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Biomedical subjects

C Veriter

Publications and source records attributed to C Veriter.

At least 55 records · Page 3Linked to original sources
PubMed1982

Effect of age on the regional perfusion and washouts of injected xenon in normal men.

The aim of this work was to localize the alveoli with low ventilation-perfusion ratio which are responsible for the age related increase of the ideal alveolar-arterial O2 partial pressure difference. For this purpose, we measured: (1) the washouts of perfused 133 Xenon (Xe) in the whole lung and in 6 horizontal slices of the right lung, and (2) the topographical distribution of perfusion (Qi) in 27 healthy, non-smoking seated men, between 18 and 65 years. The distribution of Qi is unaffected by age. The global and regional washouts slowed with age, the trends being the same in the 6 investigated regions. This data was interpreted as indicating that in our subjects the low VA/Q units are not situated predominantly at the base, but are scattered throughout the lung.

Adult↗
PubMed1981

Pattern of breathing and ventilatory response to CO2 in subjects practicing hatha-yoga.

WE studied eight Belgian subjects well advanced in the practice of hatha-yoga and compared them with eight sex-, age-, and height-matched control subjects. Practice of yoga (range 4-12 yr) involves control of posture and manipulation of breathing, including slow near-vital capacity maneuvers accompanied by apnea at end inspiration and end expiration. Average values for the yoga and the control group (in parentheses) are as follows: ventilation (VE) 5.53 1 X min-1 (7.07); tidal volume (VT), 1.03 liters (0.56); rate of breathing, 5.5 min-1 (13.4); end-tidal PCO2, 39.0 Torr (35.3). All differences are significant (P less than 0.05). Ventilatory response to CO2 (rebreathing technique) was significantly lower in the yoga group (P less than 0.01). The regression relating VE to VT during rebreathing of CO2 was VE = 8.1 (VT - 0.23) for the yoga group and VE = 15.8 (VT - 0.16) for the control group (P less than 0.005). We attribute these changes to chronic manipulation of respiration.

Adult↗
PubMed1980

Impaired early left ventricular relaxation in coronary artery disease: effects of intracornary nifedipine.

It has been shown that the maximal rate of left ventricular (LV) relaxation is impaired in patients with coronary artery disease (CAD) under basal conditions. To test the hypothesis that this impaired LV relaxation could be related to viable but metabolically abnormal myocardium, we studied the time course of isovolumic LV pressure fall in 21 patients with CAD and in 13 control subjects under basal conditions. This study was repeated after intracoronary injection of the calcium antagonist nifedipine (N) in 11 patients with CAD and in eight controls. Our data showed that isovolumic pressure fall was biexponential in 20 of 21 CAD patients and in six of 13 controls. Moreover, the time constant of isovolumic pressure fall during the first 40 msec after peak (negative) dP/dt (T1) was significantly greater in CAD patients than in controls (62 +/- 3 vs 44 +/- 1 msec, p < 0.002); the time constant of pressure fall during the 40-80 msec after peak (negative) dP/dt (T2) was similar in both groups ( 42 +/- 2 vs 39 +/- 2 msec, NS). Thirty seconds after injection of nifedipine, T1 and T2, were significantly prolonged in patients with CAD (14 msec and 16 msec, respectively, p < 0.005) and in controls 12 msec and 14 msec, respectively, p < 0.05), and a negative inotropic effect was observed in both groups (peak (positive) dP/dt - 16% in controls and -23% in CAD patients, p < 0.01). At rest, impairment of isovolumic relaxation in CAD patients is mainly limited to the first 40 msec after peak (negative) dP/dt, suggesting a dyssynchronous wall motion. This impairment of LV relaxation is better identified by T1 than by peak (negative) dP/dt in individual patients, and cannot be improved by administration of a calcium antagonist.

Adult↗
PubMed1979

Frequency dependence of respiratory resistance in healthy children.

