Lung function in our aging population.

UNLABELLED: AIMS OF INVESTIGATION: The chronological age of the Caucasian population and their anthropometrical data have significantly changed within the last five decades. Therefore the question arises whether or not the commonly used reference values of the European Community (ECCS) for lung function may still be accepted today. Since these values were obtained in the 1960s from subjects in a limited age range. For the elderly, the measured values are deduced by extrapolation beyond the range of reference equations which had been obtained in a different population. Therefore decisions concerning elderly and smaller subjects concerning remuneration due to impaired lung function after industrial exposure on the basis of EGKS values are questionable. METHODS: Lung function tests were performed by pneumotachography, recording static lung volumes and flow-volume-curves in 262 asymptomatic non smoking males, aged 20 to 90 years. Measurements were performed with the MasterLab, or PneumoScreen systems (CareFusion, Höchberg). RESULTS were compared to the reference values of ECCS, SAPALDIA and LuftiBus. - RESULTS: For simplicity analysis of age and height dependence of investigated respiratory parameters (VC, FVC, FEV⊂1, FEV⊂1%FVC, PEF, MEF⊂75,50,25) can be described by linear functions (y = a * height ? b * age + c). The forced expiratory vital capacity, FVC, was calculated by FVC = 0.0615*H - 0.0308*A - 4.673; r = 0.78. Mean FVC for younger subjects was found to be 104.7 ± 10.7% of the ECCS reference values and 96.5 ± 11.8 % in older subjects. For most parameters investigated linear regressions on age were steeper than described by the ECCS reference values. The regression of lung function to height largely follows the ECCS prescriptions. SUMMARY: Bochum lung function values of younger healthy subjects were higher compared to the reference values of the ECCS and showed a steeper age descent. The alternatively discussed reference values of the SAPALDIA-, or LuftiBus-Study are higher, but do not cover all necessary parameters and/or the age range. A multi centre study for contemporary reference values is recommended.

[Efficiency as a new parameter of physical fitness of patients in 6-minute-walk-test]. / Effizienz als ein neuer Parameter zur Objektivierung der körperlichen Leistungsfähigkeit mittels 6-Minuten-Gehtest.

UNLABELLED: AIMS OF THE INVESTIGATION: The 6-minute-walk-test (6-MWT) is an effective tool for measuring physical fitness in elderly patients. The increased walking distance is taken as a parameter for improved physical conditions. Frequently an unaltered walking distance is found after participation in a rehabilitation measure, but heart rate is significantly lower in the second challenge, indicating an improved physical fitness. This positive effect is not recognized when only the walking distance is considered. METHODS: We therefore carried out a retrospective analysis of the 6-MWT tests performed by 303 male patients (69.2 ± 8.7 years) before and after 3-4 weeks of clinical rehabilitation. Instrumented by a mobile pulse oximeter for recording oxygen saturation and heart rate, patients were instructed at the outset and at the end of their rehabilitation stay to walk as fast as they could during 6 min. Measurements were performed every 30 s and printed. A new parameter, efficiency (E = S/6/f (C)) was introduced: the ratio of the walking distance, S, divided by 6 min and divided by the mean heart frequency, f (C) (beats/minute). RESULTS: The patients group walked 351 ± 79 m at 106.2 ± 12.7 beats/min in the initial 6-MWT and 362 ± 76.0 m at a heart rate of 104.0 ± 12.2 beats/min in the final test. Along with the increase in walking distance, efficiency E increased from 0.56 ± 0.13 m/beat to 0.59 ± 0.12 m/beat. Efficiency significantly correlates with the walking distance (p < 0.01). 54 patients (18%) had an increased efficiency in the final test at the end of rehabilitation although they walked a shorter distance compared to the initial test value: they walked with a lower heart frequency. CONCLUSIONS: The patient's performance of the second walk test with an unchanged distance at a lower heart frequency reveals an improved physical fitness. This is solely described by an increase of the parameter of efficiency, E. Calculation of this parameter delivers a quantification of the effect of exercise training irrespective of the patient's cooperation. Efficiency, hence, is a meaningful complement to the sole consideration of the distance walked in the assessment of physical fitness as a benefit of rehabilitation.

Measurements of lactate in exhaled breath condensate at rest and after maximal exercise in young and healthy subjects.

Arterial lactate concentrations, taken as indicators of physical fitness, in athletes as well as in patients with cardio-respiratory or metabolic diseases, are measured invasively from arterialized ear lobe blood. Currently developed micro enzyme detectors permit a non-invasive measurement of hypoxia-related metabolites such as lactate in exhaled breath condensate (EBC). The aim of our study is to prove whether this technology will replace the traditional measurement of lactate in arterialized blood. Therefore, we determined the functional relation between lactate release in EBC and lactate concentration in blood in young and healthy subjects at rest and after exhausting bicycle exercise. During resting conditions as well as after exhausting bicycle exercise, 100 L of exhaled air along with blood samples from the ear lobe was collected after stationary load conditions in 16 healthy subjects. EBC was obtained by cooling the expired air volume with an ECoScreen I (FILT GmbH, Berlin) condenser. The analysis was performed within 90 min using an ECoCheck ampere meter (FILT GmbH, Berlin). Lactate measurements were performed using a bi-enzyme sensor after lactate oxidase-induced oxidation of lactate to pyruvate and H2O2. The rates of lactate release via the exhaled air were calculated from the lactate concentration, the volume and the collection time of the EBC. The functional relation of lactate release in exhaled air and lactate concentration of arterial blood was computed. At rest, the mean lactate concentration in arterialized blood was 0.93 ± 0.30 mmol L(-1). At a resting ventilation of 11.5 ± 3.4 L min(-1), the collection time for 100 L of exhaled air, Ts, was 8.4 ± 2.9 min, and 1.68 ± 0.40 mL EBC was obtained. In EBC, the lactate concentration was 21.4 ± 7.7 µmol L(-1), and the rate of lactate release rate in collected EBC was 4.5 ± 1.7 nmol min(-1). After maximal exercise load (220 ± 20 W), the blood lactate concentration increased to 10.9 ± 1.8 mmol L(-1) and the ventilation increased to 111.6 ± 21.4 L min(-1). The EBC collection time decreased to 3.9 ± 1.9 min, and 1.20 ± 0.44 mL EBC were obtained in the recovery period after termination of exercise. The lactate concentration in EBC increased to 40.3 ± 23.0 µmol L(-1), and the lactate release in EBC increased to 13.6 ± 8.6 nmol min(-1) (p < 0.01). Assuming a volume of 4.3 mL water in 100 L of exhaled air (saturated with water at 37 °C), we calculated a lactate release at rest of 11.5 ± 4.3 nmol min(-1) and 48.6 ± 30.7 nmol min(-1) (p < 0.01) after exhausting exercise. Detectable releases of lactate in exhaled breath condensate were found already under resting conditions. During exhausting external load on a bicycle spiroergometer, an increase in the lactate concentration was found in arterialized blood along with an increased lactate release in EBC. The correlation between expiratory lactate release via EBC and lactate concentration in arterialized blood is studied in pursuing investigations.