Anesthesiology
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Intramuscular rocuronium, in doses of 1,000 microg/kg in infants and 1,800 microg/kg in children, produces complete twitch depression in 5-6 min. To determine the rate and extent of absorption of rocuronium after intramuscular administration, blood was sampled at various intervals after rocuronium administration by both intramuscular and intravenous routes to determine plasma concentrations (Cp) of rocuronium. ⋯ After rocuronium is administered into the deltoid muscle, plasma concentrations peak at 13 min, and approximately 80% of the administered drug is absorbed systemically.
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Patients may require perioperative cooling for a variety of reasons including treatment of a malignant hyperthermia crisis and induction of therapeutic hypothermia for neurosurgery. The authors compared heat transfer and core cooling rates with five cooling methods. ⋯ Bladder lavage provided only trivial cooling and gastric lavage provoked complications. Forced-air and circulating-water cooling transferred relatively little heat but are noninvasive and easy to implement. Forced-air or circulating-water cooling, perhaps combined with intravenous administration of refrigerated fluids, may be sufficient in some patients. When noninvasive methods prove insufficient for rapid cooling, ice-water immersion or peritoneal lavage probably should be the next lines of defense.
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Observation of pharyngeal function in 14 awake volunteers demonstrated pharyngeal dysfunction and increased aspiration risk at TOF ratios < 0.90.
summary“Partial neuromuscular paralysis caused by atracurium is associated with a four- to fivefold increase in the incidence of misdirected swallowing. … The majority of misdirected swallows resulted in penetration of bolus to the larynx.”
(Sundman in a 2000 follow-up study: The incidence and mechanisms of pharyngeal and upper esophageal dysfunction in partially paralyzed humans: pharyngeal videoradiography and simultaneous manometry after atracurium.)
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Clinical Trial Controlled Clinical Trial
Subjective, psychomotor, cognitive, and analgesic effects of subanesthetic concentrations of sevoflurane and nitrous oxide.
Sevoflurane is a volatile general anesthetic that differs in chemical nature from the gaseous anesthetic nitrous oxide. In a controlled laboratory setting, the authors characterized the subjective, psychomotor, and analgesic effects of sevoflurane and nitrous oxide at two equal minimum alveolar subanesthetic concentrations. ⋯ Sevoflurane and nitrous oxide produced different profiles of subjective, behavioral, and cognitive effects, with sevoflurane, in general, producing an overall greater magnitude of effect. The differences in effects between sevoflurane and nitrous oxide are consistent with the differences in their chemical nature and putative mechanisms of action.
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Randomized Controlled Trial Clinical Trial
Spinal anesthesia speeds active postoperative rewarming.
Redistribution of body heat decreases core temperature more during general than regional anesthesia. However, the combination of anesthetic- and sedative-induced inhibition may prevent effective upper-body thermoregulatory responses even during regional anesthesia. The extent to which each type of anesthesia promotes hypothermia thus remains controversial. Accordingly, the authors evaluated intraoperative core hypothermia in patients assigned to receive spinal or general anesthesia. They also tested the hypothesis that the efficacy of active postoperative warming is augmented when spinal anesthesia maintains vasodilation. ⋯ Comparable intraoperative hypothermia during general and regional anesthesia presumably resulted because the combination of spinal anesthesia and meperidine administration obliterated effective peripheral and central thermoregulatory control. Vasodilation increased the rate of core rewarming in patients after operation with residual lower-body sympathetic blocks, suggesting that vasoconstriction decreased peripheral-to-core heat transfer after general anesthesia.