Does body height reduction influence interpretation of lung function in COPD patients?

Vertebral deformities are prevalent in chronic obstructive pulmonary disease (COPD) patients and may cause excessive loss of height. As height is used for calculating reference values for pulmonary function tests, larger than normal height reduction could cause overestimation of lung function. In this cross-sectional study of 465 COPD patients and 462 controls, we explored how often lung function is misinterpreted due to height reduction in COPD patients, and whether the number or severity of vertebral deformities correlate with height reduction. Measured height was compared to recalled tallest height (RTH) and height calculated from arm span (ASH) to assess height reduction. Vertebral deformities were assessed from radiographs and pulmonary function was assessed using standard formulae. Height reduction was frequent in both the study and control groups, and increased with the number and severity of vertebral deformities. When using current measured height, lung function was overestimated in a significant proportion of COPD patients at relatively modest height reductions. The effects were smallest for forced expiratory volume in 1 s and forced vital capacity, and most pronounced for total lung capacity and residual volume. Therefore, we propose that in COPD patients with excessive height reduction, one might use RTH or ASH in calculating predicted values. Furthermore, such patients should be evaluated for co-existing vertebral deformities and osteoporosis.

High prevalence of vertebral deformities in COPD patients: relationship to disease severity.

Bone mineral density decreases with advancing chronic obstructive pulmonary disease (COPD) severity, but it is not known whether this is reflected in higher fracture rates. The present authors wanted to compare the prevalence of vertebral deformities in COPD patients with those in a population-based reference group to determine whether the number of deformities was related to the severity of COPD and how far the use of oral corticosteroids (OCS) influenced the prevalence of deformities. In the present cross-sectional study of 465 COPD patients and 462 controls, vertebral deformities were found in 31% of the COPD patients and 18% of the controls. In subjects who had never or sporadically used OCS, deformities were found in 29% of the COPD patients and 17% of the controls. In females, the average number of vertebral deformities was almost two-fold when COPD severity increased from Global Initiative of Chronic Obstructive Lung Disease stage II to III. In males, the use of OCS had a small but significant influence. Prevalence of vertebral deformities was significantly higher in chronic obstructive pulmonary disease patients than in the controls. In females, the average number of deformities was related to chronic obstructive pulmonary disease severity even after adjustment for other known risk factors. The difference between patients and controls remained significant even in those who never or sporadically used oral corticosteroids.

Higher skeletal muscular metabolic reserve capacity in COPD patients than healthy subjects.

We investigated the interaction between skeletal muscle exercise capacity and central restrictions using exercise modalities, which recruit differing levels of muscle mass in eight patients chronic obstructive lung disease (COPD) (FEV(1)% of predicted; 35 [SE 4%]) and eight healthy controls. Subjects performed conventional bicycling, two-leg knee extensor (2-KE) and single-leg knee extensor (1-KE) exercises. Maximal values for pulmonary VO(2) (VO(2max)), power output, blood lactate, heart rate, blood pressure, and arterial oxygen saturation of hemoglobin were registered. VO(2max) in controls was 2453 (210), 1468 (124), and 976 (76) mL/min during bicycling, 2-KE and 1-KE, respectively. The COPD patients achieved 48% (P<0.05), 62% (P<0.05), and 81% (P=0.10) of the control values. The mass-specific VO(2max) (VO(2max)/exercising muscle mass) during 1-KE was 345 (25) and 263 (30) mL/kg/min (P<0.05) in controls and COPD patients, respectively. During 2-KE the controls and COPD patients achieved 85% (4%) and 67% (5%) (P=0.06) of the mass-specific VO(2) during 1-KE, while during bicycling they achieved 31% (2%) and 17% (1%) (P<0.05), respectively. The COPD patients have central restrictions when exercising with a relatively small muscle mass (2-KE) and have a higher muscular metabolic reserve capacity than controls during whole body exercise.

Low bone mineral density is related to severity of chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease (COPD) appears to be associated with low bone mineral density (BMD). BMD loss can be accelerated by a number of factors associated with COPD, but it is not known whether COPD itself has a direct effect. Our aim was to investigate in a cross-sectional study whether COPD patients have lower BMD than healthy individuals, and whether the severity of the disease affects BMD. Eighty-eight COPD patients attending a rehabilitation program were classified into stages II, III and IV using GOLD criteria. BMD was measured by dual X-ray absorptiometry in lumbar spine (L2-4), femoral neck (FN) and total body (TB). Values were converted to Z-scores (adjusted for age and sex). Associations between Z-scores and steroid use, body mass index, pack-years and six-min walking distance were analyzed. The Z-scores (mean and (CI)) for all patients were for L2-4: -0.6 (-0.9, -0.3), FN: -0.8 (-1.0, -0.5) and TB: -0.5 (-0.8, -0.2). All scores were significantly different from those of a control population (p<0.001). For all three variables (ZL2-4, ZFN, ZTB) there were significant differences between the stages. The difference for ZL2-4 was still significant after adjustment for risk factors. We conclude that BMD is low in COPD patients and decreases with increasing severity of the disease. Low BMD may to some extent be a disease-specific effect.

