The Effects of Incentive Spirometry on Pulmonary Volumes and Arterial Blood Gases After Coronary Artery Bypass Surgery

Introduction: Following thoracic and abdominal surgery, all patients experience a decrease in pulmonary volumes and atelectasis. Different methods are suggested for improvement of pulmonary volumes and blood gas parameters in these patients. In this study the effects of spirometry on pulmonary volumes and blood gases parameters (ABG) in coronary artery bypass patients, were examined.  Materials and Methods: This research is a clinical trial (self control) study. 110 consecutive male patients who candidated for coronary artery bypass surgery enrolled for study in 2000-2001. Data were collected through a questionnaire. Blood gases parameters and spirometry volumes were measured in three phases: before, first day of operation and after using incentive spirometry. Data were analyzed by descriptive and referential statistics. Results: In this study the mean of age was 52 ± 8 years old. LVEF was 50 ± 7% and mean number of grafts was 2.4 ± 0.7. The duration of mechanical ventilation was 7 ± 4.5 hours in the intensive care unit. Comparison of ABGs before anesthesia and in the first day of surgery showed a significant decrease in systemic O 2 saturation and arterial Po2 and an increase in arterial Pco2 (P<0.001). Comparison of the above parameters between the second and third phases showed no significant changes. Spirometry parameters showed a decrease of FEV 1 and FVC after surgery (P<0.0001), but in comparison with pulmonary volumes after surgery by using incentive spirometery, no significant changes occurred. Conclusion: Using incentive spirometery in the first day of operation did not show significant improvement in pulmonary volumes and blood gases parameters.