TY - JOUR
T1 - Forehead versus forearm skin vascular responses at presyncope in humans
AU - Gagnon, Daniel
AU - Matthew Brothers, R.
AU - Ganio, Matthew S.
AU - Hastings, Jeffrey L.
AU - Crandall, Craig G.
N1 - Publisher Copyright:
© 2014 the American Physiological Society.
PY - 2014/10/1
Y1 - 2014/10/1
N2 - Facial pallor is commonly observed at presyncope in humans, suggestive of reductions in facial skin blood flow (SkBF). Yet, cutaneous vasoconstriction is usually minimal at presyncope when measured at the forearm. We tested the hypothesis that reductions in forehead SkBF at presyncope are greater than in the forearm. Forehead and forearm SkBF (laser-Doppler) and blood pressure (Finometer or radial artery catheterization) were measured during lower body negative pressure (LBNP) to presyncope in 11 normothermic and 13 heat-stressed subjects (intestinal temperature increased ∼1.4°C). LBNP reduced mean arterial pressure from 91 ± 5 to 57 ± 7 mmHg during normothermia (P < 0.001) and from 82 ± 5 to 57 ± 7 mmHg during heat stress (P < 0.001). During normothermia, LBNP decreased forehead SkBF 55 ± 14% compared with 24 ± 11% at the forearm (P = 0.002), while during heat stress LBNP decreased forehead SkBF 39 ± 11% compared with 28 ± 8% in the forearm (P = 0.007). In both conditions, most (>68%) of the decreases in SkBF were due to decreases in blood pressure. However, a greater contribution of actively mediated reductions in SkBF was observed at the forehead, relative to the forearm during normothermia (32 ± 13% vs. 11 ± 11%, P = 0.031) and heat stress (30 ± 13% vs. 10 ± 13%, P = 0.004). These data suggest that facial pallor at presyncope is due to a combination of passive decreases in forehead SkBF secondary to reductions in blood pressure and to active decreases in SkBF, the latter of which are relatively greater than in the forearm.
AB - Facial pallor is commonly observed at presyncope in humans, suggestive of reductions in facial skin blood flow (SkBF). Yet, cutaneous vasoconstriction is usually minimal at presyncope when measured at the forearm. We tested the hypothesis that reductions in forehead SkBF at presyncope are greater than in the forearm. Forehead and forearm SkBF (laser-Doppler) and blood pressure (Finometer or radial artery catheterization) were measured during lower body negative pressure (LBNP) to presyncope in 11 normothermic and 13 heat-stressed subjects (intestinal temperature increased ∼1.4°C). LBNP reduced mean arterial pressure from 91 ± 5 to 57 ± 7 mmHg during normothermia (P < 0.001) and from 82 ± 5 to 57 ± 7 mmHg during heat stress (P < 0.001). During normothermia, LBNP decreased forehead SkBF 55 ± 14% compared with 24 ± 11% at the forearm (P = 0.002), while during heat stress LBNP decreased forehead SkBF 39 ± 11% compared with 28 ± 8% in the forearm (P = 0.007). In both conditions, most (>68%) of the decreases in SkBF were due to decreases in blood pressure. However, a greater contribution of actively mediated reductions in SkBF was observed at the forehead, relative to the forearm during normothermia (32 ± 13% vs. 11 ± 11%, P = 0.031) and heat stress (30 ± 13% vs. 10 ± 13%, P = 0.004). These data suggest that facial pallor at presyncope is due to a combination of passive decreases in forehead SkBF secondary to reductions in blood pressure and to active decreases in SkBF, the latter of which are relatively greater than in the forearm.
KW - Heat
KW - Lower body negative pressure
KW - Skin blood flow
KW - Syncope
KW - Vasoconstriction
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U2 - 10.1152/ajpregu.00204.2014
DO - 10.1152/ajpregu.00204.2014
M3 - Article
C2 - 25100073
AN - SCOPUS:84907662195
SN - 0363-6119
VL - 307
SP - R908-R913
JO - American Journal of Physiology - Regulatory Integrative and Comparative Physiology
JF - American Journal of Physiology - Regulatory Integrative and Comparative Physiology
IS - 7
ER -