Publications by authors named "Einar Thorsen"

38 Publications

Development of lung diffusion to adulthood following extremely preterm birth.

Eur Respir J 2021 Oct 8. Epub 2021 Oct 8.

Department of Clinical Science, University of Bergen, Bergen, Norway.

Background: Gas exchange in extremely preterm (EP) infants must take place in foetal lungs. Childhood lung diffusing capacity for carbon monoxide (DL) is reduced; however, longitudinal development has not been investigated. We describe growth of DL and its sub-components to adulthood in EP-born compared to term-born subjects.

Methods: Two area-based cohorts born at gestational age ≤28 weeks or birth weight ≤1000 grams in 1982-1985 (n=48) and 1991-1992 (n=35) were examined twice, at ages 18 and 25, and 10 and 18 years, respectively, and compared to matched term-born controls. Single-breath DL was measured at two oxygen pressures, with sub-components [membrane diffusion (D) and pulmonary capillary blood volume (V)] calculated using the Roughton-Forster equation.

Results: Age-, sex- and height-standardized transfer coefficients for carbon monoxide (K), and DL were reduced in EP-born compared to term-born and remained so during puberty and early adulthood (p-values for all time points and both cohorts ≤0.04), whereas alveolar volume was similar. Development occurred in parallel to term-born controls, with no signs of pubertal catch-up growth nor decline at 25 years (p-values for lack of parallelism within cohorts 0.99, 0.65, 0.71, 0.94, and 0.44 for -DL, -V, z-K, D, and V, respectively). Split by membrane and blood volume components, findings were less clear; however, membrane diffusion seemed most affected.

Conclusion: Pulmonary diffusing capacity was reduced in EP-born compared to term-born, and development from childhood to adulthood tracked in parallel to term-born, with no signs of catch-up growth nor decline at age 25.
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http://dx.doi.org/10.1183/13993003.04103-2020DOI Listing
October 2021

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

Undersea Hyperb Med 2020 Second Quarter;47(2):197-202

Norwegian Centre for Maritime and Diving Medicine, Haukeland University Hospital, Bergen, Norway.

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.
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January 2021

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

J Int Soc Sports Nutr 2020 01 3;17(1). Epub 2020 Jan 3.

Department of Health and Functioning, Western Norway University of Applied Sciences, Pb. 7030, 5020, Bergen, Norway.

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.
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http://dx.doi.org/10.1186/s12970-019-0324-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6941344PMC
January 2020

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

J Int Soc Sports Nutr 2019 Oct 29;16(1):48. Epub 2019 Oct 29.

Department of Health and Functioning, Western Norway University of Applied Sciences, Pb. 7030, 5020, Bergen, Norway.

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∙kg. There were no significant differences between the two nutrition supplementations measured by time to exhaustion at the cycling sessions (mean = 0.85 min, p = 0.156, 95% confidence interval (CI), - 0.37, 2.06), HR (mean = 0.8 beats pr.min, p = 0.331, 95% CI, - 0.9, 2.5), RER (mean = - 0.05, p = 0.361, 95% CI -0.07 - 0.17), blood lactate concentration (mean = - 0.24, p = 0.511, 95% CI, - 1.00, 0.53) and glucose (mean = 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 .
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http://dx.doi.org/10.1186/s12970-019-0318-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6819466PMC
October 2019

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

Undersea Hyperb Med 2019 Jun-Jul-Aug - Third Quarter;46(4):509-519

Norwegian Centre for Maritime and Diving Medicine, Haukeland University Hospital, Bergen, Norway.

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.
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November 2019

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

Undersea Hyperb Med 2019 Mar-Apr-May;46(2):159-169

Norwegian Centre for Maritime and Diving Medicine, Haukeland University Hospital, Bergen, Norway.

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.
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November 2019

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

BMC Pulm Med 2018 Dec 6;18(1):187. Epub 2018 Dec 6.

Department of Health and Functioning, Western Norway University of Applied Sciences, Inndalsveien 28, 5063, Bergen, Norway.

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 (FEV), 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 FEV 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.
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http://dx.doi.org/10.1186/s12890-018-0747-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6282360PMC
December 2018

Ventilatory Efficiency in Children and Adolescents Born Extremely Preterm.

