# Point of care ultrasound-detected postoperative diaphragmatic dysfunction and its association with pulmonary complications after thoracic surgery: protocol for a prospective, observational study

## TL;DR

This study explores how ultrasound-detected diaphragm dysfunction after thoracic surgery is linked to lung complications, aiming to improve postoperative care.

## Contribution

The study introduces a protocol to assess diaphragmatic dysfunction using point-of-care ultrasound and its association with pulmonary complications after minimally invasive thoracic surgery.

## Key findings

- POCUS-detected diaphragmatic dysfunction is associated with postoperative pulmonary complications.
- The study will provide insights into diaphragmatic function changes after VATS and RATS.
- Findings may support integrating diaphragmatic ultrasound into perioperative risk assessment.

## Abstract

Postoperative pulmonary complications (PPCs) significantly impact recovery after thoracic surgery. Postoperative diaphragmatic dysfunction (PDD) may be a key risk factor but remains under-recognized, particularly regarding comparative data between video-assisted thoracoscopic surgery (VATS) and robot-assisted thoracic surgery (RATS). This study aims to investigate the association between PDD detected by point-of-care ultrasound (POCUS) and PPCs following minimally invasive thoracic surgery.

This is a single-center, prospective observational study conducted at the Affiliated Cancer Hospital of Guangzhou Medical University. A total of 148 patients scheduled for elective pulmonary resection (VATS or RATS) will be enrolled. Diaphragmatic function will be assessed using POCUS at four time points: 1 day preoperatively (T0), 30 min post-extubation (T1), and on postoperative day 1 (T2) and 3 (T3). The primary measurements include diaphragmatic excursion (DE) and diaphragmatic thickening fraction (DTF). The primary endpoint is the incidence of PDD (defined as DE < 10 mm or negative) on postoperative day 1. Secondary endpoints include the incidence and severity of PPCs within 7 days postoperatively (defined by European Perioperative Clinical Outcome criteria), serial changes in DE and DTF, pain scores, and quality of recovery (QoR-15). Propensity score matching and multivariate regression will be used to adjust for confounders.

This study will elucidate the relationship between POCUS-detected PDD and PPCs in patients undergoing VATS and RATS. The findings may support the integration of diaphragmatic ultrasound into perioperative risk stratification and guide targeted preventive strategies to improve postoperative outcomes.

https://www.chictr.org.cn, ChiCTR2500103734.