Exercise Oximetry Correlates Better With Exercise-Induced Lactate Increase, than Ankle Brachial Index or Walking Time, in Vascular Claudicants.

In claudication, the correlation between walking-induced biomarkers and indices of clinical severity (e.g., walking distance or ankle brachial index (ABI)), is fair. We hypothesized that a correlation would be observed between the clinical estimation of ischemia severity with exercise transcutaneous oximetry (Ex-TcpO2) and lactate increase. A prospective study was performed among 377 patients with arterial claudication. We recorded age, sex, ABI, body mass index (BMI), systolic arterial blood pressure (SBP), and glycemia. Capillary blood lactate was measured at rest and 3 min after a constant load treadmill test. We recorded maximum walking time (MWT), heart rate (HRmax), the sum of minimal decrease from oxygen values for buttocks, thighs and calves Ex-TcpO2 (DROPmin), as well as the amplitude of chest-TcpO2 decrease. A multilinear regression model was used to assess the variables associated with lactate increase. BMI, SBP, HRmax, the amplitude of decrease in chest-TcpO2 and DROPmin, but not age, sex, ABI, MWT, diabetes mellitus nor glycemia, were significantly associated to lactate increase in the model. Because it accounts for the severity and diffusion of lower-limb exercise-induced ischemia and detects exercise induced hypoxemia, TcpO2 may be preferable to ABI or MWT to estimate the metabolic consequences of walking in claudicants.

Quantitative analysis of venous outflow with photo-plethysmography in patients with suspected thoracic outlet syndrome.

Background: Venous compression is the second most frequent form of thoracic outlet syndrome (TOS). Although venous photo-plethysmography (PPG) has been largely used to estimate the consequences of chronic thromboses (Paget Schroetter syndrome), systematic direct quantitative recording of hemodynamic consequences of positional venous outflow impairment in patients with suspected TOS has never been reported. Objective: We hypothesized that moving the arms forward (prayer: "Pra" position) while keeping the hands elevated after a surrender/candlestick position (Ca) would allow quantification of 100% upper limb venous emptying (PPGmax) and quantitative evaluation of the emptying observed at the end of the preceding abduction period (End-Ca-PPG), expressed in %PPGmax. Materials and methods: We measured V-PPG in 424 patients referred for suspected TOS (age 40.9 years old, 68.3% females) and retrieved the results of ultrasound investigation at the venous level. We used receiver operating characteristics curves (ROC) to determine the optimal V-PPG values to be used to predict the presence of a venous compression on ultrasound imaging. Results are reported as a median (25/75 centiles). Statistical significance was based on a two-tailed p < 0.05. Results: An End-Ca-PPG value of 87% PPGmax at the end of the "Ca" period is the optimal point to detect an ultrasound-confirmed positional venous compression (area under ROC: 0.589 ± 0.024; p < 0.001). This threshold results in 60.9% sensitivity, 47.6% specificity, 27.3% positive predictive value, 79.0% negative predictive value, and 50.8% overall accuracy. Conclusion: V-PPG is not aimed at detecting the presence of a venous compression due to collateral veins potentially normalizing outflow despite subclavicular vein compression during abduction, but we believe that it could be used to strengthen the responsibility of venous compression in upper limb symptoms in TOS-suspected patients, with the possibility of non-invasive, bilateral, recordable measurements of forearm volume that become quantitative with the Ca-Pra maneuver. Clinical trial registration: [ClinicalTrials.gov], identifier [NCT04376177].

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 < 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 < 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 the Severity of Exercise Induced Ischaemia and the Prevalence of Exercise Induced Calf Symptoms During Treadmill Testing With Transcutaneous Oximetry.

