Malnutrition is common among critically ill patients, and has negative effects on clinical outcomes. Artificial nutrition therapy in the form of enteral or parenteral nutrition is therefore considered an integral part of standard care. While it has long been widely accepted that it is unethical to withhold nutrition therapy from those at risk of malnutrition, we and our collaborators provide first evidence that nutrition practices significantly influence clinically important outcomes such as length of stay, morbidity and mortality in critically ill patients. Among these, cardiac surgery patients are routinely exposed to significant systemic inflammation due to the need for a cardiopulmonary bypass, which triggers a systemic inflammatory response syndrome. As a consequence, the releases of reactive oxygen and nitrogen species as well as pro-inflammatory cytokines lead to life-threatening complications in cardiac surgical patients. For such patients, aggressive life-sustaining therapies are needed while their organs recover.

Besides, underfeeding is a major issue in this specific patient population. Often nutrition starts late and reaches only low nutrition adequacy. Recent data from our collaborators suggest that providing at least 80% of prescribed amounts of protein and energy is associated with improved clinical outcomes. Achieving this threshold of 80% of prescribed amounts of protein has been shown to be associated with reduced mortality in "at-risk" ICU patients and is more important than achieving energy goals. Despite these benefits, enteral or parenteral feeding should always be adopted with caution, as nutrition practices themselves are not per se without adverse effects or risks. Making decisions regarding the most effective and safe means of feeding patients in the ICU can be challenging, and consequently considerable variation exists in nutrition practices in this setting, whereas no guidelines yet exists specific of cardiac surgery patients.

Clinical Practice Guidelines (CPGs) are "systematically developed statements to assist practitioner and patient decisions about appropriate health care for specific clinical circumstances", and therefore aid in the implementation of evidence-based medicine. The Canadian Clinical Practice Guidelines for Nutrition Therapy in Mechanically Ventilated, Critically Ill Adult Patients published in 2003 by our close collaborator Prof Heyland and most recently updated in 2015, sought to improve nutrition practices in ICUs across Canada and worldwide by providing guidance to select and deliver the most appropriate form of nutrition therapy at the appropriate time via the most appropriate route. A validation study prior to the widespread dissemination of the Canadian Critical Care Nutrition CPGs concluded that adoption of the recommendations should lead to improved nutrition practices and potentially to better patient outcomes [24]. To change clinical practice, attention must extend beyond initial development to guideline implementation, dissemination and evaluation. Implementation strategies will vary by ICU, health care system and region and should be guided by local factors including the ICU's barriers and facilitators to following best practice. Evaluating and monitoring nutrition performance and focussing on different groups of critically ill patients, should be part of an on-going improvement strategy to improve nutrition care and clinical outcome. The few studies regarding the process of knowledge translation conducted in the ICU setting have demonstrated by our collaborators that guidelines and guideline implementation strategies improve the processes, outcomes, and the costs of caring for critically ill patients.

Inclusion Criteria:

• Age ≥ 18 years
• Patients undergoing cardiac surgery
• Mechanically ventilated within 48 hours of ICU admission
• Stay on ICU > 72 hours

Exclusion Criteria:

• None

Patients in need of a cardiovascular surgery and meeting the inclusion criteria are considered to be eligible for this study.