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Observational Study
. 2020 Jul 11;24(1):417.
doi: 10.1186/s13054-020-03116-w.

Bedside calculation of mechanical power during volume- and pressure-controlled mechanical ventilation

Davide Chiumello  1   2   3 , Miriam Gotti  4 , Mariateresa Guanziroli  4   5 , Paolo Formenti  4 , Michele Umbrello  4 , Iacopo Pasticci  4   5 , Giovanni Mistraletti  4   6 , Mattia Busana  7
Affiliations
Observational Study

Bedside calculation of mechanical power during volume- and pressure-controlled mechanical ventilation

Davide Chiumello et al. Crit Care. .

Abstract

Background: Mechanical power (MP) is the energy delivered to the respiratory system over time during mechanical ventilation. Our aim was to compare the currently available methods to calculate MP during volume- and pressure-controlled ventilation, comparing different equations with the geometric reference method, to understand whether the easier to use surrogate formulas were suitable for the everyday clinical practice. This would warrant a more widespread use of mechanical power to promote lung protection.

Methods: Forty respiratory failure patients, sedated and paralyzed for clinical reasons, were ventilated in volume-controlled ventilation, at two inspiratory flows (30 and 60 L/min), and pressure-controlled ventilation with a similar tidal volume. Mechanical power was computed both with the geometric method, as the area between the inspiratory limb of the airway pressure and the volume, and with two algebraic methods, a comprehensive and a surrogate formula.

Results: The bias between the MP computed by the geometric method and by the comprehensive algebraic method during volume-controlled ventilation was respectively 0.053 (0.77, - 0.81) J/min and - 0.4 (0.70, - 1.50) J/min at low and high flows (r2 = 0.96 and 0.97, p < 0.01). The MP measured and computed by the two methods were highly correlated (r2 = 0.95 and 0.94, p < 0.01) with a bias of - 0.0074 (0.91, - 0.93) and - 1.0 (0.45, - 2.52) J/min at high-low flows. During pressure-controlled ventilation, the bias between the MP measured and the one calculated with the comprehensive and simplified methods was correlated (r2 = 0.81, 0.94, p < 0.01) with mean differences of - 0.001 (2.05, - 2.05) and - 0.81 (2.11, - 0.48) J/min.

Conclusions: Both for volume-controlled and pressure-controlled ventilation, the surrogate formulas approximate the reference method well enough to warrant their use in the everyday clinical practice. Given that these formulas require nothing more than the variables already displayed by the intensive care ventilator, a more widespread use of mechanical power should be encouraged to promote lung protection against ventilator-induced lung injury.

Keywords: Acute respiratory distress syndrome; Acute respiratory failure; Driving pressure; Lung protection; Lung protective ventilation; Mechanical power; Mechanical ventilation; Respiratory failure; Respiratory rate; Ventilator-induced lung injury.

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Conflict of interest statement

None to disclose.

Figures

Fig. 1
Fig. 1
Bland-Altman analysis of the comprehensive equation for volume-controlled ventilation at 30 L/min (a) and 60 L/min (b) of inspiratory flow against the reference geometrical method
Fig. 2
Fig. 2
Bland-Altman analysis of the surrogate equation for volume-controlled ventilation at 30 L/min (a) and 60 L/min (b) of inspiratory flow against the reference geometrical method
Fig. 3
Fig. 3
Bland-Altman analysis of the comprehensive (a) and the surrogate equations (b) for pressure-controlled ventilation against the reference geometrical method
See this image and copyright information in PMC

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