Antidyspnoeic action of para-aminobenzoic acid: modifications of the functional respiratory indexes in the patients treated.

Benda and Poirot,1 in 1945, in order to avoid the secondary reactions provoked by intravenous injections of procaine, which was recommended for the treatment of dyspnoea by Dos Ghali, Bourdin and Guiot,2 proposed using p-aminobenzoic acid (PAB) in the place of procaine. It is known that the latter, once in contact with the blood plasma transforms itself rapidly into p-aminobenzoic acid and diethylaminoethanol, hydrolysis favoured by the presence of an enzyme, the procainesterase which originates in the liver and thyroid gland. In 1949, one of us in collaboration with Cucchiani Acevedo3 mentioned the results obtained with the intravenous and intramuscular administration of sodium salt of PAB (10 cc. of a 5 per cent solution) in the symptomatic treatment of dyspnoea in patients with pulmonary tuberculosis and bronchial asthma. In order to outline what could be subjective in the clinical improvement often observed and to establish on the other hand the mechanism of the antidyspnoeic action of PAB, we have made the following study. In a group of chronic bronchopulmonary patients (pulmonary emphysema, pulmonary fibrosis, pulmonary tuberculosis, bronchial asthma) with some apparent dyspnoeic manifestations, we have performed several functional respiratory tests before and after parenteral administration of PAB. Apart from the frequency of pulse and respiration the degree of oxygen saturation of the Hb in arterial blood was established, the inspiratory apnoeic pause and the different spirometric data: vital capacity, complementary and reserve air, minute volume of ventilation and maximum volume of ventilation, ventilation reserve and oxygen consumption were determined. Observing these joint preliminary results and to establish their significance more precisely, we furthermore studied in some patients the blood cytology, the globulo-plasmatic relation and the possible variations of residual air, In table I the sex, age and diagnosis of the 22 cases studied can be found.