Cardiovascular diseases (CVD) such as coronary artery disease (CAD) are a major cause of mortality worldwide. With rapid growth in the treatment of CVD, cardiac surgery has tended to become more minimally invasive and has reduced mortality from CVD. However, the risk factors for postoperative complications from cardiac surgery still remain high. Postoperative rest-cantered management of pain, dyspnoea, sleep problems, and depression can cause postoperative complications related to bed rest. Bed rest contributes to decreased cardiac output, secondary complications such as deep venous thrombosis, pneumonia, and pressure sores, loss of muscle mass and strength, and a decline in aerobic capacity within the first few postoperative days. Therefore, effective countermeasures to bed rest after cardiac surgery must be developed. Early mobilization has attracted attention as one of the countermeasures to bed rest.

Respiratory considerations include intubation status, adjunctive therapies, and ventilatory parameters; cardiovascular considerations include the presence of devices, cardiac arrhythmias, and blood pressure; neurological considerations include level of consciousness, delirium, and intracranial pressure; and other considerations include intravenous lines and surgical or medical conditions. Early mobilization is defined as the physical activity within the first two to five days of critical illness or injury. In critically ill patients, early mobilization has significant effects on the length of intensive care unit (ICU) and hospital stays, ICU-acquired weakness, but safety considerations related to respiratory, cardiovascular, neurological, and other issues must be considered before conducting early mobilization.

Cardiac surgery is an invasive treatment that increases markers of inflammation that cause muscle catabolism in the postoperative phase. However, one previous study showed that muscle activity serves as an anti-inflammatory action. Bed rest induces changes in skeletal muscle atrophy and inflammatory marker. Therefore, promoting muscle activity through early mobilization may prevent muscle catabolism and physical dysfunction. In addition, bed rest also results in a decrease of peak oxygen intake as a function of aerobic capacity that is associated with decreased stroke volume and cardiac output.

Not only early mobilization but also respiratory exercise and psycho-education were conducted as interventions after cardiac surgery. Respiratory dysfunction and depression are reported likely to occur after cardiac surgery. Respiratory exercise included deep breathing exercises and incentive spirometry, and psycho-education was conducted to improve disease. Comprehensive cardiac rehabilitation programs may improve physical and psychological problems. Cardiac rehabilitation contributes to improvement in functional capacity and quality of life; however, the effect of early mobilization in these patients is poorly known.