Malnutrition is a prevalent issue among patients undergoing cardiac surgery. This can lead to delirium risk factors, including postoperative functional and cognitive impairment. Assessing the patient's nutritional status before open-heart surgery may decrease the incidence of delirium and the psychological and physiological problems associated with it. The objective of this study was to examine the relationship between nutritional status and the incidence of postoperative delirium in patients who have undergone open-heart surgery.

Upon examining the literature, it was found that the incidence of delirium after open heart surgery ranged from 3% to 70% (Tomakin et al., 2020). Postoperative delirium has numerous risk factors, including predisposing and accelerating factors. Predisposing risk factors comprise malnutrition and electrolyte imbalance, cognitive impairment, depression, and other psychiatric disorders such as dementia (Velayati et al., 2019; Wilson et al., 2020). This study aims to investigate the relationship between the nutritional status of patients undergoing open heart surgery and the development of postoperative delirium. The study will be conducted in the Cardiovascular Surgery Intensive Care Unit of Bursa Uludag University Health Application and Research Centre Hospital between September 2023 and February 2024. Data will be collected using the Personal Information Form, Nutritional Risk Screening Score 2002 (NRS-2002), Delirium Risk Assessment Form, Visual Analogue Scale for Pain Levels, Richmond Agitation Sedation Scale, Glasgow Coma Scale, and Confusion Assessment Scale in Intensive Care Unit.

Inclusion Criteria:

• Over 18 years old
• Having undergone open heart surgery
• No mental deficiency and visual and hearing impairment
• No psychiatric diagnosis and no medication for this purpose
• Participants' acceptance to participate in the research
• The patient is not in coma (RASS score between -3 and +4, GCS score of 10 and above)

Exclusion Criteria:

• Open heart surgery under emergency conditions
• Diagnosed with delirium, dementia, psychiatric illness before surgery
• Alcohol and drug addiction
• Dying in the intensive care unit within 24 hours

To be eligible for the study, the patient must be at least 18 years old and have undergone open-heart surgery. They should not have any mental or sensory impairments, psychiatric diagnoses, or be taking medication for this purpose. Additionally, they should not be in a coma, with a RASS score between -3 and +4 and a GCS score of 10 or higher.