[Physical exercise in the thromboembolism of the pulmonary artery]. / L'esercizio fisico nella tromboembolia dell'arteria polmonare.

In order to evaluate post-embolic pulmonary gas exchange responses to exercise, we studied 7 patients who had previously suffered from an acute pulmonary embolism but were presently free from clinical and functional signs of cardiorespiratory diseases. Patients came to the laboratory on two occasions, 30 and 120 days following the episode of acute embolism, respectively, and performed an incremental ramp exercise test up to the maximum attainable workload. On both occasions, the dead volume/tidal volume (VD/VT) ratio at rest increased. During the first exercise test performed 30 days after the acute pulmonary embolism, mean VD/VT decreased from a resting value of 62.5% to 38.6% at the maximum workload. During the second exercise test, VD/VT decreased, at the same workload, from 71.3% to 35.5%. There was no significant difference in exercise-related VD/VT decrease between the two exercise tests. The results suggest that in patients who have suffered from an acute pulmonary embolism, a considerable pulmonary blood flow redistribution may occur during incremental ramp exercise performed 30 and 120 days after the acute event.

Changes in respiratory activity induced by mastication in humans.

We studied the influence of mastication on respiratory activity in nine healthy volunteers who were requested to masticate a 5-g chewing gum bolus at a spontaneous rate (SR) for 5 min and "at the maximum possible rate" (MPR) for 1 min. Significant increases in respiratory frequency were induced by SR mastication due to a decrease in both the inspiratory and expiratory time. Tidal volume displayed slight nonsignificant decreases, but minute ventilation and mean inspiratory flow significantly increased. The duty cycle (TI/TT) did not change significantly. Total airway resistance significantly increased. Both peak and rate of rise of the integrated electromyographic activity of inspiratory muscles presented marked increases, accompanied by the appearance of a low level of tonic muscular activity. Similar but more intense effects on respiratory activity were induced by MPR mastication; in addition, a significant decrease in tidal volume and a significant increase in TI/TT were observed. Rhythmic handgrip exercise performed at metabolic rates comparable to those attained during SR or MPR mastication induced similar changes in the drive and time components of the breathing pattern, although accompanied respectively by nonsignificant or significant increases in tidal volume. Furthermore, the frequency of SR mastication significantly entrained the respiratory rhythm. The results suggest that mastication-induced hyperpnea does not merely represent a ventilatory response to exercise but also reflects complex interactions between respiratory and nonrespiratory functions of the upper airway and chest wall muscles.

Anaerobic threshold: reproducibility out from ventilatory parameter estimation.

Anaerobic threshold (AT) during exercise is usually noninvasively determined by assuming a two-segment mathematical relationship between two ventilatory parameters. In the literature, all the possible pairs of segments are first considered, and the most appropriate pair is then selected according to at least-squares method. In such a model, the AT is considered to be related to the joining point of the two segments. In order to test the reliability of the model, we compare the results of the least-squares method to those based on maximum probability method in discriminating the two regression coefficients. In order to test the reproducibility of the two different criteria, comparisons have been repeated after data have been filtered. A paired t test was used to carry out comparisons. Ventilatory parameters were collected in 10 healthy subjects during the use of a bicycle ergometer. The required power was increased every 15 s by steps of 30 W, starting from 50 W. Ve, VO2 and VCO2 have been sampled every 15 s, then the three functions--Ve versus VO2, Ve versus VCO2 and VCO2 versus VO2--were considered. Each function was stylized with two linear segments. Each segment was estimated by using a second-kind linear fitting. We verified that: (i) the AT may be reliably appreciated depending on the pair of selected parameters; (ii) only when data are smoothed is no difference between the two criteria documented (Ve vs. VO2, p = 0.99; Ve vs. VCO2, p = 0.54); (iii) no significant difference, related to smoothing, is documented both in using the least-squares method (Ve vs. VO2, p = 0.61; Ve vs. VCO2, p = 0.15) and the maximum p level criterion (Ve vs. VO2, p = 0.59; Ve vs. VCO2, p = 0.19).

Effects of theophylline-ethylendiamine on chronic pulmonary arterial hypertension secondary to chronic obstructive pulmonary disease.

