Anaerobic threshold as a predictor of surgical complications in colorectal robotic assisted surgery: a pilot study

Background
Cardiopulmonary fitness testing (CPET) is a recognised clinical risk stratification tool. This pilot study examined the relationship between CPET variables and postoperative complications in colorectal robot-assisted surgery (RAS).

Methods
Retrospective analysis was conducted on RAS patients (n=80). Anaerobic threshold (AT) (mL/min/kg), Peak ̇VO₂ (Peak) (mL/min/kg), BMI, age, sex, and Clavien-Dindo (CD) classification were analysed. Linear regression assessed relationships between AT, Peak and complications. Groups were compared with the Mann-Whitney U test.

Results
The regression model explained 53.9% of the variance in AT (R² = 0.539, p < 0.001). Complications were associated with a lower AT (β = -2.46, 95% CI: -4.18 to -0.74, p = 0.006, d = 0.41). CD classification was significant (p < 0.001). Class V patients recorded lower AT (-11.49 mL/min/kg, 95% CI: -18.03 to -4.95, p < 0.001, d = 1.12). Small effects were detected in the Mann-Whitney U tests, but these were not significant: Peak was lower in the complication group (U = 634, p = 0.190, d = 0.20, 95% CI: -0.60 to 2.20). AT was also lower in the complication group, (U = 623, p = 0.226, d = 0.33, 95% CI: -0.40 to 1.90).

Conclusion
Although underpowered, this pilot suggests lower AT is associated with the presence of complications following RAS and that patients with higher CD classifications were more likely to have a lower threshold. These findings support preoperative fitness assessment via CPET for risk stratification and care optimisation. Larger samples are required to confirm the findings.