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Hypercapnic respiratory failure, also known as Type 2 or ventilatory respiratory failure, is a severe condition characterized by the body's inability to effectively remove carbon dioxide (CO2) from the bloodstream. It leads to an arterial CO2 pressure (PaCO2) exceeding 45 mmHg and a blood pH above 7.35. This situation indicates that the body's ventilatory demand, or the ventilation needed to maintain normal PaCO2 levels, surpasses its supply or the maximum gas flow achievable without causing...
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Hyperventilation refers to a higher-than-normal rate and depth of breathing, often associated with anxiety attacks. This excessive breathing surpasses the body's need to expel CO2, leading to a condition known as hypocapnia - an unusually low level of carbon dioxide in the blood. Hypocapnia can constrict cerebral blood vessels, reducing blood flow to the brain, which may result in dizziness or fainting. Early signs include tingling and muscle spasms in the hands and face, caused by falling...
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MRI Mapping of Cerebrovascular Reactivity via Gas Inhalation Challenges
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Published on: December 17, 2014

Hypercapnia-induced cerebral hyperperfusion: an underrecognized clinical entity.

J M Pollock1, A R Deibler, C T Whitlow

  • 1Department of Radiology, Wake Forest University School of Medicine, Winston-Salem, NC, USA. jeffmpollock@gmail.com

AJNR. American Journal of Neuroradiology
|October 16, 2008
PubMed
Summary

Hypercapnia causes cerebral hyperperfusion and hypocapnia causes hypoperfusion in hospitalized patients. Arterial spin-labeled (ASL) perfusion imaging can identify these conditions, which may explain unexplained symptoms.

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Area of Science:

  • Neurology
  • Radiology
  • Medical Imaging

Background:

  • Cerebral hyperperfusion and hypoperfusion due to hypercapnia and hypocapnia are underrecognized.
  • Quantitative perfusion imaging is not routinely used, limiting diagnosis.

Purpose of the Study:

  • To report clinical and perfusion imaging findings in patients with hypercapnic cerebral hyperperfusion and hypocapnic hypoperfusion.
  • To highlight the utility of arterial spin-labeled (ASL) MR perfusion imaging.

Main Methods:

  • ASL MR perfusion imaging supplemented conventional MR in 45 patients.
  • Correlated imaging findings with arterial blood gas (ABG) analysis and clinical history.

Main Results:

  • No acute findings on conventional MR imaging.
  • Hypercapnia correlated with global hyperperfusion on ASL CBF maps (P < .0005).
  • Cerebral perfusion increased by 4.0 mL/100 g/min per 1-mm Hg increase in pCO(2).

Conclusions:

  • ASL imaging will increase recognition of hypercapnic cerebral hyperperfusion.
  • This condition may explain unexplained neuropsychiatric symptoms.
  • Hypocapnia may explain normal MR imaging with poor ASL perfusion.