Membrane and Capillary Blood Components of Diffusion Capacity of the Lung for Carbon Monoxide in Pulmonary Sarcoidosis

Cardiopulmonary exercise testing in interstitial lung diseases and the value of ventilatory efficiency

Interstitial lung diseases (ILDs) are diverse parenchymal pulmonary disorders, primarily characterised by alveolar and interstitial inflammation and/or fibrosis, and sharing pathophysiological similarities. Thus, patients generally harbour common respiratory symptoms, lung function abnormalities and modified exercise adaptation. The most usual and disabling complaint is exertional dyspnoea, frequently responsible for premature exercise interruption. Cardiopulmonary exercise testing (CPET) is increasingly used for the clinical assessment of patients with ILD. This is because exercise performance or dyspnoea on exertion cannot reliably be predicted by resting pulmonary function tests. CPET, therefore, provides an accurate evaluation of functional capacity on an individual basis. CPET can unmask anomalies in the integrated functions of the respiratory, cardiovascular, metabolic, peripheral muscle and neurosensory systems in ILDs. CPET uniquely provides an evaluation of all above aspects and can help clinicians shape ILD patient management. Preliminary evidence suggests that CPET may also generate valuable prognostic information in ILDs and can be used to shed light on the presence of associated pulmonary hypertension. This review aims to provide comprehensive and updated evidence concerning the clinical utility of CPET in ILD patients, with particular focus on the physiological and clinical value of ventilatory efficiency (V˙_E/V˙_CO2 ).

T Lymphocyte Maturation Profile in the EBUS-TBNA Lymph Node Depending on the DLCO Parameter in Patients with Pulmonary Sarcoidosis

Sarcoidosis (SA) is a systemic granulomatous disorder of unknown etiology with lung and mediastinal lymph nodes (LNs) as the main location. T lymphocytes play important role in the formation of granulomas in SA, but still little is known about the role of maturation profile in the development of inflammatory changes. The aim of this study was to determine the CD4+ and CD8+ T cells maturation profile in LNs and in peripheral blood (PB) and its relation to disease severity expressed by diffusing capacity of the lung for carbon monoxide (DLCO). 29 patients with newly pulmonary SA were studied. Flow cytometry was used for cells evaluation in EBUS-TBNA samples. We observed lower median proportion of T lymphocytes, CD4+ T and CD8+ T cells in patients with DLCO< 80% than in patients with normal diffusion (DLCO > 80%). Patients with DLCO < 80% had lower median proportion of effector and higher median proportion of central memory CD4+ and CD8+ T cells than patients with DLCO > 80%. We reported for the first time that LNs CD4+ and CD8+ T cells maturation differs depending on the DLCO value in sarcoidosis. Lymphocytes profiles in LNs may reflect the immune status of patients with SA and can be analysed by flow cytometry of EBUS-TBNA samples.

Frequency of peripheral blood eosinophilia and obstructive airway disease in sarcoidosis

BACKGROUND

There is limited information about peripheral blood eosinophilia (PBE) and airway obstruction in sarcoidosis. Since pulmonary sarcoidosis affects the airways, it is often confused with asthma. The aims of the study are to investigate airway obstruction and PBE in sarcoidosis patients and to examine the similarity of clinical presentation with asthma.

METHODS

The patients matching the ATS/ERS/WASOG diagnosis criteria and were between 18 and 80 years of age were included consecutively between 2018 and 2020. Other diseases causing granulomas were excluded.

RESULTS

A total of 84 patients were included of which 26 (31%) had a PBE level of ≥300 µL with no significant difference seen between sarcoidosis stage and PBE (p > 0.05). A significant (p < 0.05) decrease was only seen in FEV1 as the stage of sarcoidosis progressed. Respectively 31 (36.9%), 12 (14.3%) and 4 (4.8%) patients had an obstructive, restrictive and mixed respiratory function disorder. Twenty-four (28.6%) subjects with sarcoidosis had history of asthma. Spring fever, eczema, and skin/nose allergy were noticed in 17 (20.2%) of the patients.

DISCUSSION

Mild PBE may be seen in sarcoidosis. Patients applying with PBE, airway obstruction, bronchial hyperreactivity along with spring fever, eczema, skin/nose allergy, wheezing, chest tightness, shortness of breath and cough may be also evaluated in terms of sarcoidosis.

