Abstract 13381: The Relationship Between PAD Symptomatology and Ischemia: a Mixed Method Evaluation

Abstract

Introduction: Classic claudication is only reported by 7.5% to 33% of patients with PAD. Atypical symptom reporting is common, but it is unknown if ischemic changes are occurring since the relationship between atypical symptoms and tissue oxygen saturation (StO 2 ) has not previously been reported. The purpose of this study was to measure calf StO 2 during treadmill exercise and recovery, and evaluate its relationship with self-reported symptoms. Methods: Adults diagnosed with PAD and experiencing exercise-limiting ischemic symptoms were asked to: (a) use a numeric rating scale (0 to 5) to rate symptoms during exercise and recovery; (b) provide symptom descriptors; and (c) wear a near-infrared spectroscopy device to obtain calf StO 2 during exercise and recovery. Data analysis included descriptive statistics, exploration of individual and grouped graphical trajectories, and multilevel modeling. Results: During three successive bouts of treadmill exercise, 40 participants (80% Caucasian males, mean age 68±9 years) provided 22 symptom descriptors in eight lower extremity locations. Only 69.2% of exercise tests were stopped due to discomfort in the calf and classic descriptors were used only half the time to describe maximum calf discomfort (55.4%). The most rapid decline in StO 2 during exercise occurred between the start of exercise and the onset of symptoms. The nadir StO 2 was often reached prior to the report of maximum discomfort. In the exercise model, changes in StO 2 were related to total exercise time ( p <0.001), baseline StO 2 ( p <0.001), exercise ratings ( p <0.001) and ABI ( p <0.05). During recovery, StO 2 increased steadily for most participants between maximum discomfort and full symptom recovery; changes in StO 2 were related to recovery ratings ( p <0.001) and ABI ( p <0.03). Conclusions: Ischemic symptoms extended beyond classic locations and descriptors. Interestingly, participant perception of maximum discomfort frequently occurred after the nadir StO 2 . Similarly, most reports of full symptom recovery occurred prior to complete resolution of ischemia. Further research is necessary to explore mechanisms that could explain this objective-subjective mismatch to better understand the full range of ischemic symptoms associated with PAD.