We measured in 130 (61 girls) children aged 3--14 yr respiratory resistance (Rrs), with the oscillation technique, between 4 and 9 Hz. Rrs, at both 4 and 9 Hz, decreased as a function of height (r = 0.74, P less than 0.001). No statistical difference was found between boys and girls. Frequency dependence of resistance (Rrs 4 Hz-Rrs 9 Hz) was found in children at all ages, and decreased with increasing height (r = 0.50, P less than 0.001). We suggest that frequency dependence of resistance in children can be explained on the basis of an increased peripheral resistance, which produces an asynchronous distribution of tidal volume between dead space and lung parenchyma. During growth peripheral resistance decreases and Rrs bcome less frequency dependent to reach at about 15--16 yr independency of frequence.

Adult↗
PubMed1979

Constancy of effort and variability of maximal expiratory flow rates.

In 14 normal subjects and in 13 patients with obstructive pulmonary diseases, we studied the variability within an individual of values for the maximal expiratory flow rate (Vmax) recorded simultaneously vs expired pulmonary volume (at the mouth) and vs thoracic volume (measured with a body plethysmograph). We found that the variance of Vmax within an individual at 25, 50, and 75 percent of the expired vital capacity did not differ statistically whether pulmonary volume was the expired or the thoracic gas volume. In ten healthy subjects on two occasions (at an interval of 12 days, on the average), we measured the peak expiratory flow rate and Vmax at different levels of inflation, with respect to either expired or thoracic volume. There was no statistical differences in Vmax between the first and the last day. A larger variability of Vmax measured vs expired volume implies a change in the expiratory effort from one forced expiration to another and a different degree of compression of intrathoracic air. Since this was not the case, we conclude that muscular effort during repeated forced expirations is similar. The good reproducibility of effort explains in great measure the good reproducibility of Vmax.

Adult↗
PubMed1978

Even distribution of 133Xe bolus inhaled at residual volume in healthy subjects.

We selected from among 46 healthy students (22 to 31-yr-old) 7 subjects (group A) in whom the normalized height of phase IV (height of phase IV/phase IIIx100), after inhaling a bolus of He at RV, was very small (10%). We compared them with 6 subjects (group B) selected on the basis of a tall phase IV (78%, A vs. P P less than 0.005). Age and height were comparable, but weight was lower (P less than 0.05) and RV/TLC ratio (but not other spirographic indices) was larger (P less than 0.025) in group A. The average amplitude of cardiac oscillations was 4 times higher in group B (P less than 0.005). He closing volume, but not closing capacity was less in group A (P less than 0.05). A bolus of 133Xe inhaled at RV was nearly uniformly distributed in group A while producing a large vertical gradient in group B. The difference between groups A and B may reflect a difference in the mechanical properties of the chest wall leading to a less complete empting of the lung in the former group.

Adult↗
PubMed1977

Difference between the He bolus and N2 technique for measuring closing volume.

We measured closing volume in sixteen healthy subjects simultaneously and separately with a bolus of He (using a rapid catharaometer) and with the N2 technique. In another group of 35 active workers (some with airway obstruction), closing volume was measured separately with those two methods. In both groups the He closing volume was significantly higher than the N2 closing volume. We attribute this difference to a less marked vertical N2 concentration gradient, leading to a less clearly defined separation between phase III and IV and resulting in an underestimation of the N2 closing volume. Indeed, increasing the N2 gradient in the lung, by inspiring O2 from a higher than residual volume level, increased the N2 closing volume which became comparable to the He closing volume. We also found, for both He and N2 tracings, a significant between-observers difference in reading of the closing volume. However, the difference in reading of ts difference in reading of the closing volume. However, the difference was less important for He closing volumes. We conclude that the bolus method improves the resolution of closing volume and decreases the interobserver variability.

Adult↗
PubMed1975

A modified measurement of respiratory resistance by forced oscillation during normal breathing.

We have modified the measurements of the resistance of the respiratory system, Rrs, by the forced oscillation technique and we have developed equipment to automatically compute Rrs. Flow rate and mouth pressure are treated by selective averaging filters that remove the interference of the subject's respiratory flow on the imposed oscillations. The filtered mean Rrs represents a weighted ensemble average computer over both inspiration and expiration. This method avoids aberrant Rrs values, decreases the variability, and yields an unbiased mean Rrs. Rrs may be measured during slow or rapid spontaneous breathing, in normals and in obstructive patients, over a range of 3-9 Hz. A good reproducibility of Rrs at several days' interval was demonstrated. Frequency dependence of Rrs was found in patients with obstructive lung disease but not in healthy nonsmokers.

