Sjur Humerfelt

Haemodynamic responses to exercise in patients with COPD

The present study aimed to explore the prevalence of pre-capillary pulmonary hypertension (PH) and characterise haemodynamic vascular responses to physical exercise in chronic obstructive pulmonary disease (COPD) outpatients, where left ventricular dysfunction and comorbidities were excluded. 98 patients with COPD underwent right heart catheterisation at rest and during supine exercise. Mean pulmonary artery pressure (Ppa), pulmonary capillary wedge pressure (Ppcw) and cardiac output (CO) were measured at rest and during exercise. Exercise-induced increase in mean Ppa was interpreted relative to increase in blood flow, mean Ppa/CO, workload (W) and mean Ppa/W. Pulmonary vascular resistance (PVR) and pulmonary artery compliance (PAC) were calculated. PH at rest was defined as mean Ppa at rest ≥25 mmHg and Ppcw at rest <15 mmHg. Prevalence of PH was 5%, 27% and 53% in Global Initiative for Chronic Obstructive Lung Disease stages II, III and IV, respectively. The absolute exercise-induced rise in mean Ppa did not differ between subjects with and without PH. Patients without PH showed similar abnormal haemodynamic responses to exercise as the PH group, with increased PVR, reduced PAC and steeper slopes for mean Ppa/CO and mean Ppa/W. Exercise revealed abnormal physiological haemodynamic responses in the majority of the COPD patients. The future definition of PH on exercise in COPD should rely on the slope of mean Ppa related to cardiac output and workload rather than the absolute values of mean Ppa.

Effectiveness of postal smoking cessation advice: a randomized controlled trial in young men with reduced FEV1 and asbestos exposure

There have been few community-based randomized, controlled intervention trials for cessation in high-risk smokers. In such a trial we evaluated the effects of postal smoking cessation advice in smokers with asbestos exposure and/or reduced forced expiratory volume in one second (FEV1). All men aged 30-45 yrs (n=22,392) living in 34 municipalities in western Norway were invited to a cross-sectional community survey. Information on smoking habits and occupational asbestos exposure were obtained from self-administered questionnaires and measurements of FEV1 were performed with dry-wedge bellow spirometers. Among 16,393 participants we identified a group of 2,610 smokers with previous occupational asbestos exposure and/or adjusted FEV1 in the lowest quartile. A random half (n=1,300) received a mailed personal letter from a respiratory physician with a person-specific health advice to quit smoking and a pamphlet on smoking cessation. The remaining smokers (n=1,310) acted as controls and did not receive any information. Twelve months after the intervention, information on smoking habits was re-examined using a postal questionnaire. Among the respondents (n=2,282), smoking cessation was reported altogether by 13.7% in the intervention group versus 9.9% in the control group (p<0.01). The 1 yr sustained quit rate (no smoking at all during the last year) was 5.6 versus 35% (p<0.05), respectively. Measurements of carbon monoxide in expired air (with < or = 10 parts per million) confirmed self-reported nonsmoking in samples of the two groups. In a community this simple postal smoking cessation advice from a respiratory physician based on person-specific risk factors improved the 1 yr sustained success rate by 60% in identified high-risk smokers.

Association of years of occupational quartz exposure with spirometric airflow limitation in Norwegian men aged 30–46 years

BACKGROUND The association between occupational quartz exposure and ventilatory function was investigated in men in a general population after adjusting for other potential determinants of outcome. METHODS All eligible men aged 30–46 years living in western Norway (n = 45 380) were invited to a cross sectional community survey. This included a self administered questionnaire (with respiratory symptoms, smoking habits and occupational exposures), spirometric recordings (using dry wedge bellow spirometers), and a chest radiograph (65% attendance). Measurements of forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) were obtained in 91% (n = 26 803) of those who participated, 26 106 of whom performed successful spirometric tests and had normal chest radiographs and remained for further analysis. Age, body mass index, and technician standardised residuals ((observed minus predicted value)/residual standard error) of maximum FEV1/height2 and FVC/height2 were used as outcome variables for adjusted lung function levels, respectively. RESULTS Occupational quartz exposure was reported by 13% (n = 3445) of those who participated in the survey, with a mean duration of seven years. Among those exposed to quartz, significant inverse linear relationships were observed between years of exposure and FEV1 level and the ratio of FEV1/FVC, independent of host characteristics. Multiple linear regression analyses showed that the difference in FEV1 associated with each year of quartz exposure was –4.3 ml (95% Cl –1.1 to –7.5 ml; p = 0.01) compared with –6.9 ml (95% Cl –4.7 to –9.1 ml; p<0.01) from smoking 20 cigarettes/day for one year after adjusting for age, atopy, asthma, wheezing, marital status, and other occupational exposures. CONCLUSION In men aged 30–46 years with occupational quartz exposure and normal chest radiographs the duration of occupational quartz exposure was an independent predictor for spirometric airflow limitation.

Single breath transfer factor for carbon monoxide in an asymptomatic population of never smokers.

