Anesthesiology
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The pharmacokinetics of alfentanil were studied in 18 children (3 months to 14 yr of age) undergoing surgery. Alfentanil was administered as a 30-s infusion of either 50 or 120 micrograms.kg-1. Pharmacokinetic values were independent of dose. ⋯ The mean value of Vdss was 0.419 (SE .028) l.kg-1) for the whole group, and elimination t1/2 was 76.3 (SE 6.5) min. The clearance rate [TBC = 7.9 (SE 0.41) ml.kg-1.min-1] was within the range of values previously determined in adult studies. From these data, it would appear that, although there may be differences in the disposition kinetics between children aged 3 months to 14 yr and those measured in adults in some studies by other investigators, age-related differences within this group were not demonstrable.
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The authors have defined the margin of safety in positioning a double-lumen tube as the length of tracheobronchial tree over which it may be moved or positioned without obstructing a conducting airway. The purpose of this study was to measure the margin of safety in positioning three modern double-lumen tubes (Mallinkrodt [Broncho-Cath], Rusch [Endobronchial tubes], and Sheridan [Broncho-Trach]). The margin of safety in positioning a: 1) left-sided double-lumen tube (all manufacturers) is the length of the left mainstem bronchus minus the length from the proximal margin of the left cuff to left lumen tip; 2) Mallinkrodt right-sided double-lumen tube is the length of the right mainstem bronchus minus the length of the right cuff; and 3) Rusch right-sided double-lumen tube is the length of the right upper lobe ventilation slot minus the diameter of the right upper lobe. ⋯ The average margin of safety in positioning left-sided double-lumen tubes ranged 16-19 mm for the different manufacturers. The average margin of safety in positioning Mallinkrodt right-sided double-lumen tubes was 8 mm, and the margin of safety in positioning Rusch right-sided double-lumen tubes ranged 1-4 mm, depending on French size. The authors concluded that left-sided double-lumen tubes are much preferable to right-sided double-lumen tubes because they have a much greater positioning margin of safety, and that proper confirmation of proper position of either a left- or right-sided double-lumen tube should be aided by fiberoptic bronchoscopy, because the absolute distances that constitute the margin of safety are extremely small.
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No standard outcome measures exist to evaluate the effect of interventions intended to improve the quality of anesthesia care. The authors established a clinically practical definition of outcome, and used it to assess the effect of feedback of information about complications and the effect of pulse oximetry on the rate and severity of important anesthesia-related problems encountered in the operating room (OR) and recovery room (RR). On admission to the RR, the patient's anesthetist documented Recovery-Room-Impact Events (RRIE), defined as an "unanticipated, undesirable, possibly anesthesia-related effect that required intervention, was pertinent to recovery-room care, and did or could cause at least moderate morbidity." Following a control period with no feedback of data, intense feedback of grouped (anonymous) RRIE rates was provided. ⋯ Although significantly fewer patients experienced RRIEs (15.6% vs. 12.4%, P less than 0.0001), hypotensive RRIEs (5.2% vs. 3.8%, P = 0.0003), and hypovolemic RRIEs (0.88% vs. 0.42%, P = 0.0017) following the introduction of pulse oximetry in the OR, confounding factors prevent establishment of a cause-and-effect relationship. Quality assurance may require more direct intervention and individual feedback to be effective. Still, the RRIE measure requires minimal effort at low cost and encourages improved transmission of information at the time of admission to recovery-room care.
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A device using modification of a Pitot tube has been designed for measurement of tidal volume in infants and small children. Its accuracy was compared both n vitro and n vivo to that of a calibrated pneumotachograph (Fleish #1) designed for a similar flow range. In vitro measurement of air flow with the modified Pitot tube (MPT) was within 5% of the pneumotachograph readings over a range of 1-60 l/min. ⋯ In vivo, the insertion of the MPT into the patient circuit caused no apparent changes in ventilatory parameters in children under 20 kg. Measurement of tidal volumes with the MPT agreed to within 8% of pneumotachograph readings. The low dead space (1.5 cc) and light weight (12 gm) of the MPT confer advantages over the pneumotachograph (15 ml dead space and a weight of 90 gm) for routine use in pediatric anesthesia.