Role of fibrocytes and endothelial progenitor cells among low-differentiated CD34+ cells in the progression of lung sarcoidosis

Background

Sarcoidosis is a multisystemic granulomatous disease with still unknown etiology. Our previous studies showed a significantly higher percentage of CD34 + cells in the peripheral blood in patients with sarcoidosis (SA) compared to the control group. The objective of the present study was to characterized of the CD34 + cell population in peripheral blood in patients with SA with reference to the control group. Moreover in patients with SA, fibrocytes and endothelial cells were analysed and their relationship to the fibrosis process based on assessment of diffusing capacity for carbon monoxide (DLCO).

Methods

Data from patients diagnosed with SA at Military Institute of Medicine (Warsaw, Poland) between January 2018 and December 2019 were collected and analysed ongoing basis. Peripheral blood was collected from 26 patients with newly diagnosed pulmonary SA and 16 healthy subjects. The immunomagnetic method and flow cytometry were used. Among the CD34+ progenitor cells were assessed: low-differentiated cells, hematopoietic progenitor cells and endothelial progenitor cells. The Statistica 12.0 software was used for a statistical analysis.

Results

We observed a significantly higher percentage of low-differentiated cells (13.8 vs. 2.3, P = 0.001) and endothelial cells (0.3 vs. 0.0, P = 0.001) in patients with SA compared to the control group. In the study group the median proportion of fibrocytes was 1.877% (0.983–2.340) in patients with DLCO< 80%, while in patients with DLCO> 80% was 0.795% (0.139–1.951) (P = 0.72). The median proportion of endothelial progenitor cells was higher in patients with DLCO< 80%: 0.889% (0.391–1.741), than in patients with DLCO> 80%: 0.451% (0.177–0.857) (P = 0.44).

Conclusions

In conclusion we demonstrated for the first time the immunophenotype of peripheral CD34 + cells with the degree of their differentiation. The study confirmed the involvement of low differentiated cells and endothelial cells in patients with SA.

Using SpO2 Recovery Index after a 6-Minute Walk Test to Predict Respiratory-Related Events in Hospitalized Patients with Interstitial Pneumonia

Although the prognostic factors of interstitial pneumonia (IP) patients have been reported, IP has poor prognosis. Hospitalized patients with IP have severely impaired pulmonary diffusion capacity and prominent desaturation. We hypothesized that determining oxygen saturation recovery (SpO₂ recovery index) after the 6-minute walk test (6MWT) can provide additional prognostic information regarding rehospitalization for respiratory-related events. We evaluated 73 IP patients at our hospital for demographic characteristics, pulmonary function tests and 6MWT. The Kaplan–Meier method was used to estimate rehospitalisation for respiratory-related events using SpO₂ recovery index. Cox regression analysis revealed a relationship between SpO₂ recovery index and rehospitalisation. The optimum cutoff value of SpO₂ recovery index was 4% (sensitivity, 71.4%; specificity, 79.2%). SpO₂ recovery index was most closely related to pulmonary diffusion capacity (r = 0.684, P < 0.001). In a multivariable model, it was the strongest independent predictor of rehospitalisation for respiratory-related events (hazard ratio, 0.3; 95% confidence interval, 0.10–0.90; P = 0.032). In this study, we estimated pulmonary diffusion capacity using SpO₂ recovery index values obtained from 6MWT. A SpO₂ recovery index of <4% can be useful in predicting rehospitalisation for respiratory-related events.

Altered pulmonary gas transfer capacity and capillary blood volume in pediatric Crohn's disease

OBJECTIVES

To describe diffusing capacity for carbon monoxide (DLCO) and its components, that is, membrane diffusing capacity (DmCO) and pulmonary capillary blood volume (Vc) in children with Crohn's disease (CD), and to investigate the correlation between these parameters and disease activity.

WORKING HYPOTHESIS

The most common lung function abnormalities are a reduced pulmonary DLCO and small airways disorders which are in many instances, clinically silent. No valid explanations have been proposed regarding the modifications in gas transfer capacity in active CD.

