Sourcing UK COVID-19 News: An Analysis of Sourcing Patterns of 15 UK News Outlets Reporting on COVID-19 Across Facebook, Twitter, and Instagram.

How a health emergency is defined and presented through the news media matters for public understanding and health outcomes. Previous studies have endeavored to identify the patterns of news sourcing in crisis coverage, specifically the interplay between political sources and health expert sources, but yielded inconclusive results. This study analyses the types and roles of actors (those entities mentioned in a story) and sources cited in news coverage of COVID-19 by surveying social media posts published by 15 UK news outlets coverage across Facebook, Twitter, and Instagram between 1 January to December 31 2020. Overall, the findings show the prominence of political sources in UK news and that the most frequently named sources were representatives of the UK government. Moreover, when stories involved political actors, they were more likely to be given a voice as a source. This demonstrates how COVID-19 was a generalized crisis for the UK, which cascaded beyond health and into other economic, social, and cultural domains. The data show some variations in sourcing patterns between the different social media platforms. The analysis suggests that this may reflect the conventions of presenting news on each platform, with some tending toward the model of consensus by prioritizing political and government sources, and others contributing to a sphere of legitimate controversy by giving voice to a wider range of sources. This is distinctive and opens up the possibility for further research on how journalists adapt stories for social media and the consequences for public health communication.

Development of lung diffusion to adulthood following extremely preterm birth.

BACKGROUND: Gas exchange in extremely preterm (EP) infants must take place in fetal lungs. Childhood lung diffusing capacity of the lung for carbon monoxide (D LCO) is reduced; however, longitudinal development has not been investigated. We describe the growth of D LCO and its subcomponents to adulthood in EP compared with term-born subjects. METHODS: Two area-based cohorts born at gestational age ≤28 weeks or birthweight ≤1000 g in 1982-1985 (n=48) and 1991-1992 (n=35) were examined twice, at ages 18 and 25 years and 10 and 18 years, respectively, and compared with matched term-born controls. Single-breath D LCO was measured at two oxygen pressures, with subcomponents (membrane diffusion (D M) and pulmonary capillary blood volume (V C)) calculated using the Roughton-Forster equation. RESULTS: Age-, sex- and height-standardised transfer coefficients for carbon monoxide (K CO) and D LCO were reduced in EP compared with term-born subjects, and remained so during puberty and early adulthood (p-values for all time-points and both cohorts ≤0.04), whereas alveolar volume (V A) was similar. Development occurred in parallel to term-born controls, with no signs of pubertal catch-up growth nor decline at age 25 years (p-values for lack of parallelism within cohorts 0.99, 0.65, 0.71, 0.94 and 0.44 for z-D LCO, z-V A, z-K CO, D M and V C, respectively). Split by membrane and blood volume components, findings were less clear; however, membrane diffusion seemed most affected. CONCLUSIONS: Pulmonary diffusing capacity was reduced in EP compared with term-born subjects, and development from childhood to adulthood tracked in parallel to term-born subjects, with no signs of catch-up growth nor decline at age 25 years.

Nitric oxide in exhaled gas and tetrahydrobiopterin in plasma after exposure to hyperoxia.

The fraction of nitric oxide in exhaled gas (FENO) is decreased after exposure to hyperoxia in vivo, although the mechanisms for this decrease is not clear. A key co-factor for nitric oxide synthase (NOS), tetrahydrobiopterin (BH4), has been shown to be oxidized in vitro when exposed to hyperoxia. We hypothesized that the decrease of FENO is due to decreased enzymatic generation of NO due to oxidation of BH4. The present study was performed to investigate the relationship between levels of FENO and plasma BH4 following hyperoxic exposure in humans. Two groups of healthy subjects were exposed to 100% oxygen for 90 minutes. FENO was measured before and 10 minutes (n = 13) or 60 minutes (n = 14) after the exposure. Blood samples were collected at the same time points for quantification of biopterin levels (BH4, BH2 and B) using LC-MS/MS. Each subject was his or her own control, breathing air for 90 minutes on a separate day. Hyperoxia resulted in a 28.6 % decrease in FENO 10 minutes after exposure (p < 0.001), confirming previous findings. Moreover, hyperoxia also caused a 14.2% decrease in plasma BH4 (p = 0.012). No significant differences were observed in the group measured 60 minutes after exposure. No significant correlation was found between the changes in FENO and BH4 after the hyperoxic exposure (r = 0.052, p = 0.795), this might be due to the recovery of BH4 being faster than the recovery of FENO.

