Mechanical power (MP), the rate of mechanical energy (ME) delivery, is a recently introduced unifying ventilator parameter consisting of tidal volume, airway pressures, and respiratory rates, which predicts pulmonary complications in several clinical contexts. However, ME has not been previously studied in the perioperative context, and neither parameter has been studied in the context of thoracic surgery utilizing one-lung ventilation.
The relationships between ME variables and postoperative pulmonary complications were evaluated in this post hoc analysis of data from a multicenter randomized clinical trial of lung resection surgery conducted between 2020 and 2021 (n = 1,170). Time-weighted average MP and ME (the area under the MP time curve) were obtained for individual patients. The primary analysis was the association of time-weighted average MP and ME with pulmonary complications within 7 postoperative days. Multivariable logistic regression was performed to examine the relationships between energy variables and the primary outcome.
In 1,055 patients analyzed, pulmonary complications occurred in 41% (431 of 1,055). The median (interquartile ranges) ME and time-weighted average MP in patients who developed postoperative pulmonary complications versus those who did not were 1,146 (811 to 1,530) J versus 924 (730 to 1,240) J (P < 0.001), and 6.9 (5.5 to 8.7) J/min versus 6.7 (5.2 to 8.5) J/min (P = 0.091), respectively. ME was independently associated with postoperative pulmonary complications (ORadjusted, 1.44 [95% CI, 1.16 to 1.80]; P = 0.001). However, the association between time-weighted average MP and postoperative pulmonary complications was time-dependent, and time-weighted average MP was significantly associated with postoperative pulmonary complications in cases utilizing longer periods of mechanical ventilation (210 min or greater; ORadjusted, 1.46 [95% CI, 1.11 to 1.93]; P = 0.007). Normalization of ME and time-weighted average MP either to predicted body weight or to respiratory system compliance did not alter these associations.
ME and, in cases requiring longer periods of mechanical ventilation, MP were independently associated with postoperative pulmonary complications in thoracic surgery.
- A growing number of laboratory and clinical studies suggest that mechanical power, which can be estimated using a battery of clinically available static and dynamic ventilatory parameters, is an important variable in modulating ventilator-induced lung injury
- The role of total mechanical energy, which incorporates mechanical power and its temporal characteristics (rate and duration of delivery), has not been well characterized in the perioperative setting
- This post hoc analysis of data from a previously published multicenter randomized clinical trial that evaluated the role of driving pressure–guided ventilation in the development of postoperative pulmonary complications within the first 7 days after thoracic surgery tested the hypothesis that time-weighted average mechanical power and mechanical energy were independently associated with postoperative pulmonary complications within 7 days after lung resection surgery and that the duration of mechanical ventilation was a significant effect modifier
- In adjusted analyses, mechanical energy was independently associated with postoperative pulmonary complications, while the association of time-weighted average mechanical power was significant only in cases requiring mechanical ventilation greater than or equal to 210 min
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