Journal of clinical anesthesia
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Apneic, anesthetized patients frequently develop airway obstruction or may be disconnected from ventilatory support. The rate of PaCO2 rise is usually assumed to be equal to that of anesthetized humans who are receiving apneic oxygenation. Apneic oxygenation may eliminate CO2 because it requires a continuous O2 flow. ⋯ Piecewise linear approximation yielded a PaCO2 increase of 12 mmHg during the first minute of apnea, and 3.4 mmHg/minute thereafter. These values should be employed when estimating the duration of apnea from PaCO2 change for anesthetized patients who lack ventilatory support. In addition, it appears that the flows of O2 that most earlier investigators used when delivering apneic oxygenation probably did not eliminate significant CO2 quantities.
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Randomized Controlled Trial Comparative Study Clinical Trial
A comparison of vecuronium by continuous infusion with either isoflurane or fentanyl-nitrous oxide anesthesia.
The average infusion rate and efficacy of vecuronium bromide continuous infusions for surgical relaxation in human subjects was evaluated. Nineteen adult patients requiring more than 120 min of neuromuscular blockade for surgery were randomized to receive either fentanyl-nitrous oxide (Group 1) or isoflurane-fentanyl-nitrous oxide (Group 2). Neuromuscular function was monitored using train-of-four evoked electromyography (EMG). ⋯ An infusion of vecuronium at an initial rate of 60.0 micrograms/kg/h was then started and adjusted to maintain the first twitch at 10% of control. The average infusion rate (total infusion dose divided by the duration of the infusion) was 57.2 +/- 14 micrograms/kg/h in Group 1 (n = 10) and 42.4 +/- 12 micrograms/kg/h (n = 9) in Group 2, approximately 25% less (p = 0.02). There was a significant decrease in the infusion rate with time in Group 1 (p = 0.02), but this decrease was not observed in Group 2.
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Randomized Controlled Trial Clinical Trial
Effect of labetalol or lidocaine on the hemodynamic response to intubation: a controlled randomized double-blind study.
Labetalol, a combined alpha 1- and nonselective beta-adrenergic blocking drug, was compared to lidocaine or saline to minimize the hypertensive and tachycardic response to intubation in a controlled randomized double-blind study in patients undergoing surgical procedures under general anesthesia. Forty adult patients were divided into four groups of 10 each: placebo (saline), lidocaine 100 mg, labetalol 5 mg, or labetalol 10 mg. The double-blind preparation was administered as an IV bolus just prior to induction and 2 min before the stimulus of laryngoscopy and intubation. ⋯ Labetalol 10 mg prevented a rise in heart rate after intubation compared to patients who received placebo, lidocaine 100 mg, or labetalol 5 mg. The hypertensive response to intubation was similar in all four groups. Labetalol 10 mg IV just prior to induction of anesthesia is a safe and cost-effective means of preventing tachycardia but not hypertension in response to laryngoscopy and intubation.
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The modern version of the crystalloid-colloid debate has continued for more than 25 years, and a current appraisal of the debate is presented here. Although the effect of crystalloids and colloids on intravascular volume is important, their effect on interstitial fluid volume after hemorrhage and hemorrhagic shock is central to the debate. ⋯ The problems of pulmonary and peripheral edema also are presented, as is an appraisal of adverse reactions to colloids together with a cost comparison of crystalloids and colloids. The results of a survey of attitudes at the major Australian anesthetic departments are given, and a personal approach to fluids in resuscitation is outlined.
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The influence of increasing doses of propofol (from 6 to 12 mg/kg/h by continuous infusion) on hypoxic pulmonary vasoconstriction was studied in 10 patients prior to thoracic surgery. All patients were intubated with a left-sided double-lumen endobronchial tube. Initial anesthesia and muscle relaxation were accomplished by administering fentanyl, droperidol, and pancuronium. ⋯ There was no change in any respiratory or circulatory variables except systemic vascular resistance, which decreased significantly immediately after the propofol infusion commenced but returned to control values 15 min later for the rest of the observation period. After reestablishing two-lung ventilation, all variables did not differ from control values. In all patients, the hypoxic pulmonary vasoconstriction reflex was present after institution of one-lung ventilation and was not abolished after administration of propofol in doses from 6 to 12 mg/kg/h.