Abstract: Objective To investigate the interaction and mediating effects of thoracic paravertebral block (TPVB) and opioid consumption(oral morphine equivalent,OME) on postoperative pulmonary complications (PPCs) in the elderly patients undergoing thoracoscopic partial pulmonary resection (TPPR). Methods The data of 816 elderly patients aged ≥65 years old who underwent TPPR at the First Affiliated Hospital of Nanjing Medical University were analyzed retrospectively. The patients were divided into PPCs group and non-PPCs group according to whether they presented with PPCs. Multivariate logistic regression was used to evaluate the independent effect of TPVB and OME on PPCs, and the interaction effect and mediation effect between TPVB and OME were analyzed. Results The incidence rate of PPCs was 40.4%. Multivariate logistic regression analysis showed that OME was a risk factor for PPCs, while TPVB was a protective factor (P<0.001). The multiplicative interaction between these two factors showed that the patients who did not receive TPVB and were administered high-dose opioids had a 4.6-fold increased risk of developing PPCs (OR=4.556, 95% CI: 2.248-9.234). Even with the use of TPVB combined with high doses of opioids, the risk of PPCs was 2.1 times higher (OR=2.098, 95% CI: 1.126-3.910). Moreover, opioid consumption was found to mediate the relationship between TPVB and PPCs (Z=-2.124, P=0.034). Conclusions TPVB and opioid consumption exert significant interactive and mediating effects on the development of PPCs in the elderly patients undergoing TPPR. In clinical practice, optimizing perioperative analgesia, actively applying TPVB, and appropriately regulating opioid administration are crucial to reduce the risk of PPCs in the elderly patients with TPPR.

Key words: thoracic paravertebral block, opioids, thoracoscopic partial pulmonary resection, aged, postoperative pulmonary complications