# Intraoperative Oxygen Consumption and Postoperative Immune Response in Colorectal Oncological Surgery: A Prospective, Monocentric Pilot Study

## TL;DR

This study shows that oxygen use during colorectal cancer surgery is linked to immune changes after surgery, which could help predict recovery and cancer outcomes.

## Contribution

The study introduces intraoperative oxygen consumption as a potential early predictor of postoperative immune response in colorectal surgery.

## Key findings

- Intraoperative oxygen consumption correlates with neutrophil count changes (correlation coefficient = 0.547, p < 0.01).
- Platelet count variations are significantly correlated with oxygen consumption (correlation coefficient = −0.603, p < 0.01).
- No significant correlation was found between oxygen consumption and lymphocyte count changes (p = 0.39).

## Abstract

Surgical resection is the key treatment for colorectal cancer, but the extent of surgical trauma has been implied as a key factor for the oncologic outcome. The immune stress response to surgical trauma generates a cascade of immunological events implying neutrophils’ perioperative change generating NETosis, N killer decrease, and platelets’ activation that may influence postoperative surgical outcome, tumor cell growth, and future oncogenesis. The present study aimed to investigate the correlation between intraoperative oxygen consumption (VO2) and the dynamic variation of neutrophils, lymphocytes, and platelets in the perioperative period to identify an intraoperative tool that could predict the postoperative immune response. Twenty-six colorectal oncological surgical patients were enrolled in an observational, prospective, monocentric study, over 18 months. Serum neutrophils, lymphocytes, and thrombocytes values were collected in the preoperative period and on the third postoperative day, oxygen consumption was measured and recorded every 15 min during surgery using indirect calorimetry. We compared oxygen consumption measurements registered 30 min after induction of anesthesia (VO2a) and the first value registered after abdominal wall closure (VO2b) to perioperative variation of absolute neutrophils (VNC), lymphocytes (VLC), and platelets (VPC) count. Our results proved a significant correlation between VO2 variation and neutrophils’ perioperative dynamic assessed by VNC (correlation coefficient = 0.547, p < 0.01, 95% confidence interval (CI) =0.175, 0.783). We also noticed a correlation between VPC and VO2 (correlation coefficient = −0.603, p < 0.01, 95% CI = −0.815, −0.248). No correlation could be shown between VO2 and VLC variation (p = 0.39). In conclusion, intraoperative VO2 variation measured by indirect calorimetry correlates well with perioperative neutrophils and platelets count dynamic variations and can be used as an early prognosis marker of postoperative immune response and surgical outcome in colorectal oncological surgery.