• N Brienza, M Dambrosio, G Cinnella, M Conte, N Puntillo, and F Bruno.
• Istituto di Anestesia e Rianimazione, Università degli Studi, Bari.
• Minerva Anestesiol. 1996 Jul 1; 62 (7-8): 235-42.

Aim Of The StudyTo evaluate the effects of positive end expiratory pressure (PEEP) on intrathoracic and extrathoracic blood volumes in patients with acute respiratory failure (ARF).MethodsIn 4 ARF patients, we have measured cardiac output (CI), intrathoracic blood volume (ITBVI), global end-diastolic ventricular volume (GEDVI), pulmonary (PBVI) and total (TBVI) blood volumes, during application of two PEEP levels (0 and 10 cm H2O). These measurements have been performed by PULSION COLD Z-021 system, using the double indicator dilution technique (thermal and dye dilution).ResultsPEEP application caused a significant reduction in CI (from 3.8 +/- 0.4 to 2.9 +/- 0.1 1/min/m2) and ITBVI (from 888 +/- 48 to 698 +/- 25 ml/m2). The reduction in intrathoracic blood volume was associated with a significant reduction in GEDVI and PBVI. After PEEP application, there was a significant reduction in TBVI (from 2437 +/- 135 to 1984 +/- 49 ml/m2).ConclusionsPEEP application decreases cardiac index, mainly through a preload reduction, as evidenced by the reduction in intrathoracic and end-diastolic ventricular blood volumes. The preload effect is due to an increase in intrathoracic pressure with reduction in total circulating blood volume. TBVI reduction is consistent with blood pooling in vascular compartments, e.g., splanchnic compartment, characterized by long vascular time constant.

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