Regional Lung Blood Perfusion Measured with Laser Doppler Method During Body Position Change, Valsalva Manoeuvre and Cardiopulmonary Bypass

Methodological approaches to investigate local regulatory mechanisms of lung blood supply in humans are restricted. We tried a new approach using laser Doppler technique. During bronchoscopy, an angled laser Doppler flow probe was introduced through a biopsy channel and wedged into small bronchus. Laser light penetrated the wall of small bronchus and was reflected from blood cells running through neighbouring capillaries. Regional blood perfusion changes were recorded during body position change from vertical to supine and back to vertical, while performing Valsalva maneuver and during cardiac bypass surgery. Body position change and Valsalva maneuver markedly influenced the blood perfusion signal. During cardiac bypass when lungs were supplied with blood only through bronchial arteries regional blood perfusion dropped substantially on average from 93 ± 42 to 7.3 ± 4.3 perfusion units. We conclude that blood perfusion measured with this method reflect mainly the pulmonary vascular bed and may be used for investigation of its local regulatory mechanisms.