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H E Rosberg

Publications and source records attributed to H E Rosberg.

4 recordsLinked to original sources
PubMed1989

Nitrogen dead space in heavy smokers aged 44-58 years.

Functional and alveolar dead spaces for nitrogen (VDF and VDalv) were calculated in a population of 20 male and 20 female heavy smokers and compared to data from static and forced spirometry (functional residual capacity [FRC], residual volume [RV], lung clearance index [LCI] and volume of trapped gas [VTG]) obtained with the same multiple-breath nitrogen wash-out as the dead spaces, and to variables considered sensitive to small airways disease measured with a single-breath nitrogen elimination (closing volume in per cent of vital capacity [CV%], closing capacity in per cent of total lung capacity [CC%] and slope index [SI]). Both nitrogen dead spaces increased with tidal volume in smokers as well as in healthy non-smokers. The majority of smokers were outside the predicted mean +2 SD for VTG (75%), CC and VDalv (70%) and SI (65%). The following variables were less sensitive for disclosing abnormality: CV (55%), RV (53%), LCI (38%) and forced expired volume in the first second (FEV1, 33%). If high sensitivity is considered preferable in epidemiological studies, the nitrogen dead spaces are equally as sensitive as the better of earlier described tests, and significantly superior to LCI and FEV1. Being tests that measure alveolar distribution of inhaled gas, they are probably sensitive to small airways disease.

Adult↗
PubMed1988

Multiple breath nitrogen dead space.

Ventilatory efficiency for eliminating CO2 is expressed by the physiological dead space, VD phys = (1-PE CO2/Pa CO2) x VT, where PE is the mixed exhaled and Pa the arterial CO2-tension and VT the tidal volume. We used data from the multiple breath N2-wash-out with oxygen for calculating a functional dead space for nitrogen. VDF N2 = (1-FEN2/FidN2) x VT.FEN2 is the mixed exhaled N2-fraction and FidN2 the calculated mean alveolar N2-fraction during a wash-out with the same number of breaths to reach 2% N2 in end tidal air, but having completely even distribution. FidN2 is shown to be 0.20 +/- 0.01 for wash-outs using 20-150 breaths. The method was applied to wash-outs from 21 healthy volunteers, 18 patients with chronic obstructive lung disease and two subjects with acute bronchospasm. VDF was well related to VD phys CO2 (r = 0.78) but higher than the latter. In subjects with lung disease VDF was inversely related to the degree of obstruction expressed by forced expiratory volume in one second per cent of vital capacity (r = 0.85). The subjects with bronchospasm had very high VD/VTF in relation to their FEV%. If airway dead space predicted from height and sex is subtracted from VDF, the resulting alveolar dead space will be a good expression for uneven gas distribution in the lungs. We also deduced a direct mathematical relation between lung clearance index and VD/VTF. The documented good reproducibility of LCI is thus also valid for VD/VTF, while the latter better expresses ventilatory efficiency.

Breath Tests↗