Correction to: The effect of low dose marine protein hydrolysates on short-term recovery after high intensity performance cycling: a double-blinded crossover study.

The original article [1] contains errors in Tables 1 and 3: Table 1 erroneously mentions use of a treadmill which should instead state 'bicycle', and Table 3 has a minor typesetting mistake.

The effect of low dose marine protein hydrolysates on short-term recovery after high intensity performance cycling: a double-blinded crossover study.

BACKGROUND: Knowledge of the effect of marine protein hydrolysate (MPH) supplementation to promote recovery after high intensity performance training is scarce. The aim of this study was to examine the effect of MPH supplementation to whey protein (WP) and carbohydrate (CHO): (CHO-WP-MPH), on short-term recovery following high intensity performance, compared to an isoenergetic and isonitrogenous supplement of WP and CHO: (CHO-WP), in male cyclists. METHODS: This was a double-blinded crossover study divided into three phases. Fourteen healthy men participated. In phase I, an incremental bicycle exercise test was performed for establishment of intensities used in phase II and III. In phase II (9-16 days after phase 1), the participants performed first one high intensity performance cycling session, followed by nutrition supplementation (CHO-WP-MPH or CHO-WP) and 4 hours of recovery, before a subsequent high intensity performance cycling session. Phase III (1 week after phase II), was similar to phase II except for the nutrition supplementation, where the participants received the opposite supplementation compared to phase II. Primary outcome was difference in time to exhaustion between the cycling sessions, after nutrition supplementations containing MPH or without MPH. Secondary outcomes were differences in heart rate (HR), respiratory exchange ratio (RER), blood lactate concentration and glucose. RESULTS: The mean age of the participants was 45.6 years (range 40-58). The maximal oxygen uptake (mean ± SD) measured at baseline was 54.7 ± 4.1 ml∙min- 1∙kg- 1. There were no significant differences between the two nutrition supplementations measured by time to exhaustion at the cycling sessions (meandiff = 0.85 min, p = 0.156, 95% confidence interval (CI), - 0.37, 2.06), HR (meandiff = 0.8 beats pr.min, p = 0.331, 95% CI, - 0.9, 2.5), RER (meandiff = - 0.05, p = 0.361, 95% CI -0.07 - 0.17), blood lactate concentration (meandiff = - 0.24, p = 0.511, 95% CI, - 1.00, 0.53) and glucose (meandiff = 0.23, p = 0.094, 95% CI, - 0.05, 0.51). CONCLUSIONS: A protein supplement with MPH showed no effects on short-term recovery in middle-aged healthy male cyclists compared to a protein supplement without MPH. TRIAL REGISTRATION: The study was registered 02.05.2017 at ClinicalTrials.gov (Protein Supplements to Cyclists, NCT03136133 , https://clinicaltrials.gov/ct2/show/NCT03136133?cond=marine+peptides&rank=1 .

Hyperoxia and lack of ascorbic acid deplete tetrahydrobiopterin without affecting NO generation in endothelial cells.

