$\text{P}^\text{2}$RS: A Quantitative Rating Scale for Pain Assessment based on Pulse Wave Characterization

Area of Science:

• Biomedical Engineering
• Biophysics
• Pain Medicine

Background:

• Current pain intensity scales (e.g., VAS, ICOAP) rely on subjective self-reports, limiting consistency and comparability.
• Objective pain assessment methods are needed to overcome the limitations of subjective reporting.

Purpose of the Study:

• To develop an objective pain intensity rating scale by quantifying radial artery pulse wave instability.
• To validate the novel pulsatile perceptual rating scale (P2RS) against existing subjective pain scales.

Main Methods:

• Fabrication of an ultra-small piezoresistive pressure sensor (0.4 × 0.4 mm²).
• Construction of a flexible tactile sensing dense-array with 18 sensors (0.65 mm pitch).
• Monitoring radial artery pulse wave cross-sections and calculating the standard deviation of barycenter horizontal coordinates for the P2RS.

Main Results:

• The P2RS effectively quantifies pain intensity by measuring arterial pulse wave lateral instability.
• A support vector machine model identified a pain threshold of 0.11 in 86 clinical samples.
• The P2RS demonstrated good consistency with existing scales, achieving an average correlation coefficient of 0.804 in 43 pain samples.

Conclusions:

• The pulsatile perceptual rating scale (P2RS) offers an innovative, objective method for pain intensity assessment.
• This sensor-based approach provides a more reliable and consistent alternative to subjective pain reporting methods.
• The P2RS holds potential for improved clinical pain evaluation and research.