Front Physiol 2017 13;8:499. Epub 2017 Jul 13.

Department of Clinical Science, University of BergenBergen, Norway.

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. Two area-based cohorts of participants born with gestational age ≤28 weeks or birth weight ≤1000 g in 1982-85 ( = 46) and 1991-92 ( = 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]) and carbon dioxide output ([Formula: see text]CO) was described by a linear model, and the relationship between tidal volume (V) and [Formula: see text] 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 (FEV) as independent variables. In adjusted analyses, the slope of the [Formula: see text]-[Formula: see text]CO 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 FEV only. EP-born participants breathed with higher [Formula: see text] for any given CO 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 FEV.
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http://dx.doi.org/10.3389/fphys.2017.00499DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5508024PMC
July 2017

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

Eur Clin Respir J 2016 2;3:31265. Epub 2016 Sep 2.

Department of Clinical Science, University of Bergen, Bergen, Norway.

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.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5013260PMC
http://dx.doi.org/10.3402/ecrj.v3.31265DOI Listing
September 2016

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

Eur Clin Respir J 2016 12;3:29141. Epub 2016 May 12.

Department of Clinical Science, Pulmonary Division, University of Bergen, Bergen, Norway.

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.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4867045PMC
http://dx.doi.org/10.3402/ecrj.v3.29141DOI Listing
May 2016

Myopic Shift during Hyperbaric Oxygenation Attributed to Lens Index Changes.

Optom Vis Sci 2015 Nov;92(11):1076-84

*MSc †PhD ‡MD §MD, PhD Institute of Clinical Medicine, University of Bergen, Bergen, Norway (KE, OHH); Faculty of Science Engineering and Computing, Kingston University, Kingston-upon-Thames, United Kingdom (BKP); Hyperbaric Medicine Unit, Department of Occupational Medicine, Haukeland University Hospital, Bergen, Norway (GV, ET); Department of Clinical Science, University of Bergen, Bergen, Norway (ET); and Department of Ophthalmology, Haukeland University Hospital, Bergen, Norway (OHH).

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.
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http://dx.doi.org/10.1097/OPX.0000000000000705DOI Listing
November 2015

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

BMC Pulm Med 2015 Aug 19;15:93. Epub 2015 Aug 19.

Department of Clinical Science, University of Bergen, Bergen, Norway.

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.
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http://dx.doi.org/10.1186/s12890-015-0095-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4545368PMC
August 2015

Posterior segment changes of the eye during hyperbaric oxygen therapy.

Undersea Hyperb Med 2014 Nov-Dec;41(6):589-96

Department of Clinical Medicine, University of Bergen, Norway.

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.
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January 2015

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

Clin Physiol Funct Imaging 2016 Mar 10;36(2):85-91. Epub 2014 Oct 10.

Department of Sports Medicine, Norwegian School of Sport Sciences, Oslo, Norway.

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.
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http://dx.doi.org/10.1111/cpf.12196DOI Listing
March 2016

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

Physiol Rep 2014 Feb 7;2(2):e00222. Epub 2014 Feb 7.

Department of Clinical Science, University of Bergen, Bergen, Norway ; Department of Occupational Medicine, Haukeland University Hospital, Bergen, Norway.

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.
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http://dx.doi.org/10.1002/phy2.222DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3966235PMC
February 2014

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

Clin Physiol Funct Imaging 2015 Sep 22;35(5):338-43. Epub 2014 Jan 22.

Department of Sport Medicine, Norwegian School of Sport Sciences, Oslo, Norway.

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.
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http://dx.doi.org/10.1111/cpf.12131DOI Listing
September 2015

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

Respir Med 2014 Jan 13;108(1):86-94. Epub 2013 Sep 13.

Dept. of Clinical Science, University of Bergen, Bergen, Norway; Dept. of Occupational Medicine, Haukeland University Hospital, Bergen, Norway.

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.
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http://dx.doi.org/10.1016/j.rmed.2013.09.004DOI Listing
January 2014

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

Int Marit Health 2013 ;64(3):142-7

Norwegian Centre for Diving Medicine, Department of Occupational Medicine, Haukeland University Hospital, Bergen, Norway.

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.
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May 2014

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

Undersea Hyperb Med 2013 Jan-Feb;40(1):7-13

Institute of Medicine, University of Bergen, Bergen, Norway.

