Muñoz J, Guerrero J E, De La Calle B, Escalante J L
Servicio de Medicina Intensiva, Hospital General Gregorio Marañón, Universidad Complutense, Madrid, Spain.
Crit Care Med. 1993 Mar;21(3):348-56. doi: 10.1097/00003246-199303000-00010.
To assess the interaction between intrinsic and externally applied positive end-expiratory pressure (intrinsic PEEP and administered PEEP) in mechanically ventilated patients.
Prospective study.
Intensive care unit of a university hospital.
Twelve consecutive critically ill patients.
Application of an external PEEP of the same value as the intrinsic PEEP.
We found that when the administered PEEP was increased from 0 to the baseline value of intrinsic PEEP, mean intrinsic PEEP decreased from 6.5 +/- 4.2 (SD) to 1.3 +/- 0.7 cm H2O (p = .001). The mean end-inspiratory pressure was increased from 20.3 +/- 4.6 to 23.1 +/- 6.1 cm H2O (p < .05). The difference between the modification of intrinsic PEEP and the change in the end-inspiratory pressure was not significantly > 0 cm H2O. Thus, the increase in end-inspiratory pressure may be directly attributable to the increase in total PEEP (administered PEEP plus intrinsic PEEP). None of the other measurements of pulmonary mechanics changed (peak pressure, inspiratory resistance, compliance, and trapped-gas volume).
The administration of positive end-expiratory pressure equal to the intrinsic positive end-expiratory pressure causes the almost total disappearance of the intrinsic positive end-expiratory pressure. When the administered positive end-expiratory pressure does not exceed the intrinsic positive end-expiratory pressure, the former is applied almost in its entirety to the patient's external circuit. The administration of positive end-expiratory pressure without prior quantification of the intrinsic positive end-expiratory pressure results in an overestimation of the beneficial effects of the administered positive end-expiratory pressure on the quasi-static compliance.
评估机械通气患者内源性呼气末正压（内源性PEEP）与外部施加的呼气末正压（应用PEEP）之间的相互作用。
前瞻性研究。
大学医院重症监护病房。
连续12例危重症患者。
施加与内源性PEEP值相同的外部PEEP。
我们发现，当应用PEEP从0增加至内源性PEEP的基线值时，平均内源性PEEP从6.5±4.2（标准差）降至1.3±0.7 cm H₂O（p = 0.001）。平均吸气末压力从20.3±4.6升至23.1±6.1 cm H₂O（p < 0.05）。内源性PEEP的变化与吸气末压力变化之间的差值无显著大于0 cm H₂O。因此，吸气末压力的增加可能直接归因于总PEEP（应用PEEP加内源性PEEP）的增加。肺力学的其他测量指标均未改变（峰值压力、吸气阻力、顺应性和潴留气体量）。
施加等于内源性呼气末正压的呼气末正压会导致内源性呼气末正压几乎完全消失。当应用呼气末正压不超过内源性呼气末正压时，前者几乎全部作用于患者的外部回路。在未预先测定内源性呼气末正压的情况下施加呼气末正压会高估其对准静态顺应性的有益作用。
