Canadian journal of anaesthesia = Journal canadien d'anesthésie
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Randomized Controlled Trial Comparative Study Clinical Trial
Oral clonidine premedication reduces vomiting in children after strabismus surgery.
This is a prospective randomized double-blind trial conducted to determine whether preoperative orally administered clonidine causes or potentiates postoperative vomiting in 140 children (3-12 yr) undergoing strabismus surgery. They were all inpatients and classified randomly into four groups (n = 35 each); placebo (control), diazepam 0.4 mg.kg-1, clonidine 2 micrograms.kg-1, and clonidine 4 micrograms.kg-1. These agents were administered 93-112 min (mean; 100 min) before the anticipated time of induction of anaesthesia. ⋯ However, low-dose clonidine was ineffective. These data suggest that preanaesthetic medication with clonidine 4 micrograms.kg-1 may be useful for preventing emesis following strabismus surgery. This property of clonidine indicates that it may be superior to other sedative premedicants such as diazepam and midazolam.
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Randomized Controlled Trial Clinical Trial
Optimal stimulating current for train-of-four stimulation in conscious subjects.
The purpose of this study was to determine the optimal stimulating current for train-of-four (TOF) monitoring with regard to the return of TOF response and the discomfort associated with TOF. Two variables were examined at 60, 50, 40, 30, and 20 mA: (1) times from administration of vecuronium 80 micrograms.kg-1 to returns of responses to TOF determined accelographically in 75 anaesthetised patients and (2) discomfort associated with TOF in 15 awake volunteers using visual analogue scale (VAS). Times to return of the first response to stimulation at 60, 50, 40, and 30 mA were not different (29.1 +/- 11.2, 30.1 +/- 12.0, 31.9 +/- 12.6, and 35.4 +/- 14.2 min, respectively, mean +/- SD). ⋯ The VAS associated with TOF at 60, 50, 40, 30, and 20 mA were 7.3 +/- 1.9, 6.7 +/- 1.8, 6.0 +/- 2.0, 4.1 +/- 2.1, and 2.7 +/- 2.3, respectively. The VAS at 30 mA was less than at 60 and 50 mA (P < 0.05), and at 20 mA was less than at 60, 50, and 40 mA (P < 0.05). In conclusion it is suggested that, when testing conscious patients, 30 mA is the optimal stimulating current for TOF monitoring because it represents the best compromise of neuromuscular monitoring and patient discomfort.
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As more extensive and painful surgical procedures (e.g., laparoscopic cholecystectomy, laminectomy, knee and shoulder reconstruction, hysterectomy) are being performed on an outpatient basis, the availability of sophisticated postoperative analgesic regimens are necessary to optimize the benefits of day-case surgery for both the patient and the health care provider. However, outcome studies are needed to evaluate the effects of these newer therapeutic approaches with respect to postoperative side effects, cost and important recovery variables. Recent studies suggest that factors other than pain per se must be controlled in order to reduce postoperative morbidity and facilitate the recovery process. ⋯ In conclusion, as a result of our enhanced understanding of the mechanisms of acute pain and the physiological basis of nociception, the provision of "stress free" anaesthesia with minimal postoperative discomfort is now possible for most patients undergoing ambulatory surgical procedures. The aim of any analgesic technique should not only be to lower the pain scores but also to facilitate earlier mobilization and to reduce perioperative complications, in particular PONV. In future, clinicians should be able to effectively treat postoperative pain using a combination of "balanced," "preemptive," and "peripheral" analgesia techniques without producing emetic sequelae.
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Comparative Study
Persistent low cerebral blood flow velocity following profound hypothermic circulatory arrest in infants.
Acute neurological morbidity following repair of congenital heart disease (CHD) in infancy is well recognized, particularly with the modalities of hypothermic cardiopulmonary bypass (CPB) and profound hypothermic circulatory arrest (PHCA). Reduced O2 delivery (perfusion defect) during rewarming following PHCA has been shown in the operating room. This reduction in cerebral blood flow coincides with disordered cerebral metabolism and oxygen utilisation after PHCA. ⋯ This study demonstrates a sustained reduction in the CBFV pattern following PHCA into the postoperative period despite adequate cerebral perfusion pressures. This abnormality correlates with electroencephalographic aberrations documented after PHCA. It supports the concept of a prolonged unreactive cerebrovascular bed which could potentially contribute to the acute neurological morbidity following PHCA in neonates.
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Although the recommended dose of rectal acetaminophen (25-30 mg.kg-1) is twice that for oral administration (10-15 mg.kg-1), the literature justifies the use of a higher dose when acetaminophen is administered via the rectal route. We measured venous plasma acetaminophen concentrations resulting from 45 mg.kg-1 of rectal acetaminophen in ten ASA 1, 15 kg paediatric patients undergoing minor surgery with a standardized anaesthetic. After induction of anaesthesia, a single 650 mg suppository (Abenol, SmithKline Beecham Pharma Inc.) was administered rectally. ⋯ A 45 mg.kg-1 rectal dose of acetaminophen resulted in peak plasma concentrations comparable with those resulting from 10-15 mg.kg-1 of oral acetaminophen at three hours after suppository insertion. It is concluded that the delayed and erratic absorption of acetaminophen after rectal administration leads to unpredictable plasma concentrations. Rectal acetaminophen will not be consistently effective for providing rapid onset of analgesia in children.