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The perceived exertion rating (RPE) scale of Borg was used to investigate the relationship between perceived exertion and pedalling rate. Normal subjects and patients with chronic obstructive lung disease (Cold) were studied in repeated test series. Work load, applied in a random order, varied from 2.5 to 10 mkp/s (patients) and 5 to 20 mkp/s (normals). Pedalling rate varied from 2.5 to 10 mkp/s (patients) and 5 to 20 mkp/s (normals). Pedalling rate varied from 40 to 60, 80, 100 rpm. At constant work load, RPE decreases during increasing pedalling rate. With respect to validity, RPE, showing a closer relationship to work load than to heart rate, seems to reflect perception of physical stress rather than perception of physiological strain. In addition, the results raise the question of standardization of pedalling rate in bicycle ergometry.

The hemodynamic benefits of combined administration of prenalterol (P) with hydralazine (H) were evaluated in ten patients with severe chronic heart failure. Single administration of 100 mg H increased cardiac index (CI) from 2.3 to 3.0 l/min/m2, whereas pulmonary capillary wedge pressure (PWC) remained unchanged. After 3--4 weeks of treatment with 200 mg H hemodynamic improvementt was maintained (CI: 2.9 l/min/m2). Additional administration of P caused further augmentation of CI (3.3 l/min/m2). After long-term treatment with the combination of H and P sustained augmentation of CI (3.2 l/min/m2), and, furthermore, a slight but significant decrease of PCW were observed (p less than 0.05 vs. chronic single H-therapy). Five patients were able to perform exercise testing; H improved maximal exercise capacity and exercise hemodynamics in three patients. Further improvemen was observed after combined treatment (H + P) in three of five patients. It is concluded, the prenalterol may enhance the effectiveness of hydralazine therapy in congestive heart failure by providing concomitantly the principal actions of the vasodilator and positive inotropic agent used separately. Furthermore, the results indicate that oral long-term administration of hydralazine and prenalterol can produce sustained beneficial improvement.

Methodical aspects of the relationship between pedalling rate and rotating mass and perceived exertion rating (PER; Borg, 1962) were studied in trained, untrained, and ill subjects in bicycle ergometry. Pedalling rate varied between 40 and 100 rpm, work load steps were 5, 10, 15 and 20 mkp/sec in the healthy subjects, and 2.5, 5, 7.5 and 10 mkp/sec in the patients. PER decreased with increasing pedalling rate in all healthy subjects. In the patients, PER increased moderately at work load of 2.5 mkp/sec, but decreased at higher work loads up to 80 rpm, followed by a slight increase at 100 rpm. Higher mass of the flywheel, studied in 6 trained subjects, lowered the PER insignificantly. In the healthy subjects, test criteria, such as reproducibility, reliability, sensitivity, and linearity remained almost unaffected by pedalling rate. In patients, increasing pedalling speed diminished reproducibility and sensitivity. The strictness of the PER work load relationship is lowered at higher pedalling rate, especially at 100 rpm. When using the PER scale, pedalling rate has to be considered as an factor of main influence.

Hemodynamic response to graded immersion was studied in healthy male subjects in a thermoneutral bath in the sitting position. Pressures in the right heart and cardiac output were determined by means of a semifloating catheter with a thermistor probe. Pressures in the right atrium, pulmonary artery and in pulmonary wedge position increased with increasing depth of immersion, cardiac output was likewise augmented. Heart rate decreased from rest to hip immersion but remained constant from hip to head out water immersion. Plasma norepinephrine concentration remained constant throughout the experiment. The reported changes depend on the blood shift from capacitance vessels into the thoracic cavity. From this, preload increased and cardiac performance was improved. However, in patients with disturbed left ventricular function, immersion to the neck may be potentially hazardous due to augmented left ventricular filling pressure.