Effect of exercise mode on oxygen uptake and blood gases in COPD patients.

Patients with chronic obstructive pulmonary disease (COPD) are characterised by decreased exercise tolerance, and, more variably, exercise induced hypoxaemia (EIH). Evaluation of physical work capacity and physiological responses to exercise may be performed by various procedures, but there are diverging opinions as to which exercise test should be preferred. In the current study, oxygen uptake and arterial blood gases in COPD patients have been compared during submaximal and maximal exercise on treadmill and ergometer bicycle. Treadmill exercise resulted in higher peak oxygen uptake than bicycle exercise (1111+/-235 vs. 987+/-167 ml min(-1), P<0.02), while the plasma lactate levels were higher during cycling (1.8+/-0.8 vs. 3.8+/-1.7 mmol l(-1), P<0.001). Neither carbon dioxide output, ventilation, nor rate of perceived exertion (Borg RPE scale) showed significant differences between the two modes of exercise. The EIH during both maximal (delta Sa,O2 = -5.6+/-4.2 vs. -3.4+/-5.1%) and sub-maximal exercise was more pronounced during treadmill walking than during cycling. The present study indicates that the VO2peak in COPD patients is higher, the maximal lactate concentrations lower and the development of EIH more pronounced when exercise testing is performed on a treadmill than on a bicycle ergometer.

Four weeks' intensive rehabilitation generates significant health effects in COPD patients.

Changes in health according to World Health Organization's International Classification of Functioning, Disability and Health (ICF) after four weeks of pulmonary rehabilitation (PR) were investigated. Gender differences in the response to PR, and the correlation between improvements in the two components of ICF (Body functions and Activities and Participation) were examined. Twenty-two men and 18 women with chronic obstructive pulmonary disease in Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage II-IV attended in-patient, multidisciplinary PR consisting of endurance training four to five times/week at 70% of peak work rate (WRpeak), resistance training three to four times/week at 72% of 15 repetitions maximum, educational sessions and individual counselling. The results were compared to those of 20 Chronic Obstructive Pulmonary Disease (COPD) patients included after the same criteria and investigated while waiting for admission to PR. In the rehabilitation group, we found significant improvements in health related quality of life (HRQoL) (-7 units, St. George's Respiratory Questionnaire), arm (6%) and leg (15%) maximal voluntary contraction, peak oxygen uptake (6%), WRpeak (60%) and treadmill endurance time (93%). At iso-WR, ventilation and dyspnoea were significantly lower, but inspiratory capacity remained unchanged. Improvements in HRQoL correlated with increases in peak ventilation, but not in muscle strength or exercise capacity. Men improved their six-minute walking distance significantly in contrast to women. Clinically important improvements in HRQoL were found in two out of three of the men, and one out of three of the women. Four weeks of intensive PR generated significant health effects comparable to longer lasting programmes. Changes in exercise capacity and muscle strength were not related to improvements in HRQoL. The gender differences in the response to PR deserve attention in future studies.

Gender differences in the performance of activities of daily living among patients with chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease (COPD) limits the ability to perform activities of daily living (ADL). The Pulmonary Functional Status and Dyspnoea Questionnaire (PFSDQ) measures general dyspnoea, dyspnoea during ADL (dyspnoea score) and loss of functional performance (activity score) for a large number of activities commonly performed by adults. The questionnaire is only validated for male patients. The aim of our study was therefore to validate the PFSDQ for women with COPD. We then wanted to investigate possible gender differences in responses to the PFSDQ and whether associations between the PFSDQ and pulmonary function, exercise capacity, health related quality of life (HRQoL) and general quality of life (QoL) were influenced by gender. This cross-sectional, observational study included 110 COPD patients. Sixty-five men and 45 women, referred to pulmonary rehabilitation participated. Pulmonary function and six-minute walking distance (6MWD) were measured. Patients completed PFSDQ, St George's Respiratory Questionnaire (SGRQ, HRQoL) and Perceived Quality of Life Scale (PQoL, QoL). No gender differences were found in pulmonary function (% of predicted), 6MWD, SGRQ or PQoL. Most items in the PFSDQ were found relevant by both women and men. Activity Scores were only different for men and women for items concerning home management; women had changed their functional performance the most, particularly for the heaviest chores. No gender differences were found in dyspnoea scores. Moderate correlations were found between PFSDQ and 6MWD, SGRQ and PQoL. Multiple linear regression analyses showed that these relations were not influenced by gender. We consider PFSDQ as applicable to women as to men as a comprehensive measure of functional performance and dyspnoea. The questionnaire gives information complementary to measures of exercise capacity, HRQOL and QOL. The larger loss of functional performance in home management among women should be taken into account in the treatment of COPD patients.

