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Cerebral blood flow regulation during blood loss compared to lower body negative pressure in humans (1068.9)
Author(s) -
Barnes Jill,
Johnson Blair,
Convertino Victor,
Joyner Michael,
Rickards Caroline
Publication year - 2014
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.28.1_supplement.1068.9
Subject(s) - blood pressure , medicine , lower body , blood flow , cerebral blood flow , hemodynamics , anesthesia , cardiology
Lower body negative pressure (LBNP) is often used to simulate blood loss in humans. However, it is unknown if the effects of actual blood loss (BL) on cerebral blood flow regulation is analogous to simulated blood loss during LBNP. Nine healthy men (32±6 y) were studied at baseline, during 3 levels of LBNP (5 min each at ‐15, ‐30, ‐45 mmHg), and during 3 levels of blood loss (5 min each at 333, 667, 1000 mL). LBNP and BL conditions were randomized. Intra‐arterial mean arterial pressure (MAP) was similar during LBNP compared with BL (p>0.20). Central venous pressure (CVP; 2.8±0.7 vs. 4.0±0.8, 1.2±0.6 vs. 3.5±0.8, 0.2±0.9 vs. 2.1±0.9 mmHg for level 1, 2, and 3; p<0.01) and stroke volume (71±4 vs. 80±3, 60±3 vs. 74±3, 51±2 vs. 68±4 mL for level 1, 2, and 3; p<0.01) were lower during LBNP compared with BL. Despite differences in CVP, middle cerebral artery velocity (MCAv) and cerebrovascular conductance index (CVCi) were similar between LBNP and BL at each level (MCAv at level 3: 62±6 vs. 66±5 cm/s; p=0.37; CVCi at level 3: 0.72±0.05 vs. 0.73±0.05 cm/s/mmHg; p=0.29). Furthermore, the slope of the relationship between MAP and MCAv was not different between LBNP and BL (1.06 vs. 1.07 cm/s/mmHg). Our results suggest that the cerebral hemodynamic responses to LBNP are similar to actual blood loss. Grant Funding Source : Supported by U.S. Army MRMC Combat Casualty Care Research Program Grant # W81XWH‐11‐1‐0823