Failure of vascular autoregulations in the upper limb with increased +Gz acceleration

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Failure of vascular autoregulations in the upper limb with increased +Gz acceleration. / Green, NDC; Brown, Margaret; Coote, John.

In: European Journal of Applied Physiology, Vol. 100, 01.01.2007, p. 621-626.

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@article{8a787eaa34cb46e8bf3f61f156a4c866,
title = "Failure of vascular autoregulations in the upper limb with increased +Gz acceleration",
abstract = "Forearm pain occurring during high +Gz exposure has been linked with vascular distension from elevated transmural pressure of hydrostatic origin and is exacerbated by positive pressure breathing (PBG). We postulated that at high vascular transmural pressure vascular autoregulation might be overcome and be associated with worsened pain. Six volunteers were studied at +4, +5, +6, and +7 Gz on a human centrifuge. Forearm vascular resistance (FVR) was assessed by Doppler ultrasound resistive index (RI), and superficial forearm venous pressure (FVP) was measured via an indwelling catheter. Pain rating was assessed by numerical scale. The left arm was located at heart level (control position), or on the throttle (test position). Runs were completed with and without positive pressure breathing for G protection (PBG); subjects wore full coverage anti-G trousers and chest counter-pressure. In the test position, pain increased with increasing acceleration (P <0.0001), and was more severe with PBG at +5 Gz and +7 Gz (P <0.05). FVP rose substantially more in the test than control position (238 +/- 17 mmHg vs. 61 +/- 8 mmHg at +7 Gz, P <0.0001) but the presence or absence of PBG had no effect on the FVP increase during acceleration in either position. In the test position, RI fell with increasing acceleration above +5 Gz (P <0.0001), and the fall was greater with PBG (P <0.05). Forearm pain was thus associated with a decrease in FVR and an increase in vascular transmural pressure. PBG exacerbated forearm pain and prompted a greater fall in RI, but had no effect on FVP response. These findings support FVR but not forearm venous distension in the aetiology of +Gz arm pain.",
author = "NDC Green and Margaret Brown and John Coote",
year = "2007",
month = jan,
day = "1",
doi = "10.1007/s00421-007-0465-0",
language = "English",
volume = "100",
pages = "621--626",
journal = "European Journal of Applied Physiology",
issn = "1439-6319",
publisher = "Springer Verlag",

}

RIS

TY - JOUR

T1 - Failure of vascular autoregulations in the upper limb with increased +Gz acceleration

AU - Green, NDC

AU - Brown, Margaret

AU - Coote, John

PY - 2007/1/1

Y1 - 2007/1/1

N2 - Forearm pain occurring during high +Gz exposure has been linked with vascular distension from elevated transmural pressure of hydrostatic origin and is exacerbated by positive pressure breathing (PBG). We postulated that at high vascular transmural pressure vascular autoregulation might be overcome and be associated with worsened pain. Six volunteers were studied at +4, +5, +6, and +7 Gz on a human centrifuge. Forearm vascular resistance (FVR) was assessed by Doppler ultrasound resistive index (RI), and superficial forearm venous pressure (FVP) was measured via an indwelling catheter. Pain rating was assessed by numerical scale. The left arm was located at heart level (control position), or on the throttle (test position). Runs were completed with and without positive pressure breathing for G protection (PBG); subjects wore full coverage anti-G trousers and chest counter-pressure. In the test position, pain increased with increasing acceleration (P <0.0001), and was more severe with PBG at +5 Gz and +7 Gz (P <0.05). FVP rose substantially more in the test than control position (238 +/- 17 mmHg vs. 61 +/- 8 mmHg at +7 Gz, P <0.0001) but the presence or absence of PBG had no effect on the FVP increase during acceleration in either position. In the test position, RI fell with increasing acceleration above +5 Gz (P <0.0001), and the fall was greater with PBG (P <0.05). Forearm pain was thus associated with a decrease in FVR and an increase in vascular transmural pressure. PBG exacerbated forearm pain and prompted a greater fall in RI, but had no effect on FVP response. These findings support FVR but not forearm venous distension in the aetiology of +Gz arm pain.

AB - Forearm pain occurring during high +Gz exposure has been linked with vascular distension from elevated transmural pressure of hydrostatic origin and is exacerbated by positive pressure breathing (PBG). We postulated that at high vascular transmural pressure vascular autoregulation might be overcome and be associated with worsened pain. Six volunteers were studied at +4, +5, +6, and +7 Gz on a human centrifuge. Forearm vascular resistance (FVR) was assessed by Doppler ultrasound resistive index (RI), and superficial forearm venous pressure (FVP) was measured via an indwelling catheter. Pain rating was assessed by numerical scale. The left arm was located at heart level (control position), or on the throttle (test position). Runs were completed with and without positive pressure breathing for G protection (PBG); subjects wore full coverage anti-G trousers and chest counter-pressure. In the test position, pain increased with increasing acceleration (P <0.0001), and was more severe with PBG at +5 Gz and +7 Gz (P <0.05). FVP rose substantially more in the test than control position (238 +/- 17 mmHg vs. 61 +/- 8 mmHg at +7 Gz, P <0.0001) but the presence or absence of PBG had no effect on the FVP increase during acceleration in either position. In the test position, RI fell with increasing acceleration above +5 Gz (P <0.0001), and the fall was greater with PBG (P <0.05). Forearm pain was thus associated with a decrease in FVR and an increase in vascular transmural pressure. PBG exacerbated forearm pain and prompted a greater fall in RI, but had no effect on FVP response. These findings support FVR but not forearm venous distension in the aetiology of +Gz arm pain.

U2 - 10.1007/s00421-007-0465-0

DO - 10.1007/s00421-007-0465-0

M3 - Article

C2 - 17479280

VL - 100

SP - 621

EP - 626

JO - European Journal of Applied Physiology

JF - European Journal of Applied Physiology

SN - 1439-6319

ER -