METHODS

DLCO, DmCO, and Vc were measured in 25 CD children by the simultaneous single breath lung diffusing capacity method using nitric oxide (NO) and carbon monoxide (CO) transfer. These parameters were analyzed in relation to the CD disease activity index.

RESULTS

DLCO (90.7 ± 4.5% vs 128.5 ± 4.7%; P < 0.001), Dm (92.4 ± 5.9% vs 125.6 ± 6.3%; P < 0.001), and Vc (72.6 ± 3.7% vs 104.4 ± 4.0%; P < 0.001) were significantly decreased in the active CD group in comparison with the inactive CD group. DLCO (r = -0.60; P < 0.01), DmCO (r = -0.45; P < 0.01), and Vc (r = -0.60; P < 0.01) were inversely correlated to the PCDAI. In 8 patients who participated to the study at initial diagnosis then during remission, DmCO and Vc increased significantly between the active and the inactive period of the disease.

CONCLUSION

Pulmonary diffusing capacity is impaired in children with active CD, mainly because of a decrease of the pulmonary capillary volume.

Oxygen desaturation during a 6-minute walk test as a predictor of maximal exercise-induced gas exchange abnormalities in sarcoidosis

BACKGROUND

Common tests for evaluating gas exchange impairment have different strengths and weaknesses. Alveolar-to-arterial oxygen pressure difference (AaDO2) at peak exercise is a sensitive indicator but it cannot be measured repeatedly. Diffusing capacity of the lung for carbon monoxide (DLco) is measured at rest and may be too insensitive to predict the effects of exercise on gas exchange impairment. Oxygen desaturation during a 6-minute walk test (∆SpO2-6MWT) can be measured repeatedly, but its value in sarcoidosis is unknown. Here, we evaluated the ability of ∆SpO2-6MWT and DLco to predict gas exchange impairment during exercise in sarcoidosis.

METHODS

This retrospective study of 130 subjects with sarcoidosis investigated the relationship between DLco, ∆SpO2-6MWT, and peak AaDO2 using correlation tests, inter-test reliability analyses, and predictive values. For the analyses of inter-test reliability and predictive values, DLco, peak AaDO2, and ∆SpO2-6MWT were considered as binary variables (normal/abnormal) according to previously defined thresholds.

RESULTS

Correlation coefficients between DLco, ∆SpO2-6MWT, and peak AaDO2 were intermediate (0.53-0.67, P<0.0003) and Kappa coefficients were low (0.21-0.42, P=0.0003-0.02). DLco predicted (I) increased peak AaDO2 with a positive predictive value (PPV) of 66% and a negative predictive value (NPV) of 78% and (II) increased ∆SpO2-6MWT with a PPV at 36% and an NPV at 88%. Normal DLco was a good predictor of the absence of severe desaturation during the 6MWT (94% NPV) and at peak exercise during cardiopulmonary exercise test (CPET) (100% NPV). ∆SpO2-6MWT predicted peak AaDO2 increase with a PPV of 74% and an NPV of 60%.

CONCLUSIONS

In a large population of sarcoidosis patients, neither ∆SpO2-6MWT nor DLco was a good predictor of increased peak AaDO2. In contrast, normal DLco was a good predictor of the absence of severe desaturation during the 6MWT and at peak exercise during CPET.

Pulmonary Sarcoidosis

Sarcoidosis is a systemic disease, with lung involvement in almost all cases. Abnormal chest radiography is usually a key step for considering diagnosis. Lung impact is investigated through imaging; pulmonary function; and, when required, 6-minute walk test, cardiopulmonary exercise testing, or right heart catheterization. There is usually a reduction of lung volumes, and forced vital capacity is the most accurate parameter to reflect the impact of pulmonary sarcoidosis with or without pulmonary infiltration at imaging. Various evolution patterns have been described. Increased risk of death is associated with advanced pulmonary fibrosis or cor pulmonale, particularly in African American patients.

Advanced pulmonary sarcoidosis

PURPOSE OF REVIEW

To present an update on the most recent contributions in advanced pulmonary sarcoidosis (APS).