Nitric oxide (NO) may protect against gas bubble formation and risk of decompression sickness. We have previously shown that the crucial co-factor tetrahydrobiopterin (BH4) is oxidized in a dose-dependent manner when exposed to hyperoxia similar to diving conditions but with minor effects on the NO production by nitric oxide synthase. By manipulating the intracellular redox state, we further investigated the relationship between BH4 levels and production of NO in human endothelial cells (HUVECs). HUVECs were cultured with and without ascorbic acid (AA) and the glutathione (GSH) synthesis inhibitor buthionine sulfoximine, prior to hyperoxic exposure. The levels of biopterins and GSH were determined in cell lysates while the production of NO was determined in intact cells. Omitting AA resulted in a 91% decrease in BH4 levels (0.49 ± 0.08 to 0.04 ± 0.01 pmol/106 cells, p⟨0.001) at 20 kPa oxygen (O2), and 88% decrease (0.24 ± 0.03 to 0.03 ± 0.01 pmol/106 cells, p=0.01) after exposure to 60 kPa O2. The NO generation was decreased by 23% (74.5 ± 2.2 to 57.3 ± 5.6 pmol/min/mg protein, p⟨0.001) at 20 kPa O2, but no significant change was observed at 60 kPa O2. GSH depletion had no effects on the NO generation. No correlation was found between NO generation and the corresponding intracellular BH4 concentration (p=0.675, r=-0.055) or the BH4 to BH2 ratio (p=0.983, r=0.003), determined across 18 in vitro experiments. Decreased BH4 in HUVECs, due to hyperoxia or lack of ascorbic acid, does not imply corresponding decreases in NO generation.

Decrease of tetrahydrobiopterin and NO generation in endothelial cells exposed to simulated diving.

Purpose: Nitric oxide (NO) has been shown to protect against bubble formation and the risk of decompression sickness. We hypothesize that oxidation of tetrahydrobiopterin (BH4) leads to a decreased production of NO during simulated diving. Methods: Human umbilical vein endothelial cells (HUVEC) were exposed to hyperoxia or simulated diving for 24 hours. The levels of biopterins (BH4, BH2 and B) were determined by LC-MS/MS, and the production of NO by monitoring the conversion of L-arginine to L-citrulline. Results: Exposure to hyperoxia decreased BH4 in a dose-dependent manner; by 48 ± 15% following exposure to 40 kPa O2 (P⟨0.001 vs. control at 20 kPa O2), and 70 ± 16% following exposure to 60 kPa O2. Exposure to 40 kPa O2 decreased NO production by 25 ± 9%, but there was no further decrease when increasing oxygen exposure to 60 kPa (25 ± 10%). No additional effects of simulated diving were observed, indicating no additive or synergistic effects of hyperbaria and hyperoxia on the BH4 level or NO generation. Conclusion: NO generation in intact human endothelial cells was decreased by simulated diving, as well as by hyperoxic exposure, while BH4 levels seem to be affected only by hyperoxia. Hence, the results suggest that BH4 is not the sole determinant of NO generation in HUVEC.

Lung hyperinflation and functional exercise capacity in patients with COPD - a three-year longitudinal study.

BACKGROUND: Lung hyperinflation contributes to dyspnea, morbidity and mortality in chronic obstructive pulmonary disease (COPD). The inspiratory-to-total lung capacity (IC/TLC) ratio is a measure of lung hyperinflation and is associated with exercise intolerance. However, knowledge of its effect on longitudinal change in the 6-min walk distance (6MWD) in patients with COPD is scarce. We aimed to study whether the IC/TLC ratio predicts longitudinal change in 6MWD in patients with COPD. METHODS: This prospective cohort study included 389 patients aged 40-75 years with clinically stable COPD in Global Initiative for Chronic Obstructive Lung Disease stages II-IV. The 6MWD was measured at baseline, and after one and 3 years. We performed generalized estimating equation regression analyses to examine predictors for longitudinal change in 6MWD. Predictors at baseline were: IC/TLC ratio, age, gender, pack years, fat mass index (FMI), fat-free mass index (FFMI), number of exacerbations within 12 months prior to inclusion, Charlson index for comorbidities, forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), and light and hard self-reported physical activity. RESULTS: Reduced IC/TLC ratio (p < 0.001) was a statistically significant predictor for decline in 6MWD. With a 0.1-unit decrease in baseline IC/TLC ratio, the annual decline in 6MWD was 12.7 m (p < 0.001). Study participants with an IC/TLC ratio in the upper quartiles maintained their 6MWD from baseline to year 3, while it was significantly reduced for the patients with an IC/TLC ratio in the lower quartiles. Absence of light and hard physical activity, increased age and FMI, decreased FEV1 and FVC, more frequent exacerbations and higher Charlson comorbidity index were also predictors for lower 6MWD at any given time, but did not predict higher rate of decline over the timespan of the study. CONCLUSION: Our findings demonstrated that patients with less lung hyperinflation at baseline maintained their functional exercise capacity during the follow-up period, and that it was significantly reduced for patients with increased lung hyperinflation.

