Downs J B, Douglas M E, Sanfelippo P M, Stanford W, Hodges M R
Anesth Analg. 1977 Jan-Feb;56(1):88-96. doi: 10.1213/00000539-197701000-00021.
Continuous positive-pressure ventilation may decrease cardiac output. However, a few reports have separated the effects of positive and end-expiratory pressure (PEEP) from those of mechanical ventilation. Ten surgical patients requiring mechanical ventilatory support had catheters inserted for measurement of right atrial pressure (RAP), pulmonary artery occlusion pressure (PAOP), intrapleural, radial artery, airway, and atrial filling pressures, and cardiac output. All patients breathed spontaneously between mechanical breaths delivered every 30 seconds by intermittent mandatory ventilation (IMV). Measurements were made with 0, 5, and 10 cm H2O PEEP, and during intermittent positive-pressure ventilation (IPPV) with 12 breaths/min without PEEP. Airway pressure (Paw), intrapleural pressure, RAP, and PAOP were increased by PEEP and IPPV. Intrapleural pressure increased most during IPPV (p less than 0.001). Atrial filling pressures and cardiac output were unaffected by PEEP but decreased during IPPV (p less than 0.001). Patients receiving IMV maintained negative intrapleural pressure, atrial filling pressure, cardiac output and, therefore, O2 delivery, regardless of PEEP level. The authors conclude that patients requiring mechanical respiratory support, with or without PEEP, may maintain better cardiopulmonary function when allowed some spontaneous ventilatory activity.
持续正压通气可能会降低心输出量。然而，一些报告已将呼气末正压（PEEP）和机械通气的影响区分开来。十名需要机械通气支持的外科患者插入导管以测量右心房压力（RAP）、肺动脉闭塞压（PAOP）、胸膜腔内压、桡动脉压、气道压和心房充盈压以及心输出量。所有患者在每30秒通过间歇强制通气（IMV）进行一次机械通气之间自主呼吸。分别在0、5和10 cmH₂O的PEEP水平下以及在无PEEP、通气频率为12次/分钟的间歇正压通气（IPPV）期间进行测量。PEEP和IPPV可使气道压（Paw）、胸膜腔内压、RAP和PAOP升高。IPPV期间胸膜腔内压升高最为明显（p<0.001）。心房充盈压和心输出量不受PEEP影响，但在IPPV期间降低（p<0.001）。接受IMV的患者无论PEEP水平如何，均维持胸膜腔内负压、心房充盈压、心输出量，因此维持了氧输送。作者得出结论，需要机械呼吸支持的患者，无论有无PEEP，当允许有一些自主通气活动时，可能会维持更好的心肺功能。
