Rie Skovly Thomsen

In patients with chronic obstructive pulmonary disease (COPD) who exhibit reduced alveolar–capillary reserve, the combined assessment of pulmonary diffusing capacity for carbon monoxide and nitric oxide ( D _L,CO,NO ) during exercise may pose difficulties, and the transition from upright to supine posture may offer a useful alternative. A total of 50 participants (35 with COPD and 15 healthy controls) underwent measurements of D _L,CO,NO in the upright and supine postures. A subset (COPD: n = 12, controls: n = 12) also completed a 12‐week supervised high‐intensity interval training (HIIT) intervention. The reported D _L,CO,NO metrics were diffusing capacity for nitric oxide and carbon monoxide ( D _L,NO and D _L,CO,5s , respectively), alveolar–capillary membrane diffusing capacity ( D _M,CO ), pulmonary capillary blood volume ( V _C ), and alveolar volume ( V _A ). The upright‐to‐supine change in neither D _L,NO ( P  = 0.271), nor D _M,CO ( P  = 0.068) nor V _A ( P  = 0.934) differed between groups. In contrast, the upright‐to‐supine change in D _L,CO5s was reduced in moderate and severe COPD compared with controls (control vs. moderate: median [IQR] 0.6 [0.3, 0.9] mmol/min/kPa, P  < 0.001; control vs. severe: 0.9, [0.2, 1.5] mmol/min/kPa, P  = 0.006), whereas it did not differ between controls and mild COPD (0.3 [−0.1, 0.7] mmol/min/kPa, P  = 0.13). Similarly, the upright‐to‐supine V _C change was reduced in moderate and severe COPD compared with healthy controls (control vs. moderate: 8.3 [3.9, 12.8] mL, P  < 0.001; control vs. severe: 10.7 [1.2, 20.2] mL, P  = 0.021), but not in mild COPD (5.3 [−0.2, 10.8] mL, P  = 0.063). The HIIT intervention had no effect on these metrics. The blunted V _C response to an upright‐to‐supine postural change in moderate‐to‐severe COPD is consistent with reduced alveolar–capillary reserve and may be useful when measurements during exercise are not possible.

Background: Several patients exhibit a severity-dependent reduced pulmonary diffusing capacity (D _LCOc ) following coronavirus disease 2019 (COVID-19) infection. This has been attributed to fibrosis-like restrictive lung disease, as shown by chest high-resolution computed tomography (HRCT), and concurrent ventilatory disturbances observed by ventilation-perfusion single-photon emission computed tomography (V/Q SPECT) imaging. The aim of this study was to investigate whether reductions in D _L,COc at short- and intermediate-term follow-up were associated with initial severity of COVID-19, and to which extend this was linked to the presence of fibrosis-like abnormalities on HRCT and ventilatory disturbances on V/Q SPECT. Methods: A total of 153 patients diagnosed with COVID-19 between March 2020 and March 2021 were included in the study. The patients underwent lung function testing, chest HRCT, and V/Q SPECT at short-term (5.6 months) follow-up. Individuals exhibiting any evidence of post-COVID-19 sequelae ( n = 121) were also referred to intermediate follow-up (12.5 months). Results: At short-term follow-up, a severity dependent reduction in D _L,COc was observed, which was not evident at intermediate follow-up. At both short-term and intermediate follow-up, HRCT showed ground-glass opacity (GGO) and fibrosis-like abnormalities related to disease severity. Most patients had V/Q defects mainly with ventilatory abnormalities, including both matched and inversely matched defects at both follow-up times. Conclusion: The severity-dependent reduction in D _L,COc at short-term follow-up, associated with restrictive lung function pattern, GGO and fibrosis on HRCT, and ventilatory disturbances on V/Q SPECT, showed spontaneous recovery by intermediate follow-up. However, the restrictive ventilatory disturbances and associated morphological changes persisted.

Background: Cardiopulmonary exercise testing (CPET) is usually considered the gold standard for assessing maximal oxygen consumption (V̇O_2max), a health and performance marker in patients with chronic obstructive pulmonary disease (COPD). Despite the widespread application of CPET, the absolute and relative test‐retest reliability of CPET‐derived metrics remains unexamined.Objective: To examine and compare test‐retest reliability of CPET derived metrics in individuals with COPD and healthy matched controls.Methods: 12 individuals with COPD and 12 healthy age‐ and sex‐matched controls were included in this case‐control study. Each participant completed two CPET on a bicycle ergometer on two different days. Absolute reliability was reported as smallest real difference (SRD) and relative reliability as coefficient of variance (CV) and intraclass correlation coefficients (ICC).Main Results: SRD for peak oxygen uptake was 451.6 (267.4;1006.4) mL/min and CV was 7.8 (4.7;11.0)% in patients with COPD, whereas SRD was 244.2 (151.4;491.5) mL/min and CV was 3.0 (1.8;4.2)% in healthy controls but with no significant between group difference for SRD. CV values for all CPET derived metrics were found to be below 10%. Apart from peak workload achieved and peak minute ventilation, SRD and CV were significantly higher in COPD than in controls for all other CPET‐derived metrics.Conclusion: This study provides test‐retest reliability estimates of the most widely used CPET derived metrics in individuals with COPD and healthy matched controls. Test‐retest reliability for most metrics derived from CPET were found to be lower in individuals with COPD when compared to healthy controls.

