N-acetylcysteine instead of theophylline in patients with COPD who are candidates for elective off-pump CABG surgery: Is it possible in cardiovascular surgery unit?

Background: Forced expiratory volume in one second (FEV1) is a good predictor of chronic obstructive pulmonary disease (COPD). COPD is characterized by a chronic limitation of airflow. This study was designed to compare the effects and complications of theophylline alone, N-acetylcysteine (NAC) alone, and a combination of the two drugs on the rates of FEV1 in patients with COPD who were candidates for off-pump coronary artery bypass graft (CABG) surgery.

Methods: This clinical trial was performed on 100 patients who had a smoking history of 27 pack years with a range of 20 to 40 pack years but were not heavy smokers and were candidates for elective off-pump CABG surgery in Afshar Cardiovascular Hospital, Yazd, Iran. The patients with a history of asthma and bronchospasm and non-COPD respiratory disorders were excluded. There were three groups, that is, the theophylline group (n=33) that received theophylline 10 mg/kg TDS after consumption of food, NAC group (n=33) who received NAC 10-15 mg/kg BD after consumption of food, and the combined group (n=32) who received theophylline and NAC together. Data were analyzed by analysis of variance (ANOVA), Chi-square, and exact test for quantitative and qualitative variables.

Results: One hundred patients with COPD enrolled in this study as possible candidates for CABG surgery. Average age of the patients was 60.36±10.21 years. Of the participants, 83 (83.3%) were male and 17 (17%) were female. Rate of postoperative FEV1 to basal FEV1 was 0.76±0.32, 0.66±0.22, and 0.69±0.24 in the treatments with theophylline, NAC, and the combination, respectively. Theophylline, NAC, and a combination of these drugs can decrease the rate of postoperative FEV1 compared to basal FEV1 significantly. (P=0.0001).

Conclusion: Theophylline alone, NAC alone, and a combination of these drugs improve pulmonary function, and there are no significant differences between these protocols. Stomach discomfort and cardiac complications in treatment with theophylline alone is significantly higher than NAC alone and the combination.