Airway Driving Pressure Linked to Pulmonary Complications Post Abdominal Surgery

Airway driving pressure, but not tidal volume or positive end-expiratory pressure (PEEP), is associated with an increased risk for postoperative pulmonary complications after major abdominal surgery, researchers reported in BJA Open.

Because of the association between adverse outcomes in critically ill patients receiving mechanical ventilation and high airway driving pressure, investigators hypothesized that increased driving pressure would be linked to postoperative pulmonary complications in patients following major abdominal surgery.

The multicenter, observational study evaluated the association between dynamic driving pressure and postoperative pulmonary complications among adults who underwent a major abdominal surgical procedure (mechanical ventilation ≥120 min). Participants received care at 11 hospitals providing data to the Multicenter Perioperative Outcomes Group (MPOG) between 2004 and 2018 and had clinical data available in the integrated American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) surgical outcomes registry.

A total of 14,218 abdominal surgical procedures were included in the analysis. The participants had a median age of 57 (interquartile range, 46-67) years, and 57.8% were female. Among the surgical procedures used, 51.7% involved a minimally invasive approach and 4.1% were emergent.

The primary outcome was a composite of postoperative pulmonary complications, which included at least 1 of the following occurring within 30 days postoperatively: pneumonia, requirement of ventilatory support for any reason (unplanned tracheal intubation, failure to wean from ventilator support within 48 hours from the end of surgery), or both.

Of the cohort, 389 (2.7%) patients had a postoperative pulmonary complication, and 2202 (15.5%) had a nonrespiratory complication. Mortality occurred in 66 (0.5%) participants, and 2311 patients (16.3%) had a composite outcome of postoperative pulmonary complications, major morbidity, or 30-day mortality.

Participants who had postoperative pulmonary complications were more likely to be older (65 [56-74] years vs 57 [46-67] years, respectively, P <.001) and male (57.1% vs 41.8%, respectively, P <.001).

The median (SD) dynamic driving pressure among patients studied was 16 (12-21) cm H₂O. The tidal volume (V_T) was 489 mL (439-567), V_T predicted body weight (PBW) was 8 (7-9) mL · kg^–1, and PEEP was 5 (2-5) cm H₂O.

In the generalized linear model, dynamic driving pressure was associated with postoperative pulmonary complications (adjusted odds ratio [OR], 1.04; 95% CI, 1.02-1.06; P <.001). PEEP (adjusted OR, 1.02; 95% CI, 0.98-1.07; P =.400) and tidal volume (adjusted OR, 0.98; 95% CI, 0.92-1.04; P =.452) were not associated with postoperative pulmonary complications.

In a multivariable linear regression model assessing whether the traditional risk factors for nonprotective ventilation were associated with high driving pressures, increased body mass index (kg/m^–2) (β = 0.35; 95% CI, 0.32-0.39; P <.001), decreased height (cm) (β = –0.01; 95% CI, –0.02 to 0.00; P =.005), and female sex (β = 0.74; 95% CI, 0.63-0.86; P <.001) were associated with dynamic driving pressure.

Study limitations include the retrospective nature of the study and the possibility of unidentified confounding variables. In addition, the period of data collection (2004 to 2018) was long and practice patterns changed over time, which may have introduced unaccounted for covariates.

The investigators concluded that “Future studies, including RCTs, will be required to provide further insight into the relationship between driving pressure and postoperative pulmonary complications, including a potential causal mechanism and whether modifications in driving pressure reduce the risk for postoperative pulmonary complications.”

Disclosure: One of the study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.