Despite the beneficial effects of Coronary Artery Bypass Graft surgery (CABG) on patients' symptoms, survival rate, and quality of life, complications are common in the short and long term after the procedure (Subramanian et al., 2019). During the initial postoperative phase in the intensive care unit (ICU), patients may experience a range of complications, including arrhythmias, bleeding, myocardial infarction, wound infections, pain, and pulmonary complications (Pooria et al., 2020). These post-surgery complications increase the risk of morbidity, mortality (Hardiman et al., 2022), and lengthen the stay in the ICU and hospital (Zarrizi et al., 2020). The prolonged stay in the ICU is also a predictor of higher morbidity and long-term mortality after cardiac surgeries (Mahesh et al., 2012).

According to estimates, between 50 and 70 % of patients in the ICU experience cognitive impairment, and 60–80 % develop ICU-acquired weakness, which can delay functional recovery and prolong hospitalization (da Costa Torres et al., 2016; Wischmeyer & San-Millan, 2015). Cognitive impairment is a common complication following surgery, and patients who have undergone CABG are at a higher risk for this condition (Greaves et al., 2019). A systematic review and meta-analysis found that approximately 43 % of patients experience cognitive impairment after CABG, and around 40 % suffer from this complication in the long term, from 1 to 5 years after the surgery (Greaves et al., 2019). Postoperative cognitive impairment refers to a reduction in a patient's ability to orient themselves, pay attention, perceive things, maintain consciousness, and make judgments (Kotekar et al., 2018). Patients who are older, female, experience higher levels of bleeding, or have elevated creatinine levels after surgery are at a greater risk of developing postoperative cognitive impairment (Habib et al., 2014).

The specific cause of postoperative cognitive decline is not fully understood, but it is believed to be related to the body's stress and inflammatory response to surgery and anesthesia (Cusack & Buggy, 2020). The excessive release of inflammatory factors, such as Glial fibrillary acidic protein (GFAP) may cause neuronal dysfunction, which can result in postoperative cognitive decline (Traub et al., 2022). Furthermore, respiratory muscle weakness, reduced cardiac output (Cassina et al., 2016), and anaerobic metabolism are common complications of CABG that can lead to cerebral hypoxia, contributing to postoperative cognitive impairment (Klypa et al., 2016; Nydahl et al., 2020). Pain and analgesic medication use can also lead to cognitive impairment in these patients (Ochroch et al., 2021). Postoperative cognitive dysfunction can persist for an extended period, negatively impacting a patient's daily functioning and quality of life, and even leading to mental health disorders and death (Nydahl et al., 2020).

Early mobilization is crucial for improving patient outcomes following CABG (Marra et al., 2017; Nydahl et al., 2020), and it is now widely implemented in hospitals (Harris & Shahid, 2014). This intervention has been shown to be safe and effective in improving tissue perfusion, maintaining muscle tissue strength and mass (Roberson et al., 2018), reducing pulmonary complications and hospital stay length (Brown et al., 2018), enhancing quality of life (Alqahtani et al., 2022), and lowering mortality rates (Kanejima et al., 2020). Furthermore, early mobilization has been demonstrated to be effective in reducing delirium (Kress & Hall, 2014), which is a significant risk factor for ICU-related cognitive impairment (Marra et al., 2017). Various early mobilization interventions are available for patients following surgery, and while most are effective in improving outcomes, the most effective protocols have not yet been identified. This study aims to compare the effectiveness of two different early mobilization interventions in improving CABG patients' cognitive impairment, pain experience, and length of hospital stay.