Smartphone-based photoplethysmographic applications for assessing finger perfusion insufficiency

Area of Science:

• Emergency Medicine
• Biomedical Engineering
• Medical Technology

Background:

• Rapid assessment of distal limb perfusion is critical in prehospital trauma care.
• Existing clinical methods for assessing perfusion can be time-consuming or require specialized equipment.
• Smartphones are ubiquitous and offer potential for novel diagnostic tools.

Purpose of the Study:

• To evaluate the efficacy of smartphone applications (apps) as tools for screening distal limb perfusion in simulated prehospital trauma scenarios.
• To compare the performance of two specific smartphone apps (RhythmCam and Cardiio) against established clinical assessment methods.

Main Methods:

• An artificial ischemic limb model was created using a pneumatic tourniquet system on 40 healthy participants.
• Systolic arterial pressure (SAP) was used to set occlusive pressures ranging from -30 to +30 mm Hg in 10 mm Hg intervals.
• Performance of two smartphone apps was compared against capillary refill time (CRT), pulse palpation, pulse oximetry, and Doppler ultrasound.

Main Results:

• All tested methods showed decreased positive results with increasing occlusive pressure from -10 to +10 mm Hg.
• Smartphone apps demonstrated favorable accuracy (Cardiio: 92.5%, RhythmCam: 96.1%) despite minor errors.
• App performance was comparable to distal pulse palpation and Doppler ultrasound, outperforming pulse oximetry and CRT.

Conclusions:

• Photoplethysmography-based smartphone apps (RhythmCam, Cardiio) show potential as accessible screening tools for distal limb perfusion.
• These apps could empower non-healthcare professionals to assess limb circulation urgency in prehospital trauma.
• Further research is needed to fully explore the clinical utility of smartphone apps in emergency scenarios.