OBJECTIVE: It was hypothesised that there is a linear relationship between the severity of exercise induced calf ischaemia and the prevalence of calf claudication on a treadmill until a plateau is reached. It was expected that no pain would be present in the absence of ischaemia and all severely ischaemic calves would be symptomatic. METHODS: This was a retrospective analysis of a cross sectional acquired database recording. Transcutaneous oxygen pressure (TcPO2) on the chest and on each calf was used to evaluate calf ischaemia during treadmill tests with simultaneous recording of calf pain in 7 884 subjects (15 768 calves). The minimum value of calf changes from rest minus chest changes from rest (DROPm) was calculated. Regression analyses were used to determine the correlation between the proportion of exercise induced symptoms present in the calves and each unit of DROPm values. Analysis was repeated after objective determination of the cutoff point between the linear increase and the plateau. RESULTS: A linear relationship was found between the degree of ischaemia and the proportion of symptomatic calves for DROPm values ranging from 0 mmHg to -28 mmHg (proportion = -0.014 × DROPm + 0.32, r = 0.961, p <.001). For DROPm values lower than -28 mmHg (severe ischaemia), on average one of three limbs remained asymptomatic. The biphasic relationship between DROPm and prevalence of symptoms persists after exclusion of patients with diabetes mellitus, exercise induced hypoxaemia, and no evidence of lower extremity arterial disease (LEAD). CONCLUSION: The relationship between exercise induced pain and ischaemia is biphasic with a linear increase in the proportion of symptomatic limbs with ischaemia severity, until a plateau is reached for the more severely ischaemic limbs. The presence of exercise related calf symptoms should not automatically be reported as indicating the presence of LEAD; and the absence of exercise induced symptoms is not proof that ischaemia does not occur during exercise.

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 r 2 = 0.922 with a second-degree polynomial fitting, but only r 2 = 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.

Comparison between conventional duplex ultrasonography and the dual-gate Doppler mode for hemodynamic measurements of the carotid arteries.

PURPOSE: This study investigated the correlations of hemodynamic parameters measured to quantify stenosis between the gold-standard duplex ultrasonography and the dual-gate Doppler mode. METHODS: Patients examined due to suspicion of carotid artery stenosis or for surveillance of known stenosis were invited to participate in this prospective single-center study. Upon acceptance, the hemodynamic characteristics of the carotid arteries were determined successively in standard duplex and dual-gate Doppler modes. The correlations between the two modes were analyzed by computing Pearson coefficients (r2) and Lin concordance coefficients (ρc). The degree of agreement between the two methods was visualized using Bland-Altman graphical representations. RESULTS: The correlation between internal carotid artery peak systolic velocity measured by standard duplex ultrasonography and dual-gate Doppler mode was good (r2=0.642). The same high level of correlation was observed for the carotid ratio (r2=0.544). However, the Bland-Altman graphical representation and the Lin concordance coefficients (ρc=0.75 and ρc=0.74 for the internal carotid artery peak systolic velocity and carotid ratio, respectively) showed that a lack of precision generated some discrepancies between the two measurement methods. CONCLUSION: Although some discrepancies were observed, the hemodynamic measurements were closely correlated between the two ultrasonography modes. Therefore, the dual-gate Doppler mode may have obvious advantages over conventional ultrasonography, offering interesting development possibilities.

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

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-PPG IR . We recruited patients for a Ca + Pra maneuver with the simultaneous fingertip and forearm V-PPG R . 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-PPG IR , fingertip V-PPG R , and forearm V-PPG R . 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-PPG IR and forearm V-PPG R , respectively. Fingertip V-PPG R 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 PPG R or PPG IR but not at the fingertip level.

Kneeling-induced calf ischemia: a pilot study in apparently healthy European young subjects.

PURPOSE: Many tasks, sports or leisure activities require maximal knee flexion. We hypothesized that this position could result in reduced calf perfusion, in young European subjects. METHODS: We quantified calf ischemia resulting from the knee flexion with transcutaneous oxygen pressure (TcpO2) sensors by assessing the decrease from rest of TcpO2 (DROP) defined as limb changes minus chest changes. A minimal DROP (DROPm) <-15 mmHg defines the presence of ischemia. From the crawling position, participants kneeled for 3 min while bending as in prostration/prayer position (P). Thirty-five participants repeated this maneuver a second time, while 7 participants were also required to sit on their heels with the torso in the vertical position to attain knee flexion without significant groin flexion (S). RESULT: In 41 healthy young volunteers (30 males), 25 [20-31] years old, 37 patients showed a DROPm < -15 mmHg from "R" to "P" in one (n = 4) or both (n = 33) calves (90.2%; 95% CI 76.9-97.3). After backward regression of the DROPm, there was no significant association with side, body weight of systolic blood pressure. However, age was strongly associated with DROPm (OR 5.34 [2.45-8.69]) so that DROPm was significantly higher in older, with a correlation ρ = 0.31 (p = 0.003). CONCLUSION: Kneeling dramatically reduces calf perfusion, likely through popliteal artery kinking, possibly through muscle crushing. Eastern lifestyle includes routine flexed position since childhood. Whether or not such a chronic training reduces the risk of kneeling-induced ischemia in adults is unknown to date.

