Pulmonary function changes after cardiopulmonary bypass in cases of rheumatic mitral valve diseases

ABSTRACT

Measurement of pulmonary function parameters which calculated by spirometry in adult patients undergoing open heart surgery to assess pulmonary reserve is an important procedure to evaluate the operative morbidity. Pulmonary function was done preoperatively, before discharge, and at the 2-month follow-up in 66 randomly selected patients who underwent open-heart surgery for rheumatic mitral valve disease [6 reconstmctions, 60 replacements]. The mean preoperative cardiothoracic ratio was 0.58. Lung function was found to be impaired preoperatively in all l8 smoker patients and the majority suffered from restrictive lung disease. Better preoperative lung function was seen in nonsmokers, patients with a cardiothoracic ratio of less than 0.50, and those with a normal pulmonary artery pressure. After mitral valve surgery, the mean pulmonary artery pressure was 20.6 +/- 2.9 mm Hg, the mean mitral valve pressure gradient was 3.6 +/- 2.4 mm Hg. and the mean cardiothoracic ratio was 0.52 +/- 0.09. A significant deterioration was seen in the before discharge spirometric values of forced vital capacity, forced expiratory volume in one second, peak expiratory f low rate, flow rate at 25% to 75% of expired vital capacity, and maximum volume ventilation. The deterioration was greater in smokers and those who had prolonged cardiopulmonary bypass [more than 60 minutes]. No correlation was found with ventilation because all patients were electively mechanically ventilated during early hours of the postoperative period. There was an overall improvement in spiromctric parameters at the 2-month follow-up although the values remained lower than predicted. Spirometry was found to be useful for assessing lung function in patients undergoing mitral valve surgery and we recommended it as a routine test