Michael J. Segel

Smoke and autoimmunity: The fire behind the disease.

The association between smoke habit and autoimmunity has been hypothesized a long time ago. Smoke has been found to play a pathogenic role in certain autoimmune disease as it may trigger the development of autoantibodies and act on pathogenic mechanism possibly related with an imbalance of the immune system. Indeed, both epidemiological studies and animal models have showed the potential deleterious effect caused by smoke. For instance, smoke, by provoking oxidative stress, may contribute to lupus disease by dysregulating DNA demethylation, upregulating immune genes, thereby leading to autoreactivity. Moreover, it can alter the lung microenvironment, facilitating infections, which, in turn, may trigger the development of an autoimmune condition. This, in turn, may result in a dysregulation of immune system leading to autoimmune phenomena. Not only cigarette smoke but also air pollution has been reported as being responsible for the development of autoimmunity. Large epidemiological studies are needed to further explore the accountability of smoking effect in the pathogenesis of autoimmune diseases.

Exercise haemodynamics may unmask the diagnosis of diastolic dysfunction among patients with pulmonary hypertension

Heart failure with preserved ejection fraction can lead to pulmonary hypertension. The aim of the present study was to evaluate the role of exercise during right heart catheterization in the unmasking of diastolic dysfunction.

Continuous Positive Airway Pressure for Motion Management in Stereotactic Body Radiation Therapy to the Lung: A Controlled Pilot Study.

OBJECTIVE To determine the effect of continuous positive airway pressure (CPAP) on tumor motion, lung volume, and dose to critical organs in patients receiving stereotactic body radiation therapy (SBRT) for lung tumors. METHODS AND MATERIALS After institutional review board approval in December 2013, patients with primary or secondary lung tumors referred for SBRT underwent 4-dimensional computed tomographic simulation twice: with free breathing and with CPAP. Tumor excursion was calculated by subtracting the vector of the greatest dimension of the gross tumor volume (GTV) from the internal target volume (ITV). Volumetric and dosimetric determinations were compared with the Wilcoxon signed-rank test. CPAP was used during treatment if judged beneficial. RESULTS CPAP was tolerated well in 10 of the 11 patients enrolled. Ten patients with 18 lesions were evaluated. The use of CPAP decreased tumor excursion by 0.5 ± 0.8 cm, 0.4 ± 0.7 cm, and 0.6 ± 0.8 cm in the superior-inferior, right-left, and anterior-posterior planes, respectively (P ≤ .02). Relative to free breathing, the mean ITV reduction was 27% (95% confidence interval [CI] 16%-39%, P<.001). CPAP significantly augmented lung volume, with a mean absolute increase of 915 ± 432 cm(3) and a relative increase of 32% (95% CI 21%-42%, P=.003), contributing to a 22% relative reduction (95% CI 13%-32%, P=.001) in mean lung dose. The use of CPAP was also associated with a relative reduction in mean heart dose by 29% (95% CI 23%-36%, P=.001). CONCLUSION In this pilot study, CPAP significantly reduced lung tumor motion compared with free breathing. The smaller ITV, the planning target volume (PTV), and the increase in total lung volume associated with CPAP contributed to a reduction in lung and heart dose. CPAP was well tolerated, reproducible, and simple to implement in the treatment room and should be evaluated further as a novel strategy for motion management in radiation therapy.

Methacholine challenge testing: improved patient comfort with a 2-tiered protocol.

