SKIN VASOMOTOR REFLEXES DURING INSPIRATORY GASP - STANDARDIZATION BY SPIROMETRIC CONTROL DOES NOT IMPROVE REPRODUCIBILITY

Arteriovenous anastomoses (AVA) in skin microcirculation are mediated by the sympathetic stimuli. The inspiratory gasp test (IG test) trigge rs the sympathetic nervous system, resulting in a decrease in BVA skin blood flow, as measured by laser Doppler fluxmetry (LDF), We studied the reproducibility of the IG test under carefully standardized respir atory conditions, In each of 19 healthy (young) volunteers with a mean skin temperature during the experiment above 28 degrees C 13 IG tests were performed, either under spirometric control or uncontrolled and by using a negative pressure transducer. Starting the IG lest end-insp iratory results in the most pronounced absolute LDF decrease [140 PU ( 70-490)], median (minimum-maximum) as compared to starting end-expirat ory [100 PU (40-260)] and during inspiration [110 FU (50-350)], respec tively, p < 0.001 and p < 0.01, Inspiration as fast as possible result s in a larger absolute LDF decrease [150 PU (40-450)], compared to ins piration in 5 s [120 PU (60-340); p < 0.02] and in 10 s [130 PU (40-35 0); p < 0.05], Continuously sucking negative mouth pressure results in a larger LDF decrease [140 PU (30-420)] in comparison with taking one deep breath and holding it for 10 s [110 PU (30-270); p < 0.01], Howe ver, standardization of the IC test did not improve its reproducibilit y.