Airway Resistance↗
PubMed1975

Smoking and pulmonary diffusing capacity.

The pulmonary diffusing capacity (DLCO SB) and its two components, the capillary blood volume (Vc) and the diffusing capacity of the membrane (DMCO), expressed in absolute values and per litre of alveolar volume (VA'), were measured at rest and on exercise in healthy male smokers and nonsmokers of similar age and height, and with identical values for haemoglobin and spirographic data. DLCO, DLCO/VA', DMCO and DMCO/VA' are significantly lower in smokers, at rest and on exercise; the decrease in Vc and thetaVc/VA' in smokers at rest is due to a higher level of carboxyhaemoglobin. The decrease of DLCO, DLCO/VA', DMCO and DMCO/VA' is apparently not due to carboxyhaemoglobin or distributional factors but to anatomical lesions, probably of emphysematous nature, altering the pulmonary membrane. Formulas predicting DLCO, DMCO, Vc, DLCO/VA', DMCO/VA' and thetaVc/VA' in terms of age and height were established in smokers and in nonsmokers.

Adult↗
PubMed1975

Pulmonary gas exchange in asymptomatic smokers and nonsmokers.

Pulmonary gas exchange has been studied in 14 healthy smokers and 16 healthy nonsmokers (mean age: 36 years) breathing hypoxic, normoxic and hyperoxic gas mixtures, in a sitting position, at rest and on exercise. Alveolar-arterial oxygen tension difference is increased in smokers in hypoxia, at rest and on exercise, and the pulmonary diffusing capacity for oxygen is decreased. In normoxia the alveolar-arterial oxygen tension difference is increased on exercise. There is no difference between the two groups in hyperoxia. For the whole group there exists a negative relationship between (A-a)DO2 in normoxia and the diffusion indices measured on exercise. Arterio-alveolar carbon dioxide tension difference and the ratio physiological dead space/tidal volume are almost identical in both groups in any condition. A diffusion defect seems to be the more constant alteration of gas exchange in asymptomatic smokers.

Adult↗
PubMedDate not supplied

Hemodynamic and cardiac effects of nicardipine in patients with coronary artery disease.

The hemodynamic and cardiac effects of the calcium antagonist nicardipine, alone (n = 10 patients) or combined with propranolol (0.1 mg/kg i.v.; n = 9 patients), were assessed in patients with coronary artery disease. In the absence of beta-blockade, nicardipine (5 or 10 mg i.v.) increased heart rate (+23 and +15 beats/min after 5 and 10 mg, respectively; p less than 0.01) and cardiac output (from 4.7 +/- 1.1 to 7.4 +/- 1.3 L/min after 5 mg and from 5.1 +/- 1.1 to 8.6 +/- 1.6 L/min after 10 mg; p less than 0.005). Systemic vascular resistance decreased with both doses (-46 and -57%; p less than 0.005), whereas mean aortic pressure decreased by 14 mm Hg after 5 mg and by 28 mm Hg after 10 mg (p less than 0.004); left ventricular end-diastolic pressure was unchanged. Nicardipine also decreased significantly end-systolic left ventricular volume and increased ejection fraction (from 63 to 71% after 5 mg and from 54 to 63% after 10 mg; p less than 0.008) and velocity of shortening. Peak (+) dP/dt and (dP/dt)/DP40 (value of dP/dt at a developed pressure of 40 mm Hg) were unchanged, and Emax, the maximal left ventricular pressure/volume ratio, improved slightly (+8%; p less than 0.05). After beta-blockade, nicardipine (2.5 mg i.v.) still decreased mean aortic pressure (-16 mm Hg; p less than 0.05) and systemic vascular resistance, and improved the ejection phase indices; cardiac output and ventricular relaxation, both depressed after propranolol administration, were also normalized after infusion of nicardipine.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗
PubMedDate not supplied

In long-term smokers and former smokers the bronchodilator response is not related to the fall in FEV.