RECENT FINDINGS

Pathology is better described and the differences between fibrosing pulmonary sarcoidosis and usual interstitial pneumonia (UIP) are clarified. Serial spirometry is the most reliable tool for monitoring evolution. Survival may be predicted by an integrative algorithm based on pulmonary function and computed tomography (CT).

SUMMARY

APS is characterized by significant fibrocystic pulmonary lesions at CT and pathology. There are two main patterns of APS, one with predominant central bronchovascular distortion, often associated with airflow limitation, and the other with predominant honeycombing with a different location than in UIP with severe restrictive impairment and very low diffusion capacity of the lung for carbon monoxide. APS may be burnt out but is most often still active as evidenced by several findings, including on F-fluorodeoxyglucose-PET. There is an increased mortality and morbidity with chronic respiratory insufficiency, pulmonary hypertension stemming from multiple mechanisms, chronic pulmonary aspergillosis and extra infections. Acute worsening episodes are frequent. Serial spirometry, particularly forced vital capacity, is the most reliable tool for monitoring evolution. A new elegant algorithm based on pulmonary function and CT may predict survival. Despite important stakes, there is still a lack of therapeutic recommendations. However, the use of antisarcoidosis treatment is most often required at least as a temporary trial. Finally, the effect of pulmonary hypertension treatment has recently been the object of further evaluation.

NT-proatrial natriuretic peptide as a possible biomarker of cardiopulmonary involvement in sarcoidosis

BACKGROUND

Lung diffusion for carbon monoxide (DLCO) has been shown to associate with the risk of pulmonary arterial hypertension development and, most likely, with right ventricular (RV) myocardial dysfunction in sarcoidosis patients. Besides its known role as a marker of left ventricular dysfunction, experimental evidence suggests a role of NT-proAtrial Natriuretic Peptide (NT-proANP) also in modulating pulmonary circulation. We therefore investigated possible relationships between NT-proANP, lung diffusion impairment and RV dysfunction.

METHODS

Thirty-two pulmonary sarcoidosis outpatients and eighteen volunteers underwent full clinical assessment, including full lung function tests and Doppler echocardiography integrated with tissue Doppler imaging (TDI) study. Resting circulating NT-proBNP and NT-proANP plasma levels were also determined.

RESULTS

NT-proANP and RV-myocardial performance index (RV-MPI) were significantly higher in those patients with the greatest DLCO impairment, whereas no differences were found for NT-proBNP values. At multivariable analysis, only DLCO (β: -0.496; standard error: 3.38; p=0.000) and RV-MPI (β: 0.373; standard error: 6.56; p=0.031) remained significantly associated with NT-proANP levels.

CONCLUSIONS

Our finding may support a key role of NT-proANP in the complex mechanisms underlying modulation of lung function. An early increase in pulmonary vascular resistance may stimulate NT-proANP increase, thus explaining its association with signs of early RV myocardial dysfunction. This hypothesis warrants further confirmation.

Clinical applications of lung function tests: a revisit

The development and clinical application of lung function tests have a long history, and the various components of lung function tests provide very important tools for the clinical evaluation of respiratory health and disease. Spirometry, measurement of the diffusion factor, bronchial provocation tests and forced oscillation techniques have found diverse clinical applications in the diagnosis and monitoring of respiratory diseases, such as chronic obstructive pulmonary disease, interstitial lung diseases and asthma. However, there are some practical issues to be resolved, including the establishment of reference values for individual test parameters and the roles of these tests in preoperative risk assessment and pulmonary rehabilitation. Novel measurements, including negative expiratory pressure, the fraction of exhaled nitric oxide and analysis of exhaled breath condensate, may provide new insights into physiological abnormalities or airway inflammation in respiratory diseases, but their clinical applications need to be further evaluated. The clinical application of lung function tests continues to face challenges, which may be overcome by further improvement of conventional techniques for lung function testing and further specification of new testing techniques.