Ventilatory Efficiency in Children and Adolescents Born Extremely Preterm.

Purpose: Children and adolescents born extremely preterm (EP) have lower dynamic lung volumes and gas transfer capacity than subjects born at term. Most studies also report lower aerobic capacity. We hypothesized that ventilatory efficiency was poorer and that breathing patterns differed in EP-born compared to term-born individuals. Methods: Two area-based cohorts of participants born with gestational age ≤28 weeks or birth weight ≤1000 g in 1982-85 (n = 46) and 1991-92 (n = 35) were compared with individually matched controls born at term. Mean ages were 18 and 10 years, respectively. The participants performed an incremental treadmill exercise test to peak oxygen uptake with data averaged over 20 s intervals. For each participant, the relationship between exhaled minute ventilation ([Formula: see text]E) and carbon dioxide output ([Formula: see text]CO2) was described by a linear model, and the relationship between tidal volume (VT) and [Formula: see text]E by a quadratic model. Multivariate regression analyses were done with curve parameters as dependent variables, and the categories EP vs. term-born, sex, age, height, weight and forced expiratory volume in 1 s (FEV1) as independent variables. Results: In adjusted analyses, the slope of the [Formula: see text]E-[Formula: see text]CO2 relationship was significantly steeper in the EP than the term-born group, whereas no group difference was observed for the breathing pattern, which was related to FEV1 only. Conclusion: EP-born participants breathed with higher [Formula: see text]E for any given CO2 output, indicating lower ventilatory efficiency, possibly contributing to lower aerobic capacity. The breathing patterns did not differ between the EP and term-born groups when adjusted for FEV1.

Change in pulmonary diffusion capacity in a general population sample over 9 years.

RATIONALE: Data on the change in diffusion capacity of the lung for carbon monoxide (DLCO) over time are limited. We aimed to examine change in DLCO (ΔDLCO) over a 9-year period and its predictors. METHODS: A Norwegian community sample comprising 1,152 subjects aged 18-73 years was examined in 1987 and 1988. Of the 1,109 subjects still alive, 830 (75%) were re-examined in 1996/97. DLCO was measured with the single breath-holding technique. Covariables recorded at baseline included sex, age, height, weight, smoking status, pack years, occupational exposure, educational level, and spirometry. Generalized estimating equations analyses were performed to examine relations between ΔDLCO and the covariables. RESULTS: At baseline, mean [standard deviation (SD)] DLCO was 10.8 (2.4) and 7.8 (1.6) mmol·min(-1)·kPa(-1) in men and women, respectively. Mean (SD) ΔDLCO was -0.24 (1.31) mmol·min(-1)·kPa(-1). ΔDLCO was negatively related to baseline age, DLCO, current smoking, and pack years, and positively related to forced expiratory volume in 1 second (FEV1) and weight. Sex, occupational exposure, and educational level were not related to ΔDLCO. CONCLUSIONS: In a community sample, more rapid decline in DLCO during 9 years of observation time was related to higher age, baseline current smoking, more pack years, larger weight, and lower FEV1.

