| 1. |
- Bakker, M. Els, et al.
(författare)
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Assessment of Regional Progression of Pulmonary Emphysema With CT Densitometry
- 2008
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Ingår i: Chest. - : Elsevier BV. - 1931-3543 .- 0012-3692. ; 134:5, s. 931-937
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Tidskriftsartikel (refereegranskat)abstract
- Background: Lung densitometry is an effective method to assess overall progression of emphysema, but generally the location of the progression is not estimated. We hypothesized that progression of emphysema is the result of extension from affected areas toward less affected areas in the lung. To test this hypothesis, a method was developed to assess emphysema severity at different levels in the lungs in order to estimate regional changes. Methods: Fifty subjects with emphysema due to alpha(1)-antitrypsin deficiency (AATD) [AATD deficiency of phenotype PiZZ (PiZ) group] and 16 subjects with general emphysema (general emphysema without phenotype PiZZ [non-.PiZ] group) were scanned with CT at baseline and after 30 months. Densitometry was performed in 12 axial partitions of equal volumes. To indicate predominant location, craniocaudal locallity was defined as the slope in the plot of densities against partitions. Regional progression of emphysema was calculated after volume correction, and its slope identifies the area of predominant progression. The hypothesis was tested by investigating the correlation between predominant location and predominant progression. Results: As expected, the PiZ patients showed more basal emphysema than the non-PiZ group (craniocaudal locality, -40.0 g/L vs -6.2 g/L). Overall progression rate in PiZ patients was lower than in non-PiZ subjects. A significant correlation was found between craniocaudal locality and progression slope in PiZ subjects (R = 0.566, p < 0.001). In the non-PiZ group, no correlation was found. Conclusions: In the PiZ group, the more emphysema is distributed basally, the more progression was found in the basal area. This finding suggests that emphysema due to AATD spreads out from affected areas. (CHEST 2008; 134:931-937)
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| 2. |
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| 3. |
- Bernspång, Elisabeth, et al.
(författare)
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Lung function in 30-year-old alpha-1-antitrypsin-deficient individuals.
- 2009
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Ingår i: Respiratory Medicine. - : Elsevier BV. - 1532-3064 .- 0954-6111. ; 103, s. 861-865
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Alpha-1-antitrypsin (AAT) deficiency increases the risk of emphysema, especially in smokers. In 1972-1974, all 200,000 Swedish new-born infants were screened for AAT deficiency and individuals with severe (PiZZ) and moderate (PiSZ) deficiency have been followed-up regularly. The aim of the present study was to examine their lung function at the age of 30years, comparing them to a group of age-matched control subjects (PiMM) recruited from the general population, and to compare current smokers with never-smokers. METHOD: Static and dynamic spirometry, including TLC, FRC, RV, VC, FEV(1,)K(CO) and D(L,CO), was performed for all participants. All values were expressed as percentages of the expected values. FEV(1)/VC was expressed both as percentage of the expected value and in absolute numbers. RESULTS: Four of 60 PiZZ, none of 19 PiSZ and 9 of 33 PiMM participating individuals were current smokers. All Pi groups had a normal mean FEV(1). The mean (SD) FEV(1)/VC ratio was 75% (7.4) in the PiZZ smokers and 84% (5.5) in the PiZZ never-smokers (p<0.01). The mean (SD) K(CO) was 81 (13) in the PiZZ smokers and 99 (14) in the PiZZ never-smokers (p<0.05). CONCLUSION: AAT-deficient individuals identified by neonatal screening have normal lung function at the age of 30. The PiZZ smokers had changes in lung function that may be signs of early emphysema.
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| 4. |
- Bernspång, Elisabeth, et al.
(författare)
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Respiratory symptoms and lung function in 30-year-old individuals with alpha-1-antitrypsin deficiency.
