The hydrostatic pressure indifference point underestimates orthostatic redistribution of blood in humans

L G Petersen; Jonathan F. Carlsen; Michael Bachmann Nielsen; M Damgaard; N H Secher

doi:10.1152/japplphysiol.01175.2013

The hydrostatic pressure indifference point underestimates orthostatic redistribution of blood in humans

L G Petersen, Jonathan F. Carlsen, Michael Bachmann Nielsen, M Damgaard, N H Secher

12 Citations (Scopus)

Abstract

The hydrostatic indifference point (HIP; where venous pressure is unaffected by posture) is located at the level of the diaphragm and is believed to indicate the orthostatic redistribution of blood, but it remains unknown whether HIP coincides with the indifference point for blood volume (VIP). During graded (± 20°) head-up (HUT) and head-down tilt (HDT) in 12 male volunteers, we determined HIP from central venous pressure and VIP from redistribution of both blood, using ultrasound imaging of the inferior caval vein (VIPui), and fluid volume, by regional electrical admittance (VIPadm). Furthermore, we evaluated whether inflation of medical antishock trousers (to 70 mmHg) affected HIP and VIP. Leaving cardiovascular variables unaffected by tilt, HIP was located 7 ± 4 cm (mean ± SD) below the 4th intercostal space (IC-4) during HUT and was similar (7 ± 3 cm) during HDT and higher (P < 0.0001) than both VIPui (HUT: 22 ± 16 cm; HDT: 13 ± 7 cm) and VIPadm (HUT: 29 ± 9 cm; HDT: 20 ± 9 cm below IC-4). During HUT antishock trousers elevated both HIP and VIPui [to 3 ± 5 cm (P = 0.028) and 17 ± 7 cm below IC-4 (P = 0.051), respectively], while VIPadm remained unaffected. By simultaneous recording of pressure and filling of the inferior caval vein as well as fluid distribution, we found HIP located corresponding to the diaphragm while VIP was placed low in the abdomen, and that medical antishock trousers elevated both HIP and VIP. The low indifference point for volume shows that the gravitational influence on distribution of blood is more profound than indicated by the indifference point for venous pressure.

Original language	English
Journal	Journal of Applied Physiology
Volume	116
Issue number	7
Pages (from-to)	730-735
Number of pages	6
ISSN	8750-7587
DOIs	https://doi.org/10.1152/japplphysiol.01175.2013
Publication status	Published - 1 Apr 2014

Keywords

Adaptation, Physiological
Adult
Blood Volume
Central Venous Pressure
Diaphragm
Dizziness
Gravitation
Gravity Suits
Head-Down Tilt
Humans
Hydrostatic Pressure
Male
Posture
Regional Blood Flow
Tilt-Table Test
Vena Cava, Inferior
Young Adult

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10.1152/japplphysiol.01175.2013

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title = "The hydrostatic pressure indifference point underestimates orthostatic redistribution of blood in humans",

abstract = "The hydrostatic indifference point (HIP; where venous pressure is unaffected by posture) is located at the level of the diaphragm and is believed to indicate the orthostatic redistribution of blood, but it remains unknown whether HIP coincides with the indifference point for blood volume (VIP). During graded (± 20°) head-up (HUT) and head-down tilt (HDT) in 12 male volunteers, we determined HIP from central venous pressure and VIP from redistribution of both blood, using ultrasound imaging of the inferior caval vein (VIPui), and fluid volume, by regional electrical admittance (VIPadm). Furthermore, we evaluated whether inflation of medical antishock trousers (to 70 mmHg) affected HIP and VIP. Leaving cardiovascular variables unaffected by tilt, HIP was located 7 ± 4 cm (mean ± SD) below the 4th intercostal space (IC-4) during HUT and was similar (7 ± 3 cm) during HDT and higher (P < 0.0001) than both VIPui (HUT: 22 ± 16 cm; HDT: 13 ± 7 cm) and VIPadm (HUT: 29 ± 9 cm; HDT: 20 ± 9 cm below IC-4). During HUT antishock trousers elevated both HIP and VIPui [to 3 ± 5 cm (P = 0.028) and 17 ± 7 cm below IC-4 (P = 0.051), respectively], while VIPadm remained unaffected. By simultaneous recording of pressure and filling of the inferior caval vein as well as fluid distribution, we found HIP located corresponding to the diaphragm while VIP was placed low in the abdomen, and that medical antishock trousers elevated both HIP and VIP. The low indifference point for volume shows that the gravitational influence on distribution of blood is more profound than indicated by the indifference point for venous pressure.",

keywords = "Adaptation, Physiological, Adult, Blood Volume, Central Venous Pressure, Diaphragm, Dizziness, Gravitation, Gravity Suits, Head-Down Tilt, Humans, Hydrostatic Pressure, Male, Posture, Regional Blood Flow, Tilt-Table Test, Vena Cava, Inferior, Young Adult",

author = "Petersen, {L G} and Carlsen, {Jonathan F.} and Nielsen, {Michael Bachmann} and M Damgaard and Secher, {N H}",

year = "2014",

month = apr,

day = "1",

doi = "10.1152/japplphysiol.01175.2013",

language = "English",

volume = "116",

pages = "730--735",

journal = "Journal of Applied Physiology",

issn = "8750-7587",

publisher = "American Physiological Society",

number = "7",

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TY - JOUR

T1 - The hydrostatic pressure indifference point underestimates orthostatic redistribution of blood in humans

AU - Petersen, L G

AU - Carlsen, Jonathan F.

