Thoracic Outlet Syndrome: Fingertip Cannot Replace Forearm Photoplethysmography in the Evaluation of Positional Venous Outflow Impairments.

Jeanne Hersant,Sylvain Durand,Mickael Daligault,Pierre Ramondou,Pierre Abraham,Mathieu Feuilloy,Samir Henni

doi:10.3389/fphys.2021.765174

Abstract

Objective: Fingertip photoplethysmography (PPG) resulting from high-pass filtered raw PPG signal is often used to record arterial pulse changes in patients with suspected thoracic outlet syndrome (TOS). Results from venous (low-pass filtered raw signal) forearm PPG (V-PPG) during the Candlestick-Prayer (Ca + Pra) maneuver were recently classified into four different patterns in patients with suspected TOS, two of which are suggestive of the presence of outflow impairment. We aimed to test the effect of probe position (fingertip vs. forearm) and of red (R) vs. infrared (IR) light wavelength on V-PPG classification and compared pattern classifications with the results of ultrasound (US).Methods: In patients with suspected TOS, we routinely performed US imaging (US + being the presence of a positional compression) and Ca + Pra tests with forearm V-PPGIR. We recruited patients for a Ca + Pra maneuver with the simultaneous fingertip and forearm V-PPGR. The correlation of each V-PPG recording to each of the published pattern profiles was calculated. Each record was classified according to the patterns for which the coefficient of correlation was the highest. Cohen’s kappa test was used to determine the reliability of classification among forearm V-PPGIR, fingertip V-PPGR, and forearm V-PPGR.Results: We obtained 40 measurements from 20 patients (40.2 ± 11.3 years old, 11 males). We found 13 limbs with US + results, while V-PPG suggested the presence of venous outflow impairment in 27 and 20 limbs with forearm V-PPGIR and forearm V-PPGR, respectively. Fingertip V-PPGR provided no patterns suggesting outflow impairment.Conclusion: We found more V-PPG patterns suggesting venous outflow impairment than US + results. Probe position is essential if aiming to perform upper-limb V-PPG during the Ca + Pra maneuver in patients with suspected TOS. V-PPG during the Ca + Pra maneuver is of low cost and easy and provides reliable, recordable, and objective evidence of forearm swelling. It should be performed on the forearm (close to the elbow) with either PPGR or PPGIR but not at the fingertip level.

Highlights

Avenous origin is proposed as the second most frequent etiology of thoracic outlet syndrome (V-TOS) (Illig et al, 2016)
We recently reported our experience with lowpass filtered reflectance infrared light forearm PPG (V-PPGIR) during the Candlestick-Prayer (Ca + Pra) maneuver (Hersant et al, 2021)
The V-PPG signal varies between complete filling to complete emptying

Summary

Introduction

Avenous origin is proposed as the second most frequent etiology of thoracic outlet syndrome (V-TOS) (Illig et al, 2016). Beyond effort venous thrombosis (Moore and Wei Lum, 2015; Cook and Thompson, 2021), transient positional compression of the subclavicular vein may result in venous outflow impairment during arm elevation, leading to positional upper limb pain and/or swelling (i.e., McCleery syndrome). The V-PPG signal varies between complete filling (arm lowered used as zero value) to complete emptying (upper limb elevated in the prayer position, used as 100% value). This approach seeks to normalize results and thereby improve the interpretation of this otherwise semiquantitative technique

Methods

Results

Conclusion