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Time to consider the contact force during photoplethysmography measurement during pediatric anesthesia: A

Ji-Hyun Lee1, Seungman Yang2, Jonghyun Park2

  • 1Department of Anaesthesiology and Pain Medicine, Seoul National University College of Medicine, Seoul National University Hospital, Seoul, Korea.

Paediatric Anaesthesia
|June 20, 2018
PubMed

Insights

Contact force significantly impacts photoplethysmography (PPG) waveforms in children. This variability means PPG amplitude changes may not accurately reflect respiration-induced stroke volume variations, requiring careful interpretation by clinicians.

Area of Science:

  • Anesthesiology
  • Biomedical Engineering
  • Pediatric Critical Care

Background:

  • Photoplethysmography (PPG) amplitude variations can assess fluid status.
  • Sensor contact force is a known confounder for PPG waveform morphology.
  • The effect of contact force on PPG in pediatric patients under anesthesia is not well understood.

Purpose of the Study:

  • To investigate the impact of varying sensor contact forces on photoplethysmography (PPG) waveforms.
  • To determine how contact force affects respiratory variations in PPG amplitude in pediatric patients.
  • To assess the reliability of PPG-based volume status assessment under different contact forces.

Main Methods:

  • Photoplethysmographic signals were recorded from 34 children (3-5 years) under general anesthesia.
  • A force sensor-integrated PPG clip applied increasing contact forces (0-1.4 N) during mechanical ventilation.
  • Calculated parameters included AC amplitude, DC amplitude, AC/DC ratio, and respiratory variations in PPG amplitude.

Main Results:

  • Normalized AC amplitude peaked at 0.4-0.6 N and decreased with higher forces.
  • Normalized DC amplitude increased with forces above 0.4 N.
  • Significant alterations in PPG amplitude, AC/DC ratio, and respiratory variations were observed across tested contact forces (0.2-1.2 N).

Conclusions:

  • Respiratory variations in PPG amplitude are significantly influenced by sensor contact force.
  • PPG-derived stroke volume variation estimates may be unreliable due to contact force bias.
  • Clinicians must consider contact force effects when interpreting pediatric PPG waveform data.
Abstract

Keywords:
childcontacting forceoximetryplethysmography

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