Preoperative respiratory physical therapy in cardiac surgery

Abstract

Cardiac surgery is one of the most common surgical procedures and accounts for more resources expended in cardiovascular medicine than any other single procedure. Because cardiac surgery involves sternal incision and cardiopulmonary bypass, patients usually have a restricted respiratory function in the postoperative period. Moreover, anesthesia and analgesia affect respiratory function during and after the surgical intervention, causing changes in lung volume, diaphragmatic dysfunction, respiratory muscle strength, pattern of ventilation, and gas exchange, and in the response to carbon dioxide and oxygen concentrations. As a consequence of these changes, patients undergoing cardiac surgery have an increased risk of postoperative pulmonary complications (PPCs), which lead to increased postoperative morbidity and mortality, increased use of medical resources, longer hospital stay, and increased health care costs. The incidence of PPCs varies between 20% and 95% in cardiac surgery, depending in part on the criteria used to define PPCs and on the diagnostic techniques used to document them. As a result of the generally high incidence of these complications (including mortality) and the high costs of hospitalization, efforts have been made during the last decade to identify those patients who have a higher chance of developing such complications, and to find ways to prevent their development. Considerable effort has been put into preventing and treating PPCs, but there is no consensus on the most appropriate or effective remedy. Controversy exists concerning the possible overuse and abuse of many of the therapeutic modalities commonly used for the prevention and treatment PPCs. A few experimental studies have demonstrated that preoperative physical therapy (e.g. pulmonary rehabilitation) in cardiac surgery has advantages over postoperative physical therapy alone. The effects of these programs, however, in decreasing the incidence of PPCs and in identifying those patients who might derive the most benefit, i.e. all patients or only high-risk patients, have not been proven indisputably. So, the aim of our project was to answer these three basic questions:

[1] Is preoperative physical therapy effective in preventing PPCs after cardiac surgery?

[2] What type of preoperative physical therapy is effective in preventing PPCs after cardiac surgery?

[3] Which patients benefit the most from this intervention?

The studies described in this thesis demonstrate that it is possible to stratify preoperatively, patients according to their risk of developing PPCs, especially pneumonia, after CABG. We found that preventive physical therapy, including IMT, given to patients at high risk of PPCs before CABG decreased the incidence of PPCs (e.g. atelectasis and pneumonia) significantly and shortened the duration of mechanical ventilation and postoperative hospitalization. Our program is safe and well tolerated and should be implemented in regular care for these patients as soon as possible. In the future, it is expected that more fragile patients will undergo CABG, and in these patients preoperative physical therapy, including IMT, may be needed to help reduce the incidence of PPCs.