Anesthesiology
-
Although propofol and alfentanil are given in combination in clinical practice, the pharmacodynamic interaction between these drugs has not been described. ⋯ The alfentanil requirements in ASA physical status 1 female patients undergoing lower abdominal surgery are less when given as a supplement to propofol (4 micrograms/ml) compared to 66% N2O.
-
Although lung volume may be changed by certain procedures during anesthesia and mechanical ventilation, dependence of the dynamic mechanical properties of the lungs on lung volume are not clear. Based on studies in dogs, the authors hypothesized that changes in lung mechanics caused by anesthesia in healthy humans could be accounted for by immediate changes in lung volume and that lung resistance will not be decreased by positive end-expiratory airway pressure if tidal volume and respiratory frequency are in the normal ranges. ⋯ Increases in dynamic lung elastance and lung resistance with anesthesia can be explained by the accompanying, acute decreases in lung volume, although other factors may be involved. Increasing lung volume by increasing mean airway pressure with positive end-expiratory pressure will decrease lung resistance only if the original lung volume is low compared to awake, seated functional residual capacity.
-
Preterm and ex-preterm infants are at risk for life-threatening apnea after general anesthesia. The authors attempted to define the postconceptual age beyond which apnea is less likely to occur and to identify the factors that predispose to postanesthetic apnea. ⋯ Ex-preterm infants younger than 44 weeks postconceptual age are at greater risk for apnea after general anesthesia than are infants older than 44 weeks postconceptual age. Based on these results, the maximum long-run risk of postanesthetic apnea in preterm infants older than 44 weeks postconceptual age is 5% with 95% confidence.