Postoperative Pain Assessment Indices Based on Photoplethysmography Waveform Analysis

Area of Science:

• Biomedical Engineering
• Anesthesiology
• Physiological Monitoring

Background:

• Postoperative pain management is crucial for patient recovery.
• Objective pain assessment methods are limited.
• Photoplethysmography (PPG) offers a non-invasive approach to physiological monitoring.

Purpose of the Study:

• To derive novel parameters from PPG signals that correlate with postoperative pain.
• To validate the efficacy of these derived PPG parameters in assessing pain levels.
• To compare the performance of new PPG parameters against the Surgical Pleth Index (SPI).

Main Methods:

• Collected PPG and Visual Analog Scale (VAS) data from 65 surgical patients pre- and post-operatively.
• Extracted 51 PPG morphology-based and normalized parameters.
• Utilized statistical analyses including Wilcoxon signed rank test, logistic regression, and 4-fold cross-validation for performance assessment.

Main Results:

• 36 out of 51 derived PPG parameters showed statistically significant differences between pre- and post-operative conditions.
• Dynamic between-pulse PPG parameters outperformed static within-pulse parameters in pain classification.
• Systolic peak amplitude variation normalized by PPG AC amplitude achieved 79.5% accuracy, outperforming SPI (65.9%).

Conclusions:

• Novel PPG parameters, particularly dynamic ones, show significant potential for objective postoperative pain assessment.
• These derived PPG parameters offer a more accurate and sensitive method for pain monitoring compared to the SPI.
• Further research into PPG-based pain assessment could enhance patient care and pain management strategies.