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Biomedical subjects

D B Teculescu

Publications and source records attributed to D B Teculescu.

At least 37 records · Page 2Linked to original sources
PubMed1987

[Evaluation of the performance of 2 mini-flow meters].

Two mini-peak flow meters, the Airmed (mini-Wright) and the Medicheck (Pulmonary Monitor), were assessed against a reference electronic spirometer (Spiromatic, based on a pneumotachograph, integrator and an Apple II computer) in a series of 10 healthy subjects and 20 patients with chronic obstructive lung disease. The devices to be tested were mounted in series with the reference instrument; each subject did five trials. It was found that the Airmed instrument overestimated the flows up to 9 l X s-1 (i.e. in patients, average difference 0.86 l X s-1, p less than 0.001; in healthy subjects, average difference 0.35 l X s-1, p less than 0.001). The correlation with the results of the reference instrument was high (r = 0.992) in healthy subjects, whose regression slope was less than unity (0.763). In patients the correlation was satisfactory (r = 0.974), and the slope close to 1 (1.05). The Medicheck overestimated slightly the results of patients (difference 0.17 l X s-1, p less than 0.01); in normal subjects the overestimation was present only below 10 l X s-1 and the difference with the reference instrument nonsignificant (average 0.19 l X s-1). The results were closely related to those of the reference spirometer in both healthy subjects (r = 0.960) and patients (r = 0.936). As for the first instrument the slope of the regression was below 1 in healthy subjects (0.751) and practically one (1.01) in patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Tests of small airway dysfunction: their correlation with the "conventional" lung function tests.

"Sensitive" and "conventional" lung function tests were compared in a group of 114 males, aged 35-55 years, including healthy non-smokers, asymptomatic smokers with normal spirometry, and smokers with chronic bronchitis with or without mild airflow limitation. In non-smokers, with the exception of a MEF vs. FEV1 correlation, "sensitive" and "conventional" tests were independent of each other. In asymptomatic smokers the phase III slope and the closing volume were significantly related to FEV1, RV/TLC and CO transfer factor. In smokers with chronic bronchitis all the "sensitive" tests were related to the "conventional" tests (with the exception of the total lung capacity). Hyperinflation and CO transfer impairment suggest that early emphysema may accompany mucus hypersecretion in smokers.

Adult↗
PubMed1985

Patterns of variation in airflow obstruction and risk of death in clinically stable asthma.

In an attempt to identify patterns of variation in airflow obstruction and to detect patients with marked bronchial lability, a factor reported to be associated with an increased risk of sudden asthma death, we obtained serial peak expiratory flow rate (PEFR) recordings from out-patients with chronic, clinically stable, asthma (N = 27) for one week. Similar recordings were obtained for comparison from out-patients with chronic obstructive pulmonary disease (COPD) (N = 14) and from healthy controls (N = 14). Analysis of the recordings disclosed patterns of PEFR variation for 20 asthmatics but not for COPD patients or healthy subjects. Ten asthmatics were classified as "brittle" asthmatics (BA), nine as morning dippers (MD) and one as a gradually deteriorating (GD) asthmatic. Patients were considered at risk when their diurnal fall (DF) in PEFR was greater than 50% on at least one occasion during the survey. This was the case for seven BA, three MD and one GD patient. Diurnal falls in PEFR of this magnitude were not observed among asthmatics without a discernible pattern of variation of airflow obstruction or COPD patients. A relationship was found between the amplitude of PEFR fluctuations and the frequency of significant DF in PEFR (greater than 25%) during half or more days of the survey. A significant fraction of out-patients with chronic, clinically stable asthma may present patterns of variation in airflow obstruction and diurnal falls in PEFR of a magnitude such as has been associated with sudden asthma death.

Airway Obstruction↗
PubMed1985

[Reliability of measurements of maximal static respiratory pressure].

The variability and reproducibility of maximal static respiratory pressure measurements was evaluated in 22 healthy subjects and 17 patients with chronic respiratory disease. The difference between consecutive measurements represented 4 to 8 per cent of the result in healthy subjects and 10 to 11 per cent in patients. The difference between the first and the second measurement was not significant and the two values were highly correlated. At 1 to 3 days interval, the results may differ by 10 to 15 per cent in healthy subjects and 20 to 22 per cent in patients. These differences tend to be greater for expiratory (as compared to inspiratory) pressures and for females (as compared to males). A preliminary assessment of the variability and reproducibility of maximal respiratory pressures is compulsory for a valid interpretation of their change in clinical studies.

Adult↗
PubMed1984

[Study of maximal expiratory flows with light gases. Theoretical aspects].

