Risk factors for perioperative inspiratory muscle weakness in cardiac surgery patients: a prospective observational...

Inspiratory muscle influences postoperative outcomes following cardiac surgery. Most studies have focused on preoperative inspiratory muscle weakness (IMW). However, the prevalence, risk factors and postoperative outcomes of perioperative persistent IMW or newly developed IMW postoperatively remain inadequately understood.

A prospective observational study enrolled 210 patients undergoing cardiac surgery. Maximal inspiratory pressure (MIP) was measured preoperatively (admission, one day before surgery) and at discharge. Patients were categorised into three groups by preoperative and discharge MIP: Group A (probable persistent IMW), Group B (newly developed IMW), and Group C (normal function). Demographic, cardiovascular and comorbid conditions, clinical data were collected for analysis.

There were 84 (40.0%) patients in Group A, 78 (37.1%) patients belonged to Group B and 48 (22.9%) patients in Group C. Multivariate logistic regression analysis revealed that, relative to Group C, male (OR = 4.743, 95% CI 1.196-18.804), lower body mass index (BMI) (OR = 0.823, 95% CI 0.701-0.967), lower handgrip strength (HGS) (OR = 0.897, 95% CI 0.815-0.987) and peak expiratory flow (PEF) (OR = 0.142, 95% CI 0.066-0.304), and prolonged duration of mechanical ventilation (MV) (OR = 1.036, 95% CI 1.009-1.064) were risk factors associated with Group A. Conversely, relative to Group C, male (OR = 6.732, 95% CI 1.867-24.279), lower HGS (OR = 0.911, 95% CI 0.839-0.990) and PEF (OR = 0.477, 95% CI 0.274-0.832), and prolonged MV duration (OR = 1.027, 95% CI 1.001-1.054) were identified as independent risk factors for Group B. Patients in Group A had a higher incidence of postoperative pulmonary complications (PPCs) (69.0%), intensive care unit (ICU) stay of 46.42 (39.52-92.09) (hours) and hospital stay of 20.00 (15.00-23.75) (days), and lower quality of life at discharge (69.39 ± 11.22).

This study identified a high prevalence of probable persistent IMW and newly developed IMW in cardiac surgery patients, explored their risk factors and the worst postoperative outcomes. Classifying perioperative IMW informs targeted respiratory muscle rehabilitation and graded screening protocols.