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 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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Randomized Controlled Trial Clinical Trial
The electrophysiologic effects of volatile anesthetics and sufentanil on the normal atrioventricular conduction system and accessory pathways in Wolff-Parkinson-White syndrome.
The effects of volatile agents and sufentanil anesthesia on the electrophysiologic properties of the accessory pathway and on the incidence of intraoperative tachyarrhythmias in patients with Wolff-Parkinson-White syndrome are unknown. Therefore, we studied these agents for their use in patients undergoing ablative procedures or requiring a general anesthetic for other surgeries. ⋯ Sufentanil-lorazepam has no clinically significant effect on the electrophysiologic expression of the accessory pathway. Of the volatile agents, enflurane most, isoflurane next, and halothane least increased refractoriness within the accessory and atrioventricular pathways. Therefore, administration of these volatile agents during ablative procedures may confound interpretation of postablative studies used to determine the success of ablation treatment. Conversely, in patients with preexcitation syndrome requiring general anesthesia for nonablative procedures, volatile agents may reduce the incidence of perioperative tachyarrhythmias because of their effects on refractoriness. Enflurane would be the agent of choice because it increases refractoriness the most without prolonging the coupling interval.
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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
Use of ketorolac after lower abdominal surgery. Effect on analgesic requirement and surgical outcome.
Ketorolac is a nonsteroidal antiinflammatory agent with opioid-sparing properties. The effect of ketorolac on postoperative opioid analgesic requirement and surgical outcome was evaluated in 198 women after abdominal hysterectomy procedures using a double-blind protocol design. ⋯ The authors conclude that the opioid-sparing effects of ketorolac contributed few clinically significant advantages after abdominal hysterectomy procedures.