Diffusion capacity and CT measures of emphysema and airway wall thickness - relation to arterial oxygen tension in COPD patients.

BACKGROUND: Decreased diffusing capacity of the lung for carbon monoxide (DLCO) is associated with emphysema. DLCO is also related to decreased arterial oxygen tension (PaO2), but there are limited data on associations between PaO2 and computed tomography (CT) derived measures of emphysema and airway wall thickness. OBJECTIVE: To examine whether CT measures of emphysema and airway wall thickness are associated with level of arterial oxygen tension beyond that provided by measurements of diffusion capacity and spirometry. METHODS: The study sample consisted of 271 smoking or ex-smoking COPD patients from the Bergen COPD Cohort Study examined in 2007-2008. Emphysema was assessed as percent of low-attenuation areas<-950 Hounsfield units (%LAA), and airway wall thickness as standardised measure at an internal perimeter of 10 mm (AWT-Pi10). Multiple linear regression models were fitted with PaO2 as the outcome variable, and %LAA, AWT-Pi10, DLCO and carbon monoxide transfer coefficient (KCO) as main explanatory variables. The models were adjusted for sex, age, smoking status, and haemoglobin concentration, as well as forced expiratory volume in one second (FEV1). RESULTS: Sixty two per cent of the subjects were men, mean (SD) age was 64 (7) years, mean (SD) FEV1 in percent predicted was 50 (15)%, and mean PaO2 (SD) was 9.3 (1.1) kPa. The adjusted regression coefficient (CI) for PaO2 was -0.32 (-0.04-(-0.019)) per 10% increase in %LAA (p<0.01). When diffusion capacity and FEV1 were added to the model, respectively, the association lost its statistical significance. No relationship between airway wall thickness and PaO2 was found. CONCLUSION: CT assessment of airway wall thickness is not associated with arterial oxygen tension in COPD patients. Emphysema score measured by chest CT, is related to decreased PaO2, but cannot replace measurements of diffusion capacity in the clinical evaluation of hypoxaemia.

Exhaled nitric oxide concentration in the period of 60 min after submaximal exercise in the cold.

BACKGROUND: Fractional expired nitric oxide (FENO ) is decreased after exercise. The effect of exercise in the cold upon FENO is unknown. PURPOSE: To examine changes in FENO after a short, high intensive exercise test in a cold and in a temperate environment. METHODS: Twenty healthy well-trained subjects (eight females) aged 18-28 years performed an 8-min exercise test at 18°C (SD = 1.0) and -10°C (SD = 1.2) ambient temperature. The tests were performed in a climate chamber in random order. The workload corresponded to 90-95% of peak heart rate (HRpeak ) during the last 4 min. FENO was measured offline. Exhaled gas was sampled in Mylar(®) bags using a collector kit with a flow restrictor and analysed within 2 h. FENO was measured before exercise and repeatedly during the first hour after. ANOVA for repeated measures was used to compare differences in FENO after exercise between environments. RESULTS: There was no difference in baseline FENO . A significant difference in FENO between environments was found after warm-up and from 20 to 30 min after exercise, with FENO being lower after exercise in the cold (P<0.05). The maximal reduction in FENO was seen 5 min after exercise and was not different between environments. CONCLUSION: Recovery of FENO was slower after exercising in -10°C compared with 18°C.

Myopic Shift during Hyperbaric Oxygenation Attributed to Lens Index Changes.