Cardiopulmonary exercise testing variables as predictors of long-term outcome in thoracic sarcoidosis

Cardiopulmonary exercise testing (CPET) plays an important role in the assessment of functional capacity in patients with interstitial lung disease. The aim of this study was to identify CPET measures that might be helpful in predicting the vital capacity and diffusion capacity outcomes of patients with thoracic sarcoidosis. A longitudinal study was conducted on 42 nonsmoking patients with thoracic sarcoidosis (median age = 46.5 years, 22 females). At the first evaluation, spirometry, the measurement of single-breath carbon monoxide diffusing capacity (D_LCOsb) and CPET were performed. Five years later, the patients underwent a second evaluation consisting of spirometry and D_LCOsb measurement. After 5 years, forced vital capacity (FVC)% and D_LCOsb% had decreased significantly [95.5 (82-105) vs 87.5 (58-103) and 93.5 (79-103) vs 84.5 (44-102), respectively; P < 0.0001 for both]. In CPET, the peak oxygen uptake, maximum respiratory rate, breathing reserve, alveolar-arterial oxygen pressure gradient at peak exercise (P(A-a)O₂), and Δ SpO₂ values showed a strong correlation with the relative differences for FVC% and D_LCOsb% (P < 0.0001 for all). P(A-a)O₂ ≥22 mmHg and breathing reserve ≤40% were identified as significant independent variables for the decline in pulmonary function. Patients with thoracic sarcoidosis showed a significant reduction in FVC% and D_LCOsb% after 5 years of follow-up. These data show that the outcome measures of CPET are predictors of the decline of pulmonary function.

Comparison between cardiopulmonary exercise testing parameters and computed tomography findings in patients with thoracic sarcoidosis

BACKGROUND

Cardiopulmonary exercise testing (CPET) is a safe and clinically useful method to assess functional capacity and to follow disease progression and the response to treatment in several clinical conditions.

AIM

We set out to determine the relationship between outcome measures of CPET and high-resolution computed tomography (HRCT) findings in thoracic sarcoidosis.

METHODS

A cross-sectional study was carried out in which 42 nonsmoking outpatients (22 females; median age = 46.5 years) were evaluated. All the patients underwent pulmonary function tests (PFTs) and CPET. By using CPET, the most probable causes of exercise limitation were separated into respiratory mechanics (n = 25) and cardiovascular (n = 17). By using HRCT, the following patterns were recorded: predominant nodules (n = 18), predominant ground-glass opacity (n = 10), and predominant traction bronchiectasis and honeycombing (n = 14).

RESULTS

Although significant differences have been shown for both PFT parameters and CPET results, only the latter were able to distinguish between patients with ground-glass opacity and patients with traction bronchiectasis and honeycombing on HRCT. A statistically significant difference was found for peak VO(2), breathing reserve, and P(A-a)O(2) when patients with predominant traction bronchiectasis and honeycombing were compared to patients with other HRCT patterns (p < 0.0001). There was no statistical difference among the patterns with abnormal CPET and the patterns of abnormalities on HRCT (p > 0.05).

CONCLUSION

The functional capacity assessed by CPET was strongly influenced by HRCT patterns in sarcoidosis. Patients with traction bronchiectasis and honeycombing have lower exercise capacity measured by CPET.

Qualitative aspects of exertional dyspnea in patients with restrictive lung disease

Restrictive lung disease is a broad term encompassing a number of conditions in which lung volumes are reduced. Dyspnea is a common clinical manifestation of restrictive lung disease and frequently becomes a prominent and disabling symptom that undermines patients' ability to function and engage in activities of daily living (especially in those with more advanced restriction). Effective management of this disabling symptom awaits a better understanding of its underlying physiology. In recent decades, our understanding of the mechanisms of dyspnea in restrictive lung disease has been improved by a small, but significant, body of research. One approach to the study of dyspnea is to identify the major qualitative dimensions of the symptom in an attempt to uncover different underlying neurophysiologic mechanisms. This article will review the existing literature on the intensity and qualitative dimensions of dyspnea during exercise in patients with restrictive lung disease. The main focus will be on interstitial lung disease (ILD), since it is the prototypical restrictive disease.

Membrane diffusion- and capillary blood volume measurements are not useful as screening tools for pulmonary arterial hypertension in systemic sclerosis: a case control study

BACKGROUND

There is no optimal screening tool for the assessment of pulmonary arterial hypertension (PAH) in patients with systemic sclerosis (SSc). A decreasing transfer factor of the lung for CO (TLCO) is associated with the development of PAH in SSc. TLCO can be partitioned into the diffusion of the alveolar capillary membrane (Dm) and the capillary blood volume (Vc). The use of the partitioned diffusion to detect PAH in SSc is not well established yet. This study evaluates whether Dm and Vc could be candidates for further study of the use for screening for PAH in SSc.