- 2007
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Ingår i: Respiratory Medicine. - : Elsevier BV. - 1532-3064 .- 0954-6111. ; 101, s. 1971-1976
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Individuals with severe alpha-1-antitrypsin (AAT) deficiency have a well-known risk of developing emphysema but it is not known at which age the first symptoms occur and lung function declines. The aim of this study was to examine the prevalence of smoking, respiratory symptoms and lung function at the age of 30 in AAT-deficient individuals (PiZ and PiSZ) identified by neonatal screening. Material and methods: One hundred and seven PiZ, 45 PiSZ and 197 control subjects (PiMM) filled in a questionnaire regarding smoking habits and symptoms. Ninety PiZ, 40 PiSZ and 84 control subjects underwent spirometry including FEV1 and FVC. Results: Twenty-one percent of PiZ, 23% of PiSZ and 34% of PiMM subjects had smoked at some time (p < 0.05). Sixty-five percent of PiZ, 55% of PiSZ and 35% of PiMM ever-smokers reported shortness of breath on exertion (p < 0.05 PiZ vs PiMM). The mean FEV1, was 101% predicted (95% CI 98-104) in PiZ, 101% predicted (95% CI 97-106) in PISZ, and 96% predicted (95% 93-98) in PiMM individuals (p < 0.05). There was no difference in mean FEV1 when comparing ever- and neversmokers in the different Pi groups separately. Conclusion: At the age of 30, the AAT-deficient individuals in this cohort report more symptoms than the control subjects. Smoking is less common in the cohort compared to controls. Their lung function is normal.
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| 5. |
- Bernspång, Elisabeth, et al.
(författare)
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The liver in 30-year-old individuals with alpha(1)-antitrypsin deficiency.
- 2009
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Ingår i: Scandinavian Journal of Gastroenterology. - : Informa UK Limited. - 1502-7708 .- 0036-5521. ; 44:11, s. 1349-1355
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE. Severe (PiZZ) alpha(1)-antitrypsin (AAT) deficiency is a risk factor for liver disease, i.e. juvenile cirrhosis in infancy, and cirrhosis and hepatoma in adulthood. Little is known about the risk of liver disease in individuals with moderate (PiSZ) AAT deficiency. To investigate the natural course of AAT deficiency, a cohort of PiZZ and PiSZ individuals identified by the Swedish National neonatal screening programme in 1972-74 is followed regularly. The aim of this study was to compare liver function in this cohort with healthy control subjects aged 30 years. MATERIAL AND METHODS. Blood samples were obtained from 89 PiZZ, 40 PiSZ, and 84 control subjects (PiMM), and plasma levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and gamma-glutamyl (GT) transpeptidase were analysed. RESULTS. The mean values of all liver enzymes were within the normal range in all Pi subgroups. However, the mean AST was higher in the PiZZ and PiSZ subgroups than in the PiMM subgroup (p < 0.001), and the mean ALT was higher in the PiZZ individuals than in the controls (p < 0.05), while GT did not differ significantly among the Pi subgroups. The PiZZ women taking oral contraceptives had higher mean AST and ALT (p < 0.01) and GT (p < 0.05) than the control women taking oral contraceptives. CONCLUSIONS. At the age of 30 years, PiZZ and PiSZ individuals have normal plasma levels of the transaminases AST and ALT, although they are significantly higher than those in healthy control subjects. Use of oral contraceptives seems to influence liver enzymes in PiZZ women.
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| 6. |
- Diaz, Sandra, et al.
(författare)
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Hyperpolarized (3)He apparent diffusion coefficient MRI of the lung: Reproducibility and volume dependency in healthy volunteers and patients with emphysema.
- 2008
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Ingår i: Journal of Magnetic Resonance Imaging. - : Wiley. - 1522-2586 .- 1053-1807. ; 27, s. 763-770
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To measure the apparent diffusion coefficient (ADC) of hyperpolarized (HP) (3)He gas using diffusion weighted MRI in healthy volunteers and patients with emphysema and examine the reproducibility and volume dependency. MATERIALS AND METHODS: A total of eight healthy volunteers and 16 patients with emphysema were examined after inhalation of HP (3)He gas mixed with nitrogen (N(2)) during breathhold starting from functional residual capacity (FRC) in supine position. Coronal diffusion-sensitized MR images were acquired. Each subject was imaged on three separate days over a seven-day period and received two different volumes (6% and 15% of total lung capacity [TLC]) of HP (3)He each day. ADC maps and histograms were calculated. The mean and standard deviation (SD) of the ADC at different days and volumes were compared. RESULTS: The reproducibility of the mean ADC and SD over several days was good in both healthy volunteers and patients (SD range of 0.003-0.013 cm(2)/second and 0.001-0.009 cm(2)/second at 6% and 15% of TLC for healthy volunteers, and a SD range of 0.001-0.041 cm(2)/second and 0.001-0.011 cm(2)/second, respectively, for patients). A minor but significant increase in mean ADC with increased inhaled gas volume was observed in both groups. CONCLUSION: Mean ADC and SD of HP (3)He MRI is reproducible and discriminates well between healthy controls and patients with emphysema at the higher gas volume. This method is robust and may be useful to gain new insights into the pathophysiology and course of emphysema. J. Magn. Reson. Imaging 2008. (c) 2008 Wiley-Liss, Inc.
