Anesthesiology
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Randomized Controlled Trial Clinical Trial
Nitrous oxide in early labor. Safety and analgesic efficacy assessed by a double-blind, placebo-controlled study.
Intermittent self-administered nitrous oxide has long had widespread use as an analgesic in labor, but its efficacy has not been adequately established. Questions about its effect on maternal oxygenation between labor contractions also have been raised. ⋯ While intermittent self-administered 50% nitrous oxide in oxygen does not appear to predispose parturient women to hemoglobin oxygen desaturation, its analgesic effect has yet to be clearly demonstrated.
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Randomized Controlled Trial Comparative Study Clinical Trial
The effect of epidural versus general anesthesia on postoperative pain and analgesic requirements in patients undergoing radical prostatectomy.
Although preemptive analgesia has been shown to decrease postinjury pain in animals, studies in humans have provided controversial results. The authors studied whether surgical epidural anesthesia with local anesthetics could affect postoperative pain and analgesic demands, when compared with general anesthesia. ⋯ In patients undergoing lower abdominal surgery, the neuraxial blockade and surgical anesthesia achieved by epidural local anesthetics was associated with decreased postoperative analgesic demands. Lower postoperative analgesic requirements in the EA group, when compared with both the EG and GA groups, indicate that: (1) EA patients had less postoperative pain, and (2) an efficient intraoperative blockade of noxious afferent signals to the central nervous system is fundamental in reducing postoperative pain.
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Randomized Controlled Trial Clinical Trial
Nifedipine and intraoperative core body temperature in humans.
Initial anesthetic-induced hypothermia results largely from core-to-peripheral redistribution of heat. Nifedipine administration may minimize hypothermia by inducing vasodilation well before induction of anesthesia. Although vasodilation would redistribute heat to peripheral tissues, thermoregulatory responses would maintain core temperature. After equilibration, the patient would be left vasodilated, with a small core-to-peripheral temperature gradient. Minimal redistribution hypothermia may accompany subsequent induction of anesthesia, because heat flow requires a temperature gradient. In contrast, similar vasodilation concurrent with anesthetic-induced vasodilation may augment redistribution hypothermia. Accordingly, the authors tested the hypothesis that nifedipine treatment for 12 h before surgery would minimize intraoperative redistribution hypothermia, whereas nifedipine treatment immediately before induction of anesthesia would aggravate hypothermia. ⋯ Vasodilation induced by nifedipine well before induction of anesthesia minimized redistribution hypothermia, presumably by decreasing the core-to-peripheral tissue temperature gradient. In contrast, redistribution hypothermia was aggravated by administration of the same drug immediately before induction of anesthesia. Drug-induced modulation of vascular tone thus produces clinically important alterations in intraoperative core temperature.
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Sevoflurane is a new inhalational anesthetic agent having low solubility in blood and a relatively nonpungent odor. As such it should be useful as an inhalation induction in pediatric patients. The objectives of the study were to determine both the minimum alveolar concentration (MAC) and the concentration required for tracheal intubation (MACEI) of sevoflurane in pediatric patients. ⋯ Sevoflurane appears to be suitable for use in pediatric patients as an induction agent, permitting tracheal intubation without neuromuscular relaxants.
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In synchronized intermittent mandatory ventilation, it is generally accepted that the work of the inspiratory muscles is decreased by the ventilator so that their activity can be modulated by the frequency of assisted breaths. We examined the validity of this concept, which recently has been questioned. ⋯ The degree of inspiratory muscle rest achieved by synchronized intermittent mandatory ventilation is not proportional to the level of machine assistance; furthermore, the inspiratory motor output is not regulated breath by breath but rather is constant for a given level of machine assistance.