Neutrophil-to-Lymphocyte Ratio as an Indicator of Opioid-Induced Immunosuppression After Thoracoscopic Surgery: A Randomized Controlled Trial

Purpose: The neutrophil-to-lymphocyte ratio (NLR) is a useful prognostic marker for various diseases and surgery-induced immunosuppression. While opioids are important in general anesthesia, the association between immediate perioperative immune monitoring and opioid consumption for postoperative analgesia after video-assisted thoracoscopic surgery (VATS) is unknown. We aimed to investigate the effect of analgesic techniques on opioid-induced immune perturbation, and the feasibility of NLR as an indicator of opioid-induced immune changes. Patients and Methods: Patients were randomly assigned to two groups: Group P (n=40) or Group C (n=40). Patients in group P received ultrasound-guided paravertebral block (PVB) before surgery, and followed by sufentanil patient-controlled intravenous analgesia (PCIA) after surgery, and group C received sufentanil PCIA only. The total and differential white blood cell counts, including CD4+ T lymphocyte counts, CD8+ T lymphocyte were recorded before surgery and at 24 and 72 hours after surgery. NLR was determined using the frequencies of lymphocyte subpopulations. The cumulative dose of sufentanil were recorded at 24 and 24h after surgery while the 40-item quality of recovery questionnaire (QoR-40) score were assessed at 48h after the surgery. Results: At 24 and 48 hours after surgery, a lower sufentanil consumption, and higher QoR-40 recovery scores were found in group P than in group C (P< 0.05). In biochemical analyses, the values of NLR were lower in group P compared to group C ( p < 0.0001) and ratio of CD4/CD8 were higher in group P compared to group C ( p < 0.05) on day three after surgery. NLR showed excellent predictive capability for immunosuppression, with an area under the curve (AUC) of 0.92 [95% confidence interval (CI), 0.86– 0.98, P < 0.0001]. Conclusion: Opioid-sparing pain management strategies may affect postoperative immunosuppression and NLR could be a reliable indicator of opioid-related immunosuppression. Moreover, opioid-sparing pain management strategies could improve patient's satisfaction in VATS. Keywords: neutrophil-to-lymphocyte ratio, immunosuppression, paravertebral block, opioid, analgesia