Rises in mechanical power during operating room-to-ICU transition increase mortality odds

Key takeaways:

• The main driver behind the link between mechanical power and 28-day mortality was an increased respiratory rate.
• In the ICU, mechanical power significantly went up compared with in the operating room.

Mechanically ventilated patients requiring surgery faced elevated odds for 28-day mortality when mechanical power, or ventilation intensity, rose during the transition from operating room to ICU, according to study results.

“Increases in mechanical power during the transition were associated with higher odds of 28-day mortality, and this association was primarily driven by higher [respiratory rates],” Dario von Wedel, MD, research associate at the Institute of Medical Informatics of Charité and clinical research student in the department of anesthesia, critical care and pain medicine at Beth Israel Deaconess Medical Center, and colleagues wrote.

In a hospital registry study published in American Journal of Respiratory and Critical Care Medicine, von Wedel and colleagues evaluated 2,103 mechanically ventilated patients undergoing general anesthesia between 2008 and 2022 to see how ventilator parameters differ between the last hour of surgery in the operating room and the first 6 hours in the ICU.

An analysis to determine how changes in ventilator parameters during the operating room-to-ICU transition impact the odds for 28-day mortality was also carried out.

Researchers observed significant reductions (P < .001) in tidal volume by 1.1 mL/kg predicted body weight and driving pressure by 4.3 cm H₂O upon the operating room-to-ICU transition. In terms of respiratory rate, there was a 5 breaths per minute higher rate upon transition (P < .001).

In the ICU, mechanical power significantly went up by 0.7 J per minute compared with in the operating room.

Notably, from 2008 to 2022, tidal volume and driving pressure went down in both the last hour of surgery in the operating room and the first 6 hours in the ICU. In contrast, respiratory rates went up in both surgery and the ICU.

By day 28, researchers reported that 212 (10.1%) patients passed away.

The likelihood for 28-day mortality significantly rose with each 1 J per minute elevation in mechanical power during the operating room to ICU transition (adjusted OR = 1.1; 95% CI, 1.06-1.14).

“This translated into an increase in 28-day mortality from 9.2% in patients with stable [mechanical power] during transition to 12.9% when [mechanical power] was increased by 5 J/min,” von Wedel and colleagues wrote.

Researchers further noted that the main driver behind the link between mechanical power and 28-day mortality was an increased respiratory rate (aOR = 1.08 per 1 breath per minute; 95% CI, 1.04-1.12) rather than tidal volume or driving pressure.

Similar to the mortality finding, patients experienced significantly fewer days ventilator-free and alive with each 1 J per minute rise in mechanical power upon transition to the ICU (incidence rate ratio, 0.99; 95% CI, 0.98-0.99).

“Prospective validation of these findings is now warranted, which ultimately could facilitate real-time monitoring of ventilator adjustments to aid prognostication or clinical decision-making,” von Wedel and colleagues wrote.