Introduction
The burden of cardiovascular disease within a progressively ageing population has resulted in a shift in the demographic of cardiac surgery patients to include those that are older, increasingly frail and presenting with multiple co-morbidities (1), (2). Despite a higher risk profile, mortality post-cardiac surgery remains low, due to continued advances in peri-operative care(3). However, the complex nature of these patients means they are likely to encounter a longer and more complicated post-operative course, often involving a prolonged length of stay (LOS) in intensive care (ITU). Prolonged ITU stay has been reported as occurring in 4-11% of cardiac patients (4) with other sources citing it to be as high as 36%(5). This poses both clinical and ethical issues as a very small proportion of patients are consuming an extremely high level of both human and financial resources. Care of the critically ill requires a high level of expenditure of time, money and resources; this includes specialist staff, one to one nursing care and sophisticated equipment and treatments (6). Critical care units across the UK are running at, or near full, capacity whilst also struggling with staffing shortages (7). Lack of critical care bed availability often leads to cancellation of procedures, extension of waiting lists and compromised patient safety, thereby reducing operational performance across all areas of cardiac surgery and directly affecting patient care. Williams et al . (8) identified a disproportionate usage of ITU beds in their study and concluded that the poor outcomes that have been reported after prolonged ITU stays may indicate it is neither beneficial to the patient nor cost effective. This is echoed by Gaudino et al. (9) who commented that although life-saving treatment should not be withheld, resources should be allocated wisely to consider those waiting for treatment.
It is widely accepted that short-term outcomes for those with a prolonged LOS in ITU are poor, with higher rates of in-hospital mortality (10% vs 0.6%) and morbidity (10), (11). Additionally, both physical and cognitive impairments have been reported in those who have survived admission to an ICU, symptoms of which can persist for years following discharge, with more recent classification under the term ‘post-intensive care syndrome’ or PICS(12) . Post-operative delirium in intensive care is a common occurrence in cardiac surgery patients (26-52%(13)) and there is evidence to suggest that those who experience delirium are at higher risk of long-term cognitive dysfunction (14). This is compounded by the growing number of elderly patients undergoing surgery, with 37% of critically unwell adults over the age of 65 having pre-existing cognitive impairments such as dementia and depression (14). PICS also encompasses physical impairments; muscle weakness as a result of critical care admission occurs in 40% of adult patients and in a small number of cases persists beyond discharge, resulting in poor functional ability and reduced quality of life. The mental health repercussions of ITU admission are perhaps the most marked, with 30% of patients experiencing depression, 70% anxiety and up to 50% demonstrating symptoms of post-traumatic stress disorder (14).
Poorer outcomes for those with prolonged intensive care stay, increasing demand for critical care and a lack of resources has resulted in the development of enhanced recovery programmes. Enhanced recovery after surgery (ERAS) or ‘fast track’ programmes are a multidisciplinary approach that covers the entire patient journey (pre, intra and post-operatively) and have been designed to limit psychological and physiological stress in surgical patients in order to promote faster recovery (15). Techniques include thorough preparation for surgery through patient assessment and education, minimally invasive surgical techniques, optimal fluid management and pain control and the early promotion of oral nutrition and mobilisation post-operatively(16). ERAS was first implemented in colorectal surgery but its usage has spread to other specialities including cardiac surgery. The implementation of enhanced recovery pathways in cardiac surgery has been found to reduce not only LOS in hospital but also ITU LOS, post-operative complications and cost (17). Coleman et al.( 18) reported that although patient demographics, lifestyle and disease severity were similar between the ERAS and the control groups, the ERAS patients had better understanding of coronary artery disease, shorter fasting and water deprivation times, increased engagement with physiotherapy and improved physical performance post-operatively. Williams et al.(19) saw a reduction in post-operative LOS by one day in the ERAS group and a reduction in intensive care unit LOS from 43 to 28 hours. Evidence demonstrating the positive effects of ERAS programmes within cardiac surgery, however, remains limited in comparison to other surgical specialties, and, as a consequence, ERAS is not yet widely implemented.
As a result of worse short-term clinical outcomes for patients with prolonged ITU stay, discharge from hospital was, until recently, considered the key measure of success. However, there has been a shift towards long-term outcomes, functional recovery and quality of life (QoL) as measures of surgical quality. There is now a body of primary research into long-term post-operative outcomes for cardiac patients with a focus on prolonged ICU stay, but it lacks consolidation. It is the aim of this review, therefore, to compare and critique the findings of multiple studies and provide an overview of the best available research on this topic in order to determine the long-term effects of prolonged ITU stay, and to inform and influence clinical practice in this area. Better understanding of the outcomes of this demographic of patients will also promote informed decision making for those considering cardiac surgery and allow clinicians to make more accurate decisions regarding treatment options, resource allocation and medical priorities. However in order to do so, greater understanding of prognosis, long-term survival and QoL is required.