The complications may range from sub-clinical functional changes to full-blown ARDS (acute respiratory distress syndrome) with the latter occurring in less than 2% of the cases post CPB (Ng et al. 2002). ARDS leads to prolonged hospital stays and recoveries, and in more than half the cases, death.
There are several triggering factors for pulmonary dysfunction post cardiac surgery. A very significant triggering factor is the general anaesthesia that the patient undergoes, which causes atelectasis. There could also be lung injury and delayed pulmonary recovery due to the damaging effects of a systemic inflammatory response associated with cardiopulmonary bypass (Ng et al. 2002). Oxygenation which may induce increased free radical activity is a potential risk of ARDS after CPB. The use of CPB can also lead to the development of pulmonary edema. Arterial hypoxaemia is another aftermath that is usually associated with CABG.
Chest physical therapy has been a widely used treatment option for prevention of pulmonary complications post cardiac surgery. Different countries use different techniques of treatment. However, the routine use of breathing exercises following cardiac surgery has been subject to controversy in the recent years (Westerdahl et al. 2005, p. 3482). Breathing exercises along with physical therapy have not been found to be more beneficial than physical therapy with early mobilisation alone in reducing atelectasis, pneumonia, gas exchange and lung function impairment and such other pulmonary complications post cardiac surgery.
Are breathing exercises necessary
A study was conducted by Jenkins et al. (1989), to investigate whether breathing exercises or incentive spirometry along with early mobilisation and training in huffing and coughing can help improve lung function and prevent chest infection in post-CABG patients (Jenkins et al. 1989, p. 634). The study included consecutive white men undergoing elective coronary artery bypass grafting during one year. Lung volumes were measured before surgery and the highest values were used for the study. Arterial oxygen and carbon dioxide tensions were measured. Forced vital capacity, forced expiratory volume in one second and peak expiratory flow were measured, and the highest of five maximal forced expirations were taken. Patients with forced expiratory ratio less than 60% were not included in the study. Before surgery, all patients were advised of the need to move about after surgery and to expectorate excess bronchial secretions. The Group 3 patients participating in the study were trained in huffing or forced expirations with the glottis open, coughing with sternal support, and exercises of the upper and lower limbs (Jenkins et al. 1989, p. 635). The patients sat up in a chair when they were able to, walked on the second postoperative day and climbed stairs on the fourth postoperative day. In addition to the above treatment, group 1 patients were advised on the need for taking deep breaths and group 2 patients on using an incentive spirometer. Maximum oral temperature and medication received, distance walked by the patient, patients' subjective assessments of chest discomfort and the number of self-treatment sessions undergone were recorded every day over the course of the study. Measurements were taken for five days only, as most hospitals gave postoperative physiotherapy for