Venous blood ammonia can be associated with cerebral blood flow in hepatic encephalopathy

The effects of partial acclimatization to high altitude (HA; 5,050 m) on cerebral metabolism and cerebrovascular function have not been characterized. We hypothesized (1) increased cerebrovascular reactivity (CVR) at HA; and (2) that CO2 would affect cerebral metabolism more than hypoxia. PaO2 and PaCO2 were manipulated at sea level (SL) to simulate HA exposure, and at HA, SL blood gases were simulated; CVR was assessed at both altitudes. Arterial–jugular venous differences were measured to calculate cerebral metabolic rates and cerebral blood flow (CBF). We observed that (1) partial acclimatization yields a steeper CO2-H+ relation in both arterial and jugular venous blood; yet (2) CVR did not change, despite (3) mean arterial pressure (MAP)-CO2 reactivity being doubled at HA, thus indicating effective cerebral autoregulation. (4) At SL hypoxia increased CBF, and restoration of oxygen at HA reduced CBF, but neither had any effect on cerebral metabolism. Acclimatization resets the cerebrovasculature to chronic hypocapnia.

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Cerebral blood flow measured by arterial-spin labeling MRI: A useful biomarker for characterization of minimal hepatic encephalopathy in patients with cirrhosis

European Journal of Radiology ◽

10.1016/j.ejrad.2013.06.002 ◽

2013 ◽

Vol 82 (11) ◽

pp. 1981-1988 ◽

Cited By ~ 15

Author(s):

Gang Zheng ◽

Long Jiang Zhang ◽

Jianhui Zhong ◽

Ze Wang ◽

Rongfeng Qi ◽

...

Keyword(s):

Blood Flow ◽

Cerebral Blood Flow ◽

Hepatic Encephalopathy ◽

Arterial Spin Labeling ◽

Minimal Hepatic Encephalopathy ◽

Spin Labeling

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Changes in cerebral blood flow after transjugular intrahepatic portosystemic shunt can help predict the development of hepatic encephalopathy: An arterial spin labeling MR study

European Journal of Radiology ◽

10.1016/j.ejrad.2012.07.003 ◽

2012 ◽

Vol 81 (12) ◽

pp. 3851-3856 ◽

Cited By ~ 17

Author(s):

Gang Zheng ◽

Long Jiang Zhang ◽

Ze Wang ◽

Rong Feng Qi ◽

Donghong Shi ◽

...

Keyword(s):

Blood Flow ◽

Cerebral Blood Flow ◽

Hepatic Encephalopathy ◽

Transjugular Intrahepatic Portosystemic Shunt ◽

Arterial Spin Labeling ◽

Spin Labeling ◽

Portosystemic Shunt ◽

Intrahepatic Portosystemic Shunt ◽

Mr Study

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Erratum

Journal of Cerebral Blood Flow & Metabolism ◽

10.1038/jcbfm.1992.24 ◽

1992 ◽

Vol 12 (1) ◽

pp. 177-177

Keyword(s):

Blood Flow ◽

Cerebral Blood Flow ◽

Liver Disease ◽

Hepatic Encephalopathy ◽

Minimal Hepatic Encephalopathy ◽

Severe Liver ◽

Ammonia Metabolism ◽

The Third ◽

Ph Values ◽

Severe Liver Disease

Cerebral Ammonia Metabolism in Patients with Severe Liver Disease and Minimal Hepatic Encephalopathy Alan H. Lockwood, Eddy W. H. Yap, and Wai-Hoi Wong [Originally published in Journal of Cerebral Blood Flow and Metabolism 1991;11;337–341] [Originally published in Journal of Cerebral Blood Flow and Metabolism 1991;11;337–341] The first sentence of the third paragraph of the Discussion, on page 339, should read as follows: “In aqueous solutions at physiological pH values, about 1–2% of all ammonia exists as a diffusible gas, with the remainder present as the less mobile charged ammoniumion.”

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