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.
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February 2013

Pulmonary gas transfer in children and adolescents born extremely preterm.

Eur Respir J 2013 Dec 22;42(6):1536-44. Epub 2012 Nov 22.

University of Bergen, Bergen.

In extremely preterm-born infants, gas exchange takes place in developmentally fetal lungs, disturbing normal acinar growth and differentiation, potentially with long term negative consequences for lung function. The aim was to compare alveolar function in children and adolescents born extremely preterm and at term by measuring diffusing capacity of the lung for carbon monoxide (DLCO). Since this procedure may be challenging for subjects with shortcomings often seen after extremely preterm birth, we also assessed the reproducibility of the method. DLCO and DLCO adjusted for lung volume (KCO) were measured twice within 2 weeks in two population-based cohorts born at gestational age ≤28 weeks or with birth weight ≤1000 g, aged 10.6 years (n = 35) and 17.7 years (n = 46), and in 81 term-born controls individually matched for sex, age and place of birth. Reproducibility of DLCO measurements was in the same range for preterm and term-born children and young adults, and coefficients of variation were below 10% for all subgroups. KCO was significantly reduced with 7.9% and 7.2% for the oldest and youngest preterm birth cohorts, respectively. Reproducibility of DLCO in children and young adults born extremely preterm was adequate. DLCO and KCO were modestly reduced, supporting recent reports suggesting continuing alveolar growth throughout childhood.
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http://dx.doi.org/10.1183/09031936.00027112DOI Listing
December 2013

Aerobic capacity and exercise performance in young people born extremely preterm.

Pediatrics 2012 Jan 26;129(1):e97-e105. Epub 2011 Dec 26.

Department of Pediatrics, Haukeland University Hospital, N-5021, Bergen, Norway.

Objectives: The goal of this study was to compare aerobic capacity and exercise performance of children and adolescents born extremely preterm and at term, and to relate findings to medical history and lifestyle factors. Potential cohort effects were assessed by studying subjects born in different decades.

Methods: Two area-based cohorts of subjects born with gestational age ≤28 weeks or birth weight ≤1000 g in 1982-1985 and 1991-1992 and matched control subjects born at term were compared by using standardized maximal treadmill exercise and pulmonary function tests. Background data were collected from questionnaires and medical records.

Results: Seventy-five of 86 eligible preterm subjects (87%) and 75 control subjects were assessed at mean ages of 17.6 years (n = 40 + 40) and 10.6 years (n = 35 + 35). At average, measures of aerobic capacity for subjects born preterm and at term were in the same range, whereas average running distance was modestly reduced for those born preterm. Leisure-time physical activity was similarly and positively associated with exercise capacity in preterm and term-born adolescents alike, although participation was lower among those born preterm. Neonatal bronchopulmonary dysplasia and current forced expiratory vol in 1 second was unrelated to exercise capacity. Differences between subjects born preterm and at term had not changed over the 2 decades studied.

Conclusion: Despite their high-risk start to life and a series of potential shortcomings, subjects born preterm may achieve normal exercise capacity, and their response to physical training seems comparable to peers born at term.
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http://dx.doi.org/10.1542/peds.2011-0326DOI Listing
January 2012

Bronchial nitric oxide flux and alveolar nitric oxide concentration after exposure to hyperoxia.

Aviat Space Environ Med 2011 Oct;82(10):946-50

Institute of Medicine, University of Bergen, Haukeland University Hospital, N-5021 Bergen, Norway.

Background: The fraction of nitric oxide in exhaled gas (FE(NO)) is reduced by 30-70% after exposure to partial pressures of oxygen (Po2) of 200-240 kPa for 90 min. The purpose of this study was to partition FE(NO) into its flow-independent alveolar and bronchial components. A reduced bronchial NO flux (JawNO) is associated with induced bronchoconstriction, while increased alveolar NO concentration (C(A)NO) is associated with increased alveolar dead space.

Methods: There were 12 patients undergoing hyperbaric oxygen (HBO) therapy for 90 min at a Po2 of 240 kPa and 20 healthy subjects exposed to normobaric hyperoxia (NBO) breathing 100% oxygen for 90 min who were compared to a control group of 6 subjects breathing ambient air. FE(NO) was measured at flow rates from 30 to 250 ml x s(-1) before and after the exposures and the Högman Märilainen algorithm was used to calculate JawNO and C(A)NO.

