# Effects of secular changes in tidal volume and respiratory rate on the mechanical power of ventilation: a retrospective single-center study of invasively ventilated patients

## TL;DR

This study found that over two decades, changes in breathing patterns in ventilated patients led to reduced mechanical power, especially in those with poor lung compliance.

## Contribution

The study identifies secular trends in tidal volume and respiratory rate and their impact on mechanical power in ventilated patients.

## Key findings

- Median tidal volume decreased while respiratory rate increased over the study period.
- Mechanical power decreased significantly, especially in patients with low respiratory system compliance.
- The reduction in mechanical power was more pronounced in patients with poor lung compliance.

## Abstract

To evaluate how secular changes in tidal volume and respiratory rate influence the mechanical power of ventilation during the first 24 hours in critically ill patients over two decades and to compare their effects in patients with high and low respiratory system compliance.

This secondary analysis of the Amsterdam University Medical Center database included two time periods: 2003 to 2009 and 2010 to 2016. The primary endpoint was mechanical power. Analyses also assessed secular changes in mechanical power in patients with respiratory system compliance groups.

Among 4,877 patients (2,536 patients in 2003 - 2009, and 2,341 in 2010 - 2016), median tidal volume decreased (mean difference of −0.6 [-0.4 to −0.7] mL/kg predicted body weight; p < 0.01), median respiratory rate increased (mean difference of +1.0 [+0.75 to +1.25] breath/minute; p < 0.01), and median mechanical power fell from 12.1 (8.7 - 16.7) J/minute to 10.4 (7.6 - 14.6) J/minute (mean difference of −1.7 [-1.2 to −2.0] J/minute; p < 0.01). In patients with low respiratory system compliance, median mechanical power decreased more significantly (13.4 J/minute to 11.7 J/minute, mean difference of −1.7 J/minute; p < 0.01) compared to those with high respiratory system compliance (10.5 J/minute to 9.7 J/minute, mean difference of −0.8 J/minute; p < 0.01) despite comparable respiratory rate changes

In this single-center cohort, secular changes in tidal volume and respiratory rate were associated with lower mechanical power, particularly in patients with low respiratory system compliance.