PURPOSE: To examine ocular lens parameters and structural changes to elucidate mechanisms underlying the myopic shift and cataract-related changes that occur in some patients during hyperbaric oxygen (HBO) therapy. METHODS: Scheimpflug images (Nidek EAS-1000) of the crystalline lens, measurements of scattered light, objective refraction, keratometry, tonometry, and axial length of the eye were obtained after the first day of HBO therapy and repeated when patients had completed 19 days of the treatment. RESULTS: Significant reduction in mean (± SD) optical density was found in the lens nucleus, -2.8 (± 4.3) units (p = 0.009) and -2.2 (± 4.1) units (p = 0.027) within circular and oval areas, respectively. Significant decrease in mean (± SD) backward scattered light was measured, -0.4 (± 0.8) units (p = 0.022). Mean (± SD) myopic shift was -0.58 (± 0.39) diopters (p < 0.001), whereas cortical optical density, forward scattered light, lenticular parameters, keratometry, tonometry, anterior chamber depth, and axial length of the eye appeared unchanged. CONCLUSIONS: Transient myopic shift reported in patients during HBO therapy is attributed to changes in the refractive index of the lens. No changes in lens curvatures or thickness were found after treatment.

Peak oxygen uptake and breathing pattern in COPD patients--a four-year longitudinal study.

BACKGROUND: Activities of daily living in patients with chronic obstructive pulmonary disease (COPD) are limited by exertional dyspnea and reduced exercise capacity. The aims of the study were to examine longitudinal changes in peak oxygen uptake (V̇O2peak), peak minute ventilation (V̇Epeak) and breathing pattern over four years in a group of COPD patients, and to examine potential explanatory variables of change. METHODS: This longitudinal study included 63 COPD patients, aged 44-75 years, with a mean forced expiratory volume in one second (FEV1) at baseline of 51 % of predicted (SD = 14). The patients performed two cardiopulmonary exercise tests (CPETs) on treadmill 4.5 years apart. The relationship between changes in V̇O2peak and V̇Epeak and possible explanatory variables, including dynamic lung volumes and inspiratory capacity (IC), were analysed by multivariate linear regression analysis. The breathing pattern in terms of the relationship between minute ventilation (V̇E) and tidal volume (VT) was described by a quadratic equation, VT = a + b∙V̇E + c∙V̇E (2), for each test. The VTmax was calculated from the individual quadratic relationships, and was the point where the first derivative of the quadratic equation was zero. The mean changes in the curve parameters (CPET2 minus CPET1) and VTmax were analysed by bivariate and multivariate linear regression analyses with age, sex, height, changes in weight, lung function, IC and inspiratory reserve volume as possible explanatory variables. RESULTS: Significant reductions in V̇O2peak (p < 0.001) and V̇Epeak (p < 0.001) were related to a decrease in resting IC and in FEV1. Persistent smoking contributed to the reduction in V̇O2peak. The breathing pattern changed towards a lower VT at a given V̇E and was related to the reduction in FEV1. CONCLUSION: Increasing static hyperinflation and increasing airway obstruction were related to a reduction in exercise capacity. The breathing pattern changed towards more shallow breathing, and was related to increasing airway obstruction.

Exhaled nitric oxide after high-intensity exercise at 2800 m altitude.

BACKGROUND: Nitric oxide (NO) concentration in exhaled gas is a marker of some inflammatory processes in the lung, and endogenous NO plays a role in the physiological responses to exercise and altitude. The aim of this study was to compare changes in exhaled NO concentration 5-60 mins after high-intensity exercise at 2800 m and at 180 m altitude. METHODS: Twenty trained healthy volunteers (12 men), aged 19-28 years, were included in this open, crossover study. Subjects performed two exercise tests at different altitudes, 2800 m and 180 m, in a randomized order. The fraction of NO in exhaled gas (FE(NO)) was measured 5 mins before and 5-60 mins after 8 mins of running on a treadmill at a heart rate (HR) of 90% of peak HR. Peak HR was assessed during a pretest at 180 m. Ambient temperature was 20.1°C (SD = 1.2) and relative humidity 40.2% (SD = 3.2). FE(NO) measurements were corrected for altitude gas density effects and converted to partial pressure of NO (PE(NOcorr)). RESULTS: PE(NOcorr) was reduced from 1.47 (1.21, 1.73) millipascal (mPa) at baseline to 1.11 (0.87, 1.34) mPa 5 mins after exercise at 2800 m and from 1.54 (1.24, 1.84) to 1.04 (0.87, 1.22) mPa 5 mins after exercise at 180 m. There was no difference in PE(NOcorr) between exercise at 2800 m and 180 m, and PE(NOcorr) was normalized within 20 mins. CONCLUSIONS: Exercise at 2800 m induces a similar acute reduction in exhaled nitric oxide concentration as compared with 180 m in healthy subjects.

