Comparison of transcutaneous oximetry with symptoms and arteriography in thoracic outlet syndrome

Participation of Arterial Ischemia in Positional-Related Symptoms among Patients Referred for Thoracic Outlet Syndrome

Objectives: The coexistence of arterial compression with neurogenic thoracic outlet syndrome (TOS) is associated with a better post-surgical outcome. Forearm transcutaneous oxygen pressure (TcpO2) using the minimal decrease from rest of oxygen pressure (DROPmin) can provide an objective estimation of forearm ischemia in TOS. We hypothesized that a linear relationship exists between the prevalence of symptoms (PREVs) and DROPmin during 90° abduction external rotation (AER) provocative maneuvers. Thereafter, we aimed to estimate the proportion of TOS for which arterial participation is present. Methods: Starting in 2019, we simultaneously recorded forearm TcpO2 recordings (PF6000 Perimed®) and the presence/absence of ipsilateral symptoms during two consecutive 30 s AER maneuvers for all patients with suspected TOS. We retrospectively analyzed the relationship between the prevalence of symptoms and DROPmin results. We estimated the number of cases where ischemia likely played a role in the symptoms, assuming that the relationship should start from zero in the absence of ischemia and increase linearly to a plateau of 100% for the most severe ischemia. Results: We obtained 2560 TcpO2 results in 646 subjects (69% females). The correlation between PREVs and DROPmin was 0.443 (p < 0.001). From these results, we estimated the arterial participation in TOS symptoms to be 22.2% of our 1669 symptomatic upper limbs. Conclusions: TcpO2 appears to be an interesting tool to argue for an arterial role in symptoms in TOS. Arterial participation is frequent in TOS. Whether DROPmin could predict treatment outcomes better than the sole presence of compression is an interesting direction for the future.

Exercise transcutaneous oximetry in functional popliteal artery entrapment syndrome diagnosis

INTRODUCTION

Functional popliteal artery entrapment syndrome is a subtype of popliteal artery entrapment syndrome (PAES) without vascular disease or musculotendinous anomaly behind the knee. Symptoms are induced by popliteal artery extrinsic compression, leading to calf pain during lower limbs exercise. Non-invasive tests are still required to improve the diagnostic management of functional PAES. Exercise transcutaneous oxygen pressure (Ex-tcpO2) is of interest to provide objective arguments for the presence of regional blood flow impairment.

OBJECTIVES

The aim of the study was to analyze whether Ex-tcpO2 could serve as a non-invasive technique for detecting ischemia resulting from PAES.

METHODS

Patients with suspected PAES were recruited between 2017 and 2020. The diagnosis was confirmed or rejected, according to the surgical decision based on our diagnosis management involving a multidisciplinary team. Each patient underwent Ex-tcpO2 with specific maneuvers. The decrease from rest of oxygen pressure (DROP) index served for the interpretation of exercise results.

RESULTS

Sixty-five legs with suspected PAES were recruited. Diagnosis was confirmed in 34 (52.3%) and rejected in 32 (47.7%). The average DROP values found in confirmed and rejected group at left leg were - 21.6 ± 15.4 mmHg and - 10.9 ± 11.1 mmHg, respectively (p for Mann-Whitney 0.004), and - 15.8 ± 11 mmHg and - 11.1 ± 7.5 mmHg, respectively, at right leg (p = 0.088). Ex-tcpO2 sensitivity and specificity were 52.9% and 78.1%, respectively.

CONCLUSION

Ex-tcpO2 is an original non-invasive investigation for patients with claudication of doubtful arterial origin. The sensitivity and specificity are 52.9% and 78.1% in functional PAES diagnosis using 15 mmHg as threshold to detect ischemia during tiptoeing elevations.

Validity of Ultrasound for the Diagnosis of Arterial Thoracic Outlet Syndrome

Objective

Thoracic outlet syndrome (TOS) is a rare disorder mostly seen in younger individuals. Although patient wellbeing is relevantly impaired, it often takes a long time before the diagnosis is made. Digital subtraction angiography (DSA) is routinely used despite its radiation exposure, which is a major concern in this young patient population. Moreover, DSA offers limited opportunities for functional assessment. By contrast, ultrasonography is widely accessible without causing radiation exposure and allows for flexible functional assessment. The main goal of the study was to investigate whether ultrasound (US) was a viable alternative to DSA in diagnosing arterial TOS (aTOS).

Methods

Patients, referred to a tertiary centre for evaluation of suspected TOS, were recruited into the study. DSA was routinely performed with the patient's arms both in the raised (abducted) and neutral (adducted) position. Two vascular surgeons and two radiologists assessed the resulting images for the presence of aTOS. Additionally, two examiners performed US according to a standardised protocol. The reference for presence of aTOS was the DSA based interdisciplinary vascular conference consensus. Inter-rater agreement and latent class analysis (LCA) were performed between assessors and diagnostic methods.

Results

Fifty one consecutive patients (two thirds female) aged 39.3 ± 13.0 years were included within 11 months. US agreement was excellent at 0.94 (0.841-0.980), DSA agreement for vascular surgeons was good at 0.779 (0.479-1.000), whereas it was moderate at 0.546 (0.046-1.000) for radiologists. Results suggest that DSA is untenable as the gold standard for aTOS diagnosis. In LCA, US was shown to be a reliable diagnostic tool for the detection of aTOS.

Conclusion

US examination is a valid test for the detection of haemodynamically relevant compression of arteries in the diagnostic work up of aTOS using a standardised protocol. The role of DSA as the gold standard should be reviewed and needs to be reconsidered.