There is limited knowledge on diffusing capacity in scoliosis patients. It remains to be determined if impaired pulmonary diffusing capacity is mostly influenced by reduced alveolar–capillary membrane diffusing capacity (D_{M, CO}), reduced pulmonary capillary blood volume (V_C) or both. This study aims to report findings from dual test gas pulmonary diffusing capacity for carbon monoxide and nitric oxide (D_{L, CO, NO}) with quantification of pulmonary diffusing capacity for carbon monoxide corrected for haemoglobin with a five s breath‐hold (D_{L, COc, 5s}) and nitric oxide with a five s breath‐hold (D_{L, NO, 5s}), D_{M, CO} and V_C. The study included 57 patients with idiopathic scoliosis seen at our department from 1972 to 1983, all of whom underwent radiological assessment and measurement of D_{L, CO, NO} during examination 40 years after diagnosis. One‐way ANOVA was performed for between‐group differences and Pearson's correlation coefficient was used to assess correlations between D_{L, CO, NO} metrics and Cobb angle. No significant between‐group differences based on disease severity were detected. Thirty‐nine percent of the patients were presented with either reduced D_{L, COc, 5s} or reduced D_{L, NO, 5s} represented as Z‐scores below −1.65. No significant correlations between Cobb angle and Z‐scores for D_{L, COc, 5s}, D_{L, NO, 5s}, D_{M, CO} and V_C according to height measurements were found. When using arm span instead, a weak negative correlation between D_{L, COc, 5s} and Cobb angle (r = −0.29; P = 0.04) was detected. In conclusion, approximately 39% of patients with idiopathic scoliosis had either reduced D_{L, COc, 5s} or reduced D_{L, NO, 5s} 40 years after diagnosis with varying contributions from V_C or D_{M, CO}.

The objective of the current review was to identify whether clinically established lung function metrics of ventilatory and diffusion capacity obtained by standardised methodology are consistent with superior lung function in athletes, and whether this is related to maximal oxygen uptake (VO2max). Three independent reviewers performed a literature search in PubMed, Scopus, and reference screening. Data was extracted and analysed according to a predefined strategy. Studies published between 1970 and 2023 on athletes reporting VO(2)max and at least one of the following lung function metrics: predicted forced expiratory volume in the first second of a forced vital capacity manoeuvre (FEV1%pred); predicted forced vital capacity (FVC%pred); predicted total lung capacity (TLC%pred); predicted pulmonary diffusion capacity for carbon monoxide (DL,CO%pred). Data on population size, age, sex, type of sports, as well as FEV1%pred, FVC%pred, TLC%pred, DL,CO%pred, and VO2max were extracted. Standardised mean, differences, and 95% CI were calculated when data were sufficient. In total, 13 original studies encompassing 193 individuals across various sports disciplines met the inclusion criteria. Pooled FEV1%pred was 111% (108-113%; 13 studies; n=193), FVC%pred 112% (108-116 %; 7 studies; n=118), TLC%pred 106% (103-108 %; 4 studies; n=60), and DL,CO%pred 121% (120-122 %; 2 studies; n=23). None of the studies provided sufficient data to evaluate the relationship between any of the lung function metrics and VO2max. In conclusion, athletes consistently exhibit high ventilatory and diffusing capacity metrics, but it is still unknown whether this is related to VO2max.

D_LCO/NO, the combined single‐breath measurement of the diffusing capacity to carbon monoxide (D_LCO) and nitric oxide (D_LNO) measured either during exercise or in the resting supine position may be a useful physiological measure of alveolar–capillary reserve. In the present study, we investigated the between‐day test–retest reliability of D_LCO/NO‐based metrics. Twenty healthy volunteers (10 males, 10 females; mean age 25 (SD 2) years) were randomized to repeated D_LCO/NO measurements during upright rest followed by either exercise (n = 11) or resting in the supine position (n = 9). The measurements were repeated within 7 days. The smallest real difference (SRD), defined as the 95% confidence limit of the standard error of measurement (SEM), the coefficient of variance (CV), and intraclass correlation coefficients were used to assess test–retest reliability. SRD for D_LNO was higher during upright rest (5.4 (95% CI: 4.1, 7.5) mmol/(min kPa)) than during exercise (2.7 (95% CI: 2.0, 3.9) mmol/(min kPa)) and in the supine position (3.0 (95% CI: 2.1, 4.8) mmol/(min kPa)). SRD for D_LCOc was similar between conditions. CV values for D_LNO were slightly lower than for D_LCOc both during exercise (1.5 (95% CI: 1.2, 1.7) vs. 3.8 (95% CI: 3.2, 4.3)%) and in the supine position (2.2 (95% CI: 1.8, 2.5) vs. 4.8 (95% CI: 3.8, 5.4)%). D_LNO increased by 12.3 (95% CI: 11.1, 13.4) and D_LCOc by 3.3 (95% CI: 2.9, 3.7) mmol/(min kPa) from upright rest to exercise. The D_LCO/NO technique provides reliable indices of alveolar–capillary reserve, both during exercise and in the supine position.