Airway obstruction, dynamic hyperinflation, and breathing pattern during incremental exercise in COPD patients.

Ventilatory capacity is reduced in chronic obstructive pulmonary disease (COPD) patients. Tidal volume (V T) is lower and breathing frequency higher at a given ventilation (V E) compared to healthy subjects. We examined whether airflow limitation and dynamic hyperinflation in COPD patients were related to breathing pattern. An incremental treadmill exercise test was performed in 63 COPD patients (35 men), aged 65 years (48-79 years) with a mean forced expiratory volume in 1 sec (FEV1) of 48% of predicted (SD = 15%). Data were averaged over 20-sec intervals. The relationship between V E and V T was described by the quadratic equation V T = a + bV E + cV E (2) for each subject. The relationships between the curve parameters b and c, and spirometric variables and dynamic hyperinflation measured as the difference in inspiratory capacity from start to end of exercise, were analyzed by multivariate linear regression. The relationship between V E and V T could be described by a quadratic model in 59 patients with median R (2) of 0.90 (0.40-0.98). The linear coefficient (b) was negatively (P = 0.001) and the quadratic coefficient (c) positively (P < 0.001) related to FEV1. Forced vital capacity, gender, height, weight, age, inspiratory reserve volume, and dynamic hyperinflation were not associated with the curve parameters after adjusting for FEV1. We concluded that a quadratic model could satisfactorily describe the relationship between V E and V T in most COPD patients. The curve parameters were related to FEV1. With a lower FEV1, maximal V T was lower and achieved at a lower V E. Dynamic hyperinflation was not related to breathing pattern when adjusting for FEV1.

Physical activity and longitudinal change in 6-min walk distance in COPD patients.

BACKGROUND: The 6-min walk distance (6MWD) is widely used to evaluate functional capacity in patients with chronic obstructive pulmonary disease (COPD). AIM: To examine predictors for longitudinal change in 6MWD including self-reported physical activity, smoking habits, body composition, exacerbations, comorbidity and lung function. METHODS: The cohort included 389 patients aged 44-75 years, with clinically stable COPD in GOLD stages II-IV. The follow-up time was 3 years. Measurements included 6MWD, spirometry, fat and fat free mass index (FMI and FFMI), and assessment of physical activity, smoking habits, comorbidities and exacerbations by questionnaires. Generalized estimating equations (GEE) regression analyses were used to analyze predictors for the change in 6MWD. RESULTS: There was a reduction in 6MWD from baseline to 3 years for patients in GOLD stages III and IV (B = -36 m, 95% CI = -51 to -7, p = 0.009 and B = -79 m, CI = -125 to -20, p = 0.007). The unadjusted GEE analysis demonstrated that baseline self-reported physical activity level, forced expiratory volume in one second (FEV1), forced vital capacity, FFMI, GOLD stages and age predicted change in 6MWD, but in the adjusted GEE analysis only self-reported physical activity level (p = 0.001) and FEV1 (p = 0.019) predicted change over time. CONCLUSION: Patients in GOLD stage II maintained their functional capacity assessed by 6MWD over 3 years, while it was significantly reduced for patients in GOLD stages III and IV. Level of physical activity and FEV1 were predictors for longitudinal change in functional capacity.

Posterior segment changes of the eye during hyperbaric oxygen therapy.

