Which statement about accuracy of transcutaneous measures is true?

Which statement about accuracy of transcutaneous measures is true?

• A. PtcO2 is more accurate in adults than in premature infants
• B. PtcO2 is less accurate in adults than in premature infants; PtcCO2 correlates well in both
• C. PtcCO2 is unreliable in all ages
• D. PtcO2 and PtcCO2 are identical in accuracy across age groups

Answer: (B)

Transcutaneous monitoring accuracy hinges on how gases diffuse through the skin and how well the skin is perfused. Oxygen diffuses through skin more slowly and is highly sensitive to skin thickness and perfusion. Premature infants have very thin, highly perfused skin, so PtcO2 readings tend to track arterial O2 more closely. In adults, the skin is thicker and less permeable, and perfusion can be more variable, which makes PtcO2 readings less reliable. CO2 diffuses more readily and is less affected by these skin thickness differences when the sensor is heated to boost local perfusion, so PtcCO2 tends to correlate well with arterial CO2 across both adults and premature infants. Thus, PtcO2 is less accurate in adults than in premature infants, while PtcCO2 correlates well in both age groups.

Transcutaneous monitoring accuracy hinges on how gases diffuse through the skin and how well the skin is perfused. Oxygen diffuses through skin more slowly and is highly sensitive to skin thickness and perfusion. Premature infants have very thin, highly perfused skin, so PtcO2 readings tend to track arterial O2 more closely. In adults, the skin is thicker and less permeable, and perfusion can be more variable, which makes PtcO2 readings less reliable. CO2 diffuses more readily and is less affected by these skin thickness differences when the sensor is heated to boost local perfusion, so PtcCO2 tends to correlate well with arterial CO2 across both adults and premature infants. Thus, PtcO2 is less accurate in adults than in premature infants, while PtcCO2 correlates well in both age groups.