METHODS

Eleven SSc patients with PAH (SScPAH+), 13 SSc patients without PAH (SScPAH-) and 10 healthy control subjects were included. Pulmonary function testing took place at diagnosis of PAH. TLCO was partitioned according to Roughton and Forster. As pulmonary fibrosis in SSc influences values of the (partitioned) TLCO, these were adjusted for fibrosis score as assessed on HRCT.

RESULTS

TLCO as percentage of predicted (%) was lower in SScPAH+ than in SScPAH- (41 +/- 7% vs. 63 +/- 12%, p < 0.0001, respectively). Dm% in SScPAH+ was decreased as compared with SScPAH- (22 +/- 6% vs. 39 +/- 12%, p < 0.0001, respectively), also after adjustment for total fibrosis score (before adjustment: B = 17.5, 95% CI 9.0-25.9, p = < 0.0001; after adjustment: B = 14.3, 95% CI 6.0-21.7, p = 0.008). No difference was found in Vc%. There were no correlations between pulmonary hemodynamic parameters and Dm% in the PAH groups.

CONCLUSION

SScPAH+ patients have lower Dm% than SScPAH- patients. There are no correlations between Dm% and hemodynamic parameters of PAH in SScPAH+. These findings do not support further study of the role of partitioning TLCO in the diagnostic work- up for PAH in SSc.

BAL fluid cells and pulmonary function in different radiographic stages of newly diagnosed sarcoidosis

PURPOSE

Sarcoidosis affected lungs detected in more than 90% of patients. The relationship between different stages of pulmonary sarcoidosis and pulmonary function tests (PFT) as well as bronchoalveolar lavage fluid (BALF) cells can be established. Geographic and ethnic factors are known to be linked to the specific characteristics of patients with sarcoidosis. The purpose of the study was to evaluate peculiarities of BALF cells pattern and pulmonary function tests at the time of the diagnosis of different radiographic types of sarcoidosis in a large group of Lithuanian sarcoid patients.

MATERIAL AND METHODS

This is the prospective study of BALF cells and PFT of patients with newly diagnosed sarcoidosis. The study population consisted of 221 non-treated non-smoker patients. All patients underwent BAL and the majority of them underwent PFT.

RESULTS

Comparing Stage I to Stage III groups, a slight increase in the macrophage and neutrophil count and a decrease of lymphocyte count was apparent. However, the leukocyte population difference was not statistically significant. We have observed significant increase of CD8 cell count, as well as a decrease of both the CD4 cell count and the CD4/CD8 ratio from Stage I to Stage III. We have determined statistically significant differences in all PFT parameters among the patient groups with different radiographic stages of sarcoidosis. The values of FVC, VC and TLC tended to decrease with an elevation of BALF neutrophils and/or eosinophils count. However BALF cells did not correlate well with PFT indices.

CONCLUSIONS

In newly diagnosed sarcoid patients, BALF cell and PFT markers depend on the sarcoidosis stage.

Determinants of maximal oxygen uptake in moderate acute hypoxia in endurance athletes

The factors determining maximal oxygen consumption were explored in eight endurance trained subjects (TS) and eight untrained subjects (US) exposed to moderate acute normobaric hypoxia. Subjects performed maximal incremental tests at sea level and simulated altitudes (1,000, 2,500, 4,500 m). Heart rate (HR), stroke volume (SV), cardiac output (.Q), arterialized oxygen saturation (Sa'O2), oxygen uptake (.VO2max), ventilation (.VE, expressed in normobaric conditions) were measured. At maximal exercise, ventilatory equivalent (.VE/.VO2max), O2 transport (.QaO2max) and O2 extraction (O2ERmax) were calculated. In TS, .Qmax remained unchanged despite a significant reduction in HRmax at 4,500 m. SVmax remained unchanged. .VEmax decreased in TS at 4,500 m, .VE/.VO2max was lower in TS and greater at 4,500 m vs. sea level in both groups. Sa'O2max decreased at and above 1,000 m in TS and 2,500 m in US, O2ERmax increased at 4,500 m in both groups. .QaO2max decreased with altitude and was greater in TS than US up to 2,500 m but not at 4,500 m. .VO2max decreased with altitude but the decrement (Delta.VO2max) was larger in TS at 4,500 m. In both groups Delta.VO2max in moderate hypoxia was correlated with Delta.QaO2max. Several differences between the two groups are probably responsible for the greater Delta.VO2max in TS at 4,500 m : (1) the relative hypoventilation in TS as shown by the decrement in .VEmax at 4,500 m (2) the greater.QaO2max decrement in TS due to a lower Sa'O2max and unchanged .Qmax 3) the smaller increase in O2ERmax in TS, insufficient to compensate the decrease in .QaO2max.

