Comparison of total-breath and single-breath diffusing capacity in healthy volunteers and COPD patients
ABSTRACT The measurement of single-breath diffusing capacity (Dlco(SB)) assumes that diffusing capacity per liter of alveolar volume (Dlco/VA) determined in a 750-mL gas sample represents the diffusing capacity (Dlco) of the entire lung. Fast-responding gas analyzers provide the opportunity to verify this assumption because of the possibility to measure CO and CH(4) fractions continuously throughout the entire expiration. Continuous gas sampling provides more information per measurement, but this information cannot be expressed in the traditional parameters. Our goals were to find new parameters to express the extra information of the continuous gas sampling, and to compare these new parameters with the traditional parameters.
We compared a new method to determine Dlco with the traditional method in 62 healthy volunteers and 26 COPD patients. Traditionally, Dlco(SB) is determined by multiplying Dlco/VA with alveolar volume, both calculated from gas concentrations in a 750-mL gas sample. The new method calculates total-breath Dlco (Dlco(TB)) by integration of Dlco/VA against exhaled volume.
In healthy volunteers, Dlco/VA shows a slight upward slope during exhalation, while in COPD patients Dlco/VA shows a horizontal line. Total-breath total lung capacity (TLC) is larger than single-breath TLC both in healthy volunteers and in COPD patients, leading to a Dlco(TB) that is significantly larger than Dlco(SB) in both groups (p < 0.001).
The assumption that a 750-mL gas sample represents the entire lung seems to be correct for Dlco/VA but not for the CH(4) fraction in case of ventilation inhomogeneity.
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ABSTRACT: This study aimed to evaluate the total and abdominal adiposity markers in asthmatic patients and their relation to asthma severity and PFTs. Seventy non-smoking adult asthmatics, aged 38.6 ±11.8, (42.9% male), were subjected to history, clinical and radiological examination, measurement of weight, BMI, waist circumference, waist/hip ratio, abdominal height and PFTs. Patients were classified by asthma severity into: 11 intermittent, 15 mild, 26 moderate and 18 severe asthmatics and categorized by BMI into: 25 normal weights, 16 overweight, 22 obese and 7 morbidly obese patients. There was significant increase in total and abdominal adiposity markers with direct linear correlations with increasing asthma severity. Obesity category showed significant inverse correlations with FVC%, FEV1%, TLC% and FRC% and direct linear correlations with DLCO% and DLCO/AV. The interactions between the adiposity markers and PFTs were analyzed using general linear model with MANOVA and revealed more significant associations for the abdominal than total adiposity markers with most PFTs. The results of the study suggest that adiposity markers increase with increasing asthma severity. The abdominal adiposity markers are more effective predictors of obesity on PFTs than total adiposity markers.Journal of Medical Sciences(Faisalabad) 02/2009; 9(2). DOI:10.3923/jms.2009.59.69
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ABSTRACT: Complete anatomical resection of the primary tumour is still the standard of care in patients with early stage lung cancer. Because these patients are usually smokers who also suffer from chronic obstructive pulmonary disease, regional differences in pulmonary function due to lung tissue destruction exist. The purpose of the present article is to evaluate the currently available guidelines and to discuss novel methods for the pre-operative functional and anatomical pulmonary evaluation in lung cancer patients. Despite the fact that knowledge on the pre-operative evaluation of the pulmonary function has substantially increased during the past decade, the majority of the studies are small, underpowered and, with exception of a proposed algorithm, not prospectively validated in independent cohorts. The future harmonisation of guidelines is required and novel imaging techniques should be incorporated in the pre-operative evaluation in chronic obstructive pulmonary disease patients with borderline pulmonary function.European Respiratory Journal 06/2009; 33(5):1206-15. DOI:10.1183/09031936.00020508 · 7.13 Impact Factor