The effect of body position and intrathoracic pressure on blood perfusion recorded with laser Doppler flowmeter from small bbonchi in humans

Purpose: To find out whether the signal recorded with angled endoscopic laser Doppler(LD) probe wedged into small bronchus reflect the blood perfusion in small arch of circulation and whether such recordings may be used for the detection of local abnormalities in the small arch of circulation. Methods: Angled endoscopic LD probe was introduced through the instrument channel of bronchoscope, passed through the orifice of 3d segmental bronchus until wedging into small bronchus. Recordings were made in supine position and lying on the side when probe tip being in the inferior (I) or superior lung (S). Results: Blood perfusion signal recorded from peripheral bronchi differed in range from 39 to 768 perfusion units (PU) (mean±SE=215±52). Amplitude waves followed heart rate and respiration, augmenting during systole and inspiration. The change of body position did not influence significantly the perfusion value (supine=193±39, n=15, I=178±29, n=15, S=291±74, n=8; mean±SE). During Valsalva manoeuvre (P>40 torr) there was significant decrease in blood perfusion by 40%, followed by significant increase after cessation of the manoeuvre by 255% (n=29). Conclusions: changes in blood perfusion during Valsalva manoeuvre are consistent with presumption that signal recorded with wedged endoscopic probe reflect mostly the blood perfusion in the small arch of circulation. Clinical implications: Method may be developed further for the detection of rough local affections of pulmonary circulation.