Prolonged expiration down to residual volume leads to severe arterial hypoxemia in athletes during submaximal exercise

The goal of this study was to assess the effects of a prolonged expiration (PE) carried out down to the residual volume (RV) during a submaximal exercise and consider whether it would be worth including this respiratory technique in a training programme to evaluate its effects on performance. Ten male triathletes performed a 5-min exercise at 70% of maximal oxygen consumption in normal breathing (NB(70)) and in PE (PE(70)) down to RV. Cardiorespiratory parameters were measured continuously and an arterialized blood sampling at the earlobe was performed in the last 15s of exercise. Oxygen consumption, cardiac frequency, end-tidal and arterial carbon dioxide pressure, alveolar-arterial difference for O(2) (PA(O2) - Pa(O2)) and P(50) were significantly higher, and arterial oxygen saturation (87.4+/-3.4% versus 95.0+/-0.9%, p<0.001), alveolar (PA(O2)) or arterial oxygen pressure, pH and ventilatory equivalent were significantly lower in PE(70) than NB(70). There was no difference in blood lactate between exercise modalities. These results demonstrate that during submaximal exercise, a prolonged expiration down to RV can lead to a severe hypoxemia caused by a PA(O2) decrement (r=0.56; p<0.05), a widened PA(O2) - Pa(O2) (r=-0.85; p<0.001) and a right shift of the oxygen dissociation curve (r=-0.73; p<0.001).

Moderate exercise in hypoxia induces a greater arterial desaturation in trained than untrained men

During moderate exercise breathing a low inspired O(2) fraction (F(I)O(2)), arterial O(2) desaturation may depend on the fitness level. Seven trained (TM) and seven untrained men (UTM) cycled in normoxia and in hypoxia (F(I)O(2)=0.187, 0.173, 0.154, 0.13 and 0.117). We compared TM and UTM at submaximal intensities below the ventilatory threshold. Ventilatory variables were monitored and arterial oxygen saturation was measured by pulse oximetry. O(2) saturation was not different between groups at sea level. In hypoxia, O(2) saturation was lower in TM than in UTM at F(I)O(2)=0.154 (87.3 +/- 2.9% vs 90.4 +/- 1.5% at 90 W) and below. Both the ventilatory-equivalent and the end-tidal O(2) pressure were lower in TM at sea level and at every F(I)O(2), with the differences between TM and UTM becoming apparent at lower exercise intensity and increasing in magnitude as the severity of hypoxia increased. O(2) saturation was correlated with the ventilatory parameters at every F(I)O(2) and the correlations were stronger in severe hypoxia. These results demonstrate that a moderate exercise carried out in hypoxia, contrary to normoxic conditions, can lead to a greater arterial desaturation in TM compared with UTM. This phenomenon could be partly attributed to a relative hypoventilation in trained subjects.

Diffusing Capacity for Nitric Oxide and Carbon Monoxide in Patients With Diffuse Parenchymal Lung Disease and Pulmonary Arterial Hypertension

BACKGROUND

The passage of carbon monoxide (CO) through the alveolocapillary membrane and into the plasma and intraerythrocytic compartments determines the diffusing capacity of the lung for CO (DLCO) as defined by the Roughton and Forster equation. On the other hand, the single-breath diffusing capacity of the lung for nitric oxide (DLNO) is thought to represent the true membrane diffusing capacity because of its very high affinity for hemoglobin (Hb) and its independence from pulmonary capillary blood volume. Therefore, the DLNO/DLCO ratio can be used to differentiate between thickened alveolocapillary membranes (both DLNO and DLCO are decreased, and the DLNO/DLCO ratio is normal) and decreased perfusion of ventilated alveoli (the DLNO less decreased than the DLCO; therefore, the DLNO/DLCO ratio is high) in patients with pulmonary disease.