Results: FE(NO) at an expiratory flow rate of 50 ml x s(-1) was reduced from 17.6 +/- 8.3 to 12.3 +/- 6.3 ppb after HBO exposure and from 17.8 +/- 6.2 to 13.3 +/- 5.2 ppb after NBO exposure. There was a significant reduction in JawNO, but unchanged C(A)NO. There were no changes in the control experiment.

Discussion: The reduction in FE(NO) after exposure to normobaric and hyperbaric hyperoxia appears to be predominantly an airway effect. An unchanged and low C(A)NO indicate preserved integrity of the gas exchange units without increased alveolar dead space at rest.
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http://dx.doi.org/10.3357/asem.2995.2011DOI Listing
October 2011

Risk of misclassification of decompression sickness.

Int Marit Health 2011 ;62(1):17-9

Department of Occupational Medicine, Haukeland University Hospital, Bergen, Norway.

Decompression sickness (DCS) is classified on the basis of which organ system is affected, and neurological DCS is considered more severe than DCS in joints and skin with respect to response to recompression treatment and risk of long-term sequelae. Gas bubble formation interstitially in the tissues or in the circulation is considered to be the mechanism for all types of DCS. Ten patients diagnosed as having DCS in joints or skin, by doctors experienced in diving medicine, underwent clinical examination by a neurologist and had an electroencephalogram. Eight of the ten subjects had findings suggesting central nervous system deficits. The findings indicate that DCS of the central nervous system often accompanies DCS of the joints and skin, and that local skin and joint symptoms may draw attention away from cerebral symptoms. We recommend that all cases with DCS should initially be treated as neurological DCS.
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August 2011

Phakic and pseudophakic eyes in patients during hyperbaric oxygen therapy.

Optom Vis Sci 2011 Jun;88(6):691-6

Department of Clinical Medicine, University of Bergen, Bergen, Norway.

Purpose: To examine the optical components of phakic and pseudophakic eyes during hyperbaric oxygen (HBO) therapy, and to quantify their relative impact on ocular refractive changes.

Methods: HBO therapy was given to 16 phakic and six pseudophakic patients for 90 min daily at a pressure of 240 kPa, 5 d a week for 20 days. An eye examination was performed on the first day of HBO therapy and repeated when the patients had completed 19 days of the treatment. Refractive error, best-corrected visual acuity, corneal power, radius, thickness and volume, anterior chamber depth, axial length, lens opacity, and intraocular pressure were measured in all patients. Serum glucose, glycosylated hemoglobin, serum electrolytes, and protein were measured in the phakic patients.

Results: In the phakic group, a significant myopic shift (≥ -0.50 D) occurred in 26 (81%) single eyes during the treatment. The median myopic shift was -0.63 D (min -0.25 D/max -1.88 D) in the OD, and -0.69 D (min -0.38 D/max -2.25 D) in the OS. No myopic shift appeared in the pseudophakic patients; the median refractive changes were +0.06 D (min -0.13 D/max +0.25 D) in the OD and +0.13 D (min 0.00 D/max +0.25 D) in the OS. Intraocular pressure, serum electrolytes, glucose, and glycosylated hemoglobin remained unchanged.

Conclusions: Myopic shifts occurred in phakic but not in pseudophakic eyes during HBO therapy. The myopic shifts must be attributed to changes in the crystalline lens.
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http://dx.doi.org/10.1097/OPX.0b013e318213f001DOI Listing
June 2011

Quantitative CT measures of emphysema and airway wall thickness are related to D(L)CO.

Respir Med 2011 Mar 11;105(3):343-51. Epub 2010 Nov 11.

Department of Thoracic Medicine, Haukeland University Hospital, Jonas Lies v 65, N-5021 Bergen, Norway.

Unlabelled: There is limited knowledge on the relationship between diffusing capacity of the lung for carbon monoxide (D(L)CO) and quantitative computed tomography (CT) measures of emphysema and airway wall thickness.

Study Question: What is the relationship between D(L)CO and the quantitative CT measures of emphysema and airway wall thickness in subjects with and without COPD?