The use of theophylline in the treatment of chronic lung disease is wide spread thanks to the positive effects on the bronchial tree, on ventilation and on diaphragmatic contractile activity, which are well documented. On the other hand, the cardiovascular effects of this drug have not been studied much, particularly the effects on the hemodynamics of the pulmonary circulation. The latest studies were carried out by Parker (1966 and 1967) and by Jezek (1970) with heart catheterization and by Matthay (1978) with isotopic angiocardiography, but the problem has not been fully explored from the standpoint of pulmonary arterial hypertension. Therefore we are studying the effects of intravenous infusions of aminophylline in patients with chronic obstructive lung disease, trying to examine the effects of this drug on three different groups of patients: the 1st without pulmonary arterial hypertension; the 2nd with latent pulmonary arterial hypertension; the 3rd with evident pulmonary arterial hypertension. We consider pulmonary arterial hypertension as pulmonary arterial pressure greater than 20 mmHg at rest and pulmonary arterial pressure greater than 35 mmHg at the end of 8 min of exercise in the supine position, with 40 W load cycle ergometer. The experimental protocol includes the clinical and functional identification of subjects with chronic obstructive long disease, the performance of right heart catheterization and the cannulation of a peripheral artery, measuring all pressure levels, cardiac output, hemogasanalytic data and theophylline levels in steady state (20-30 min. after the end of invasive manoeuvres) at the 10th, 20th and 30th min after the end of an infusion of 10 mg/kg of aminophylline.(ABSTRACT TRUNCATED AT 250 WORDS)

Classification of respiratory functional impairment in chronic obstructive pulmonary disease.

Starting from a paper published in 1964 by Wilson et al., we explored the possibility of classifying the clinical and functional deficit of patients with chronic obstructive lung disease into six classes, class 0 representing normality and class 5 greatest severity. Each symptom or sign was classified into six degrees of increasing severity. Next, we looked for a possible dependence of the collegially assigned score on anthropometric, clinical, or instrumental data in each case. More particularly, we tried (1) to identify such combinations of variables as would permit classification of the patient with the smallest possible error, and (2) to determine which of the variables reflected the severity of the case more faithfully. The results emerging from this study suggest the possibility of evaluating and classifying respiratory impairment in three different ways, as follows: (1) On the basis of clinical data only. This method is the easiest to use and affords a fairly good determination coefficient (R2 = 0.812). (2) Using only some combinations of laboratory data (static and dynamic pulmonary volumes, blood gases, etc.), with or without the addition of vital statistics and anthropometric data. These subensembles would allow a posteriori estimates in cases where the subject is no longer available for questioning and examination. In that case the best multiple regression affords a determination coefficient R2 = 0.82. (3) Using all clinical and laboratory data available. In that case, the best multiple regression (R2 = 0.899) for predictive purposes is that which includes the sum of clinical data, the pulmonary volumes before and after pharmacological bronchodilation, and the PaCO2 value. For practical purposes, however, the most convenient function is the one that includes the sum of clinical data plus FEV1 and RV (R2 = 0.863). Even with the best of the three functions proposed in this paper, however, the standard error of estimate entails tolerance limits sometimes amounting to one whole class of severity. Still, the probability of making an error exceeding one class of severity occurs in only 3.7% of the cases, an average which seems quite acceptable from the clinical point of view.

[The ventilation-perfusion ratio, with special reference to muscular exercise]. / Il rapporto ventilazione/perfusione, con particolare riguardo al lavoro muscolare

The values of VA/Q obtained at rest in 12 normal subjects undergoing cardiac catheterization in a supine position were between 0.63 and 1.695, with a mean of 1.142 +/- 0.295. The VA/Q values obtained in another 10 healthy subjects tested in a sitting position with a rebreathing method for calculating Q. were somewhat less scattered (between 0.77 and 1.50), and also lower (mean 0.975 +/- 0.210). A highly significant correlation was demonstrated during muscular exercise on the bicycle ergometer (sitting position), both between oxygen consumption and alveolar ventilation and between oxygen consumption and cardiac output. However, since at various submaximal work loads cardiac output increased much less than alveolar ventilation, the overall VA/Q ratio showed a progressive increment with increasing oxygen consumption.