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| 7. |
- Diaz, Sandra, et al.
(författare)
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Progression of Emphysema in a 12-month Hyperpolarized (3)He-MRI Study Lacunarity Analysis Provided a More Sensitive Measure than Standard ADC Analysis(1).
- 2009
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Ingår i: Academic Radiology. - : Elsevier BV. - 1878-4046 .- 1076-6332. ; 16:6, s. 700-707
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Tidskriftsartikel (refereegranskat)abstract
- RATIONALE AND OBJECTIVES: Inhaled hyperpolarized (3)He magnetic resonance (MR) imaging has been used to measure alveolar size in patients with emphysema. The aim of this study was to test the hypothesis that (3)He MR images could be used to develop a biomarker of emphysema progression. MATERIALS AND METHODS: Twelve healthy controls and 18 patients with emphysema (eight current smokers, 10 ex-smokers) were imaged at baseline and 6 and 12 months. An additional nine subjects with alpha-1 antitrypsin deficiency (four with emphysema, six without symptoms) were also imaged at baseline and at 6 months. Each subject was imaged at two lung volumes: functional residual capacity (FRC) and FRC plus 15% of total lung capacity. Means and standard deviations of apparent diffusion coefficients (ADCs) were calculated from coronal images of the entire lung and correlated with pulmonary function test results. The lacunarity hypothesis was tested and calculated from the data using a range of 2x2 x 2 to 6x6 x 6 voxels, and the average was calculated. RESULTS: There was no change in the mean ADC at either lung volume in any subject over the 6- or 12-month period. FRC and residual volume increased over the 12 months, suggesting air trapping. The lacunarity of images collected at FRC increased at 6 and 12 months in smokers only (P=.063 and P=.023, respectively). CONCLUSIONS: The mean ADC calculated from MR images of the lungs with helium was not sufficiently sensitive to detect changes over a 12-month period. However, lacunarity captured more of the spatial information in the images and detected emphysema progress in the smokers.
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| 8. |
- Diaz, Sandra, et al.
(författare)
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Validity of apparent diffusion coefficient hyperpolarized He-3-MRI using MSCT and pulmonary function tests as references
- 2009
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Ingår i: European Journal of Radiology. - : Elsevier BV. - 1872-7727 .- 0720-048X. ; 71:2, s. 257-263
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To compare apparent diffusion coefficient (ADC) measurements from hyperpolarized (HP) helium (He-3)-magnetic resonance imaging (MRI) with quantitative data from multislice Computed Tomography (CT) (MSCT) of the whole lungs and pulmonary function tests (PFT). Materials and methods: Twenty-seven subjects, 22 with established emphysema and 5 with preclinical emphysema defined by PFT criteria, were examined with Hp He-3-MRI and MSCT. Mean age was 55 (+/- 12) years, 18 female and 9 male. Mean ADC from He-3-MRI was compared with emphysema index (EI), 15th percentile and mean lung density (MLD) values from MSCT. Both mean ADC and MSCT data were compared to PFT, especially percent of predicted diffusing capacity of carbon monoxide (%predicted DLCO), using Pearson's correlation test. Results: Mean ADC and standard deviation values were 0.392 +/- 0.119 cm(2)/s for the established emphysema group and 0.216 +/- 0.046 for the pre-clinical emphysema group. MSCT values for the established emphysema group and pre-clinical emphysema group were: EI (%) 11 +/- 12 and 0.4 +/- 0.6, respectively; 15th percentile (Hounsfield Units (HU)), -956 +/- 25 and -933 +/- 13, respectively and MLD (HU) -877 +/- 20 and -863 +/- 15, respectively. Correlations between mean ADC and El and 15th percentile were both r=0.90 and for MLD r=0.59. There was higher correlation between mean ADC and %predicted DLCO (r=0.90) than between El and %predicted DLCO (r=0.76). Conclusion: Hp He-3-MRI correlates well with density measurements from MSCT and agrees better than MSCT with %predicted DLCO which is the PFT most related to emphysema. (C) 2008 Elsevier Ireland Ltd. All rights reserved.
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| 9. |
- Dirksen, A., et al.
