Pupillary dilation to monitor nociception in awake volunteers: A stimuli-randomised placebo-controlled study
Authors' conclusion
In awake volunteers, PRD differentiates between painful and nonpainful stimuli and correlates with pain intensity.
Study context
- Population
- Healthy awake volunteers (25 ± 2 years, 50% male), Germany
- Participants
- 30 volunteers
- Comparison
- Pupillary reflex dilation to painful vs nonpainful stimuli
- Primary endpoint
- Pupil dilatation as PRD (%) measured with AlgiScan during rest and during/after each stimulus
- Follow-up
- 60 s
Methodological detailsplacebo-controlled, stimuli-randomised, single-centre, BG University Hospital Bergmannsheil Bochum, Germany, November 2021–January 2022
- Placebo-controlled
- Stimuli-randomised
- Single-centre
- BG University Hospital Bergmannsheil Bochum, Germany, November 2021–January 2022
Primary result
As reported in the abstract
PRD (%)
Announced painful stimulus (APS) vs nonpainful stimulus (NPS): P = 0.024 · UPS vs Rest: P < 0.001 · UPS vs Placebo: P < 0.001 · UPS vs NPS: P < 0.0001
Further findings
| Outcome | APS | UPS | Placebo | NPS | P value |
|---|---|---|---|---|---|
| Subjective pain intensity (NRS 0–10)APS vs UPS | 6.0 ± 1.9 | 5.5 ± 1.7 | 0.0 ± 0.0 | 0.0 ± 0.0 | P = 0.007 |
| Subjective pain intensity (NRS 0–10)APS vs Placebo | P = 0.027 | ||||
| Subjective pain intensity (NRS 0–10)APS vs NPS | P = 0.001 |
Correlation of pupillary reflex dilation (PRD) with pain intensity
- Spearman r
- 0.35
- P < 0.0001
Original publication
Pupillary dilation to monitor nociception in awake volunteers: A stimuli-randomised placebo-controlled study. Eur J Anaesthesiol. Published 24 February 2025. doi:10.
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