Author: Justin Seemueller, Respiratory Clinical Specialist, Sentara Norfolk General Hospital

Date of first publication: 24.02.2021

As our understanding of VILI grows, there is a greater focus on mechanical power (MP) as a potential predictor of negative outcomes.

Data currently suggests that a MP of 17.0 J/min is associated with higher risk of death (

**Power _{surr.corr }= [VE x (Peak Pressure + PEEP + F/6)] / 20**

If we use the corresponding values shown in the ventilator's Monitoring window, the equation is as follows:

**Power _{surr.corr }= [ExpMinVol x (Ppeak + PEEP/CPAP + Insp Flow/6)] / 20**

Figure 1 below shows the calculation using the corresponding values as shown in the Monitoring window.

Below is a simplified method of calculating mechanical power in Pressure Control proposed by Van der Meijden et al. and Becher et al. (

**MP _{PCV} = 0.098 x RR x VT x (∆P_{insp} + PEEP)**

It is possible to further simplify their formula by replacing "∆P_{insp} + PEEP” with plateau pressure, as they are equivalent by definition. Pplateau can be measured by means of an inspiratory hold (available in the Tools window). Alternatively, an estimated value of Pplateau is displayed in the Monitoring window of Hamilton Medical ventilators. If we use the corresponding values as shown in the Monitoring window, the equation is as follows:

**MP _{PCV} = 0.098 x fTotal x VTI x Pplateau**

Figure 2 below shows the calculation using the corresponding values as shown in the Monitoring window.

These formulas may assist in identifying mechanically ventilated patients in need of earlier intervention.

- 1. Serpa Neto A, Deliberato RO, Johnson AEW, et al. Mechanical power of ventilation is associated with mortality in critically ill patients: an analysis of patients in two observational cohorts. Intensive Care Med. 2018;44(11):1914-1922. doi:10.1007/s00134-018-5375-6
- 2. Giosa L, Busana M, Pasticci I, et al. Mechanical power at a glance: a simple surrogate for volume-controlled ventilation. Intensive Care Med Exp. 2019;7(1):61. Published 2019 Nov 27. doi:10.1186/s40635-019-0276-8
- 3. Becher T, van der Staay M, Schädler D, Frerichs I, Weiler N. Calculation of mechanical power for pressure-controlled ventilation. Intensive Care Med. 2019;45(9):1321-1323. doi:10.1007/s00134-019-05636-8