PURPOSE: To examine central retinal thickness, retinal and vitreo-retinal structures, and ocular blood flow during a standard protocol of hyperbaric oxygen (HBO2) therapy. METHODS: Retinal thickness and color scans of the vitreo-retinal structures were obtained before and after 19 days of HBO2 therapy in 15 patients by optical coherence tomography (OCT). Pulsatile ocular blood flow was measured by ocular blood flow tonometry. Ocular refraction and axial length of the eye were monitored for control. RESULTS: Significant reduction was found in mean retinal thickness, -1.7 ± 1.6 µm (range -3.9 to 1.1 µm) (p < 0.001) in nine subfields within the 6-mm-diameter circle around the central macula. An insignificant decrease in pulsatile ocular blood flow of -19.0 ± 148.8 µl/minute was measured. No morphological changes were seen in retinal and vitreo-retinal structures. A mean myopic shift of -0.62 ± 0.39 D (p < 0.001) developed while axial length of the eye remained unchanged. CONCLUSIONS: A small decrease in central retinal thickness was seen during the study period, but the changes were not correlated to the myopic shift. No significant changes in vitreo-retinal structures or ocular pulsatile blood flow occurred.

Prevalence and causes of loss of consciousness in former North Sea occupational divers.

BACKGROUND: Loss of consciousness (LOC) is a serious event during diving. The purpose of this study wasto estimate the prevalence and causes of LOC during diving in former North Sea divers, and the impacton health-related quality of life. MATERIALS AND METHODS: Up to 1990 a total of 373 Norwegian offshore divers worked in the North Sea. From 2000 to 2011, 221 of these were referred to the Department of Occupational Medicine at Haukeland University Hospital for examination due to health complaints. They filled in a questionnaire for registration of diving experience and health complaints, including the SF-36 version 1 for the assessment of quality oflife. The questionnaire and the hospital records were systematically reviewed by 2 independent observers. Episodes of LOC during diving and the causes were registered. All participants underwent a clinical neurological examination. Electroencephalogram (EEG) and the event-related brain potential (P300) were recorded. RESULTS: One or more episodes of LOC were reported by 58 of 219 divers. LOC due to gas cut was reportedby 27 of these. Divers having experienced LOC due to gas cut had lower SF-36 sub-scores then the rest of the diving population. EEG and P300 recordings did not differ between the groups. CONCLUSIONS: A high proportion of former Norwegian North Sea divers reported episodes of LOC, for whichgas cut was the most common cause. Both hypoxia and peritraumatic stress associated with the episodecould have a long term impact on the quality of life. Neurophysiological functions, however, did not differbetween the groups.

Exhaled nitric oxide and lung function after moderate normobaric hyperoxic exposure.

INTRODUCTION: Pulmonary oxygen toxicity is associated with inflammatory responses in the airways and alveoli. The purpose of this study was to investigate whether the changes in exhaled nitric oxide (FE(NO)) after exposure to normobaric hyperoxia (NBO), 100% oxygen (O2) at 1 atmosphere absolute (atm abs) for 90 minutes, are associated with changes in lung function. METHODS: Eighteen healthy non-smoking subjects were exposed to NBO breathing 100% oxygen and to breathing ambient air, both for 90 minutes on separate days and in random order. Dynamic and static lung volumes, maximal expiratory flow rates, distribution of ventilation including closing volume and slope of phase III of the nitrogen washout curve (delta N2), diffusion capacity (D(L)CO) and FE(NO) were measured before and after the exposures. RESULTS: The mean reduction in FE(NO) was 20% (SD = 20) after the NBO exposure (p < 0.001). Static and dynamic lung volumes, maximal expiratory flow rates, DLCO and distribution of ventilation were unchanged. No association was found between the changes in the lung function variables and the change in FE(NO). DISCUSSION: Unchanged indices of distribution of ventilation and maximal expiratory flow rates indicate no small airways' dysfunction, and unchanged DLCO suggests preserved gas transfer in the lung despite a significant reduction in FE(NO). FE(NO) might be an index of oxygen exposure, but further studies over a wide range of oxygen exposures are necessary to establish the role of FE(NO) as a marker of pulmonary oxygen toxicity.