EFFECTIVE PULMONARY BLOOD FLOW IN PRETERM INFANTS WITH AND WITHOUT RESPIRATORY DISTRESS: A SIMPLE BEDSIDE METHOD USING NITROUS OXIDE

[摘要] We have devised a method of measuring pulmonary capillary blood flow (Qpc eff) suitable for infants with idiopathic respiratory distress syndrome (IRDS). The uptake of nitrous oxide is measured during a 40-second period of rebreathing 40% nitrous oxide in oxygen from a 40- to 80-ml bag. The rate of uptake of nitrous oxide is divided by the solubility in cord blood and the mean alveolar concentration to give Qpc eff.We studied 14 preterm infants, 7 hours to 14 days of age, on 73 occasions; nine had classical IRDS and five were healthy preterm infants (controls). During the first five days of life Qpc eff was significantly lower in infants with IRDS than in the control infants, 106 ml/kg/min compared with 177 ml/kg/min (P < 0.001). Qpc eff was not related to arterial Po2, Pco2, or pH but was inversely related to the inspired oxygen concentration needed to keep the arterial Po2 within normal limits (P < 0.02). Qpc eff showed a highly significant increase with age in infants with IRDS (P < 0.001). This method provides a reasonably rapid, safe and noninvasive technique for estimating effective pulmonary blood flow in sick infants.

[学科分类] 儿科学