Relationships between hormone-induced and compensatory weight changes in reindeer (Rangifer tarandus tarandus).

1. In connection with a study of hormonal effects on food consumption in reindeer, weight changes during treatment were compared with weight changes during a 3-week period following treatment. 2. Rates of weight change during the post-treatment period were inversely proportional to induced weight changes. 3. This inverse relationship is interpreted as evidence for a functional set-point for body weight in reindeer.

Effects of nutrition on seasonal changes in testosterone levels in young male reindeer (Rangifer tarandus tarandus).

Food restriction during autumn in male reindeer calves decreased peak testosterone levels at 4-6 months, and also at 16-17 months of age. Peak testosterone levels at the age of 16-17 months were significantly correlated to body weight at 6 months but not to body weight at 16 months of age. There were small secondary testosterone peaks (1-3 ng/ml) in March or April in 11 of 16 animals. Testosterone levels started to increase before summer solstice in 50% of the yearlings.

The effect of feeding on the metabolic rate in harbour seals (Phoca vitulina).

The heat increment of feeding was estimated in harbour seals (Phoca vitulina). Seals were given different amounts of herring, ranging from 0.8 to 2.65 kg. The caloric content of the herring ranged from 6575 to 12560 kJ.kg-1 depending on time of year. Metabolic rate increased within 30 min after feeding, and the magnitude and duration of heat increment of feeding depended on the size of the meal and the caloric content of the herring. Measured heat increment of feeding was up to 14.9% of gross energy intake and metabolic rate increased as much as 46% above resting, postabsorptive metabolic rate for 15 h duration in a harbour seal with a body weight of approximately 40 kg.

Effect of hypobaric hypoxia on blood gases in patients with restrictive lung disease.

Several publications have reported effects of hypobaric conditions in patients with chronic obstructive pulmonary disease. To the current authors' knowledge, similar studies concerning patients with restrictive lung disease have not been published. The effect of simulated air travel in a hypobaric chamber on arterial blood gases, blood pressure, and cardiac frequency during rest and 20 W exercise, and the response to supplementary oxygen in 17 patients with chronic restrictive ventilatory impairment has been investigated. Resting oxygen tension in arterial blood (Pa,O2) decreased from 10.4+/-1.6 kPa at sea level to 6.5+/-1.1 kPa at 2,438 m simulated altitude, and decreased further during light exercise in all patients (5.1+/-0.9 kPa). Pa,O2 at this altitude correlated positively with sea-level Pa,O2 and transfer factor of the lung for carbon monoxide (TL,CO), and negatively with carbon dioxide tension in arterial blood (Pa,CO2). Pa,O2 increased to acceptable levels with an O2 supply of 2 L x min(-1) at rest and 4 L x min(-1) during 20 W exercise. In conclusion, most of the patients with restrictive ventilatory impairment developed hypoxaemia below the recommended levels of in-flight oxygen tension in arterial blood during simulated air travel. Light exercise aggravated the hypoxaemia. Acceptable levels of oxygen tension in arterial blood, with only a minor increase in carbon dioxide tension in arterial blood, were obtained by supplementary oxygen.

Relationship between exercise desaturation and pulmonary haemodynamics in COPD patients.

Pulmonary hypertension (PH) in patients with chronic obstructive pulmonary disease (COPD) has traditionally been explained as an effect of hypoxaemia. Recently, other mechanisms, such as arterial remodelling caused by inflammation, have been suggested. The aim of this study was to investigate whether exercise-induced PH (EIPH) could occur without concurrent hypoxaemia, and whether exercise-induced hypoxaemia (EIH) was regularly accompanied by increased pulmonary artery pressure or pulmonary vascular resistance index (PVRI). Pulmonary haemodynamics in 17 patients with COPD of varying severity, but with no or mild hypoxaemia at rest, were examined during exercise equivalent to the activities of daily living (ADL) and exhaustion. EIPH occurred in 65% of the patients during ADL exercise. Pulmonary arterial pressure during exercise was negatively correlated with arterial oxygen tension, but EIPH was not invariably accompanied by hypoxaemia. Conversely, EIPH was not found in all patients with EIH. The resting PVRI was negatively correlated with arterial oxygen tension during ADL exercise, but an elevated PVRI without EIH occurred in 35% of the patients. In conclusion, exercise-induced pulmonary hypertension occurred during exercise equivalent to the activities of daily living in chronic obstructive pulmonary disease patients with no or mild hypoxaemia at rest. Although pulmonary artery pressure and arterial oxygen tension were negatively correlated during exercise, a consistent relationship between hypoxaemia and pulmonary hypertension could not be demonstrated. This may indicate that mechanisms other than hypoxaemia contribute significantly in the development of pulmonary hypertension in these patients.