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.

Forearm Volume Changes Estimated by Photo-Plethysmography During an Original Candlestick/Prayer Maneuver in Patients With Suspected Thoracic Outlet Syndrome.

Objective: Hemodynamic investigations in thoracic outlet syndrome (TOS) remain difficult, even in trained hands. Results are generally reported as either presence or absence of venous compression. In fact, in patients with suspected TOS but without chronic venous occlusion, the forearm volume changes may result from various combinations of forearm position from heart level, arterial inflow, and/or venous outflow positional impairment. Design: Cross sectional, retrospective, single center study, accessible on Clinicaltrial.gov under reference NCT04376177. Material: We used venous photo-plethysmography (V-PPG) in 151 patients with suspected TOS. The subjects elevated their arms to the "candlestick" (Ca) position for 30 s and then kept their arm elevated in front of the body for an additional 15 s ("prayer" position; Pra). This CA-Pra procedure was repeated three times by each patient with recording of both arms. Method: We classified V-PPG recordings using an automatic clustering method. Result: The blinded clustering classification of 893 V-PPG recordings (13 missing files) resulted in four out of seven clusters, allowing the classification of more than 99% of the available recordings. Each cluster included 65.73, 6.16, 17.13, and 10.8% of the recordings, respectively. Conclusion: Venous hemodynamic profiles in TOS are not only either normal or abnormal. With V-PPG, four clusters were observed to be consistent with, and assumed to result from, the four possible associations of presence/absence of arterial inflow/venous outflow positional impairment: (1) normal response (maximal emptying in Ca and Pra), (2) isolated inflow impairment (emptying in Ca and filling in Pra due to post-ischemic vasodilation), (3) isolated venous outflow impairment (emptying then filling in Ca due to arterial inflow and emptying in Pra), and (4) simultaneous inflow/outflow impairment (emptying in Ca but no filling due to concomitant inflow impairment and further emptying in Pra).

Calf and non-calf hemodynamic recovery in patients with arterial claudication: Implication for exercise training.

BACKGROUND: Previous studies in patients with arterial claudication have focused on calf hemodynamic recovery. We hypothesized that the duration of hemodynamic recovery with TcpO2 at calf and non-calf levels would be shorter than 10 min. We analyzed the factors that influence the recovery time. METHODS: We monitored limb changes minus chest changes from rest (DROP) of transcutaneous oximetry on buttocks, thighs and calves, during and following a treadmill test (3.2 km/h; 10% grade). We calculated the time required to reach 50% (50%RT) and 10% (90%RT) of minimal DROP value (DROPm) from walking cessation. Regression analyses were used to determine the factors associated to 50%RT and 90%RT. RESULTS: Of the 132 patients studied, 18.2% reported isolated non-calf pain by history. Of the 792 recovery time values, only 3 (0.4%) and 23 (2.9%) were in excess of 10 min for 50%RT and for 90%RT, respectively. A weak correlation was found between each of the 792 DROPm and 50%RT (r = -0.270, p < 0.001) as well as for 90%RT (r = -0.311 p < 0.001). Lowest DROPm and BMI (but not age, sex, the use of beta-blockers, the duration of the walking period) were associated to both 50%RT and 90%RT. CONCLUSION: Although recovery duration correlates significantly with the severity of ischemia of the same location, a wide discrepancy exists and the longest recovery time does not always correlate to the localization of the most severe ischemia. Non-calf ischemia should be measured when one aims at objectifying the biological effects of exercise or the effects of treatments on recovery from exercise.