(författare)
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Exploring the role of CT densitometry: a randomised study of augmentation therapy in alpha(1)-antitrypsin deficiency
- 2009
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Ingår i: European Respiratory Journal. - : European Respiratory Society (ERS). - 1399-3003 .- 0903-1936. ; 33:6, s. 1345-1353
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Tidskriftsartikel (refereegranskat)abstract
- Assessment of emphysema-modifying therapy is difficult, but newer outcome measures offer advantages over traditional methods. The EXAcerbations and Computed Tomography scan as Lung End-points (EXACTLE) trial explored the use of computed tomography (CT) densitometry and exacerbations for the assessment of the therapeutic effect of augmentation therapy in subjects with alpha(1)-antitrypsin (alpha(1)-AT) deficiency. In total, 77 subjects (protease inhibitor type Z) were randomised to weekly infusions of 60 mg.kg(-1) human alpha(1)-AT (Prolastin (R)) or placebo for 2-2.5 yrs. The primary end-point was change in CT lung density, and an exploratory approach was adopted to identify optimal methodology, including two methods of adjustment for lung volume variability and two statistical approaches. Other end-points were exacerbations, health status and physiological indices. CT was more sensitive than other measures of emphysema progression, and the changes in CT and forced expiratory volume in 1 s were correlated. All methods of densitometric analysis concordantly showed a trend suggestive of treatment benefit (p-values for Prolastin (R) versus placebo ranged 0.049-0.084). Exacerbation frequency was unaltered by treatment, but a reduction in exacerbation severity was observed. In patients with alpha(1)-AT deficiency, CT is a more sensitive outcome measure of emphysema-modifying therapy than physiology and health status, and demonstrates a trend of treatment benefit from alpha(1)-AT augmentation.
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| 10. |
- Parr, David G., et al.
(författare)
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Exploring the optimum approach to the use of CT densitometry in a randomised placebo-controlled study of augmentation therapy in alpha 1-antitrypsin deficiency
- 2009
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Ingår i: Respiratory Research. - : Springer Science and Business Media LLC. - 1465-9921 .- 1465-993X. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Background: Computed tomography (CT) lung densitometry has been demonstrated to be the most sensitive and specific outcome measure for the assessment of emphysema-modifying therapy, but the optimum densitometric index has yet to be determined and targeted sampling may be more sensitive than whole lung assessment. The EXAcerbations and CT scan as Lung Endpoints (EXACTLE) trial aimed to clarify the optimum approach to the use of CT densitometry data for the assessment of alpha 1-antitrypsin (AAT) augmentation therapy on the progression of emphysema in AAT deficiency (AATD). Methods: Patients with AATD (n = 77) were randomised to weekly infusions of 60 mg/kg human AAT (Prolastin (R)) or placebo over 2 to 2.5 years. Lung volume was included as a covariate in an endpoint analysis and a comparison was made of different CT densitometric indices (15th percentile lung density [PD15], mean lung density [MLD] and voxel index at a threshold of -910 [VI-910] and -950 [VI-950] Hounsfield Units) obtained from whole lung scans at baseline and at 24 to 30 months. Targeted regional sampling was compared with whole lung assessment. Results: Whole lung analysis of the total change (baseline to last CT scan) compared with placebo indicated a concordant trend that was suggestive of a treatment effect for all densitometric indices (MLD [1.402 g/L, p = 0.204]; VI-910 [-0.611, p = 0.389]; VI-950 [-0.432, p = 0.452]) and that was significant using PD15 (1.472 g/L, p = 0.049). Assessment of the progression of emphysema in the apical, middle and basal regions of the lung by measurement with PD15 showed that this treatment effect was more evident when the basal third was sampled (1.722 g/L, p = 0.040). A comparison between different densitometric indices indicated that the influence of inspiratory variability between scans was greatest for PD15, but when adjustment for lung volume was made this index was the most sensitive measure of emphysema progression. Conclusion: PD15 is the most sensitive index of emphysema progression and of treatment modification. Targeted sampling may be more sensitive than whole lung analysis. Trial registration: Registered in ClinicalTrials.gov as 'Antitrypsin (AAT) to Treat Emphysema in AAT-Deficient Patients'; ClinicalTrials.gov Identifier: NCT00263887.
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| 11. |
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| 12. |
- Sandström, Caroline, et al.
