Weakness of expiratory muscles and pulmonary complications in malnourished patients undergoing upper abdominal surgery

Background and objective: Malnutrition is prevalent in hospitalized patients and causes systemic damage including effects on the respiratory and immune systems, as well as predisposing to infection and increasing postoperative complications and mortality. This study aimed to assess the impact of malnutrition on the rate of postoperative pulmonary complications, respiratory muscle strength and chest wall expansion in patients undergoing elective upper abdominal surgery. Methods: Seventy‐five consecutive candidates for upper abdominal surgery (39 in the malnourished group (MNG) and 36 in the control group (CG)) were enrolled in this prospective controlled cohort study. All patients were evaluated for nutritional status, respiratory muscle strength, chest wall expansion and lung function before surgery. Postoperative pulmonary complications (pneumonia, tracheobronchitis, atelectasis and acute respiratory failure) before discharge from hospital were also evaluated. Results: The MNG showed expiratory muscle weakness (MNG 65 ± 24 vs CG 82 ± 22 cm H₂O; P < 0.001) and decreased chest wall expansion (P < 0.001), whereas inspiratory muscle strength and lung function were preserved (P > 0.05). The MNG also had a higher incidence of postoperative pulmonary complications compared with the CG (31% and 11%, respectively; P = 0.05). In addition, expiratory muscle weakness was correlated with BMI in the MNG (r = 0.43; P < 0.01). The association between malnutrition and expiratory muscle weakness increased the likelihood of postoperative pulmonary complications after upper abdominal surgery (P = 0.02). Conclusions: These results show that malnutrition is associated with weakness of the expiratory muscles, decreased chest wall expansion and increased incidence of pulmonary complications in patients undergoing elective upper abdominal surgery.