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The role of differential oxygen distribution between the brain and peripheral tissues on tolerance to induced central hypovolemia
Author(s) -
Lee Kay Victoria,
George Mebin,
Soller Babs R.,
Ryan Kathy L.,
HinojosaLaborde Carmen,
Convertino Victor A.,
Rickards Caroline A.
Publication year - 2013
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.27.1_supplement.lb667
Subject(s) - hypovolemia , medicine , oxygenation , vasoconstriction , peripheral , cardiology , anesthesia , cerebral blood flow
Background Maintenance of cerebral perfusion and oxygenation is essential for survival from hemorrhage. As individuals vary in tolerance to reduced blood volume (e.g., central hypovolemia), we hypothesized that subjects with high tolerance (HT) will maintain cerebral oxygenation compared to low tolerant (LT) subjects, which will be associated with greater peripheral vasoconstriction. Methods 13 human subjects were instrumented for cerebral (ScO 2 ) and muscle (SmO 2 ) oxygenation (near‐infrared spectroscopy, NIRS), then completed a step‐wise presyncopal‐limited lower body negative pressure (LBNP) protocol. Total hemoglobin (HbT) was calculated as an index of local peripheral resistance (inverse relationship) at the muscle. Results Progressive decreases in ScO 2 were observed in LT subjects (n=5) from −45 mmHg LBNP (P≤0.01 compared to baseline), while ScO 2 did not change throughout LBNP for the HT subjects (n=8; P≥0.44). SmO 2 decreased at −30 and −60 mmHg LBNP (P≤0.01) in the HT group with concomitant increases in resistance (decreases in HbT; P≤0.03). In contrast, both SmO 2 (P=0.01) and HbT (P=0.06) only decreased at −60 mmHg LBNP in the LT group. Conclusions In support of our hypothesis, increased tolerance to progressive central hypovolemia was associated with maintained cerebral oxygenation, due, in part, to earlier onset of peripheral vasoconstriction. Source of Funding: US Army MRMC