Cardiorespiratory changes induced in man by the acute occlusion of the main bronchus]

Following the exclusion of the ventilation of a lung, perfusion is arrested as a consequence of the Von Euler and Liljestrand vasoconstrictive reflex. However it is as yet unknown how long this phenomenon takes to manifest itself in human beings. In order to verify whether hypoxic pulmonary vasoconstriction follows immediately on the arrest of ventilation or whether there is one some delay, in 21 candidates for pneumonectomy a bronchial block was provoked during fibrobronchoscopy and the hemogasanalytic modifications induced by the acute occlusion of the main bronchus have been studied. The analysis of the resulting data allows for the hypothesis that the exclusion of lung ventilation for 14 minutes is not sufficient to cause the complete manifestation of the hypoxic vasoconstrictive reflex.