(författare)
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Endotoxin receptor CD14 in PiZ alpha-1-antitrypsin deficiency individuals
- 2008
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Ingår i: Respiratory Research. - : Springer Science and Business Media LLC. - 1465-9921 .- 1465-993X. ; 9:34
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Tidskriftsartikel (refereegranskat)abstract
- Background: CD14, a receptor for lipopolysaccharides (LPS), is found in both a membrane-bound form (mCD14) and a soluble form (sCD14). It is suggested that sCD14 is mainly released from blood monocytes by serine protease-mediated shedding. Because alpha(1)-antitrypsin (AAT), an inhibitor of serine proteases, has been shown to regulate CD14 expression in human monocytes in vitro, we sought to investigate plasma levels of sCD14 and monocyte expression of mCD14 in subjects at age 30 years with normal MM and deficient PiZZ and PiSZ genotypes of AAT. Methods: Plasma levels of AAT and sCD14 were measured in 75 PiZZ and 34 PiSZ individuals with normal lung function identified from the Swedish neonatal AAT deficiency screening, and in 95 age matched PiMM controls. The mCD14 expression in monocytes from 9 PiZZ, 6 PiSZ and 11 PiMM subjects was analysed by FACS and Quantitative Real Time Reverse Transcription PCA. Results: As expected, plasma AAT concentrations were PiMM > PiSZ > PiZZ (p < 0.001). Plasma sCD14 levels were higher in PiZZ than in PiMM subjects (p < 0.01). The expression level of mCD14 was higher (1.89-fold) in monocytes isolated from PiZZ subjects compared to PiMM controls (p = 0.00189). Conclusion: This study is the first to show higher levels of plasma sCD14 and monocyte mCD14 expression in young, clinically healthy PiZZ AAT subjects.
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| 13. |
- Stockley, R A, et al.
(författare)
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Ongoing research in Europe: Alpha One International Registry (AIR) objectives and development.
- 2007
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Ingår i: European Respiratory Journal. - : European Respiratory Society (ERS). - 1399-3003 .- 0903-1936. ; 29:3, s. 582-586
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Tidskriftsartikel (refereegranskat)abstract
- In 1997, the World Health Organization recommended establishing an international registry of alpha(1)-antitrypsin deficiency. The objective of the present article is to describe the Organisation of an international network of registries, the Alpha One International Registry (AIR), and the processes of enrolling and entering data. By the end of 2005, the registry included individuals from 21 countries (from four continents). The inclusion criterion was either phenotypes PiZZ, PiSZ or other severely deficient variants. Demographic and clinical information have been collected by a standardised questionnaire, translated for each country. Data are transferred to the AIR database at the Dept of Respiratory Medicine, University Hospital, Malmo, Sweden, either by e-mail or via two web-enabled questionnaires in HTML. All data are merged and checked for consistency and missing values. Collection of data started in 1999 and, by September 2005, data on 2,150 individual patients (1,180 male) had been submitted. Of these, 1,855 (84%) have phenotype PiZ, 181 (8%) PiSZ and 114 (5%) other rare Pi phenotypes. The mean age at inclusion was 49.8 yrs (SD=13.3) and the majority were index cases (64.1%). The Alpha One International Registry is the largest specific alpha(1)-antitrypsin deficiency registry, fulfilling a major World Health Organization recommendation. The success related to the convergence of national registries into a common database creating a unique registry beyond geographic boundaries and encompassing alpha(1)-antitrypsin deficiency from various ethnic groups.
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| 14. |
- Stolk, Jan, et al.
(författare)
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Progression parameters for emphysema: A clinical investigation
- 2007
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Ingår i: Respiratory Medicine. - : Elsevier BV. - 1532-3064 .- 0954-6111. ; 101:9, s. 1924-1930
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Tidskriftsartikel (refereegranskat)abstract
- In patients with airflow limitation caused by cigarette smoking, lung density measured by computed tomography is strongly correlated with quantitative pathology scores of emphysema, but the ability of lung densitometry to detect progression of emphysema is disputed. We assessed the sensitivity of lung densitometry as a parameter of disease progression of emphysema in comparison to FEV1 and gas transfer. At study baseline and after 30 months we measured computed tomography (CT)-derived lung density, spirometry and carbon monoxide diffusion coefficient in 144 patients with chronic obstructive pulmonary disease (COPD) in five different centers. Annual change in lung density was 1.31 g/L/year (CI 95%: -2.12 to -0.50 HU, p = 0.0015, 39.5 mL/year (CI 95%: -100.0-21.0 mL, p = 0.2) for FEV1, (-39.5 mL) and 24.3 mu mol/min/kPa/L/year for gas transfer (CI 95%: -61.0-12.5 mu mol/min/kPa/L/year, p = 0.2). Signal-to-noise ratio (mean change divided by standard error of the change) for the detection of annual change was 3.2 for lung densitometry, but 1.3 for both FEV1 and gas diffusion. We conclude that detection of progression of emphysema was found to be 2.5-fold more sensitive using lung densitometry than by using currently recommended lung function parameters. Our results support CT scan as an efficacious test for novel drugs for emphysema. (c) 2007 Published by Elsevier Ltd.