BACKGROUND The methacholine challenge test (MCT) is a test of bronchial hyperreactivity used as an aid in the diagnosis of asthma. MCT results are reported as the provocation concentration at which the forced expiratory volume in 1 second (FEV1) decreases 20% (PC20). The requirement for a 20% or greater decrease in FEV1 results in precipitous decreases in FEV1 in some patients. OBJECTIVE To improve MCT safety without compromising accuracy. METHODS We performed a retrospective analysis of 879 consecutive MCTs (derivation cohort). A novel protocol for MCT was developed and validated in a cohort of 564 MCTs performed in a second institution. RESULTS In comparison with a PC20 cutoff of less than 8 mg/mL, a provocation concentration at which the FEV1 decreases 10% (PC10) cutoff of 1 mg/mL or less has a sensitivity of 86%, a specificity of 98%, a positive predictive value (PPV) of 97%, and a negative predictive value (NPV) of 91%. We propose a novel 2-tiered protocol for MCT. If the PC10 is 1 mg/mL or less, bronchial hyperreactivity is present; if the PC10 is greater than 1 mg/mL, the test is continued until the provocative concentration is 8 mg/mL or a 20% decrease in FEV1 is achieved. Compared with the standard protocol, the proposed protocol has a sensitivity, specificity, PPV, NPV, and overall accuracy of 100%, 98%, 97.6%, 100%, and 99%, respectively. The modified protocol would have enabled us to avoid 26 of 42 cases (62%) in which a 40% or greater decrease in FEV1 occurred and would save 0.65 dose for every MCT performed. The 2-tiered protocol performed well in the validation cohort; sensitivity, specificity, PPV, NPV, and overall accuracy were 100%, 98%, 87%, 100%, and 98%, respectively. CONCLUSION The proposed 2-tiered protocol is accurate, saves time, and avoids precipitous decreases in FEV1.

Chronic iliofemoral vein obstruction – an under-recognized cause of exercise limitation†

Abstract Local symptoms of chronic venous insufficiency after deep vein thrombosis (DVT) are well described, but little is known about the effect of residual venous obstruction on exercise capacity. We tested our hypothesis that chronic residual iliofemoral vein occlusion (IFVO) after DVT may impair exercise capacity. Nine post-DVT patients with residual IFVO and effort intolerance were studied; a comparison cohort consisted of 11 healthy volunteers. Exercise tolerance was assessed by bimodality incremental symptom-limited cardiopulmonary testing, using leg and arm ergometers. In healthy subjects, leg vein obstruction was modelled by application to the thighs of cuff tourniquets inflated to 30–40 mmHg. Leg exercise tolerance as measured by oxygen uptake at peak exercise (peak ⩒’O2) was reduced in patients (median 50% predicted (range 36–83%) vs. 88% predicted (67–129%) in normal subjects, p < 0.001). Arm exercise tolerance was also reduced in patients, but less severely than in the legs – the median arm: leg ratio of peak ⩒’O2 was 0.95 (0.77–1.43) in patients vs. a normal ratio of 0.73 (0.6–1.0) in healthy subjects (p < 0.003). In healthy subjects, bilateral leg vein obstruction by tourniquets reduced peak ⩒’O2 in leg exercise to 76% predicted (range 55–108%; p < 0.001 vs. standard test). In conclusion, the comparison of arm vs. leg exercise capacity in post-DVT patients with residual IFVO and the effect of experimental venous obstruction (thigh tourniquets) in healthy subjects suggest that reduced exercise capacity in patients was at least partially caused by reduced venous return. Chronic venous obstruction should be recognized as a cause of exercise limitation.

Cardio-vascular reserve index (CVRI) during exercise complies with the pattern assumed by the cardiovascular reserve hypothesis

OBJECTIVES The Cardio-vascular reserve index (CVRI) had been empirically validated in diverse morbidities as a quantitative estimate of the reserve assumed by the cardiovascular reserve hypothesis. This work evaluates whether CVRI during exercise complies with the cardiovascular reserve hypothesis. DESIGN Retrospective study based on a database of patients who underwent cardio-pulmonary exercise testing (CPX) for diverse indications. METHODS Patients physiological measurements were retrieved at four predefined CPX stages (rest, anaerobic threshold, peak exercise and after 2min of recovery). CVRI was individually calculated retrospectively at each stage. RESULTS Mean CVRI at rest was 0.81, significantly higher (p<0.001) than at all other stages. CVRI decreased with exercise, reaching an average at peak exercise of 0.35, significant lower than at other stages (p<0.001) and very similar regardless of exercise capacity (mean CVRI 0.33-0.37 in 4 groups classified by exercise capacity, p>0.05). CVRI after 2min of recovery rose considerably, most in the group with the best exercise capacity and least in those with the lowest exercise capacity. CONCLUSIONS CVRI during exercise fits the pattern predicted by the cardiovascular reserve hypothesis. CVRI decreased with exercise reaching a minimum at peak exercise and rising with recovery. The CVRI nadir at peak exercise, similar across groups classified by exercise capacity, complies with the assumed exhaustion threshold. The clinical utility of CVRI should be further evaluated.