The modification of maximum expiratory flows with low gas density breathing was proposed a decade ago as a test of small airway obstruction. This short review discusses the theoretical bases of the method. Three kinds of approaches have been proposed to interpret the findings: the "equal pressure point" concept of Mead et al. has stressed the role of the resistance upstream and of elastic recoil; the "flow limiting segment" concept of Pride et al. has underlined the role of central airways compliance (the compressed segment acting as a resistor); recently, the "choke point theory" proposed by Dawson and Eliott discusses the role of wave speed propagation in the walls of elastic tubes. All these three interpretations take into account the influence of the density of the gas breathed--a factor governing the drop in transmural pressure between the alveoli and the central airways, and a determinant of the speed of pressure wave propagation. In principle, every reduction in gas density should lead to an increase in maximal flow; this modification would be less marked if the flow in the upstream segment is essentially laminar due to obstruction in the peripheral airways. Several points complicating the interpretation are discussed: a) the flow in the small airways is never strictly laminar; b) the change in gas density (usually-breathing a He-O2 mixture) also influences the length of the upstream segment and the pressure wave speed; c) the influence of the cross sectional area and compliance of central airways cannot be neglected.(ABSTRACT TRUNCATED AT 250 WORDS)

Forced Expiratory Flow Rates↗
PubMed1983

1-second forced expiratory volume and density dependence in early airflow limitation.

Density dependence variables (helium-to-air difference in forced expiratory flows at 50 and 25% vital capacity and volume of isoflow) were compared with spirographic performance (vital capacity, FEV 1.0) in 76 men aged 33-56 years. The group included nonsmokers, asymptomatic smokers, subjects with chronic expectoration, but normal ventilatory function and subjects with chronic expectoration and minimal obstructive ventilatory impairment. Low-level correlations were found (coefficients of less than 0.3) between delta He25% or volume of isoflow on one side and FEV1.0 or FEV1.0/VC. Some possibly confounding factors for these correlations are discussed. We conclude that density dependence variables are not consistently related to the FEV1.0 in subjects 'at risk' or with minimal airflow limitation.

Adult↗
PubMed1982

Variability, reproducibility and observer difference of body plethysmographic measurements.

The variability (coefficient of variation of five consecutive measurements), reproducibility (difference of results at 1 h and 24 h), and interobserver difference (independent reading of the tracings by two observers) of airways resistance (Raw) and static lung volumes (residual volume, functional residual capacity, total lung capacity) using a body plethysmograph were assessed in 14 healthy subjects and in 25 patients with various respiratory disorders. The variability was low for TLC (4-5%), moderate for FRC (7-8%) and high for Raw (28%). No significant changes of Raw or lung volumes were found for the groups at 1 h and 24 h. Between observers, a slight difference existed for FRC and Raw in normal subjects; the difference was higher (4.5% for FRC and 11% for Raw) and became significant in patients. The overestimation of Raw by observer 2 as compared to observer 1 was more important at larger values. The present findings call for caution when pooling results obtained by several observers in large-scale studies, or when comparing figures obtained by different technicians in the pulmonary function laboratory.

Adult↗
PubMed1982

Density dependence of maximal expiratory flows in normal subjects: influence of sex, age, body build and spirographic variables.

We studied the correlation between density-dependence parameters (delta He, volume of isoflow) and age, body build, spirography and forced expiratory fows in 69 healthy non-smokers (16 females) aged 18 to 51 years. Density dependence variables showed no significant differences between young (less than 35 years) males and females. Volume of isoflow per cent of forced vital capacity (Viso V % FVC) was poorly significantly related to age (r = +0.25 P less than 0.05) and weight (r = +0.27 P less than 0.05). Significant correlations were found between density dependence at low lung volume and the FEV1/VC ratio (r = 0.31, P = 0.01 for delta He 25%; r = -0.40, P less than 0.001 for Viso V% FVC) or the forced expiratory flows with air (Viso V% FVC vs. FEF 25% r = -0.42, P less than 0.001). These correlations were closer in females as compared to males. Volume of isoflow was well related to delta He 25% (r = -0.64, P less than 0.001), but the relationship with delta He 50% was weaker (r = -0.38; P less than 0.01).

Adolescent↗
PubMed1980

Cigarette smoking and density-dependence of maximal expiratory flow in asymptomatic men.

The influence of cigarette smoking on helium response of maximal expiratory flows was studied in 26 asymptomatic male smokers 35 to 55 yr of age. The subjects had smoked 18.0 +/- 10.6 cigarettes/day for 19.2 +/- 6.7 yr (total consumption, 16.1 +/- 9.8 pack/yr) and were selected because they had no history of cardiopulmonary disease, and their physical examination, chest roentgenogram, and spirographic results were normal. Maximal expiratory flow (at the mouth)-volume curves were recorded while the subjects breathed air and a mixture of an 80% helium and 20% oxygen; the helium response (delta He) was expressed as the difference between maximal expiratory flow with helium and maximal expiratory flow with air at 50 and 25% of vital capacity. Current cigarette consumption and total tobacco use were not related to either delta He50% or delta He25%. However, maximal expiratory flows with air and helium were significantly related to current cigarette consumption (for cigarettes/day versus Vmax50% air, r = - 0.587 and p < 0.01; for cigarettes/day versus Vmax25% He+O2, r = - 0.594 and p <0.01) or to lifetime tobacco consumption (for packyr versus Vmax50% air, r = - 0.39 and p < 0.05; for pack-yr versus Vmax25% He + O2, r = - 0.643 and p < 0.001). The result were compatible with a tobacco effect on both central and peripheral airways: increase in upstream resistance due to peripheral airway obstruction, and slight downstream displacement of equal pressure points due to increase in central airway resistance. We concluded that the helium response of maximal expiratory flows is less sensitive than maximal expiratory flows with air in detecting an early effect of tobacco in asymptomatic cigarette smokers.

Adult↗