Respiratory muscle strength, pain and pulmonary complications in adult patients following median sternotomy during hospital stay: a longitudinal observational study

Abstract

Abstract Background Pulmonary complications influence morbidity, mortality and hospital stay in patients following cardiac surgery. Acute post-operative pain and less than optimal respiratory muscle strength may affect a patient’s ability to take deep breaths, cough and clear secretions, thereby influencing recovery after surgery. To date, few studies described patients’ pain levels, respiratory muscle strength and the presence of pulmonary dysfunction preoperatively and evaluated the effect of a median sternotomy on parameters at hospital discharge. This study investigates this in patients at a private urban hospital in South Africa. Methods Participants were consecutively sampled for this longitudinal observational study and assessed at hospital admission and discharge. The visual analogue scale provides information on participants’ pain levels. Respiratory muscle strength (maximal inspiratory pressure and peak inspiratory flow) was assessed with a POWERbreathe KHI device. The presence of pulmonary complications was determined with a chest X-ray radiographic scoring tool. Descriptive and inferential analyses with significance set at p ≤ 0.05 were performed. Results The population consisted of 61 participants [males: n = 47 (77%)], and the majority underwent coronary artery bypass graft surgery (n = 35, 57%) and had a theatre time of 5.84 (± 1.30) h and time on cardiopulmonary bypass 2.01 (IQR1.14) h. Intensive care stay was 5 (IQR 2.75) days with mechanical ventilation time 17.33 (IQR 11.21) h and hospital stay 9 (IQR 7) days. Forty-one (67.2%) participants had weak respiratory muscles at hospital admission. Respiratory muscle strength reduced significantly between hospital admission and discharge: maximal inspiratory pressure: 55 cmH20 vs 30.66 cmH20, p < 0.001, and peak inspiratory flow: 2.70 l/s vs. 1.66 l/s, p < 0.001. Atelectasis (n = 28, 46, 6%) and pleural fluid (n = 26, 43, 3%) were chest X-ray abnormalities at hospital discharge. Chest X-ray scores (Z = − 5.825, p < 0.001) and pain levels (Z = − 5.867, p < 0.001) increased significantly over time. There was a fair, negative correlation between admission maximal inspiratory pressure and chest X-ray scores, which was statistically significant (r = − 0.356, p = 0.004). Conclusions Respiratory muscle weakness, abnormal chest X-ray findings and persistent pain were noted in study participants. This study highlights the need for continued rehabilitation services to optimise patient outcomes as it relates to ventilation and pain management.

Keywords

• Breathing dysfunction
• Median sternotomy
• Pain
• Physiotherapy
• Pulmonary complications
• Respiratory muscle strength