Sinusoidal changes in transcutaneous oxygen pressure, suggesting Cheyne-Stokes respiration, are frequent and of poor prognosis among patients with suspected critical limb ischemia.

BACKGROUND AND AIMS: Transcutaneous oxygen pressure (TcpO2) is used in patients with suspected critical limb ischemia (CLI). Sinusoidal changes (SC~) in TcpO2 are found in patients with Cheyne-Stokes respiration (CSR). We aimed to determine the characteristics of TcpO2 changes at rest in patients with suspected CLI, define the objective criteria for SC ~ TcpO2 patterns (SC+), and estimate the prevalence of SC+ in our population and its impact on the outcome. METHODS: We retrospectively analyzed 300 chest TcpO2 recordings performed in a 16-month period. We determined the presence/absence of SC ~ TcpO2 by visual analysis. We determined the acceptable error in the regularity of peaks of the cross-correlation with ROC curve analysis, among patients with typical SC ~ TcpO2 and non-sinusoidal patterns. Then, we defined SC + as a minimum of five peaks, a standard deviation of TcpO2 >1.25 mmHg, an error in regularity of peaks of the cross-correlation < 10%, and a cycle length between 30 and 100 s. In patients included until October 2019, we compared the outcome as a function of SC + or SC- with Cox models. RESULTS: Mathematical detection of SC + found that 43 patients (14.3%) fulfilled all four defined criteria at the chest level, but only 23 did so at the limb level. In the follow-up of 207 patients, the presence of Sc ~ TcpO2 at the chest significantly increased the risk of mortality: hazard ratio: 2.69 [95%CI: 1.37-5.30]; p < 0.005. CONCLUSIONS: SC ~ TcpO2 is frequent, and is associated with a poor outcome in patients with suspected CLI.

Current-Induced Vasodilation Specifically Detects, and Correlates With the Time Since, Last Aspirin Intake: An Interventional Study of 830 Patients.

BACKGROUND: Galvanic current-induced vasodilation (CIV) is impaired in patients under low-dose aspirin (ASA; ≤ 500 mg/day), but potential covariates and the impact of the time since the last ASA intake are unknown. OBJECTIVES: We used tissue viability imaging (TiVi) in patients at risk of cardiovascular disease and examined its association with self-reported treatments. PATIENTS/METHODS: We recorded the age, gender, height, weight, smoking status, and use of 14 different drug categories in 822 patients either with known peripheral artery disease or at risk thereof. The difference between TiVi arbitrary units (TAUs) where stimulation was applied and an adjacent skin area was recorded, as well as the time since the last ASA intake. Step-by-step regression analysis was used to determine the factors that affect CIV amplitude. RESULTS AND CONCLUSIONS: CIV was 28.2 ± 22.9 vs. 14.6 ± 18.0 TAUs (P < 0.001) in patients treated with ASA (n = 287) and not treated with ASA (n = 535), respectively. The main determinants of CIV amplitude, by order of importance, were: aspirin intake, diabetes mellitus, age, and male sex. In ASA-treated patients, the main determinants were diabetes mellitus, time since the last ASA intake, male gender, and age. Non-invasive determination of the physiological effects of low-dose ASA is feasible in routine clinical practice. It could be a clinical approach to provide objective evidence of ASA intake, and potentially could be used to test adherence to treatment in ASA-treated patients.

Investigation of arterial claudication with transcutaneous oxygen pressure at exercise: Interests and limits.

