We have tested the hypothesis that there is a positive relation between arterial elasticity and physical working capacity (PWC) at a given age. The subjects were 28 young men, 16-18 yr old. Arterial elasticity was evaluated by measuring the carotid to femoral pulse-wave velocity (c) at rest. The slope, S(c) of the relation between c and the diastolic blood pressure was studied during a cold pressor test to test vascular reactivity. The relationship between heart rate (HR) and work load was determined using a cycle ergometer; the variables measured were the slope of this relation S(PWC) and the power output at a HR of 170 min-1 (PWC170). The PWC170 ranged from 1.8 to 4.6 W/kg, and values of c ranged from 3.9 to 6.8 m/s. A strong inverse linear relation was found between c and PWC170 (r = -0.76), whereas the HR at rest was positively related to both c (r = 0.68) and PWC170 (r = 0.74). There was no relationship between HR at rest and the slopes S(c) and S(PWC); the latter two variables depend mainly on the sympathetic response. These results show the importance of the intrinsic mechanical properties of the cardiovascular system, particularly arterial elasticity, in human adaptations to muscular exercise.

The beneficial haemodynamic effects of sequential atrioventricular (AV) pacing have been clearly established and are dependent on the AV delay and pacing rate. However, the optimal AV delay is difficult to determine in each particular patient. We used a modified impedance plethysmographic method to assess variations in stroke volume for different AV delay and pacing rate settings. Impedance measurements showed a good correlation with CO2 rebreathing stroke volume measurements in VVI patients. Impedance variations were then used to set the optimal AV delay at different pacing rates in DDD patients. The inverse relationship between the optimal AV delay and the pacing rate has been accurately identified in most of the patients but is not predictable. In all cases, the cardiac output was higher in DDD mode at the optimal AV delay than in VVI mode. In some patients with a damaged myocardium, the stroke volume appeared to be highly sensitive to multiple AV delay settings. Impedance plethysmography can permit such repetitive non-invasive quick measurements, increasing the accuracy of optimal AV delay determination and is well suited for routine examination of patients with cardiac dual chamber pacemakers.

We carried out a maximum expiratory flow-volume curve (MEFV) and a spirometric recording with 67 athletes of different ages (15-27 years) and disciplines (rowers, kayakists, cyclists, swimmers) and with 20 adult and 13 adolescent nonathletic controls of matching ages. These recordings were repeated, with athletes only, after 6-10 months of training. Significant differences between the groups of adult athletes and the controls were observed for some parameters, the most discriminating of which were, in order, the peak expiratory flow (PEF), the forced expiratory volume in the first second (FEV1), and the flow at 75% of the vital capacity (V75). The vital capacity (VC) itself was only higher in the rowers group. The adult athletes, when grouped together (n = 47), produced a higher flow at 50% of their VC (V50) than the control group (+15%, P less than 0.05) with no difference in the flow at 25% of VC (V25) nor in the VC. A study of the effects of training showed no evolution among high level athletes while increases of 14% of the PEF, 5% of the V75, and 7% of the FEV1 were found after 7-10 months of training in adolescents; the VC increased during that time by only 2.7%. The reproducibility of these ventilatory parameters after 6-8 months was studied with adult athletes. The upper limit of the variation (95% CLl) was 12% for the FEV1 and forced vital capacity (FVC), 18% for PEF, 21% for V75 and V50, and 40% for V25.(ABSTRACT TRUNCATED AT 250 WORDS)

This study deals with the particle size measurement of nine aerosol metered dose inhalers. Calibration was made possible by the use of a laser particle velocimeter (aerodynamic Particle Sizer from TSI). The count median aerodynamic diameters (CMAD) show little variation, from 0.63 to 0.73 micron, with standard deviations (sigma g) between 1.2 and 1.8. Aerodynamic diameter aerosol diagram analysis showed multimodal mass distribution for all the tested dose inhalers. Calculations for the airway deposition probabilities (extrathoracic, tracheobronchial and alveolar) refer to the studies made by W. Stahlhofen and co-workers. As most aerosol metered dose inhalers have a predominantly bronchial therapeutic destination, the deposition at the bronchial level could be enhanced with the following parameters: inspired volume of 1500 ml, inspiratory time of 2 sec, aerosol mass median aerodynamic diameter (MMAD) of 7.5 microns, with a monodispersed distribution. The respective influences of the excipients and propellents used for the aerosolization of these dose metered inhalers are also discussed.

Nasal filter efficiency for particles has been described by several authors as showing large individual variations, probably somehow related to airflow resistance. Twelve children, aged 5.5-11.5 yrs and 8 aged 12-15 yrs were compared to a group of ten adults. Deposition of polystyrene beads (1, 2.05, 2.8 microns mass median aerodynamic diameter (MMAD] was measured by comparing inhaled aerosols and exhaled air concentrations, for both nose and mouth breathing. Ventilation was controlled to scale breathing patterns appropriate for each age either at rest or during moderate exercise to allow comparison between subjects in similar physiological conditions. Anterior nasal resistance (as a function of flow rate) and standard lung function were measured for each subject. For the same inhalation flow rate of 0.300 l.s-1, children had much higher nasal resistances than the adults, 0.425 +/- 0.208 kPa.l.1.s under 12 yrs, 0.243 +/- 0.080 kPa.l.1.s over 12 yrs and 0.145 +/- 0.047 kPa.l.1.s in adults. Individually, nasal deposition increased with particle size, ventilation flow rate and nasal resistance, from rest to exercise. The average nasal deposition percentages were lower in children than in adults, in similar conditions: at rest, 12.9 and 11.7 versus 15.6 for 1 microns; 13.3 and 15.9 versus 21.6 for 2.05 microns; 11 and 17.7 versus 20 for 2.8 microns. This was even more significant during exercise, 17.8 and 15.9 versus 29.2 for 1 microns; 21.3 and 18.4 versus 34.7 for 2.05 microns; 16 and 16.1 versus 36.8 for 2.8 microns.(ABSTRACT TRUNCATED AT 250 WORDS)