Transcutaneous Oxygen Monitoring During Exercise Stress Testing1,2

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Abstract
Transcutaneous oxygen tension (tcPo2) was compared with simultaneous arterial oxygen tension (Pao2) in 3 normal young adults and 4 pediatric lung disease patients at rest and during exercise to assess the usefulness of tcPo2 monitoring during exercise stress testing. At rest, the regression coefficient of tcPo2 on Pao2 was 0.78 ± 0.03 (SEM) (r = 0.924; P < 0.0005). During exercise, the regression coefficient of tcPo2 on Pao2 was 0.88 ± 0.02 (r = 0.958; P < 0.0005), indicating that tcPo2 approximates Pao2 equally well at rest and during exercise. After a step change in inspired oxygen concentration (FIo2) from 0.21 to 0.17, there was no significant difference in the tcPo2 time constant at rest (66.2 ± 8.5 s) and during exercise (73.0 ± 3.1 s). Neither Pao2 nor tcPo2 fell in normal subjects during graded exercise stress testing. However, in 3 of 4 pediatric lung disease patients, there were decreases in both Pao2 (40.7 ± 11.6 mm Hg) and tcPo2 (28.7 ± 10.0 mm Hg) during 7 exercise stress tests. These results indicate that tcPo2 approximates Pao2 equally well at rest and during exercise.