Background  Postoperative pulmonary complications (PPCs) is a common and important cause of death in elderly patients undergoing abdominal surgery. Prevention and treatment of PPCs is of great importance to ensure the postoperative safety. But there are few proved simple and effective treatments.

  Objective  To observe the effect of extracorporeal diaphragm pacing (EDP) on preventing pulmonary complications after abdominal surgery in the elderly.

  Methods  Fifty-one elderly patients undergoing abdominal surgery in the Second Medical Center of Chinese PLA General Hospital were randomly divided into experimental group (EDP group), 26 of whom were treated with external diaphragm pacemaker after operation, twice per day, 30 min for each time. Patients in the control group (Vest TM group, n=25) were treated with VEST airway clearance system after operation, twice per day, 15 min for each time. The treatment began at the first day after operation and lasted for 5 days. By comparing the postoperative pulmonary complications, pulmonary function, arterial blood gas analysis, percutaneous blood saturation, sputum excretion and incision pain score, the effect of EDP on preventing pulmonary complications after abdominal operation in elderly patients was evaluated.

  Results  The pulmonary function indexes of the two groups decreased after surgery. Compared with the control group, the indexes of pulmonary function in the EDP group including forced vital capacity (FVC)(L) (2.75 ± 0.51 vs 2.45 ± 0.48), forced expiratory volume in one second (FEV1)(L/s) (1.98 ± 0.53 vs 1.69 ± 0.29), FEV1/FVC (72.6 ± 8.72 vs 66.45 ± 9.83) and transdermal blood oxygen saturation (95% ± 5% vs 90% ± 6%) were significantly higher than those in the Vest TM group (all P＜0.05). VAS score on the 3^rd (2.8 ± 0.9 vs 3.6 ± 1.7, P＜0.05) and the 5^th day (1.0 ± 0.7 vs 1.8 ± 0.8, P＜0.05) after surgery were significantly lower than those of the control group (P＜0.05, respectively). The incidence of postoperative pulmonary complications (total complications: 15.38% vs 28%, atelectasis: 7.69%% vs 16%, pulmonary infection: 3.85% vs 8%, respiratory failure: 3.85% vs 4%, Re-intubation mechanical ventilation: 0 vs 4%), the level of PCO₂ (mmHg) and the volume of sputum excretion (mL) in the EDP group were lower than those in the Vest TM group, and the level of the PO₂ (mmHg) was higher than those in the Vest TM group, but all the differences were not significant (P＞0.05).

  Conclusion  Extracorporeal diaphragm pacemaker can reduce the decline of pulmonary function, improve blood oxygen saturation and promote sputum excretion in elderly patients after abdominal surgery, which may reduce PPCs with good tolerance, and can be used as a precaution to prevent PPCs in elderly patients undergoing abdominal surgery.