Transcutaneous oxygen pressure (TcpO2) measurement has been used for years at rest in patients with lower extremity artery disease. It was proposed for exercise testing (Ex-TcpO2) in the 80ies to evaluate regional blood flow impairment (RBFI) at the proximal and distal levels simultaneously and on both sides, in case of claudication. It was suggested that the use of a chest electrode was mandatory to show that decreases in TcpO2 at the limb level result from limb RBFI and not from a systemic pO2 decrease of cardiopulmonary origin (exercise-induced hypoxemia). Unfortunately, a major pitfall of Ex-TcpO2 was the low absolute reliability of the regional perfusion index (RPI: ratio of limb to chest values) and the technique was almost abandoned until 2003, when the DROP index (Decrease from rest of oxygen pressure: limb changes minus chest changes from rest) was proposed. The DROP mathematical formula makes Tcpo2 results independent from the absolute pO2 starting values, improving reliability of Ex-TcpO2 as compared to the RPI. Since then, Ex-TcpO2 has been of renewed interest. The present paper addresses the physiology of Ex-TcpO2, interpretation of its results, and common misunderstandings about its use.

The hidden side of calf claudication: Hemodynamic and clinical results of treadmill testing in 584 patients complaining of isolated exertional calf pain.

BACKGROUND AND AIMS: Calf pain is the most frequent symptom of arterial claudication. We hypothesized that patients with self-reported isolated calf claudication have frequent exertional non-calf symptoms during objective laboratory testing, and that many would show not only distal, but also proximal ischemia. METHODS: We retrospectively analyzed the patients referred since 2016 for exercise transcutaneous oxygen pressure (Ex-tcpO2). The Edinburgh Claudication Questionnaire (ECQ) was self-completed before and during a treadmill test. For calf and non-calf (buttock and thigh) Ex-tcpO2, a lowest decrease of rest of oxygen pressure (DROP) < -15 mmHg was indicative of ischemia. We selected the patients that reported calf claudication only and analyzed minimal DROP and per-test ECQ observations. RESULTS: Exertional symptoms on a treadmill occurred in 526 (90.1%) of the 584 patients analyzed (65.6 ± 11.4 years old), with 391 (74.3%) of these symptoms affecting only the calf. Isolated calf ischemia with or without symptoms was found in only 139 (23.8%) patients. Overall, among the 584 patients self-reporting isolated calf symptoms, a perfect concordance between symptoms on a treadmill and Ex-tcpO2 (i.e. calf symptoms associated to calf ischemia) was observed in only 114 (19.5%) cases. CONCLUSIONS: Our study demonstrated that patients self-reporting exertional limb pain strictly limited to the calf may also have non-calf claudication on a treadmill and frequently show not-only-calf ischemia. These observations are important when planning reeducation or when studying the tissue consequences of ischemia in patients with claudication.

Specific slow tests are not mandatory in patients with extremely short standard (3.2 km/hr 10% slope) test durations during exercise oximetry.

AIM: To compare the transcutaneous oxygen pressure results observed in patients with severe walking limitation during standard procedures (3.2 km/hr, 10% slope) versus during a test performed at a low speed (2 km/hr, 10% slope). METHODS: In 31 patients, the decrease from rest of oxygen pressure (DROP) index was measured on both buttocks, both thighs and both calves during two consecutive tests on treadmill. The maximal walking time (MWT) and the minimal DROP values (DROPmin ) observed during the 2 tests were compared with t test. Correlation of DROPmin values during the slow and standard procedure was performed with linear regression. The -15 mmHg cut-off value defined for standard test interpretation was used arbitrarily for the interpretation of slow test results. RESULTS: MWT was 80 ± 52 s versus 376 ± 269 s at standard and slow speed, respectively (p < .001). No difference on all recorded DROPmin values at a standard (-9.5 ± 6.9 mmHg) and slow (-10.5 ± 7.9 mmHg) speed was found; n = 186, p = .168. Coefficient of correlation between DROPmin s found at the two tests was r = 0.820 (p < .01), with regression line close to the line of identity. With the identical -15 mmHg cut-off, 166 (89.2%) of 186 the results were classified similarly after standard and slow procedures. CONCLUSION: Specific slow treadmill procedures are not mandatory in patients with extremely short test durations when performing standard (3.2 km/hr 10% slope) exercise oximetry. In patients expected to be unable to walk at standard speed, the -15 mmHg normal limit seems to be valid for the interpretation of tests with a slow procedure (2.0 km/hr).