STUDY DESIGN

We measured the combined values of DLCO and DLNO in 41 patients with diffuse parenchymal lung disease (DPLD), 26 patients with pulmonary arterial hypertension (PAH), and 71 healthy subjects.

RESULTS

The DLCO (corrected to the standard Hb value) was lowered in the DPLD group (64% of predicted) and in the PAH group (64% of predicted), and was normal in the control group (105% of predicted). The DLNO/DLCO ratio in patients with PAH (4.98) was significantly higher than that in patients with DPLD (4.56) and in healthy subjects (4.36).

CONCLUSION

The DLNO/DLCO ratio is significantly higher in patients with PAH than in healthy subjects, although this ratio cannot be applied as a screening test to discriminate between patients with DPLD and PAH as the overlap between these groups is too large.

[Pathophysiology of interstitial lung disease]

Chronic interstitial lung disease (ILD) groups a number of diseases with the common feature of radiological pulmonary infiltration, typical functional syndrome, and diffuse involvement of the deep pulmonary parenchyma identified histologically. Correlations between histological and radiological findings have enabled progress in both fields, leading to better interpretation of the radiological findings and optimizing the etiological diagnosis. Besides the signs themselves, their distribution in relation to the normal lung structures is highly contributive. Function tests can be used to quantify the impact on the respiratory system and assess the effect of treatment. Evidence-based criteria will progressively replace the consensual criteria enabling more effective evaluation of treatment in difficult pathological conditions such as idiopathic pulmonary fibrosis.

Paediatric sarcoidosis

Sarcoidosis is a multisystem granulomatous disease of unknown aetiology, most commonly affecting young adults. Divergent prevalence rates and clinical appearances in different races indicate the existence of predisposing genes, with probably a major effect of the major histocompatibility complex. The diagnosis is relatively rare in children. Lesions can occur in almost any tissue or organ but the lungs, lymph nodes, eyes, skin and liver are the most commonly involved. Clinical symptoms are non-specific and often minor. The diagnosis can only be supported by typical histopathological findings with non-caseating epithelioid-cell granulomas. The prognosis seems to be more severe in younger children and in cases of multi-organ involvement. Corticosteroids are the therapeutic agents most commonly used and are indicated in cases of significant lung or eye lesions, cardiac, neurological, or multiorgan involvement. Close monitoring is mandatory during and after treatment because relapses are common.

Pulmonary sarcoidosis

Sarcoidosis is a multisystemic disease of unknown aetiology characterized by the formation of immune granulomas in involved organs. It is a worldwide disease that mainly affects 25-40 years old people with a lifetime incidence rate of 0.85-2.4%. Multiple clinical phenotypes are observed according to presentation, involved organs, disease duration and severity. Sarcoidosis primarily affects the lungs and the lymphatic system. The prevailing pathogenic hypothesis is that various antigens could promote sarcoidosis in genetically susceptible hosts, both these factors modulating the incidence and the clinical phenotype of sarcoidosis. So far, environmental agents have been suspected, including possible mycobacteria and propionibacteria. Interferon-gamma, tumour necrosis factor (TNF)-alpha, interleukin (IL)-12 and IL-18 play a critical role in driving the Th1 commitment in the course of granulomatous process. Evolution of sarcoidosis is often marked by spontaneous resolution within 12-36 months, but can be severe because of chronic cases with pulmonary fibrosis or involving other organs, including heart, central nervous system and eyes. Mortality, ranging between 0.5 and 5%, is most often related to pulmonary fibrosis. Corticosteroids can reverse the granulomatous process, but are only suspensive, and their long-term benefit remains under question. Corticosteroids are recommended when sarcoidosis shows unfavourable clinical tolerance and evolution. Alternative and corticosteroid-sparing therapies are of increased interest in difficult cases, while targeted new drugs such as anti-TNF-alpha are still under investigation.