Evaluation of Pupillometry as a Predictor of Pain Intensity Upon Withdrawal of Sedation in the Postoperative Period Following Cardiac Surgery: A Prospective Cohort Study

Postoperative pain is a significant issue following surgery, and pain that is either inadequately treated or, conversely, overtreated can increase morbidity. For example, severe chest pain following cardiac or pulmonary surgery impairs the patient's respiratory rehabilitation, which can lead to fluid retention and, consequently, pneumonia. Conversely, overtreatment through excessive use of opioids can cause drowsiness and respiratory depression. Currently, planning postoperative pain management for intubated, ventilated, and sedated patients relies on indirect signs of pain assessed using scales, and on the clinician's subjective judgment. It is only after sedation is discontinued that the actual level of pain can be assessed, once the patient becomes communicative, which then allows analgesic treatment to be adjusted to the pain. This approach inevitably results in a period of discomfort and pain for the patient. In addition to semi-quantitative and subjective scales, a number of analgesia monitoring tools have been developed.

Among these, the use of pupillometry and the Pupillary Pain Index (PPI) during surgeries (gynecological, pediatric, cardiac) has been associated with a reduction in intraoperative opioid doses and a decrease in postoperative pain. In our department, pupillometry is routinely used to assess analgesia in intubated, ventilated, and sedated patients undergoing painful procedures. This method is integrated into standard care in the operating room in accordance with the PUCCAR study algorithm, as well as in the intensive care unit according to a specific departmental protocol, in addition to standard assessment scores. We hypothesize that performing pupillometry with a PPI score is predictive of pain intensity at extubation. If our hypothesis is confirmed, this would allow us to tailor analgesic management for each patient prior to discontinuing sedation.