Background: Numerous randomized controlled trials (RCTs) have reported the benefits of external diaphragm pacing combined with conventional rehabilitation therapies (EDP-CRTs) on pulmonary function and exercise capacity in patients with chronic obstructive pulmonary disease (COPD). However, evidence-based regarding its effects remains unclear.
Objectives: This systematic review and meta-analysis aimed to evaluate the effects of EDP-CRTs versus CRTs on patients with COPD.
Design: Systematic review and meta-analysis.
Data sources and methods: We performed a systematic review and meta-analysis, searching PubMed, Embase, Cochrane Central Register of Controlled Trials, Scopus, China Biology Medicine Disc, Chinese National Knowledge Infrastructure, Wan-Fang Database, and Chinese Scientific Journal Database from inception to 10 September 2023. RCTs investigating the effects of EDP-CRTs versus CRTs on COPD patients were included. The primary outcome was pulmonary function, including forced expiratory volume in 1 s (FEV1), the percentage of predicted values of FEV1 (FEV1%pred), and FEV1/forced vital capacity (FVC)%. Secondary outcomes included arterial blood gas analysis [the partial pressure of arterial oxygen (PaO2) and the partial pressure of arterial carbon dioxide (PaCO2)]; dyspnea [modified Medical Research Council Dyspnea Scale (mMRC)]; exercise capacity [6-min walking distance (6MWD)]; and quality of life [COPD assessment test (CAT)]. RevMan 5.3 software was used for meta-analysis. The quality of the included studies was assessed using the revised Cochrane Risk of Bias tool for randomized trials (RoB 2.0). The certainty of the evidence was evaluated with the Grading of Recommendations Assessment, Development, and Evaluation system.
Results: In total, 13 studies/981 participants were included. The pooled results revealed significant benefits of EDP-CRTs versus CRTs on the FEV1 [standardized mean difference (SMD) = 1.07, 95% confidence interval (CI) = 0.58-1.56], FEV1%pred [weighted mean difference (WMD) = 6.67, 95% CI = 5.69-7.64], the FEV1/FVC% (SMD = 1.24, 95% CI = 0.48-2.00), PaO2 (SMD = 1.29, 95% CI = 0.74-1.84), PaCO2 (SMD = -1.88, 95% CI = -2.71 to -1.04), mMRC (WMD = -0.55, 95% CI = -0.65 to -0.45), 6MWD (SMD = 1.63, 95% CI = 0.85-2.42), and CAT (WMD = -1.75, 95% CI = -3.16 to -0.35), respectively. Planned subgroup analysis suggested that EDP-CRTs had a better effect on FEV1, FEV1/FVC%, 6MWD, and CAT in the duration of 2-4 weeks.
Conclusion: EDP-CRTs have better effects on pulmonary function, PaCO2, dyspnea, exercise capacity, and quality of life in COPD patients than CRTs, and the duration to achieve the most effective treatment is 2-4 weeks.
Trial registration: This systematic review and meta-analysis protocol was prospectively registered with PROSPERO (No. CRD42022355964).
Keywords: chronic obstructive pulmonary disease; diaphragm; external diaphragm pacing; pulmonary rehabilitation.