Which of the following statements are true concerning in vivo arterial blood gas analyzers?

a. They incorporate a polarographic elec-trode.
b. The operating principle is light transmis-sion.
c. Temperature correction is unnecessary.
d. They are more accurate than in vitro blood gas analyzers.

ANS: B
In vivo arterial blood gas monitors use optical sensors and fiberoptic technology for light trans-mission through the sensors. Polarographic electrodes are not used in vivo. In many cases, tem-perature corrections might be required because the sensor may be in a peripheral artery, where the measured temperature might not equal the patient's core temperature. Correlations may not be as good for PCO2 and PO2 as they are for pH and therefore may be less accurate than in vitro blood gas analyzers.