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Elevated Core and Skin Temperatures Independently Attenuate Simulated Hemorrhagic Tolerance
Author(s) -
Pearson James,
Lucas Rebekah,
Schlader Zachary,
Gag Daniel,
Crandall Craig
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.994.18
Subject(s) - chemistry , core temperature , thermoregulation , lower body , skin temperature , zoology , core (optical fiber) , medicine , biomedical engineering , biology , materials science , composite material
The separate influences of increased core (Tcore) and skin (Tskin) temperatures upon tolerance to a simulated hemorrhagic challenge (Lower Body Negative Pressure; LBNP) are unknown. Nine participants underwent progressive LBNP to pre‐syncope on four occasions: 1) Control: Neutral Tskin and Tcore (34.3±0.5 and 36.8±0.2 ºC), 2) Combined: High Tskin and high Tcore (38.8±0.6 and 38.1±0.2 ºC), 3) Hot Skin: High Tskin and neutral Tcore (37.6±0.2 and 37.1±0.2 ºC) and 4) Hot Core: Neutral Tskin and High Tcore (35.0±0.5 and 38.3±0.2 ºC). LBNP tolerance was quantified via a cumulative stress index (CSI; LBNP level * time). Cutaneous vascular conductance (CVC) was measured throughout. LBNP tolerance (CSI) was not different between Hot Skin and Hot Core (569±151 vs. 563±194; P = 0.92), while both were greater than Combined (257±106; both P 蠄 0.05) and all were lower than Control (1010±246; all P 蠄 0.05). Prior to LBNP CVC was not different between Combined, Hot Skin and Hot Core (2.3±0.6, 2.2±0.5 and 2.1±0.7 AU/mmHg, respectively; all P > 0.05) but all were higher than control (0.6±0.4 AU/mmHg; all P蠄0.05). Relative to pre‐LBNP, the decrease in CVC at pre‐syncope was not different between Combined and Hot Skin (‐12±14 vs. ‐11±19 %; P = 0.90) but both were appreciably lower than Hot Core (‐65±9%; both P 蠄 0.05). These data indicate that tolerance to a simulated hemorrhagic challenge is similarly reduced by elevations in Tskin and Tcore alone despite large reductions in CVC with increased Tcore.