Estimation of lung vital capacity before and after coronary artery bypass grafting surgery: a comparison of incentive spirometer and ventilometry

Cross-sectional comparative study with patients undergoing cardiac surgery. Respiratory parameters were evaluated through the measurement of VC performed by ventilometer and inspirometer. To analyze data normality the Kolmogorov-Smirnov test was applied, for correlation the Pearson correlation coefficient was used and for comparison of variables in pre and post operative period Student's t test was adopted. We established a level of ignificance of 5%. Data was presented as an average, standard deviation and relative frequency when needed. The significance level was set at 5%.We studied 52 patients undergoing cardiac surgery, 20 patients in preoperative with VC-ventilometer: 32.95 ± 11.4 ml/kg and VC-inspirometer: 28.9 ± 11 ml/Kg, r = 0.7 p < 0.001. In the post operatory, 32 patients were evaluated with VC-ventilometer: 28.27 ± 12.48 ml/kg and VC-inspirometer: 26.98 ± 11 ml/Kg, r = 0.95 p < 0.001. Presenting a very high correlation between the evaluation forms studied.There was a high correlation between DVC measures with ventilometer and incentive spirometer in pre and post CABG surgery. Despite this, arises the necessity of further studies to evaluate the repercussion of this method in lowering costs at hospitals.Vital capacity (VC), defined as the maximum amount of air that can be exhaled after a maximum inhalation, is an indispensable measure for the diagnosis of pulmonary mechanical limitation as well as for adequation of pulmonary reexpansion therapy applied to patients after cardiac surgery. The normal value of the VC is from 65 to 75 ml/kg, however, there may be variations regarding ethnicity, age, gender, height and weight [1-5].The evaluation of pulmonary volumes and capacities is essential to characterize pulmonary mechanical limitation, especially in postoperative cardiac surgery patients [6,7].It has been described that VC lower than 25 ml/Kg can predispose atelectasis, hypoxemia and inefficient cough [6,7]. After cardiac surgery, the impairment of VC ha