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| 15. |
- Tanash, Hanan, et al.
(författare)
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Clinical course and prognosis of never-smokers with severe alpha-1-antitrypsin deficiency (PiZZ).
- 2008
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Ingår i: Thorax. - : BMJ. - 1468-3296 .- 0040-6376. ; 63, s. 1091-1095
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Previous studies of non-smoking individuals with severe alpha-1-antitrypsin deficiency (PiZZ) have been sparse and included only a limited number of individuals, mostly identified by respiratory symptoms. The aim of this study was to estimate the prognosis of non-smoking PiZZ individuals and to analyze the most common causes of death by including a large number of individuals who had been identified due to reasons other than respiratory symptoms. METHODS: The study included 568 non-smoking PiZZ subjects who were selected from the Swedish National AAT Deficiency Registry and followed-up from 1991 to September 2007. Of these, 156 (27%) were identified by respiratory symptoms (respiratory cases) and 412 were identified by extra pulmonary symptoms or screening (non-respiratory cases). RESULTS: Ninety-three subjects (16%) died during the follow-up time. The specific Standardized Mortality Rate (SMR) for the whole study population was 2.32 (95% confidence interval (CI) 1.87-2.83) with no significant difference between men and women. The SMR was 2.55 (95% CI 1.91-2.83) for the respiratory cases and 2.07 (95% CI 1.49-2.81) for the non-respiratory cases. Further calculation of SMR for subgroups in the non-respiratory cases showed that the SMR was 0.70 (95% CI 0.14-2.04) for individuals identified by family/population screening. Emphysema and liver cirrhosis were the most common causes of death (45% and 28%, respectively). Malignant transformation was found in 38% of the cirrhotic cases. CONCLUSION: Non-smoking PiZZ individuals identified by screening do not have an increased mortality risk compared with the Swedish general population.
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| 16. |
- Thylefors, Joakim, et al.
(författare)
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Dark adaptation during systemic hypoxia induced by chronic respiratory insufficiency
- 2009
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Ingår i: Investigative Ophthalmology & Visual Science. - : Association for Research in Vision and Ophthalmology (ARVO). - 1552-5783. ; 50:3, s. 12-1307
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To investigate dark adaptation during hypoxia in patients with chronic respiratory failure.METHODS: At three visits, dark adaptation was recorded by computerized dark adaptometry in 13 patients with chronic respiratory insufficiency treated by long-term oxygen therapy. At visits 1 and 3, the patients were administered their usual oxygen supplement. At visit 2, no oxygen was given. At each visit, an analysis of arterial blood gases measured pH, partial pressure of O(2) (Pao(2)), partial pressure of CO(2) (Paco(2)), base excess (BE), standard bicarbonate (HCO(3)), and arterial oxygen saturation. Pulse oximetry (POX) was also recorded.RESULTS: Significant differences were recorded between visits 1 and 2 and between visits 2 and 3 for Pao(2), arterial oxygen saturation, and POX; no differences were found for pH, Paco(2), BE, or HCO(3). No differences were seen between visits 1 and 3 for any of the laboratory parameters. All patients had normal and unchanged dark adaptation at the three visits.CONCLUSIONS: Hypoxia in chronic respiratory insufficiency was associated with normal dark adaptation, in contrast to hypoxia in healthy persons at high altitudes, which is known to produce impaired dark adaptation. The result may partly reflect the influence of Paco(2) on the lumen of choroidal and retinal vessels. At high altitudes, with hypocapnic vasoconstriction the oxygen supply to the retina is further compromised, resulting in reduced dark adaptation. The authors hypothesize that respiratory insufficiency with hypercapnia or normocapnia will have larger choroidal and retinal vessel lumens, added to by further dilation of retinal vessels during hypoxia. The tentative net effect would be preserved dark adaptation.
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