SOME OBSERVATIONS ON THE NATURE OF THE RESPIRATORY WAVES IN ARTERIAL BLOOD PRESSURE

Abstract

When artificial ventilation was accomplished by rhythmically decreasing the pressure on the external surfaces of the lungs without altering the pressure on other thoracic structures well marked respiratory waves in blood pressure were observed, characterized after a lag, by an inspiratory fall and an expiratory rise in pressure commonly seen with natural ventilation. Artificial ventilation produced by rhythmically forcing air into the lungs through the bronchi reversed these effects. Inspiration produced by decreasing the pressure on the external surfaces of the lungs apparently results in an increase in the capacity of the vascular bed of the lungs. This is probably partly responsible for the inspiratory fall in blood pressure normally seen and is important in delaying the rise in pressure resulting from increased filling of the right atrium during inspiration.