Gabriele G, Rosenfeld C R, Fixler D E, Wheeler J M
Pediatrics. 1977 Jun;59(6):858-64.
Continuous airway pressure delivered by a head-box is an accepted means of treating clinical hyaline membrane disease. To investigate hemodynamic alterations resulting from its use, eight newborn lambs, 1 to 6 days of age, were studied at 6 and 11 mm Hg of positive pressure, while spontaneoulsy breathing room air. Organ blood flows and cardiac output were measured with 25 micron-diameter radioactive microspheres. Heart rate, left ventricular pressure, and arterial blood gases did not change during the study. Jugular venous pressures increased from 6.4 mm Hg to 18.6 and 24.2 mm Hg at 6 and 11 mm Hg, respectively (P less than .005). Cardiac output decreased approximately 20% at either intrachamber pressure setting. Renal blood flow fell 21% at 11 mm Hg. No significant changes in blood flow were found in the brain, gastrointestinal tract, spleen, heart, or liver when compared to control flows. Of particular interest was the finding of a 28% reduction in ocular blood flow at 6 mm Hg and 52% at 11 mm Hg. From these results, we conclude that substantial cardiovascular alterations may occur during the application of head-box continuous airway pressure breathing, including a significant reduction in ocular blood flow.
头箱提供的持续气道正压是治疗临床透明膜病的一种公认方法。为了研究使用该方法引起的血流动力学改变，对8只1至6日龄的新生羔羊进行了研究，在其自主呼吸室内空气时，分别施加6和11毫米汞柱的正压。使用直径25微米的放射性微球测量器官血流量和心输出量。在研究过程中，心率、左心室压力和动脉血气没有变化。颈静脉压力在6和11毫米汞柱时分别从6.4毫米汞柱增加到18.6和24.2毫米汞柱（P小于0.005）。在任一腔内压力设置下，心输出量均下降约20%。在11毫米汞柱时肾血流量下降21%。与对照血流量相比，脑、胃肠道、脾脏、心脏或肝脏的血流量没有显著变化。特别值得关注的是，在6毫米汞柱时眼血流量减少28%，在11毫米汞柱时减少52%。从这些结果我们得出结论，在应用头箱持续气道正压呼吸期间可能会发生实质性的心血管改变，包括眼血流量显著减少。
