Coughs cause systemic blood flow

Abstract

Although it is known that rhythmic coughing can preserve consciousness during ventricular fibrillation, the arterial pressure transients which result have not yet been shown to reflect forward blood flow in man. The effectiveness of cough in causing foward flow in eight normal volunteers with bradycardia was studied. They coughed between cardiac cycles, using an audio and visual display of the electrocardiogram. The force of the cough was varied and measured with an oesophageal balloon. Blood flow was recorded with a Doppler velocity probe over the radial artery and a finger or ear photoplethysmograph. Motion artefact on the Doppler record due to coughing was excluded by transiently obstructing the brachial artery. We compared the areas under 5-10 consecutive Doppler and photoplethysmograph pulse flow tracings due to the cough and heart beat with those due to the immediately preceding heart beat alone. They were significantly increased. This augmentation was greater in those flow pulses accompanied by a more vigorous cough. It is concluded that coughing is associated with an effort dependent foward flow pulse in the arterial circulation.