This study aims to investigate the utility of the perfusion index (PI) as an objective tool for pain assessment in critically ill postoperative patients admitted to the surgical ICU. Pain management is a crucial component of care in such patients, but conventional methods like the Visual Analog Scale (VAS) and Behavioral Pain Scale-Non Intubated (BPS-NI) often have limitations due to the subjective nature of their measurements, especially in patients who are non-verbal or have altered mental status.

The perfusion index (PI), derived from photoplethysmography (PPG), offers a potential solution. It is a non-invasive method that measures peripheral blood flow, providing real-time data on the patient’s hemodynamic status. Since stress responses to pain can affect peripheral circulation, PI may serve as an indirect indicator of pain levels. This study will evaluate the correlation between PI and traditional pain scales, such as VAS and BPS-NI, to determine whether PI can provide a reliable and objective assessment of pain in critically ill patients. By establishing a correlation between PI and conventional pain metrics, the research aims to improve pain management strategies in the ICU, potentially leading to better patient outcomes, reduced complications, and enhanced comfort.