Upper arm versus forearm transcutaneous oximetry during upper limb abduction in patients with suspected thoracic outlet syndrome

Context: Thoracic outlet syndrome (TOS) is common among athletes and should be considered as being of arterial origin only if patients have “clinical symptoms due to documented symptomatic ischemia.” We previously reported that upper limb ischemia can be documented with DROPm (minimal value of limb changes minus chest changes) from transcutaneous oximetry (TcpO2) in TOS.

Purpose: We aimed to test the hypothesised that forearm (F-) DROPm would better detect symptoms associated with arterial compression during abduction than upper arm (U-) DROPm, and that the thresholds would differ.

Methods: We studied 175 patients (retrospective analysis of a cross-sectional acquired database) with simultaneous F-TcpO2 and U-TcpO2 recordings on both upper limbs, and considered tests to be positive (CS+) when upper limb symptoms were associated with ipsilateral arterial compression on either ultrasound or angiography. We determined the threshold and diagnostic performance with a receiver operating characteristic (ROC) curve analysis and calculation of the area under the ROC curve (AUROC) for absolute resting TcpO2 and DROPm values to detect CS+. For all tests, a two-tailed p &lt; 0.05 was considered indicative of statistical significance.

Results: In the 350 upper-limbs, while resting U-TcpO2 and resting F-TcpO2 were not predictive of CS + results, the AUROCs were 0.68 ± 0.03 vs. 0.69 ± 0.03 (both p &lt; 0.01), with the thresholds being −7.5 vs. −14.5 mmHg for the detection of CS + results for U-DROPm vs. F-DROPm respectively.

Conclusion: In patients with suspected TOS, TcpO2 can be used for detecting upper limb arterial compression and/or symptoms during arm abduction, provided that different thresholds are used for U-DROPm and F-DROPm.

Clinical Trial Registration:ClinicalTrials.gov, identifier NCT04376177.

Relationship Between Inflow Impairment and Skin Oxygen Availability to the Upper Limb During Standardized Arm Abduction in Patients With Suspected Thoracic Outlet Syndrome

Objective

Thoracic outlet syndrome (TOS) should be considered of arterial origin only if patients have clinical symptoms that are the result of documented symptomatic ischemia. Simultaneous recording of inflow impairment and forearm ischemia in patients with suspected TOS has never been reported to date. We hypothesized that ischemia would occur in cases of severely impaired inflow, resulting in a non-linear relationship between changes in pulse amplitude (PA) and the estimation of ischemia during provocative attitudinal upper limb positioning.

Design

Prospective single center interventional study.

Material

Fifty-five patients with suspected thoracic outlet syndrome.

Methods

We measured the minimal decrease from rest of transcutaneous oximetry pressure (DROPm) as an estimation of oxygen deficit and arterial pulse photo-plethysmography to measure pulse amplitude changes from rest (PA-change) on both arms during the candlestick phase of a “Ca + Pra” maneuver. “Ca + Pra” is a modified Roos test allowing the estimation of maximal PA-change during the “Pra” phase. We compared the DROPm values between deciles of PA-changes with ANOVA. We then analyzed the relationship between mean PA-change and mean DROPm of each decile with linear and second-degree polynomial (non-linear) models. Results are reported as median [25/75 centiles]. Statistical significance was p < 0.05.

Results

DROPm values ranged −11.5 [−22.9/−7.2] and − 12.3 [−23.3/−7.4] mmHg and PA-change ranged 36.4 [4.6/63.8]% and 38.4 [−2.0/62.1]% in the right and left forearms, respectively. The coefficient of determination between median DROPm and median PA-change was r² = 0.922 with a second-degree polynomial fitting, but only r² = 0.847 with a linear approach.

Conclusion

Oxygen availability was decreased in cases of severe but not moderate attitudinal inflow impairments. Undertaking simultaneous A-PPG and forearm oximetry during the “Ca + Pra” maneuver is an interesting approach for providing objective proof of ischemia in patients with symptoms of TOS suspected of arterial origin.

Arterial Digital Pulse Photoplethysmography in Patients with Suspected Thoracic Outlet Syndrome: A Study of the "Ca+Pra" Maneuver

The level of pulse amplitude (PA) change in arterial digital pulse plethysmography (A-PPG) that should be used to diagnose thoracic outlet syndrome (TOS) is debated. We hypothesized that a modification of the Roos test (by moving the arms forward, mimicking a prayer position (“Pra”)) releasing an eventual compression that occurs in the surrender/candlestick position (“Ca”) would facilitate interpretation of A-PPG results. In 52 subjects, we determined the optimal PA change from rest to predict compression at imaging (ultrasonography +/− angiography) with receiver operating characteristics (ROC). “Pra”-PA was set as 100%, and PA was expressed in normalized amplitude (NA) units. Imaging found arterial compression in 23 upper limbs. The area under ROC was 0.765 ± 0.065 (p < 0.0001), resulting in a 91.4% sensitivity and a 60.9% specificity for an increase of fewer than 3 NA from rest during “Ca”, while results were 17.4% and 98.8%, respectively, for the 75% PA decrease previously proposed in the literature. A-PPG during a “Ca+Pra” test provides demonstrable proof of inflow impairment and increases the sensitivity of A-PPG for the detection of arterial compression as determined by imaging. The absence of an increase in PA during the “Ca” phase of the “Ca+Pra” maneuver should be considered indicative of arterial inflow impairment.

Epidemiology of thoracic outlet syndrome

Thoracic outlet syndrome (TOS) describes a complex disease process with three anatomic variations each with their own individual characteristics. Understanding the prevalence, diagnosis, and treatment of TOS is challenging for many providers. For this reason, the establishment of comprehensive care models and expert leadership by dedicated vascular surgeons with TOS experience has been invaluable.