The aim of this randomized controlled study is to investigate the effect of implementing a preoperative nutrition education and fasting protocol prepared in accordance with Enhanced Recovery After Surgery (ERAS) guidelines during the 24-hour preoperative period on postoperative hydration status and the incidence of nausea and vomiting in patients scheduled for total knee arthroplasty.

Total knee arthroplasty is a commonly performed surgical procedure, particularly in older adults, and postoperative recovery may be negatively affected by surgical stress, anesthesia-related complications, dehydration, and postoperative nausea and vomiting. ERAS protocols emphasize the optimization of preoperative nutrition and hydration as key components to improve postoperative outcomes.

In this study, patients undergoing elective total knee arthroplasty will be randomly assigned to an intervention group or a control group. Patients in the intervention group will receive ERAS-based preoperative nutrition education and a standardized fasting protocol during the 24 hours prior to surgery, while patients in the control group will receive routine standard care.

Postoperative hydration status, nausea and vomiting severity, and fluid intake-output balance will be assessed and compared between the two groups. The findings of this study are expected to contribute to improving perioperative nursing care practices and enhancing patient recovery and comfort following total knee arthroplasty.

This randomized controlled trial is designed to evaluate the effect of ERAS protocol-based preoperative nutrition education and fasting management on postoperative hydration status and nausea-vomiting outcomes in patients undergoing elective total knee arthroplasty.

Total knee arthroplasty is an effective and frequently performed surgical intervention, particularly among older adults with degenerative joint disease. However, perioperative stress, prolonged fasting, and anesthesia-related factors may adversely affect postoperative recovery, leading to dehydration, nausea, and vomiting. Optimizing perioperative care through evidence-based ERAS protocols is therefore essential to improve patient outcomes.

ERAS protocols promote a multidisciplinary approach aimed at reducing surgical stress and accelerating postoperative recovery. One of the core components of ERAS is the optimization of preoperative nutrition and hydration. According to evidence-based guidelines, solid foods may be consumed up to 6 hours and clear liquids up to 2 hours prior to elective surgery. This approach reduces unnecessary prolonged fasting, prevents dehydration and insulin resistance, and improves postoperative comfort without increasing anesthesia-related risks.

The study will be conducted in the orthopedic clinic of Acıbadem Altunizade Hospital. Eligible patients scheduled for elective total knee arthroplasty will be recruited and randomly assigned to either the intervention or control group using a simple randomization method. Written informed consent will be obtained from all participants prior to enrollment.

Patients in the intervention group will receive an ERAS-based preoperative nutrition education leaflet and will be instructed to follow the standardized nutrition and fasting protocol during the 24-hour preoperative period. Patients in the control group will receive routine standard preoperative care as applied in the clinic.

Data collection will include demographic and clinical characteristics, postoperative hydration status, nausea and vomiting frequency and severity, and fluid intake-output monitoring. The following validated instruments will be used: the Surgical Thirst Discomfort Scale, the Rhodes Index of Nausea, Vomiting and Retching, a numeric nausea rating scale, and fluid balance monitoring forms.

Postoperative outcomes will be assessed for both groups, including hydration status, nausea and vomiting incidence, and fluid intake-output balance. Statistical analyses will be performed using SPSS software. Appropriate parametric or non-parametric tests will be applied based on data distribution, with a significance level set at p < 0.05.

This study aims to provide evidence on the effectiveness of ERAS-based preoperative nutrition education and fasting protocols in improving postoperative hydration and reducing nausea and vomiting, thereby supporting the development of structured, evidence-based nursing interventions in perioperative care.

Inclusion Criteria:

• Inclusion Criteria:
• Adults aged 18 years and older.
• Patients scheduled for elective total knee arthroplasty.
• Patients expected to be hospitalized for at least 48 hours postoperatively.
• Ability to communicate verbally and provide informed consent.
• Patients with adequate cognitive and neurological capacity to understand study procedures.

Exclusion Criteria:

• Presence of any chronic disease requiring fluid restriction.
• Diagnosed cognitive impairment or psychiatric disorders affecting comprehension (e.g., Alzheimer's disease, dementia, psychotic disorders).
• Acute conditions causing dehydration in the preoperative period (e.g., vomiting, diarrhea, excessive fluid loss).
• Intraoperative complications requiring intensive care unit admission.
• Postoperative follow-up shorter than 48 hours due to early discharge or transfer to another clinic.