BACKGROUND: Cigarette smoking is the cardinal cause of chronic obstructive pulmonary disease (COPD), but only a relatively small percentage of smokers are developing clinically overt disease, suggesting, therefore, that other risk factors than smoking are involved. Several studies have shown that the bronchodilator response (BR) is related to the progress of COPD, as assessed by the fall in forced expiratory volume in 1 s (FEV(1)). However, the relationship between BR and fall in FEV(1), is a disputed one. OBJECTIVE: To assess the relationship between BR and fall in FEV(1) in a group of long-term smokers and ex-smokers who were 60 years old on the average. METHODS: Questionnaire, spirographic tests and BR were assessed in 56 smokers and ex-smokers of mean age 62.5 +/- (SD) 2.7 years at the end of a 13-year follow-up period. BR was expressed as a percentage change of the prebronchodilator value ('% initial') and as a percentage change of predicted value ('% predicted'). RESULTS: The FEV(1)/VC vital capacity was 68.9 +/- 7.6% at the start and 64.5 +/- 11.3% at the end of the study. The average fall in FEV(1) over 13 years was 26 +/- 25 ml/year. The FEV(1) increased after albuterol on the average with 5.9 +/- 6.6%, 4.5 +/- 3.9% of predicted, and the vital capacity with 2.5 +/- 6.5%, 2.3 +/- 6.4% of predicted. BR and fall in FEV(1) were correlated: the greater the BR, the more rapid the fall in FEV(1) (r = 0.4 and p < 0.01 for FEV(1)% and r = 0.3 and p < 0.05 for FEV(1) predicted). However, when adjusting for prebronchodilator FEV(1), the BR was no more related to the fall in FEV(1) (r = 0.15, p > 0.05). CONCLUSIONS: In long-term smokers and ex-smokers, the BR measured at the end of the follow-up period was correlated with the fall in FEV(1). However, after adjusting for prebronchodilator FEV(1) values, BR was no more related to the decline in FEV(1). The BR appears not to be associated with the development of COPD.

Aged↗
PubMedDate not supplied

Pulmonary diffusing capacity for carbon monoxide in simple coal workers' pneumoconiosis.

The lung diffusing capacity for carbon monoxide (DLCO single-breath) and its two components, the capillary blood volume (Vc) and the diffusing capacity of the membrane (DMCO) were measured at rest in 43 miners and 141 control subjects, the values in whom enabled reference formulae to be established; in 30 control subjects and in the majority of the miners these indices were measured during exercise. The main results are as follows: the diffusion indices are on average slightly decreased in simple coal workers' pneumoconiosis; both DMCO and Vc contribute to the lowering of DLCO, at rest and during exercise; individually Vc is more often significantly altered than DMCO; on effort the percentage increase of DLCO is normal in coal miners; the data during exercise suggest that smoking habit contributes more to lowering DLCO than does pneumoconiosis itself; lastly the diffusion indices are lower in miners with "pin-head" than those with micronodular opacities: this tendency is more pronounced during exercise. These findings are discussed.

Adult↗
PubMedDate not supplied

Blood gases in simple coal workers' pneumoconiosis.

Pulmonary gas exchange was measured at rest and during exercise in 30 normal males (14 smokers) and 43 coal workers free of obstructive syndrome, at three levels of oxygenation: hypoxia, normoxia and hyperoxia. The main results are the following: a) in normoxia PaO2 and (A--a)DO2 are slightly abnormal in coal workers at rest and during exercise; b) in hyperoxia (A--a)DO2 and venous admixture are higher in the miners at rest but not during exercise; c) in hypoxia (A--a)DO2 and DLO2 are abnormal in miners as compared with the control subjects; during exercise there is however no difference between the miners and the smokers of the control subjects; d) there is a correlation between PaO2 and (A--a)DO2 during exercise in normoxia and the various diffusion indices; e) (a--A)DCO2 and VD/VT show relatively slight increases in the miners; f) there are several differences between the miners with pin-head images and those with micronodular ones; g) at rest, (a--A)DCO2 and VD/VT are influenced by the degree of oxygenation. These various findings are discussed.

Carbon Dioxide↗