BACKGROUND: Data on reference values of transfer factor variables in general populations of asymptomatic never smokers are limited. The aim of this study was to examine the relation between test variables and age, height, haemoglobin concentration and carboxyhaemoglobin concentration. METHODS: Measurements of single breath transfer factor for carbon monoxide (TLCO) were obtained for a randomly selected sample of never smokers in north western Europe who were 18-73 years old and had no respiratory symptoms or disorders. Two recordings of TLCO with a ratio of inspiratory vital capacity to forced vital capacity of greater than 0.09 were obtained by standardised techniques for 304 subjects. RESULTS: The measurement errors expressed as a percentage of the common mean value of TLCO, volume adjusted TLCO (KCO), and alveolar volume (VA) were 4.5%, 4.2%, and 2.4% respectively. Multiple linear regressions showed sex specific effects of height and age on TLCO, and, in addition, of haemoglobin and carboxyhaemoglobin concentrations on KCO. VA was associated with height but not with age. The 5th and 95th centiles for TLCO and KCO in men and women were between 78% and 82% and between 120% and 127%, respectively, of predicted values when age and height were taken into account. CONCLUSION: Reference equations and normal values for transfer test variables in a large healthy population of never smokers are described in relation to age, height, and haemoglobin concentrations. To our knowledge, this is the first report of an association between carboxyhaemoglobin concentrations and KCO in a population of never smoking men and women.

Factors associated with a prolonged length of stay after acute exacerbation of chronic obstructive pulmonary disease (AECOPD).

Background Early identification of patients with a prolonged stay due to acute exacerbation of chronic obstructive pulmonary disease (COPD) may reduce risk of adverse event and treatment costs. This study aimed to identify predictors of prolonged stay after acute exacerbation of COPD based on variables on admission; the study also looked to establish a prediction model for length of stay (LOS). Methods We extracted demographic and clinical data from the medical records of 599 patients discharged after an acute exacerbation of COPD between March 2006 and December 2008 at Oslo University Hospital, Aker. We used logistic regression analyses to assess predictors of a length of stay above the 75th percentile and assessed the area under the receiving operating characteristic curve to evaluate the model’s performance. Results We included 590 patients (54% women) aged 73.2±10.8 years (mean ± standard deviation) in the analyses. Median LOS was 6.0 days (interquartile range [IQR] 3.5–11.0). In multivariate analysis, admission between Thursday and Saturday (odds ratio [OR] 2.24 [95% CI 1.60–3.51], P<0.001), heart failure (OR 2.26, 95% CI 1.34–3.80), diabetes (OR 1.90, 95% CI 1.07–3.37), stroke (OR 1.83, 95% CI 1.04–3.21), high arterial PCO2 (OR 1.26 [95% CI 1.13–1.41], P<0.001), and low serum albumin level (OR 0.92 [95% CI 0.87–0.97], P=0.001) were associated with a LOS >11 days. The statistical model had an area under the receiver operating characteristic curve of 0.73. Conclusion Admission between Thursday and Saturday, heart failure, diabetes, stroke, high arterial PCO2, and low serum albumin level were associated with a prolonged LOS. These findings may help physicians to identify patients that will need a prolonged LOS in the early stages of admission. However, the predictive model exhibited suboptimal performance and hence is not ready for clinical use.

The association between lung function and fatal stroke in a community followed for 4 decades

Background Previous studies, all of <20 years of follow-up, have suggested an association between lung function and the risk of fatal stroke. This study investigates the stability of this association in a cohort followed for 4 decades. Methods The Bergen Clinical Blood Pressure Survey was conducted in Norway in 1964–1971. The risk of fatal stroke associated with forced expiratory volume after one second (FEV1) was estimated with Cox proportional hazards regression, making progressive adjustment for potential confounders. Results Of 5617 (84%) participants with recorded baseline FEV1, 462 died from stroke over 152 786 subsequent person-years of follow-up according to mortality statistics of 2005; mean (SD) follow-up was 27 (12) years. An association between baseline FEV1 (L) and fatal stroke was observed; HR=1.38 (95% CI 1.11 to 1.71) and HR=1.62 (95% CI 1.22 to 2.15) for men and women, respectively (adjusted for age and height). The findings were not explained by smoking, hypertension, diabetes, atherosclerosis, socioeconomic status, obstructive lung disease, physical inactivity, cholesterol or body mass index and persisted in subgroups of never-smokers, subgroups without respiratory symptoms and survivors of the first 20 years of follow-up. For male survivors with a valid FEV1 at follow-up (1988–1990) (n=953), baseline FEV1 (L) indicated a possible strong and independent association to the risk of fatal stroke after adjustments for individual changes in FEV1 (ml/year) (HR 1.95 (95% CI 0.98 to 3.86)). Conclusion There is a consistent, independent and long-lasting association between lung function and fatal stroke, probably irrespective of changes during adult life.

Acetazolamide improves oxygenation in patients with respiratory failure and metabolic alkalosis.

Coexistent respiratory failure and metabolic alkalosis is a common finding. Acidotic diuretics cause a fall in pH that may stimulate respiration.