Use of anthropometric measurements in assessing risk for coronary heart disease: a useful tool in worksite health screening?

The study examined the association between the anthropometric measurements body mass index (BMI), waist/hip ratio (WHR), and waist/thigh ratio (WTR) and cardiovascular risk factors, and assessed whether a combination of BMI and WHR could be used in routine screening of risk for cardiovascular arteriosclerotic disease at worksites. The data were obtained from a cross-sectional survey designed to assess the nutritional situation, with special reference to cardiovascular risk factors. The study population comprised 372 healthy men working on platforms in the North Sea. Serum cholesterol, triglyceride, fibrinogen, and blood pressure were positively related to the anthropometric variables, while high-density lipoprotein (HDL) was inversely related with them. The relations remained after adjusting for possible confounders, such as age, smoking, physical activity, and an indicator of dietary fat intake. In stepwise multiple linear regression models, BMI, WHR, and WTR were positively related to serum cholesterol, triglycerides, fibrinogen, diastolic blood pressure, and systolic blood pressure, and inversely related to HDL. When controlling for the anthropometric variables WHR and WTR, BMI was not independently related to fibrinogen and risk score. WHR and WTR were not independently related to systolic and diastolic blood pressure, and WTR was in addition not related to triglycerides when controlling for BMI. Overall, the anthropometric variables BMI and WHR were considered the best predictors for CAD risk when taking several risk factors into consideration. A joint variable between BMI and WHR, called "body score", constituted the four categories lean, lean android, overweight gynoid, and overweight ovoid. This body score was positively associated with levels of serum lipids, fibrinogen, and blood pressure, and inversely associated with HDL. In stepwise multiple linear regression models, controlling for possible confounding variables, body score was positively related to CAD risk. Dividing the risk score into tertiles, about 51% of the lean were in the first, while 46% of the overweight ovoid were in the third tertile. Those classified as lean android or overweight gynoid had about the same distribution, namely between 31% and 39% in each tertile if the two categories were combined. These data support the hypothesis that BMI, WHR, and WTR are independent predictors for risk factors for CAD among oil workers, and that combinations of BMI and WHR are strong enough predictors to be useful in routine screening for CAD risk at worksites. Based on these findings, supported by data from the literature, a matrix aimed at screening for follow-up at worksites is proposed.

Development of severe hypoxaemia in chronic obstructive pulmonary disease patients at 2,438 m (8,000 ft) altitude.

The arterial oxygen tensions (Pa,02) in chronic obstructive pulmonary disease (COPD) patients travelling by air, should, according to two different guidelines, not be lower than 7.3 kPa (55 mmHg) and 6.7 kPa (50 mmHg), respectively, at a cabin pressure altitude of 2,438 m (8,000 ft). These minimum in-flight Pa,O2 values are claimed to correspond to a minimum Pa,O2 of 9.3 kPa (70 mmHg) at sea-level. The authors have tested whether this limit is a safe criterion for predicting severe in-flight hypoxaemia. The authors measured arterial blood gases at sea-level, at 2,438 m and at 3,048 m (10,000 ft) in an altitude chamber at rest and during light exercise in 15 COPD patients with forced expiratory volume in one second (FEV1) <50% of predicted, and with sea-level Pa,O2 >9.3 kPa. Resting Pa,O2 decreased below 7.3 kPa and 6.7 kPa in 53% and 33% of the patients, respectively, at 2,438 m, and in 86% and 66% of the patients at 3,048 m. During light exercise, Pa,O2 dropped below 6.7 kPa in 86% of the patients at 2,438 m, and in 100% of the patients at 3,048 m. There was no correlation between Pa,O2 at 2,438 m and pre-flight values of Pa,O2, FEV1 or transfer factor of the lung for carbon monoxide. In contrast to current medical guidelines, it has been found that resting arterial oxygen tension >9.3 kPa at sea-level does not exclude development of severe hypoxaemia in chronic obstructive pulmonary disease patients travelling by air. Light exercise, equivalent to slow walking along the aisle, may provoke a pronounced aggravation of the hypoxaemia.