Key result
Tidal ventilation and positive end-expiratory pressure increased venous and arterial pressures by 2.4 and 1.9 mmHg respectively, challenging mean systemic filling pressure estimation methods.
Why the study?
Does positive pressure ventilation alter mean systemic filling pressure in critically ill patients after death?
Observational
Yes
Does positive pressure ventilation alter mean systemic filling pressure in critically ill patients after death?
Positive pressure ventilation increases mean systemic filling pressure, challenging the validity of estimating it in heart-beating patients using cardiopulmonary interactions during mechanical ventilation.
Questions accuracy of MSFP estimates from cardiopulmonary interactions; leaves open need for ventilation-independent methods in critically ill patients.
Mean systemic filling pressure (P ms ) 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 P ms is altered by tidal ventilation and positive end-expiratory pressure (PEEP), which would challenge this extrapolation method based on cardiopulmonary interactions. We conducted a two-center, noninterventional, 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 PEEP. Arterial (P art ) and venous pressures (P ra ) were recorded in five conditions: at end expiration and end inspiration with and without PEEP and finally once the ventilator was disconnected. P art and P ra did not differ in any experimental conditions. Tidal ventilation increased P ra and P art 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, P ra and P art were 10.0 ± 4.2 and 9.9 ± 4.2 mmHg, respectively. P ms increases during mechanical ventilation, with an effect of tidal ventilation and PEEP. This calls into question the validity of its evaluation in heart-beating patients using cardiopulmonary interactions during mechanical ventilation. NEW & NOTEWORTHY The physiology of the mean systemic filling pressure (P ms ) is not well understood in human beings. This study is the first report of a tidal ventilation- and positive end-expiratory pressure-related increase in P ms in critically ill patients. The results challenge the utility and the value estimating P ms in heart-beating patients by reconstruction of the venous return curve using varying inflation pressures.
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Repessé et al. (2017) conducted an observational in Critically ill, mechanically ventilated patients after death. Tidal ventilation and positive end-expiratory pressure (PEEP) vs. Ventilator disconnected / without PEEP was evaluated on Arterial (P art) and venous pressures (P ra). Tidal ventilation and positive end-expiratory pressure increased venous and arterial pressures by 2.4 and 1.9 mmHg respectively, challenging mean systemic filling pressure estimation methods.
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