Acute severe radiation pneumonitis among non-small cell lung cancer (NSCLC) patients with moderate pulmonary dysfunction receiving definitive concurrent chemoradiotherapy: Impact of pre-treatment pulmonary function parameters

PURPOSE

Severe acute radiation pneumonitis (SARP) is a life-threatening complication of thoracic radiotherapy. Pre-treatment pulmonary function (PF) may influence its incidence. We have previously reported on the incidence of SARP among patients with moderate pulmonary dysfunction who received definitive concurrent chemoradiotherapy (dCCRT) for non-small cell lung cancer (NSCLC).

METHODS

The clinical outcomes, dose-volume histograms (DVH), and PF parameters of 122 patients (forced expiratory volume in 1 s [FEV1%]: 60-69%) receiving dCCRT between 2013 and 2019 were recorded. SARP was defined as grade ≥3 RP occurring during or within 3 months after CCRT. Logistic regression, receiver operating characteristics curves (ROC), and hazard ratio (HR) analyses were performed to evaluate the predictive value of each factor for SARP.

RESULTS

Univariate and multivariate analysis indicated that the ratio of carbon monoxide diffusing capacity (DLCO%; odds ratio [OR]: 0.934, 95% confidence interval [CI] 0.896-0.974, p = 0.001) and mean lung dose (MLD; OR: 1.002, 95% CI 1.001-1.003, p = 0.002) were independent predictors of SARP. The ROC AUC of combined DLCO%/MLD was 0.775 (95% confidence interval [CI]: 0.688-0.861, p = 0.001), with a sensitivity and specificity of 0.871 and 0.637, respectively; this was superior to DLCO% (0.656) or MLD (0.667) alone. Compared to the MLD-low/DLCO%-high group, the MLD-high/DLCO%-low group had the highest risk for SARP, with an HR of 9.346 (95% CI: 2.133-40.941, p = 0.003).

CONCLUSION

The DLCO% and MLD may predict the risk for SARP among patients with pre-treatment moderate pulmonary dysfunction who receive dCCRT for NSCLC. Prospective studies are needed to validate our findings.

Overcoming safety challenges in CO therapy - Extracorporeal CO delivery under precise feedback control of systemic carboxyhemoglobin levels

Carbon monoxide (CO) has demonstrated therapeutic potential in multiple inflammatory conditions including intensive care applications such as organ transplantation or sepsis. Approaches to translate these findings into future therapies, however, have been challenged by multiple hurdles including handling and toxicity issues associated with systemic CO delivery. Here, we describe a membrane-controlled Extracorporeal Carbon Monoxide Release System (ECCORS) for easy implementation into Extracorporeal Membrane Oxygenation (ECMO) setups, which are being used to treat cardiac and respiratory diseases in various intensive care applications. Functionalities of the ECCORS were investigated in a pig model of veno-arterial ECMO. By precisely controlling CO generation and delivery as a function of systemic carboxyhemoglobin levels, the system allows for an immediate onset of therapeutic CO-levels while preventing CO-toxicity. Systemic carboxyhemoglobin levels were profiled in real-time by monitoring exhaled CO levels as well as by pulse oximetry, enabling self-contained and automatic feedback control of CO generation within ECCORS. Machine learning based mathematical modeling was performed to increase the predictive power of this approach, laying foundation for high precision systemic CO delivery concepts of tomorrow.

Differences and similarities between bronchopulmonary dysplasia and asthma in schoolchildren

BACKGROUND

The long-term respiratory characteristics of ex-preterm children with bronchopulmonary dysplasia (BPD) are not established. The objective of this study was to describe hallmarks of BPD at school age in comparison to children with atopic asthma.

METHODS

This study was a cross-sectional descriptive comparative study in a hospital-based setting. Thirty schoolchildren diagnosed with BPD (10.4 years/born at 26.6 weeks' gestation) and 30 age- and sex-matched children with asthma and sensitized to airborne allergens (IgE >0.35 kU_A /L) were analyzed. Measurements included fraction of exhaled nitric oxide (FENO, ppb), dynamic and static lung function, and bronchial provocation with methacholine (PD:20) and mannitol (PD:15), as well as an evaluation of respiratory symptoms using the asthma control test (C-ACT).

RESULTS

Lung function measures (FEV1% 77 vs 84, FEV1/FVC% 85 vs 91, FEF50% 61 vs 80) and carbon monoxide diffusion capacity (DLCO%, 81 vs 88) were all reduced in children with BPD compared to asthma (P values <0.042). FENO values were also significantly lower in children with BPD (12 vs 23, P = 0.019). The proportion of positive methacholine tests (74% vs 93%, P = 0.14) was comparable between BPD and asthma. However, less responsiveness towards mannitol (19% vs 61%, P = 0.007) and fewer self-reported symptoms (C-ACT, median 26 vs 24, P = 0.003) were found in the BPD group.

CONCLUSION

Respiratory hallmarks of BPD at school-age were reduced lung function, limited responsiveness towards indirectly acting mannitol but hyper-responsiveness towards direct acting methacholine and impairment in diffusion capacity. Children with BPD displayed less evidence of airway inflammation compared with atopic asthma.

