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The relationship of conjunctival and arterial blood gas oxygen measurements
S Podolsky1, J Wertheimer, S Harding
1Department of Emergency Medicine, Albert Einstein Medical Center, York, PA.
Abstract:
Conjunctival oxymetry (CjO2) measures peripheral tissue oxygen at the conjunctival level. CjO2 changes can indicate pulmonary or circulatory conditions leading to shock. Literature review does not define 'normal' CjO2/ABG PaO2 ratios. We designed a study to measure these ratios. Twenty-two healthy patients undergoing cardiac catheterization had simultaneous PcjO2 and PaO2 measurements completed. The range of conjunctival oxygen measurements was from 34 to 68 mmHg with a mean of 50.5 mmHg. The PaO2 readings ranged from 65 to 93 mmHg with a mean of 77.1 mmHg. The average PcjO2/PaO2 ratio was 0.656 with a range of 0.47-0.93. Thus the PcjO2 is on average 66% of the arterial blood gas PaO2. This ratio of 0.66 can serve as a base for further clinical studies in which PcjO2 is looked at in patients with pulmonary or circulatory illnesses or injuries.
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