airway technique was useful in dealing with unanticipated instances of simultaneous difficulty with mask ventilation and tracheal intubation. ⋯ Twenty-five cases of simultaneous difficulty with mask ventilation and tracheal intubation occurred after the induction of general anesthesia during the study period. The laryngeal mask was used in 17 cases, and it provided rescue ventilation without complication in 94% of these cases (95% confidence interval 77-100).
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Anesthesia and analgesia · Sep 1998
Randomized Controlled Trial Clinical TrialSimulation of an epidural test dose with intravenous isoproterenol in sevoflurane- and halothane-anesthetized children.
Isoproterenol has been suggested as an alternative marker for epidural test dosing in children receiving halothane anesthesia. The purpose of this prospective, randomized, double-blind study was to determine the chronotropic response to IV isoproterenol in sevoflurane-anesthetized children. Thirty-six ASA physical status I children (0.5-8 yr) were anesthetized with either halothane or sevoflurane at 1 minimum alveolar anesthetic concentration adjusted for age in 70% nitrous oxide. Patients received incremental IV injections of isoproterenol until their heart rate increased > or = 20 bpm above baseline. The minimal effective dose of isoproterenol required to produce an increase of > or = 20 bpm was 55 ng/kg (42-72 ng/kg; 95% confidence interval) in sevoflurane-anesthetized children and 32 ng/kg (26-38 ng/kg; 95% confidence interval) in halothane-anesthetized children (P < 0.05). This dose-response study suggests that sevoflurane antagonizes beta-adrenergic-mediated chronotropic responses to isoproterenol more than halothane. These observations also suggest that larger doses of isoproterenol will be necessary for epidural test dosing in children receiving sevoflurane rather than halothane anesthesia. ⋯ Isoproterenol has been suggested as an alternative marker for epidural test dosing in children receiving halothane anesthesia. This isoproterenol dose-response study indicates that larger doses of isoproterenol will be necessary for epidural test dosing in children undergoing sevoflurane rather than halothane anesthesia.