Introduction:

Mechanical power (MP) involves the energy supplied toward the lung parenchyma at each respiratory cycle. MP reflects damage over the lung through some calculus derived from the equation of motion of the respiratory system.

Material and methods:

It is an observational study of patients under mechanical ventilation, with a PaO2/FiO2 ratio < 200 at PEEP ≥ 5 cmH2O. Pressure y volumes were recorded at days 1 and 3, and PM calculations were made using these formulae: Gattinoni = 0.098 FR Vt (Ppico-½ΔPaw ); Marini = 0.098 FR Vt Paw.

Results:

67 patients under mechanical ventilation were analyzed by both formulae. A high MP discriminates mortality at day three, with an area under the ROC curve: 0.66 (IC 95% 0.52-0.79) and 0.63 (IC 95% 0.47-0.79), respectively. Also, a high MP by Gattinoni formula in subjects with more than seven days under mechanical ventilation, was associated to a higher mortality at hospital discharge, HR = 5.89 (IC 95% 0.96-36.22, p = 0.055).

Discussion and conclusions:

In this cohort, a high MP value is related to a higher mortality in patients under prolonged mechanical ventilation (> 7 days). This calculation is a promising tool, that can be calculated at patient bedside.

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