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 has a multifactorial meaning and the restrictive pattern can last for more than 116 days, predisposing atelectasis and post operatory complications [8–16]. In order to obtain pulmonary volumes and capacities, spirometry and ventilometry are the most used techniques in clinical practice, nevertheless, both methods are very costly and not always available in hospitals [3, 5, 17–20].
Due to its low cost, incentive spirometers are widely used in hospitals. They are used for treating and preventive purposes regarding pulmonary complications. This device works with visual stimulation to deep inspiration and is largely used by patients in post operatory periods of abdominal and thoracic surgery [21, 22].
Due to the importance of accessing VC in patients who underwent cardiac surgery and considering the high cost of ventilometers and spirometries, arises the necessity of an inexpensive alternative method which can reflect in a reliable manner the VC.
The aim of this study was to evaluate the incentive spirometers as a method of assessment VC in patients in pre and post coronary artery bypass grafting (CABG) surgery.