Methods: We included 288 COPD subjects (70% men) and 425 non-COPD subjects (54% men). All subjects were current or ex-smokers older than 40 years and all subjects underwent spirometry, diffusing capacity tests and CT examination. Quantitative CT measures included % low attenuation areas < -950 HU (%LAA) and standardized airway wall thickness (AWT-Pi10).

Results: Multiple linear regression analyses showed significant associations between D(L)CO and both %LAA and AWT-Pi10 in the COPD group. The adjusted regression coefficients (SE) for D(L)CO (mmol min(-1) kPa(-1)) were -1.15 (0.11) per 10% increase in %LAA and 0.08 (0.03) per 0.1 mm increase in AWT-Pi10, and the models' adjusted R(2) was 0.65 and 0.49, respectively.

Conclusions: CT measured emphysema explains a large fraction of the variation of D(L)CO among COPD subjects, and more so in men. Airway wall thickness is also significantly associated with D(L)CO, but explains a much smaller fraction of the variation.
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http://dx.doi.org/10.1016/j.rmed.2010.10.018DOI Listing
March 2011

Diving and intrapulmonary shunting of venous gas microemboli.

J Clin Ultrasound 2010 Nov-Dec;38(9):497; author reply 498

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http://dx.doi.org/10.1002/jcu.20730DOI Listing
February 2011

Cerebral diffusion and perfusion deficits in North Sea divers.

Acta Radiol 2010 Nov;51(9):1050-8

Department of Radiology, Haukeland University Hospital, Bergen, Norway.

Background: Diving is associated with a risk of cerebral decompression illness, and the prevalence of neurological symptoms is higher in divers compared with control groups. Microvascular dysfunction due to gas microembolism and exposure to hyperoxia are possible mechanisms, which may result in cerebral diffusion and perfusion deficits.

Purpose: To investigate if possible functional derangements of the microvasculature and microstructure would be more prevalent among symptomatic divers.

Material And Methods: Magnetic resonance imaging (MRI) was performed in 91 former divers and 45 controls. Individual parametric images of apparent diffusion coefficient (ADC), cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) were generated on the basis of diffusion- and perfusion-weighted imaging. To identify regions with statistically significant differences between groups (P < 0.05, corrected for false discovery rate), voxel-wise ANCOVA analysis was performed for each of the four parametric images.

Results: Significant regional group differences were found in all four parametric comparisons. Gross regional ADC differences were seen throughout the brain, including large frontal and temporal white-matter regions, the hippocampus, and parts of the cerebellum. Differences in the perfusion maps were localized in fewer and smaller clusters, including parts of the cerebellum, the putamen, and the anterior watershed regions.

Conclusion: Regional functional abnormalities as measured by diffusion- and perfusion-weighted imaging were identified in the divers, and there was a partial co-localization of the regions identified in the perfusion and the diffusion images. The findings may explain some of the long-term clinical symptoms reported among professional divers.
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http://dx.doi.org/10.3109/02841851.2010.515245DOI Listing
November 2010

Anticipating maximal or submaximal exercise: no differences in cardiopulmonary responses.

Clin Physiol Funct Imaging 2010 Sep 2;30(5):333-337. Epub 2010 Jul 2.

Institute of Medicine, University of Bergen, Bergen.

Background: Anticipation before the start of exercise may influence the cardiopulmonary responses during exercise. If anticipation influences the responses differently with maximal and submaximal exercises, normative values for submaximal responses will not be comparable unless exercise has been continued to the same end point.

Methods: Twelve healthy subjects (five men) aged 18-27 years had a maximal exercise test and a submaximal exercise test on a cycle ergometer on different days and in random order. They were not aware of the specific purpose of the study and were informed 15 min before the tests whether it should be maximal or submaximal. Workload increased with 15 W min(-1) until exhaustion or to 80% of predicted maximal heart rate (HR). HR, oxygen uptake (VO(2)), carbon dioxide production (VCO(2)), minute ventilation (V(E)) and tidal volume (V(T)) were averaged over 20 s intervals. Linear regression of the HR-VO(2) relationship and quadratic regression of the V(T)-V(E) relationship were performed for each individual, and the regression coefficients for maximal and submaximal tests were compared.

