Motivation:

To assess the presence of alterations in respiratory muscle strength in patients with a programmed cardiovascular surgery, the impact of the surgery on respiratory muscle function and their relationship with ventilatory alterations during mediate postoperative period. Methods: Prospective observational study. Respiratory function tests (spirometry) and respiratory muscle strength tests (inspiratory: maximum inspiratory pressure, and expiratory: maximum expiratory pressure) were conducted in two moments: immediate preoperative (2 ± 1 days before surgery) and mediate postoperative period (2 ± 1, before being discharged). Respiratory complications included prolonged mechanical ventilation, pulmonary thromboembolism, pneumothorax, hemothorax; pneumonia; pleural effusion; pulmonary edema and atelectases.

Results:

30 adult patients were assessed (n = 30) (ages 62 ± 12). Spirometry performance decreased by 54% in the preoperative period (35% obstructive alteration, 19% non-obstructive) and inspiratory and expiratory weakness was confirmed at 67 and 100% respectively. Respiratory complications were present in 93% (more frequently atelectasis and pleural effusion). Severe postoperative deterioration of maximum inspiratory pressure increased by 10-fold the risk of atelectasis (OR = 10, IC 95% 0.85-117.02; p = 0.067). Upon discharge, ejection fraction of the left ventricle was 29% lower, forced vital capacity -32%, maximum inspiratory pressure -32% and maximum expiratory pressure -32% with regards to baseline values.

Conclusion:

Patients undergoing cardiovascular surgery suffer an unsuspected respiratory muscle dysfunction that worsens with surgery and hospitalisation, associated to a increase of the risk of respiratory complications.

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