AU - Nielsen, Michael Bachmann

AU - Damgaard, M

AU - Secher, N H

PY - 2014/4/1

Y1 - 2014/4/1

N2 - The hydrostatic indifference point (HIP; where venous pressure is unaffected by posture) is located at the level of the diaphragm and is believed to indicate the orthostatic redistribution of blood, but it remains unknown whether HIP coincides with the indifference point for blood volume (VIP). During graded (± 20°) head-up (HUT) and head-down tilt (HDT) in 12 male volunteers, we determined HIP from central venous pressure and VIP from redistribution of both blood, using ultrasound imaging of the inferior caval vein (VIPui), and fluid volume, by regional electrical admittance (VIPadm). Furthermore, we evaluated whether inflation of medical antishock trousers (to 70 mmHg) affected HIP and VIP. Leaving cardiovascular variables unaffected by tilt, HIP was located 7 ± 4 cm (mean ± SD) below the 4th intercostal space (IC-4) during HUT and was similar (7 ± 3 cm) during HDT and higher (P < 0.0001) than both VIPui (HUT: 22 ± 16 cm; HDT: 13 ± 7 cm) and VIPadm (HUT: 29 ± 9 cm; HDT: 20 ± 9 cm below IC-4). During HUT antishock trousers elevated both HIP and VIPui [to 3 ± 5 cm (P = 0.028) and 17 ± 7 cm below IC-4 (P = 0.051), respectively], while VIPadm remained unaffected. By simultaneous recording of pressure and filling of the inferior caval vein as well as fluid distribution, we found HIP located corresponding to the diaphragm while VIP was placed low in the abdomen, and that medical antishock trousers elevated both HIP and VIP. The low indifference point for volume shows that the gravitational influence on distribution of blood is more profound than indicated by the indifference point for venous pressure.

AB - The hydrostatic indifference point (HIP; where venous pressure is unaffected by posture) is located at the level of the diaphragm and is believed to indicate the orthostatic redistribution of blood, but it remains unknown whether HIP coincides with the indifference point for blood volume (VIP). During graded (± 20°) head-up (HUT) and head-down tilt (HDT) in 12 male volunteers, we determined HIP from central venous pressure and VIP from redistribution of both blood, using ultrasound imaging of the inferior caval vein (VIPui), and fluid volume, by regional electrical admittance (VIPadm). Furthermore, we evaluated whether inflation of medical antishock trousers (to 70 mmHg) affected HIP and VIP. Leaving cardiovascular variables unaffected by tilt, HIP was located 7 ± 4 cm (mean ± SD) below the 4th intercostal space (IC-4) during HUT and was similar (7 ± 3 cm) during HDT and higher (P < 0.0001) than both VIPui (HUT: 22 ± 16 cm; HDT: 13 ± 7 cm) and VIPadm (HUT: 29 ± 9 cm; HDT: 20 ± 9 cm below IC-4). During HUT antishock trousers elevated both HIP and VIPui [to 3 ± 5 cm (P = 0.028) and 17 ± 7 cm below IC-4 (P = 0.051), respectively], while VIPadm remained unaffected. By simultaneous recording of pressure and filling of the inferior caval vein as well as fluid distribution, we found HIP located corresponding to the diaphragm while VIP was placed low in the abdomen, and that medical antishock trousers elevated both HIP and VIP. The low indifference point for volume shows that the gravitational influence on distribution of blood is more profound than indicated by the indifference point for venous pressure.

KW - Adaptation, Physiological

KW - Adult

KW - Blood Volume

KW - Central Venous Pressure

KW - Diaphragm

KW - Dizziness

KW - Gravitation

KW - Gravity Suits

KW - Head-Down Tilt

KW - Humans

KW - Hydrostatic Pressure

KW - Male

KW - Posture

KW - Regional Blood Flow

KW - Tilt-Table Test

KW - Vena Cava, Inferior

KW - Young Adult

U2 - 10.1152/japplphysiol.01175.2013

DO - 10.1152/japplphysiol.01175.2013

M3 - Journal article

C2 - 24481962

SN - 8750-7587

VL - 116

SP - 730

EP - 735

JO - Journal of Applied Physiology

JF - Journal of Applied Physiology

IS - 7

ER -

The hydrostatic pressure indifference point underestimates orthostatic redistribution of blood in humans

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Keywords

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