Respiratory dysfunction following cardiac surgery is well documented and due in part to the location of the incision and nature of the surgery (Weissman, 2000; Garcia-Delgado M, et al., 2014). Patients undergoing cardiac surgery are at an increased risk of postoperative pulmonary complications including hypoxemia, atelectasis, and pneumonia (Weissman, 2000; Garcia-Delgado M, et al., 2014; O'Donohue WJ, 1992); with an increased risk in older individuals and individuals with obstructive lung disease (Crowe & Bradley, 1997; Weissman 2000; Jensen et al., 2007). Standard postoperative care includes early mobility and deep breathing and coughing (DB&C) (Stiller K, et al., 1995; Johnson D., et al., 1996) usually initiated within the first 24 hours following surgery. Although standard care is sufficient in some instances, postoperative pulmonary complications (PPCs) remain a significant problem following cardiac surgery and can cause prolonged length of stay in the hospital and an increase in morbidity and mortality (Weissman, 2000; Garcia-Delgado M, et al., 2014) in a significant number of patients. Positive expiratory pressure (PEP) therapy is thought to increase lung volumes and facilitate secretion clearance in many populations (Orman J & Wasterdahl E, 2009) and has been shown to be particularly effective in individuals with obstructive lung disease (Bott et al ., 2009). In consideration of the well documented respiratory dysfunction observed following cardiac surgery, PEP therapy may serve as a promising treatment in facilitating recovery in older, 'higher risk' individuals following elective cardiac surgery. Thus, the purpose of this study is to investigate whether the addition of oscillating PEP therapy is more effective than standard treatment alone in improving functional status at time of discharge, as well as decreasing oxygen requirements and the incidence of postoperative pulmonary complications (e.g., pneumonia, atelectasis, pneumothorax, pleural effusions) in 'high risk' patients undergoing elective cardiac surgery.