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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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.