Brain oxygen, CO2, pH, and temperature monitoring

Evaluation in the feline brain

A. Zauner, Ross Bullock, X. Di, H. F. Young, J. D. Miller, C. J. Hodge

Research output: Contribution to journalArticle

136 Citations (Scopus)

Abstract

CURRENTLY, NO IDEAL method exists for monitoring the injured brain. Recently, a single, compact, fiberoptic sensor has become available for measuring oxygen, CO2, pH and temperature in blood. We have adapted this instrument for continuous use in brain tissue to measure oxygen tension, carbon dioxide tension (pCO2), pH, and temperature. To evaluate this new technique, we produced hypercapnia, hypocapnia, intracranial pressure increase, and hypoxemia in seven normal cats. In an additional six animals, sensors were placed within a zone of focal brain ischemia induced by occluding the left middle cerebral artery. The sensor readings were compared with cerebral blood flow measurements, intracranial pressure, and brain histological findings. An in vitro experiment was also performed using human blood to test the accuracy of the sensor over a wide range of pCO2 and oxygen tension values. After careful precalibration and rigid cranium fixation, stable measurements could be obtained throughout the 6- to 8-hour experiments. In normal animals, brain oxygen was 42 ± 9 mm Hg, brain CO2 was 59 ± 14 mm Hg, brain pH was 7.0 ± 0.2, and brain temperature was 36.7 ± 0.7°C. Hypocapnia and hypoxemia produced a significant decline in tissue oxygen (≤30 ± 3 mm Hg; P < 0.001), whereas hypercapnia caused by hypoventilation and intracranial pressure increase produced a significant increase in tissue CO2 (≥74 ± 4 mm Hg; P < 0.001). Focal ischemia produced a rapid 42% decline in brain oxygen (25 ± 7 mm Hg) and a 25% increase in tissue pCO2 (71 ± 23 mm Hg). Brain oxygen further decreased to 19 ± 6 mm Hg toward the end of the experiment, 4 hours later. After middle cerebral artery occlusion, the regional cerebral blood flow decreased to 10 ± 5 ml per 100 g per minute, within the 1st hour, from a baseline value of 65 ± 15 ml per 100 g per minute. It then gradually increased to 15 ± 5 ml per 100 g per minute by the end of the 4-hour experiment. Brain pH was closely and inversely related to brain CO2. The brain temperature in the focally ischemic tissue decreased from 36.7 ± 0.7 to 35.5 ± 1.6°C by the end of the experiment. The in vitro experiment demonstrated good linear correlation between the sensor readings and the blood gas analysis. Continuous monitoring of oxygen, CO2, pH, and temperature in damaged or at-risk brain tissue using a single sensor is now feasible and will, thus, allow improved continuous monitoring of neurosurgical patients who are at risk of significant secondary brain damage.

Original languageEnglish
Pages (from-to)1168-1177
Number of pages10
JournalNeurosurgery
Volume37
Issue number6
StatePublished - Jan 1 1995
Externally publishedYes

Fingerprint

Felidae
Oxygen
Temperature
Brain
Cerebrovascular Circulation
Hypocapnia
Intracranial Hypertension
Hypercapnia
Reading
Hypoventilation
Blood Gas Analysis
Middle Cerebral Artery Infarction
Regional Blood Flow
Middle Cerebral Artery
Intracranial Pressure
Physiologic Monitoring
Hematologic Tests
Brain Ischemia
Skull
Carbon Dioxide

Keywords

  • Brain carbon dioxide
  • Brain oxygen
  • Brain pH
  • Cerebral blood flow
  • Continuous monitoring
  • Focal ischemia

ASJC Scopus subject areas

  • Clinical Neurology
  • Surgery

Cite this

Zauner, A., Bullock, R., Di, X., Young, H. F., Miller, J. D., & Hodge, C. J. (1995). Brain oxygen, CO2, pH, and temperature monitoring: Evaluation in the feline brain. Neurosurgery, 37(6), 1168-1177.

Brain oxygen, CO2, pH, and temperature monitoring : Evaluation in the feline brain. / Zauner, A.; Bullock, Ross; Di, X.; Young, H. F.; Miller, J. D.; Hodge, C. J.

In: Neurosurgery, Vol. 37, No. 6, 01.01.1995, p. 1168-1177.

Research output: Contribution to journalArticle

Zauner, A, Bullock, R, Di, X, Young, HF, Miller, JD & Hodge, CJ 1995, 'Brain oxygen, CO2, pH, and temperature monitoring: Evaluation in the feline brain', Neurosurgery, vol. 37, no. 6, pp. 1168-1177.
Zauner A, Bullock R, Di X, Young HF, Miller JD, Hodge CJ. Brain oxygen, CO2, pH, and temperature monitoring: Evaluation in the feline brain. Neurosurgery. 1995 Jan 1;37(6):1168-1177.
Zauner, A. ; Bullock, Ross ; Di, X. ; Young, H. F. ; Miller, J. D. ; Hodge, C. J. / Brain oxygen, CO2, pH, and temperature monitoring : Evaluation in the feline brain. In: Neurosurgery. 1995 ; Vol. 37, No. 6. pp. 1168-1177.
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