Sinusoidal changes in transcutaneous oxygen pressure, suggesting Cheyne-Stokes respiration, are frequent and of poor prognosis among patients with suspected critical limb ischemia.

Background and Aims: Transcutaneous oxygen pressure (TcpO ₂ ) is used in patients with suspected critical limb ischemia (CLI). Sinusoidal changes (SC~) in TcpO ₂ are found in patients with Cheyne-Stokes respiration (CSR). We aimed to determine the characteristics of TcpO ₂ changes at rest in patients with suspected CLI, define the objective criteria for SC ~ TcpO ₂ patterns (SC+), and estimate the prevalence of SC+ in our population and its impact on the outcome.
Methods: We retrospectively analyzed 300 chest TcpO ₂ recordings performed in a 16-month period. We determined the presence/absence of SC ~ TcpO ₂ by visual analysis. We determined the acceptable error in the regularity of peaks of the cross-correlation with ROC curve analysis, among patients with typical SC ~ TcpO ₂ and non-sinusoidal patterns. Then, we defined SC + as a minimum of five peaks, a standard deviation of TcpO ₂ >1.25 mmHg, an error in regularity of peaks of the cross-correlation < 10%, and a cycle length between 30 and 100 s. In patients included until October 2019, we compared the outcome as a function of SC + or SC- with Cox models.
Results: Mathematical detection of SC + found that 43 patients (14.3%) fulfilled all four defined criteria at the chest level, but only 23 did so at the limb level. In the follow-up of 207 patients, the presence of Sc ~ TcpO ₂ at the chest significantly increased the risk of mortality: hazard ratio: 2.69 [95%CI: 1.37-5.30]; p < 0.005.
Conclusions: SC ~ TcpO ₂ is frequent, and is associated with a poor outcome in patients with suspected CLI.
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