Introduction Mean systemic filling pressure (Pms) defines the pressure measured in the venous-arterial system when the cardiac output is nil. Its estimation has been proposed in patients with beating hearts by building the venous return curve, using different pairs of right atrial pressure/cardiac output during mechanical ventilation. We raised the hypothesis according to which the Pms is altered by tidal ventilation and PEEP, which would challenge this extrapolation method based on cardiopulmonary interactions. Material and methods We conducted a two-center, non-interventional, observational and prospective study, using an arterial and a venous catheter to measure the pressure in the circulatory system at the time of death in critically ill, mechanically ventilated patients with a positive end-expiratory pressure (PEEP). Arterial (Part) and venous pressures (Pra) were recorded in five conditions: at end-expiration and end-inspiration with and without PEEP, and finally once the ventilator was disconnected. Results Part and Pra did not differ in any experimental conditions. Tidal ventilation increased Pra and Part by 2.4 and 1.9 mmHg, respectively, whereas PEEP increased both values by 1.2 and 1 mmHg, respectively. After disconnection of the ventilator, Pra and Part were 10.0±4.2 and 9.9±4.2 mmHg, respectively. Conclusion Pms increases during mechanical ventilation, with an effect of tidal ventilation and PEEP. This calls into question the validity of its evaluation in beating-heart patients using cardiopulmonary interactions during mechanical ventilation.
- mean systemic filling pressure
- venous return
- mechanical ventilation
- Copyright © 2016, Journal of Applied Physiology