DeMaria E J, Burchard K W, Carlson D E, Gann D S
Department of Surgery, Brown University, Providence, Medical College of Virginia.
Surg Gynecol Obstet. 1990 Jun;170(6):501-9.
Right atrial volume (RAV) and other hemodynamic parameters were measured in ten anesthetized swine with an impedance catheter in the right atrium during ventilation and increasing levels of positive end-expiratory pressure (PEEP) to determine the effects of PEEP on right atrial dynamics. RAV and cardiac output (CO) decreased progressively during ventilation with 5, 10 and 15 centimeters of water PEEP, whereas central venous pressure and pulmonary capillary wedge pressure increased. Despite this decrease in RAV, atrial ejection fraction increased significantly and active atrial output (AAO equals stroke volume times heart rate) was maintained. Thus, the decrease in CO resulted from a decrease in the passive component of ventricular filling. Compensatory increases in AAO helped to minimize the fall in CO in some swine (r = 0.73, p less than 0.01). Peripheral adenocorticotropin (ACTH) increased from 14.0 +/- 4.5 picograms per milliliter at zero centimeters of water PEEP to 46.8 +/- 18.3 picograms per milliliter at 10 centimeters of water PEEP (p less than 0.05). Volume expansion that restored CO to control levels despite PEEP led to a significant increase in RAV and in passive ventricular filling, as well as a decrease in ACTH to 11.2 +/- 1.5 picograms per milliliter (p less than 0.05). Changes in the ACTH levels correlated with changes in the RAV (r = 0.58, p less than 0.05), but did not correlate with changes in CO, arterial pressure or central venous pressure. The data herein suggest that the decrease in CO with PEEP results from decreased venous return, RAV and passive ventricular filling, whereas a compensatory increase in right atrial contractility helps to maintain CO. Ventilation with PEEP stimulates hormonal secretion that can be terminated by adequate volume expansion.
在十头麻醉猪中，于通气期间及呼气末正压（PEEP）水平逐渐升高时，使用置于右心房的阻抗导管测量右心房容积（RAV）及其他血流动力学参数，以确定PEEP对右心房动力学的影响。在5、10和15厘米水柱PEEP通气期间，RAV和心输出量（CO）逐渐下降，而中心静脉压和肺毛细血管楔压升高。尽管RAV下降，但心房射血分数显著增加，且主动心房输出量（AAO等于每搏量乘以心率）得以维持。因此，CO的下降是由于心室充盈的被动成分减少所致。AAO的代偿性增加有助于在一些猪中使CO的下降最小化（r = 0.73，p小于0.01）。外周促肾上腺皮质激素（ACTH）从0厘米水柱PEEP时的14.0±4.5皮克/毫升增加至10厘米水柱PEEP时的46.8±18.3皮克/毫升（p小于0.05）。尽管有PEEP，但通过扩容使CO恢复至对照水平导致RAV和心室被动充盈显著增加，同时ACTH降至11.2±1.5皮克/毫升（p小于0.05）。ACTH水平的变化与RAV的变化相关（r = 0.58，p小于0.05），但与CO、动脉压或中心静脉压的变化无关。本文数据表明，PEEP导致的CO下降是由于静脉回流、RAV和心室被动充盈减少所致，而右心房收缩性的代偿性增加有助于维持CO。PEEP通气刺激激素分泌，而充分的扩容可终止这种刺激。
