Relationship Between Foot Transcutaneous Oxygen Tension and Ankle Systolic Blood Pressure at Rest and Following Exercise

To determine whether foot transcutaneous oxygen tension (TcPO₂) and ankle systolic blood pressure (SBP) measure similar aspects of peripheral vascular occlusive disease (PVOD), the authors examined their relationship at rest and following treadmill exercise. Thirty-seven PVOD patients (mean age 69.2 ± 0.8 years) rested supine for twenty minutes, followed by a progressive treadmill walking test at a constant speed of 2 mph. The initial grade was 0 % ; this increased 2 % every two minutes until maximal claudication pain (n = 19) or until the occurrence of such limiting symptoms as volitional fatigue (n = 6), ST segment depression (n = 4), dyspnea (n = 3), multiple premature ventricular contractions (n = 2), and angina (n = 2). Patients then rested supine for fifteen minutes. Foot TcPO₂ was recorded before, during, and after exercise, whereas ankle SBP was measured before and after exercise. At rest, a curvilinear relationship was found between foot TcPO₂ and ankle SBP (foot TcPO₂ = 41.89 + 0.22(ankle SBP) + 0.0005 (ankle SBP2); SEE = 9.2, R = 0.64, R2 = 0.41, p < 0.001). In contrast, the relationship was stronger and more linear during recovery, particularly at the sixth minute (foot TcPO₂) = 8.33 + 0.35 (ankle SBP); SEE = 13.6, R = 0.86, R² = 0.73, p < 0.001). At rest, foot TcPO₂ and ankle SBP charac terized different aspects of PVOD because they shared only 41 % common vari ance. During recovery, they provided similar information because up to 73 % of the variance was shared. It is concluded that foot TcPO₂ should also be used to assess PVOD patients because unique information is obtained at rest and values can be recorded during exercise.