Transcutaneous oxygen tension measurement in patients with chronic arterial obstructive disease: reliability and long term variability of the method

Although transcutaneous oxygen tension (TcpO2) measurement may be useful for assessing changes in regional perfusion induced over time by drug or surgical treatment in patients with chronic arterial obstructive disease (CAOD), the reliability of the method over a long-term period is not know. To approach this problem, the authors evaluated retrospectively the behavior of TcpO2 measurement over time in patients with CAOD. To eliminate confounding influences due to the concomitant vascular disease at the limb level, data analysis was performed on TcpO2 measured at the right infraclavicular position. The median length of follow-up ranged from twenty days in 34 patients to 832 days in 3 patients (n = 2 and n = 10 individual sequential replications respectively). Initial and final TcpO2 values did not differ significantly even at the longest follow-up term, which indicates that the parameter is constant over time. The intrapatient variation coefficient of TcpO2 (calculated over at least three individual replications) ranged between an average of 11% to 16.2%. The corresponding interpatient variation fluctuated between 15.5% and 33.4%, a variability explained to some extent by sex-related influences, but, at least in the range of this sample, not by age, arterial oxygen levels, or disease status. Thus TcpO2 levels per se are stable, implying that TcpO2 measurement has the potential to record consistent changes caused by specific therapeutic interventions or the clinical evolution of patients with CAOD. However, the intrapatient and interpatient variability of the method has to be taken into account when TcpO2 is used for the follow-up and the physiopathologic study of patients with CAOD