Results: The regression models described the V(T)-V(E) responses with a R(2) > 0.85 in 23 of 24 tests, and the HR-VO(2) responses with a R(2) > 0.90 in all tests. The regression coefficients of the relationships were not significantly different with maximal and submaximal exercises.

Conclusion: Anticipation appears not to influence the responses to progressive maximal and submaximal exercise tests with the same rate of increase in load. Normative values at submaximal exercise levels are not influenced by the targeted end point of exercise.
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http://dx.doi.org/10.1111/j.1475-097X.2010.00948.xDOI Listing
September 2010

Quantitative computed tomography measures of emphysema and airway wall thickness are related to respiratory symptoms.

Am J Respir Crit Care Med 2010 Feb 19;181(4):353-9. Epub 2009 Nov 19.

Department of Thoracic Medicine, Haukeland University Hospital, N-5021 Bergen, Norway.

Rationale: There is limited knowledge about the relationship between respiratory symptoms and quantitative high-resolution computed tomography measures of emphysema and airway wall thickness.

Objectives: To describe the ability of these measures of emphysema and airway wall thickness to predict respiratory symptoms in subjects with and without chronic obstructive pulmonary disease (COPD).

Methods: We included 463 subjects with chronic obstructive pulmonary disease (COPD) (65% men) and 488 subjects without COPD (53% men). All subjects were current or ex-smokers older than 40 years. They underwent spirometry and high-resolution computed tomography examination, and completed an American Thoracic Society questionnaire on respiratory symptoms.

Measurements And Main Results: Median (25th percentile, 75th percentile) percent low-attenuation areas less than -950 Hounsfield units (%LAA) was 7.0 (2.2, 17.8) in subjects with COPD and 0.5 (0.2, 1.3) in subjects without COPD. Mean (SD) standardized airway wall thickness (AWT) at an internal perimeter of 10 mm (AWT-Pi10) was 4.94 (0.33) mm in subjects with COPD and 4.77 (0.29) in subjects without COPD. Both %LAA and AWT-Pi10 were independently and significantly related to the level of dyspnea among subjects with COPD, even after adjustments for percent predicted FEV(1). AWT-Pi10 was significantly related to cough and wheezing in subjects with COPD, and to wheezing in subjects without COPD. Odds ratios (95% confidence intervals) for increased dyspnea in subjects with COPD and in subjects without COPD were 1.9 (1.5-2.3) and 1.9 (0.6-6.6) per 10% increase in %LAA, and 1.07 (1.01-1.14) and 1.11 (0.99-1.24) per 0.1-mm increase in AWT-Pi10, respectively.

Conclusions: Quantitative computed tomography assessment of the lung parenchyma and airways may be used to explain the presence of respiratory symptoms beyond the information offered by spirometry.
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http://dx.doi.org/10.1164/rccm.200907-1008OCDOI Listing
February 2010

Time course of the reduction in nitric oxide concentration in exhaled gas after exposure to hyperbaric hyperoxia.

Diving Hyperb Med 2009 Jun;39(2):77-80

University of Bergen, Haukeland University Hospital, N-5021 Bergen, Norway.

Exposure to hyperoxia is associated with oxidative stress and is known to cause inflammation in the lung and the airways. Exhaled nitric oxide concentration (FENO) is a marker of some inflammatory processes in the lung and airways, and is reduced immediately after a single session of hyperbaric oxygen (HBO) exposure. The purpose of this study was to characterize the time course of this decrease in FENO. Ten patients who had HBO treatment were included. The daily HBO exposures were at a pressure of 240 kPa for 90 min. FENO was measured before a single HBO treatment session and immediately after and 30, 60, 120, and 240 minutes after. Thirteen healthy controls had FENO measured at the same time intervals as the patients without hyperoxic or hyperbaric exposure. FENO was significantly reduced by 30.0 (SD 22.3) % (P = 0.009) immediately after HBO treatment. It remained reduced by 27.3 (SD 19.6) % (P = 0.013) at 120 min, and had not recovered completely by 240 min. There were no changes in FENO in the control group. The results confirm the finding of a decrease in FENO immediately after exposure to hyperbaric hyperoxia. The reduction in FENO persists for up to 240 min.
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June 2009
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