Norwegian population surveys on respiratory health in adults: objectives, design, methods, quality controls and response rates

Background and Aims:  Quantifying the prevalence of asthma, chronic obstructive pulmonary disease (COPD) and restrictive pulmonary diseases in Norway is needed to document the burden of chronic respiratory inflammatory diseases on disability, health care costs and impaired quality of life. To introduce effective interventions for prevention, cure and care, there is a prerequisite to know the environmental causes. Furthermore, using relevant and precise phenotypes from community‐based studies are important for detecting molecular‐genetic causes for diseases.

Increased awareness of COPD in the Norwegian population

In 2001 the goals of the Global Initiative for Chronic Obstructive Lung Disease (GOLD) were to increase awareness of COPD and decrease morbidity and mortality as a result of the disease (1). In particular, the GOLD aimed to increase awareness in the medical community, in public health officials and in the general public. In general, the initiative wanted to demonstrate to the community that COPD is a public health problem. A Norwegian Medical Association’s Strategy Group dedicated to the study of COPD (2) was initiated in the spring of 2002. The group translated the GOLD pocket guide to COPD management and prevention in order to make it more applicable to Norwegian Primary Care Physicians and Health Allies. The pocket guide was distributed to 18 000 Norwegian physicians. The Norwegian Heart and Lung Patient Organization (LHL) has, since 2002, collaborated with The Norwegian Medical Association’s COPD Strategy Group to increase the awareness of COPD in Norway. The COPD strategy group, the LHL and the Norwegian College of General Practitioners Respiratory Group have used the last five World COPD days to increase the focus on COPD. A telephone survey was conducted by the LHL in October/November from 2002 until 2005 using identical methods and questions. For each survey a random sample of people aged 15 years and above was interviewed by telephone until answers had been received from 1002 respondents. The questions were always the same. One question used was: ‘Have you ever heard about COPD?’. The percentage giving an affirmative answer to this question increased from 27% in 2002 to 78% in 2005 (Figure 1). Increased awareness of COPD was seen among women, among people older than 40 years, among those with an income of more than 60 000 Euro, as well among those with a university education. In 2005, 65% of the respondents thought that smoking was the main cause for COPD and 58% stated that COPD could not be cured by drug treatment. The Norwegian Government has taken public responsibility for the development of a national strategy plan for COPD which is to run from 2006 until 2011 (3). The Minister of Health focused on eight goals in her strategy plan including prevention, reduction of undiagnosed cases of COPD, equal and effective treatment, identification of persons with high risk, systematic follow-up of all patients in primary and secondary care, development of national guidelines, strengthening of the rehabilitations service, and increasing the resources for research on COPD. It is hoped that a national council of COPD will be established to follow-up the eight public aims. The Norwegian Directorate for Health and Social Affairs undertook an evaluation in January 2006 of their anti-smoking drive called ‘Smoking takes your breath away’ (4). The campaign was divided into several parts. Television slots carried clips of COPD sufferers speaking about what it was like living with the condition. The campaign also ran adverts and radio slots with descriptions and information about COPD. The public were invited to visit various websites where they could find more detailed information on COPD. An age and smoking stratified random sample of 1750 individuals was interviewed by telephone before and after the campaign. In the age group of 16–19 years the awareness of COPD increased from 51% to 98%, and in the age group of 35–55 years it increased from 91% to 100%. The campaign was successful in educating the public on the likely causes and symptoms of COPD. 27 58 71 78

Assessment of Right Ventricular Afterload in COPD

Abstract Background: We aimed to study whether pulmonary hypertension (PH) and elevated pulmonary vascular resistance (PVR) could be predicted by conventional echo Doppler and novel tissue Doppler imaging (TDI) in a population of chronic obstructive pulmonary disease (COPD) free of LV disease and co-morbidities.Methods: Echocardiography and right heart catheterization was performed in 100 outpatients with COPD. By echocardiography the time-integral of the TDI index, right ventricular systolic velocity (RVSmVTI) and pulmonary acceleration-time (PAAcT) were measured and adjusted for heart rate. The COPD patients were randomly divided in a derivation (n = 50) and a validation cohort (n = 50). Results: PH (mean pulmonary artery pressure (mPAP) ≥ 25mmHg) and elevated PVR ≥ 2Wood unit (WU) were predicted by satisfactory area under the curve for RVSmVTI of 0.93 and 0.93 and for PAAcT of 0.96 and 0.96, respectively. Both echo indices were 100% feasible, contrasting 84% feasibility for parameters relying on contrast enhanced tricuspid-regurgitation. RVSmVTI and PAAcT showed best correlations to invasive measured mPAP, but less so to PVR. PAAcT was accurate in 90- and 78% and RVSmVTI in 90- and 84% in the calculation of mPAP and PVR, respectively. Conclusions: Heart rate adjusted-PAAcT and RVSmVTI are simple and reproducible methods that correlate well with pulmonary artery pressure and PVR and showed high accuracy in detecting PH and increased PVR in patients with COPD. Taken into account the high feasibility of these two echo indices, they should be considered in the echocardiographic assessment of COPD patients.