Anesthesiology
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Vecuronium and atracurium provide addition flexibility to the clinician using neuromuscular blocking drugs. The shorter duration of action, lack of significant cardiovascular effects, and the lack of dependence on the kidney for elimination provide clinical advantages over, or alternatives to, currently available nondepolarizing neuromuscular blocking drugs.
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Lung perfusion was studied in 10 patients (mean age 58 yr) in the lateral position during enflurane anesthesia. They were ventilated through a double-lumen endotracheal catheter: 1) by one ventilator with free distribution of ventilation between the lungs, with no (zero) end-respiratory pressure (ZEEP); 2) as above but with a general positive end-expiratory pressure (PEEP) of 9 cmH2O; or 3) by two ventilators with equal distribution of ventilation between the lungs and with a selective PEEP of 8 cmH2O to the dependent lung only. Total ventilation was on average 8 l/min (BTPS) throughout the study. ⋯ Peak and end-inspiratory airway pressures were 5-18 cm H2O lower during selective than during general PEEP. Arterial oxygen tension was significantly greater during the third method than during either of the other ventilator settings and the alveolar-arterial oxygen tension difference was almost halved compared with the first method. It is concluded that differential ventilation with selective PEEP improves ventilation-perfusion matching and thus oxygenation.
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The dose-response relationship, onset, duration of action, atropine requirement, and pharmacokinetic variables of edrophonium were determined in infants and children during N2O-halothane anesthesia. The technique of steady state infusion of d-tubocurarine anesthesia. The technique of steady state infusion of d-tubocurarine (dTc) was used to determine the ED50 for edrophonium (i.e., the dose producing 50% antagonism of 90% neuromuscular depression) in 4 infants (145 micrograms/kg) and 12 children (233 microgram/kg). ⋯ The pharmacokinetics of edrophonium (1 mg/kg) were studied in four infants and four children and were compared with published values for adults: distribution and elimination half-lives and distribution volumes were similar for the three groups. Total clearance (ml.kg-1.min-1) was greatest for infants (17.8 +/- 1.2) compared with children (14.2 +/- 7.3) and adults (8.3 +/- 2.9). The authors conclude that the dose of edrophonium required toantagonize dTc-induced neuromuscular blockade is similar or possibly greater for infants and children than for adults.(ABSTRACT TRUNCATED AT 250 WORDS)
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The effects of 46 h of mechanical ventilation and PEEP on urinary output, sodium excretion, and renal and cardiovascular function were examined. Dogs sedated with sodium pentobarbital were ventilated using one of three modes: spontaneous ventilation (SV), controlled mechanical ventilation (CMV), or CMV with 10 cmH2O positive end-expiratory pressure (CMV with PEEP). Intravenous fluids were given at a constant rate throughout the study and measurements of renal and cardiovascular function were made over four periods. ⋯ There were no significant differences in glomerular filtration rate, renal corticomedullary blood flow distribution, or renal blood flow between groups. During the 46 h, cardiac index increased (SV, +16%; CMV, +19%; CMV with PEEP, +64%), while systemic vascular resistance (SV, -28%; CMV, -30%; CMV with PEEP, -57%), renal vascular resistance (SV, -12%; CMV, -20%; CMV with PEEP, -23%), and mean arterial pressure (SV, -16%; CMV, -15%; CMV with PEEP, -15%) decreased in all groups. This study has demonstrated that when a constant sodium and water load was provided, the SV and CMV groups were rapidly able to adjust the urinary excretion to meet input, while the return of renal function toward normal in the CMV with PEEP group was delayed until almost 46 h from the start of ventilation.