Jugular venous pooling during lowering of the head affects blood pressure of the anesthetized giraffe

E. Brøndum; John Michael Hasenkam; Niels H. Secher; Mads Frost Bertelsen; C. Grøndahl; K.K. Petersen; Rikke Buhl; C. Aalkjaer; U. Baandrup; H. Nygaard; Morten Holdgaard Smerup; F. Stegmann; E. Sloth; K.H. Østergaard; P. Nissen; M. Runge; K. Pitsillides; T. Wang

doi:10.1152/ajpregu.90804.2008

Jugular venous pooling during lowering of the head affects blood pressure of the anesthetized giraffe

E. Brøndum, John Michael Hasenkam, Niels H. Secher, Mads Frost Bertelsen, C. Grøndahl, K.K. Petersen, Rikke Buhl, C. Aalkjaer, U. Baandrup, H. Nygaard, Morten Holdgaard Smerup, F. Stegmann, E. Sloth, K.H. Østergaard, P. Nissen, M. Runge, K. Pitsillides, T. Wang

45 Citations (Scopus)

Abstract

How blood flow and pressure to the giraffe's brain are regulated when drinking remains debated. We measured simultaneous blood flow, pressure, and cross-sectional area in the carotid artery and jugular vein of five anesthetized and spontaneously breathing giraffes. The giraffes were suspended in the upright position so that we could lower the head. In the upright position, mean arterial pressure (MAP) was 193 +/- 11 mmHg (mean +/- SE), carotid flow was 0.7 +/- 0.2 l/min, and carotid cross-sectional area was 0.85 +/- 0.04 cm(2). Central venous pressure (CVP) was 4 +/- 2 mmHg, jugular flow was 0.7 +/- 0.2 l/min, and jugular cross-sectional area was 0.14 +/- 0.04 cm(2) (n = 4). Carotid arterial and jugular venous pressures at head level were 118 +/- 9 and -7 +/- 4 mmHg, respectively. When the head was lowered, MAP decreased to 131 +/- 13 mmHg, while carotid cross-sectional area and flow remained unchanged. Cardiac output was reduced by 30%, CVP decreased to -1 +/- 2 mmHg (P < 0.01), and jugular flow ceased as the jugular cross-sectional area increased to 3.2 +/- 0.6 cm(2) (P < 0.01), corresponding to accumulation of approximately 1.2 l of blood in the veins. When the head was raised, the jugular veins collapsed and blood was returned to the central circulation, and CVP and cardiac output were restored. The results demonstrate that in the upright-positioned, anesthetized giraffe cerebral blood flow is governed by arterial pressure without support of a siphon mechanism and that when the head is lowered, blood accumulates in the vein, affecting MAP

Original language	English
Journal	American Journal of Physiology: Regulatory, Integrative and Comparative Physiology
Volume	297
Issue number	4
Pages (from-to)	R1058-R1065
Number of pages	8
ISSN	0363-6119
DOIs	https://doi.org/10.1152/ajpregu.90804.2008
Publication status	Published - 2009

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10.1152/ajpregu.90804.2008

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Brøndum, E., Hasenkam, J. M., Secher, N. H., Bertelsen, M. F., Grøndahl, C., Petersen, K. K., Buhl, R., Aalkjaer, C., Baandrup, U., Nygaard, H., Smerup, M. H., Stegmann, F., Sloth, E., Østergaard, K. H., Nissen, P., Runge, M., Pitsillides, K., & Wang, T. (2009). Jugular venous pooling during lowering of the head affects blood pressure of the anesthetized giraffe. American Journal of Physiology: Regulatory, Integrative and Comparative Physiology, 297(4), R1058-R1065. https://doi.org/10.1152/ajpregu.90804.2008

Jugular venous pooling during lowering of the head affects blood pressure of the anesthetized giraffe. / Brøndum, E.; Hasenkam, John Michael; Secher, Niels H. et al.
In: American Journal of Physiology: Regulatory, Integrative and Comparative Physiology, Vol. 297, No. 4, 2009, p. R1058-R1065.

Research output: Contribution to journal › Journal article › Research › peer-review

Brøndum, E, Hasenkam, JM, Secher, NH , Bertelsen, MF, Grøndahl, C, Petersen, KK, Buhl, R, Aalkjaer, C, Baandrup, U, Nygaard, H, Smerup, MH, Stegmann, F, Sloth, E, Østergaard, KH, Nissen, P, Runge, M, Pitsillides, K & Wang, T 2009, 'Jugular venous pooling during lowering of the head affects blood pressure of the anesthetized giraffe', American Journal of Physiology: Regulatory, Integrative and Comparative Physiology, vol. 297, no. 4, pp. R1058-R1065. https://doi.org/10.1152/ajpregu.90804.2008

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title = "Jugular venous pooling during lowering of the head affects blood pressure of the anesthetized giraffe",

abstract = "How blood flow and pressure to the giraffe's brain are regulated when drinking remains debated. We measured simultaneous blood flow, pressure, and cross-sectional area in the carotid artery and jugular vein of five anesthetized and spontaneously breathing giraffes. The giraffes were suspended in the upright position so that we could lower the head. In the upright position, mean arterial pressure (MAP) was 193 +/- 11 mmHg (mean +/- SE), carotid flow was 0.7 +/- 0.2 l/min, and carotid cross-sectional area was 0.85 +/- 0.04 cm(2). Central venous pressure (CVP) was 4 +/- 2 mmHg, jugular flow was 0.7 +/- 0.2 l/min, and jugular cross-sectional area was 0.14 +/- 0.04 cm(2) (n = 4). Carotid arterial and jugular venous pressures at head level were 118 +/- 9 and -7 +/- 4 mmHg, respectively. When the head was lowered, MAP decreased to 131 +/- 13 mmHg, while carotid cross-sectional area and flow remained unchanged. Cardiac output was reduced by 30%, CVP decreased to -1 +/- 2 mmHg (P < 0.01), and jugular flow ceased as the jugular cross-sectional area increased to 3.2 +/- 0.6 cm(2) (P < 0.01), corresponding to accumulation of approximately 1.2 l of blood in the veins. When the head was raised, the jugular veins collapsed and blood was returned to the central circulation, and CVP and cardiac output were restored. The results demonstrate that in the upright-positioned, anesthetized giraffe cerebral blood flow is governed by arterial pressure without support of a siphon mechanism and that when the head is lowered, blood accumulates in the vein, affecting MAP",

