Exercise oximetry in clinical practice: A single-centre perspective on procedure and techniques

In moderate lower extremity artery disease (LEAD), when tissue ischaemia due to impaired inflow occurs at exercise but not during rest, exercise oximetry may be evaluated as a part of the diagnosis process. Initially used when assessing critical limb ischaemia at rest, transcutaneous oximetry (TcpO₂) has also been used in the last two decades during exercise assessment as a non-invasive method to measure oxygen pressure at the skin's surface, offering insights into loco-regional oxygen delivery-requirement mismatch. The introduction of decrease from rest of oxygen pressure (DROP) analysis in the TcpO₂ technique, which corresponds to the difference between limb oxygen pressure changes and chest oxygen pressure changes from rest, provides new information about the severity of the local ischaemia during exercise. In this paper, we elucidate the utilization of TcpO₂ during exercises (Ex-TcpO₂) over the years and provide information about how the technique has evolved and how the changes in the testing procedures have provided the opportunity for detecting abnormalities in both vascular and non-vascular clinical practice. We discuss the importance of Ex-TcpO₂ in the diagnosis of peripheral artery disease and its valuable contribution as a differential diagnostic tool for patients with co-morbid conditions such as lumbar spinal stenosis. We also provide recommendations about the utilization of Ex-TcpO₂ and contribute to a better understanding of the techniques in terms of efficacy, limitations and clinical applications. However, clarifications about its role in the diagnostic algorithm are needed, to ensure a better integration of the technique in clinical practice.