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Phase-related changes in right ventricular cardiac output under volume-controlled mechanical ventilation with positive end-expiratory pressure

1999; Lippincott Williams & Wilkins; Volume: 27; Issue: 5 Linguagem: Inglês

10.1097/00003246-199905000-00033

1530-0293

Heinz Theres, Jana Binkau, Michael Laule, Roland Heinze, J. Hundertmark, Manfred Blobner, W. Erhardt, Gert Baumann, Karl Stangl,

Pulmonary Hypertension Research and Treatments

Objective To examine determinants of right ventricular function throughout the ventilatory cycle under volume-controlled mechanical ventilation with various positive end-expiratory pressure (PEEP) stages. Design Prospective observational animal pilot study. Setting Animal research laboratory at a university hospital. Subjects Eight healthy swine under volume- controlled mechanical ventilation. Interventions Flow probes were implanted in eight swine in order to continuously measure blood flow in the pulmonary artery and inferior vena cava. After a recovery phase of 14 days, the swine were subjected to various PEEP stages (0, 5, 10 cm H (2) O) during volume-controlled positive pressure ventilation. Measurements and Main Results Continuous flow measurement took place in the pulmonary artery and inferior vena cava. Data on standard hemodynamic parameters were additionally acquired. Respiration-phase-specific analysis of right ventricular cardiac output and of additional hemodynamic function parameters followed, after calculation of mean values throughout five respiration cycles. PEEP at 5 cm H2 O led to significant decreases in inferior vena cava flow (4.1%), and in right ventricular cardiac output (5.2%); the respective decreases at PEEP 10 cm H2 O were 13.9% and 18.3%. In the inspiration phase at PEEP 10 cm H2 O, results revealed an overproportionally pronounced decrease in comparison with the expiration phase in inferior vena cava flow (-24.6% vs. -10%) and right ventricular cardiac output (-35% vs. -13.5%). This phenomenon is presumably caused by a PEEP-related increase in mean airway pressure by the amount of 10.7 cm H2 O in inspiration. Conclusions Increases in PEEP during volume-controlled mechanical ventilation leads to respiration-phase-specific reduction of right ventricular cardiac output, with a significantly pronounced decrease during the inspiration phase. This decrease in cardiac output should be taken into particular consideration for patients with already critically reduced cardiac output. (Crit Care Med 1999; 27:953-958)