Ventilatory Muscle Strength Six Months After Coronary Artery Bypass Grafting in Patients Submitted to Inspiratory Muscular Training Based on Anaerobioc Threshold: A Clinical Trial

Abstract Introduction Coronary artery bypass grafting (CABG) surgery is associated with a decline in ventilatory muscle strength and lung function. Inspiratory muscle training (IMT) based on anaerobic threshold (AT) has been used to minimize the impact of CABG on these parameters, but the long-term impact is unknown. Objective To test the hypothesis that AT-based IMT improves inspiratory muscle strength and lung function even six months after CABG. Methods This is a randomized controlled clinical trial. In the preoperative period, maximum inspiratory pressure (MIP), maximum expiratory pressure (MEP), vital capacity (VC) and peak expiratory flow (PEF) rate were assessed. On the first postoperative day, patients were randomized into two groups: AT-based IMT (IMT-AT) (n=21) where the load was prescribed based on glycemic threshold and conventional IMT (IMT-C) (n=21), with load of 40% of MIP. Patients were trained during hospitalization until the day of discharge and were assessed at discharge and six months later. For within-group comparison, paired Student's t-test or Wilcoxon test was used, and independent Student's t-test or the Mann-Whitney test was used to analyze the different time points. A p<0.05 was considered significant. Results At six months after CABG surgery, statistical difference was found between the IMT-AT and the IMT-C groups in MIP (difference between the means of -5cmH2; 95% CI=- 8.21to-1.79) and VC (difference between the means of -2ml/kg;95%CI=-3.87to-0.13). No difference was found between groups in the other variables analyzed. Conclusion IMT-AT promoted greater recovery of inspiratory muscle strength and VC after six months of CABG when compared to conventional training.

Impact of drains positioning on pulmonary function after coronary artery bypass grafting: an observational study.

INTRODUCTION: Coronary artery bypass grafting (CABG) is a procedure associated with a decline in pulmonary function. Among the main causes is the presence of the drain that is usually positioned in the intercostal or subxiphoid region. OBJECTIVE: To measure the interference of drains positioning on pulmonary function in patients undergoing CABG. METHODS: Observational study that assessed preoperative pulmonary function through vital capacity (VC), maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP), and peak expiratory flow (PEF). These variables were evaluated in three different moments: in the presence of two drains, when removing one, and after removing all drains. RESULTS: We evaluated 45 patients with a mean age of 62 ± 7 years with male prevalence of 29 (64%) individuals. The insertion of drains caused a decline in pulmonary function after surgery by reducing MIP by 48%, MEP by 11%, VC by 39%, and PEF by 6%. CONCLUSION: This study has demonstrated that drains positioning after CABG surgery may produce weakness of the respiratory muscles, change ventilatory mechanics, and impair normal pulmonary function postoperatively.

Factors associated with pulmonary complacence in patients submitted to coronary artery bypass grafting: cross-sectional study.

BACKGROUND: Coronary artery bypass grafting (CABG) is one of the most studied surgical procedures worldwide and is associated with deleterious effects on respiratory function in the postoperative period, corroborating the incidence of factors that can cause a decrease in lung compliance, generating possible respiratory complications. OBJECTIVE: To identify factors associated with low pulmonary compliance in patients submitted to coronary artery bypass grafting. METHODS: This is a cross-sectional study. After admission to the Intensive Care Unit (ICU), the static compliance calculation was performed and the patients were divided into two groups: Low Compliance Group (LCG) and Normal Compliance Group (NCG), to verify which factors were associated with low compliance. RESULTS: The final sample consisted of 62 patients, with male prevalence, with a mean age of 60 ± 9.5 years. Clinical variables body mass index (BMI) (P=0.04), smoking (P=0.05), chronic obstructive pulmonary disease (P < 0.001) and ejection fraction (P=0.03) were associated with reduced static pulmonary compliance. CONCLUSION: It is concluded that factors such as age, COPD, smoking, BMI and ejection fraction may be associated with worsening pulmonary compliance after CABG.