author = "E. Br{\o}ndum and Hasenkam, {John Michael} and Secher, {Niels H.} and Bertelsen, {Mads Frost} and C. Gr{\o}ndahl and K.K. Petersen and Rikke Buhl and C. Aalkjaer and U. Baandrup and H. Nygaard and Smerup, {Morten Holdgaard} and F. Stegmann and E. Sloth and K.H. {\O}stergaard and P. Nissen and M. Runge and K. Pitsillides and T. Wang",

year = "2009",

doi = "10.1152/ajpregu.90804.2008",

language = "English",

volume = "297",

pages = "R1058--R1065",

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T1 - Jugular venous pooling during lowering of the head affects blood pressure of the anesthetized giraffe

AU - Brøndum, E.

AU - Hasenkam, John Michael

AU - Secher, Niels H.

AU - Bertelsen, Mads Frost

AU - Grøndahl, C.

AU - Petersen, K.K.

AU - Buhl, Rikke

AU - Aalkjaer, C.

AU - Baandrup, U.

AU - Nygaard, H.

AU - Smerup, Morten Holdgaard

AU - Stegmann, F.

AU - Sloth, E.

AU - Østergaard, K.H.

AU - Nissen, P.

AU - Runge, M.

AU - Pitsillides, K.

AU - Wang, T.

PY - 2009

Y1 - 2009

N2 - How blood flow and pressure to the giraffe's brain are regulated when drinking remains debated. We measured simultaneous blood flow, pressure, and cross-sectional area in the carotid artery and jugular vein of five anesthetized and spontaneously breathing giraffes. The giraffes were suspended in the upright position so that we could lower the head. In the upright position, mean arterial pressure (MAP) was 193 +/- 11 mmHg (mean +/- SE), carotid flow was 0.7 +/- 0.2 l/min, and carotid cross-sectional area was 0.85 +/- 0.04 cm(2). Central venous pressure (CVP) was 4 +/- 2 mmHg, jugular flow was 0.7 +/- 0.2 l/min, and jugular cross-sectional area was 0.14 +/- 0.04 cm(2) (n = 4). Carotid arterial and jugular venous pressures at head level were 118 +/- 9 and -7 +/- 4 mmHg, respectively. When the head was lowered, MAP decreased to 131 +/- 13 mmHg, while carotid cross-sectional area and flow remained unchanged. Cardiac output was reduced by 30%, CVP decreased to -1 +/- 2 mmHg (P < 0.01), and jugular flow ceased as the jugular cross-sectional area increased to 3.2 +/- 0.6 cm(2) (P < 0.01), corresponding to accumulation of approximately 1.2 l of blood in the veins. When the head was raised, the jugular veins collapsed and blood was returned to the central circulation, and CVP and cardiac output were restored. The results demonstrate that in the upright-positioned, anesthetized giraffe cerebral blood flow is governed by arterial pressure without support of a siphon mechanism and that when the head is lowered, blood accumulates in the vein, affecting MAP

AB - How blood flow and pressure to the giraffe's brain are regulated when drinking remains debated. We measured simultaneous blood flow, pressure, and cross-sectional area in the carotid artery and jugular vein of five anesthetized and spontaneously breathing giraffes. The giraffes were suspended in the upright position so that we could lower the head. In the upright position, mean arterial pressure (MAP) was 193 +/- 11 mmHg (mean +/- SE), carotid flow was 0.7 +/- 0.2 l/min, and carotid cross-sectional area was 0.85 +/- 0.04 cm(2). Central venous pressure (CVP) was 4 +/- 2 mmHg, jugular flow was 0.7 +/- 0.2 l/min, and jugular cross-sectional area was 0.14 +/- 0.04 cm(2) (n = 4). Carotid arterial and jugular venous pressures at head level were 118 +/- 9 and -7 +/- 4 mmHg, respectively. When the head was lowered, MAP decreased to 131 +/- 13 mmHg, while carotid cross-sectional area and flow remained unchanged. Cardiac output was reduced by 30%, CVP decreased to -1 +/- 2 mmHg (P < 0.01), and jugular flow ceased as the jugular cross-sectional area increased to 3.2 +/- 0.6 cm(2) (P < 0.01), corresponding to accumulation of approximately 1.2 l of blood in the veins. When the head was raised, the jugular veins collapsed and blood was returned to the central circulation, and CVP and cardiac output were restored. The results demonstrate that in the upright-positioned, anesthetized giraffe cerebral blood flow is governed by arterial pressure without support of a siphon mechanism and that when the head is lowered, blood accumulates in the vein, affecting MAP

U2 - 10.1152/ajpregu.90804.2008

DO - 10.1152/ajpregu.90804.2008

M3 - Journal article

C2 - 19657096

SN - 0363-6119

VL - 297

SP - R1058-R1065

JO - American Journal of Physiology: Regulatory, Integrative and Comparative Physiology

JF - American Journal of Physiology: Regulatory, Integrative and Comparative Physiology

IS - 4

ER -