Utility of FVC/DLCO ratio to stratify the risk of mortality in unselected subjects with pulmonary hypertension

In patients with systemic sclerosis, a ratio between forced vital capacity (FVC) and diffusing capacity of carbon monoxide (DLCO, FCV%/DLCO%) >1.5 might be a predictor of pulmonary hypertension (PH). The aim of this study is, therefore, to evaluate whether this index can be used in patients with PH, regardless of etiology. 83 consecutive outpatients with suspected PH at non-invasive work-up underwent spirometry and DLCO test before right heart catheterization (RHC); FVC%/DLCO% ratio was then calculated and compared with mean pulmonary-artery-pressure (mPAP) and mortality at 5-year follow-up. Significant correlations between FVC%/DLCO% and PAsP and mPAP levels were found (p < 0.05). After ROC curve analysis and definition of best cut-off values for PAsP and FVC%/DLCO%, increased mPAP values at RHC were observed comparing subjects with both PAsP and FVC%/DLCO% values below cut off values (-/-), either PAsP or FVC%/DLCO% above cut off values (±), or both above (+/+) (p < 0.05). Poorer survival rates are observed at follow-up with higher FVC%/DLCO% values (0% for <1, 17.4% for 1-3, 33.3% for >3, p < 0.05), when comparing subjects with either increased PAsP and FVC%/DLCO% values or both with those with lower (log-rank p < 0.05). Even in subjects with mPAP at RHC >25 mmHg, increased FVC%/DLCO% values predicted a worse outcome (p < 0.05). FVC%/DLCO% values are related to mPAP in subjects with suspected PH, and may further stratify the risk of mortality in addition to PAP.

Gasotransmitters in cancer: from pathophysiology to experimental therapy

The three endogenous gaseous transmitters - nitric oxide (NO), carbon monoxide (CO) and hydrogen sulfide (H2S) - regulate a number of key biological functions. Emerging data have revealed several new mechanisms for each of these three gasotransmitters in tumour biology. It is now appreciated that they show bimodal pharmacological character in cancer, in that not only the inhibition of their biosynthesis but also elevation of their concentration beyond a certain threshold can exert anticancer effects. This Review discusses the role of each gasotransmitter in cancer and the effects of pharmacological agents - some of which are in early-stage clinical studies - that modulate the levels of each gasotransmitter. A clearer understanding of the pharmacological character of these three gases and the mechanisms underlying their biological effects is expected to guide further clinical translation.

Relevance of partitioning DLCO to detect pulmonary hypertension in systemic sclerosis

We investigated whether partitioning DLCO into membrane conductance for CO (DmCO) and pulmonary capillary blood volume (Vcap) was helpful in suspecting precapillary pulmonary (arterial) hypertension (P(A)H) in systemic sclerosis (SSc) patients with or without interstitial lung disease (ILD). We included 63 SSc patients with isolated PAH (n=6), isolated ILD (n=19), association of both (n=12) or without PAH and ILD (n=26). Partitioning of DLCO was performed by the combined DLNO/DLCO method. DLCO, DmCO and Vcap were equally reduced in patients with isolated PAH and patients with isolated ILD but Vcap/alveolar volume (VA) ratio was significantly lower in the isolated PAH group. In patients without ILD, DLCO, DmCO, Vcap and Vcap/VA ratio were reduced in patients with isolated PAH when compared to patients without PAH and both Vcap/VA and DLCO had the highest AUC to detect PAH. In patients with ILD, Vcap had the highest AUC and performed better than DLCO to detect PH in this subgroup. In conclusion, Vcap/VA was lower in PAH than in ILD in SSC whereas DLCO was not different. Vcap/VA ratio and DLCO had similar high performance to detect PAH in patients without ILD. Vcap had better AUC than DLCO, DmCO and FVC/DLCO ratio to detect PH in SSC patients with ILD. These results suggest that partitioning of DLCO might be of interest to detect P(A)H in SSC patients with or without ILD.

Diffusion capacity in children: what happens with exercise?

There is comparatively little data on diffusion capacity in children during exercise. With the advent of improved technology, there is an increasing interest in exercise testing of children in order to predict the evolution of lung disease. In addition to the standard measure of exercise capacity, the VO(2max), interest is evolving in the consequences of alterations in diffusion capacity which may be unmasked with exercise. This review will consider what is known about diffusion capacity with exercise in children with well documented lung disease in the form of cystic fibrosis, healthy controls and swimmers as elite athletes with the largest lung volumes.

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.

Examination of the carbon monoxide diffusing capacity (DL(CO)) in relation to its KCO and VA components

The single-breath carbon monoxide diffusing capacity (DL(CO)) is the product of two measurements during breath holding at full inflation: (1) the rate constant for carbon monoxide uptake from alveolar gas (kco [minute(-1)]) and (2) the "accessible" alveolar volume (Va). kco expressed per mm Hg alveolar dry gas pressure (Pb*) as kco/Pb*, and then multiplied by Va, equals Dl(CO); thus, Dl(CO) divided by Va (DL(CO)/Va, also called Kco) is only kco/Pb* in different units, remaining, essentially, a rate constant. The notion that DL(CO)/Va "corrects" DL(CO) for reduced Va is physiologically incorrect, because DL(CO)/Va is not constant as Va changes; thus, the term Kco reflects the physiology more appropriately. Crucially, the same DL(CO) may occur with various combinations of Kco and Va, each suggesting different pathologies. Decreased Kco occurs in alveolar-capillary damage, microvascular pathology, or anemia. Increased Kco occurs with (1) failure to expand normal lungs to predicted full inflation (extrapulmonary restriction); or (2) increased capillary volume and flow, either globally (left-to-right intracardiac shunting) or from flow and volume diversion from lost or damaged units to surviving normal units (e.g., pneumonectomy). Decreased Va occurs in (1) reduced alveolar expansion, (2) alveolar damage or loss, or (3) maldistribution of inspired gases with airflow obstruction. Kco will be greater than 120% predicted in case 1, 100-120% in case 2, and 40-120% in case 3, depending on pathology. Kco and Va values should be available to clinicians, as fundamental to understanding the clinical implications of DL(CO). The diffusing capacity for nitric oxide (DL(NO)), and the DL(NO)/DL(CO) ratio, provide additional insights.