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

BACKGROUND: Non-invasive tests are still required to improve the holistic diagnostic approach of thoracic outlet syndrome (TOS). OBJECTIVES: We aimed to analyze the diagnostic accuracy of the decrease from rest oxygen pressure (DROP) index of transcutaneous oximetry (TcpO2) in TOS. METHODS: Seventy-six patients and 40 asymptomatic volunteers (Controls) were enrolled. In TOS-suspected patients, the arteriograms were investigated for the presence of≥75% stenosis. The area under receiver operating characteristics curve (AUC) analysis tested the ability of forearm TcpO2 during provocative maneuvers to discriminate patients from controls and, to predict a positive arteriographic findings in the 44 TOS-suspected patients that had an arteriography. RESULTS: The media [25/75° centile] DROP values of controls and patients were -14 [-8/-22] mmHg and -22 [-12/-42] mmHg, respectively (p for Mann-Whitney<0.02). AUC analysis showed a significant ability of TcpO2 to predict the presence of subclavian arterial compression on arteriography (AUC, 0.694). CONCLUSIONS: Although time consuming, tcpO2 is independent of the observer expertise and could be useful in TOS-suspected patients to select the patients that should undergo arteriography.

The risk of lower-limb superficial vein thrombosis relative to lower-limb venous thrombotic events is not increased in winter months.

OBJECTIVES: Ambient temperature (that impacts differently venous flow in superficial and deep veins) could have a different effect on the risk of superficial and deep venous thrombosis. We searched for a trimestral variation of the risk of superficial venous thrombosis among all lower-limb thrombotic events (lower-limb thrombotic events = superficial venous thrombosis + deep venous thrombosis). METHODS: We retrospectively analyzed the results of venous ultrasound investigations performed among 11,739 patients (aged 67 ± 19 years old, 56.1% males) referred for suspected lower-limb thrombotic events over a 12-year period. Chi-square test was used to compare the superficial venous thrombosis/lower-limb thrombotic events ratio observed by trimesters to a homogeneous distribution. RESULTS: The proportion of lower-limb thrombotic events were 30.7%, 28.8%, 31.1%, and 31.4% (Chi2: 0.133; p = 0.987) of total investigations, while that of superficial venous thrombosis among all lower-limb venous thrombotic events were 27.2%, 30.0%, 31.4%, and 31.0%, for the first, second, third, and fourth trimesters respectively (Chi2: 0.357; p: 0.949). CONCLUSION: No trimestral variation of the superficial venous thrombosis/lower-limb venous thrombotic events ratio was observed.

Comparison of exercise oximetry and ankle pressure measurements for patients with intermittent claudication: an observational study of 433 patients.

To study the concordance of exercise-oximetry and of ankle-brachial pressure index (ABI) and ankle pressure (AP) at rest, and after exercise, in patients complaining of vascular-type claudication to diagnose lower extremity artery disease (LEAD). Treadmill test in 433 patients with exercise-oximetry included constant load (3.2 km/h, 10% slope) phase for up to 15 min followed by an increment phase, if necessary. The presence (TcpO2e+) or absence (TcpO2e-) of ischemia was a decrease of limb minus chest oxygen pressure change greater than or less than - 15 mmHg. The post-exercise ABI and AP were measured after another test of a maximum of 5 min except if resting-ABI < 0.90. LEAD was diagnosed (+) based on resting-ABI < 0.90, post-exercise ABI < 0.8∙resting-ABI, or a difference of 30 mmHg between post-exercise and resting AP, or diagnosis was considered negative for all other cases (-). The discrepancies between the exercise-oximetry and pressure results were analyzed. We found 351 patients with resting-ABI+, of whom 52 were classified as TcpO2e-. Of the 82 patients with resting-ABI-, 25 had post-exercise ABI+ or AP+, of whom, 10 had TcpO2e-, while 57 had post-exercise ABI- and AP-, of whom, 28 had TcpO2e+. Discrepancies arose mainly from nonvascular limitations, isolated proximal ischemia, and detection of LEAD in the incremental phase of the exercise-oximetry. Post-exercise pressure measurements were easy and useful, but exercise-oximetry provided additional information for both resting-ABI- and resting-ABI+ patients and can help to prove the vascular origin of walking limitation of LEAD patients.