IJCS | Volume 32, Nº2, March/April 2019

105 Cordeiro et al. Pulmonary function after hospital discharge Int J Cardiovasc Sci. 2019;32(2)104-109 Original Article Operative conditions such as cardiopulmonary bypass (CPB), surgical incision, anesthesia, the patient’s hemodynamics, type and duration of the procedure, length of drainage or pain can cause lung disorders. All of these components seem to lead to decreased pulmonary volumes and capacities, thoracic expansion and respiratory muscle dysfunction. 2,4 The efficacy of respiratory physiotherapy is as an important marker for cardiac rehabilitation both inside and outside the intensive care unit. 5 The physiotherapist contributes directly to the best prognosis, prevention and treatment in patientswho undergo coronary artery bypass grafting, where rehabilitation treatments are applied, such as: manual, respiratory and pulmonary reexpansion maneuvers, postural advice and bed positioning. 6 There is still little information on the behavior of lung function after cardiac surgery related to the time required to reestablish the lungs to preoperative values. Therefore, the objective of this study was to describe the behavior of pulmonary function after hospital discharge in patients undergoing CABG. Methodology This is a prospective study involving patients from a reference hospital in Feira de Santana - BA, Brazil, from August 2017 to April 2018. This study was approved by the research ethics committee of Faculdade Nobre (FAN) of Feira de Santana-Bahia under opinion no. 2.088.639. All patients signed an Informed Consent Form. The inclusion criteria were individuals of both sexes, aged equal to or above 18 undergoing coronary artery bypass grafting procedure via median sternotomy and extracorporeal circulation. The exclusion criterion were patients who were readmitted to the hospital, patients who did not return for the review, who found it hard to understand or to collaborate, who present post-surgical complications, hemodynamic instability, previous cardiac surgery, previous neurological symptoms, cardiac arrhythmia, andwho remained at least 6 days in hospital. After meeting all inclusion criteria, the patients had their pulmonary function assessed preoperatively. This evaluation consisted of maximal inspiratory pressure (MIP) and maximum expiratory pressure (MEP), and vital capacity (VC). Respiratorymuscle strengthwas testedwith the patient sitting on a chair. Initially, the patient was asked to breathe close to the current volume and, after three breaths, to performamaximal forcedexpiration (residual volume) and then a maximal static inspiration sustained for 3 seconds with nasal occlusion in order to get the MIP measure. Subsequently, to measure the PEM, the patient had to breathe close to the current volume for three cycles and perform a maximal inspiration (total pulmonary capacity) followed by a maximum sustained expiration for 3 seconds. Both maneuvers were repeated at least three times with an interval of one minute and the highest value, which cannot be the one from the last measurement, was recorded. These measurements were performed using an analogue Instrumentation Industries manovacuometer model MV - 120, with a range of 0 to 120 cmH 2 O. Vital capacity was measured using the Wright Mark 8 analogue ventilator (Ferraris) with a 35 mm display, two 0-1 l/min and 0100 l/min dials. The patients are required to perform a maximal inspiration up to the total lung capacity and then a slow maximal expiration until the residual volume is reached. All patients should be sitting and perform three measurements, with a one- minute interval between them, adopting the highest value obtained as a reference. After the initial evaluations, the patients were referred to the surgical center where they were always handled by the same medical team and were later sent to the intensive care unit (ICU) where they were managed according to the unit’s routine, which consists of non- invasive ventilation, breathing exercises and positive end-expiratory pressure. Finally, they were admitted to the ward after discharge from the ICU. Upon hospital discharge, the patients had their lung function evaluated again. Note that no researcher has influence on the procedures adopted during the hospitalization or decision on hospital discharge. One month after the surgery, the patients were evaluated for respiratory muscle strength and vital capacity upon their return to medical reevaluation. The evaluations at the two moments are always carried out by the same examiner. Statistical analysis The program SPSS 20.0 was used for data analysis. To evaluate the normality, the Kolmogorov-Smirnov test was used. Data were expressed as mean and standard deviation. The pulmonary function at the different operative moments was analyzed by the Student’s paired t-test. P < 0.05 was considered statistically significant.