PCO gap, its ratio to arteriovenous oxygen content, ScvO and lactate in high-risk abdominal surgery patients: An observational study.

Background: The difference between arterial and central venous carbon dioxide partial pressure (PCO gap), a marker of oxygen delivery (DO) and oxygen consumption (VO) adequacy, has been evaluated as a promising prognostic tool in intensive care unit (ICU) patients. We therefore sought to study the association between intraoperative PCO gap and postoperative complications (POC) in the perioperative setting of elective major abdominal surgery.

Methods: We conducted a single-centre prospective observational study. All adult patients who underwent major planned abdominal surgery were eligible. PCO gap was measured every 2 h during surgery, at ICU admission and repeated 12 h and 24 h later. Severe POC within 28 days after surgery were defined as complications graded 3 or more according to Clavien-Dindo classification. Following a univariate analysis, a multivariable analysis using a logistic regression model was performed.

Results: Ninety patients were included and divided into two groups according to the occurrence of POC. No significant difference was found between groups regarding baseline characteristics at inclusion. Thirty-nine (43%) patients developed postoperative complications. The median [IQR] intraoperative PCO gap was significantly higher in patients who had complications (6.5 [5.5-7.3] mmHg) compared to those who did not (5.0 [3.9-5.8] mmHg; p < 0.001). The area under the receiver operating characteristic curve for occurrence of POC was 0.78 for the PCO gap. After multivariable analysis, PCO gap was found independently associated with POC (OR: 14.9, 95% CI [4.68-60.1], p < 0.001) with a threshold value of 6.2 mmHg. The duration of surgery (OR: 1.01, 95% CI [1.00; 1.01], p = 0.04) and the need for vasoactive support during surgery (OR: 5.76, 95% CI [1.72; 24.1], p = 0.006) were also independently associated with POC.

Conclusion: Intraoperative PCO gap is a relevant predictive factor of severe postoperative complications in high-risk elective surgery patients.

Trial Registration: ClinicalTrials.gov, NCT03914976.