No abstract

We have studied the ventilatory volumes, flow rates, transfer factor and its components (membrane component and capillary volume) in 19 women and 23 children with moderate obesity. The adults showed restrictive defects, but the pulmonary volumes of children were within normal range. Peak flow, flows at 75 and 50% forced expiratory volume, in two groups, normalized for the forced expiratory volume, did not differ between the two groups. The transfer factor was reduced in adults, because of reduction of the alveolar volume, the membrane component was low in both groups; transfer factor and membrane component normalized for functional residual capacity were not different between the two groups. The capillary volume was greater in children than adults, because the excess body weight was greater for the children. In simple obesity, the main alteration is the decrease of distensibility of the chest wall that becomes worse as time goes on and is the cause for the alterations in ventilatory volume, flow and transfer factor.

No abstract

The ventilatory response to carbon dioxide, using the rebreathing technique, was investigated in 5 healthy nonsmoker volunteers, without obstructive bronchopathy. The administration of propranolol (20 mg) in a single oral dose did not produce significant modifications of the slopes of the response curves, but caused a significant increase of the intercept of the curves (p < 0.05). Since no changes of the spirographic values were noted, the results obtained were attributed to a decrease of ventilation. It is concluded that propranolol, even at the dose of 20 mg, is able to induce a depression of the respiratory center, concomitant with a significant reduction of heart rate and arterial blood pressure.

Healthy males (23–29 years) volunteered as subjects. We studied the ventilatory response to carbon dioxide and to isometric exercise (50% of maximum voluntary contraction) after administration of propranolol (20 mg), mepindolol (5 mg), salbutamol (20 mg) and placebo (single dose orally). The increase of pulmonary ventilation (V_E) activated by central (CO₂) and reflex stimulus (hand-grip) did not differ statistically between the four drugs.Analysis of V_E in terms of inspiratory drive (V_t/T_i) and timing ratio (T_i/T_tot) showed that during CO₂ stimulation mepindolol and salbutamol increased V_E predominantly by the increase of V_t/T_i, presumably through the direct stimulation on the respiratory center.During rebreathing, T_i/T_tot increased significantly after administration of placebo and propranolol, so V_E increased by a rise of V_t/T_i and by an increase of an effective ‘timing component’ (T_i/T_tot). Propranolol does not modify the ventilatory response to CO₂ and hand-grip when V_E is analyzed in terms of V_t/T_i and T_i/T_tot.