Beyond pressure and volume: mechanical power levels in a cohort of intensive care unit patients

Background

Several ventilator parameters can be used to evaluate gas exchange and mechanical properties of the respiratory system in acute respiratory failure patients. The calculation of mechanical power (MP), a critical parameter that summarizes the energy transferred from the ventilator to the patient’s lungs, is not routinely made in these patients.

Methods

This study analyzed the distribution of MP in a cohort of 70 patients requiring mechanical ventilation and investigated its association with clinical outcomes.

Results

This study included 39 men and 31 women with a mean age of 57.7 ± 15.1 years. The mean MP index decreased significantly from 10.4 J/min ± 5.65 on day 2 of mechanical ventilation to 8.3 J/min ± 4.1 on day 4 (p = 0.045). The mean length of mechanical ventilation was 5.2 $\pm 6.5\text{days}.$ Mechanical power measured on day 2 (r = 0.317, p = 0.052) and day 4 (r = 0.352, p = 0.030) positively correlated with the duration of mechanical ventilation. There were no differences in MP between survivors and non-survivors on both day 2 (p = 0.458) and day 4 (p = 0.373).

Conclusions

This study analyzed the distribution of MP levels in mechanically ventilated patients in an ICU. Mechanical power measured on days 2 and 4 of mechanical ventilation had a positive correlation with the duration of ventilation, but it was not a significant predictor of ICU mortality.