Abstract
INTRODUCTION: Published normal transcutaneous oxygen partial pressures (P(tc)O(2)) for the chest and lower limb have defined tissue hypoxia as a value of < 40 mmHg (< 30 mmHg in some patients, < 50 mmHg in others). AIM: To determine 'normal' P(tc)O(2) for the upper and lower limb in healthy, non-smoking adults using the Radiometer® TCM400 with tc Sensor E5250. METHOD: Thirty-two volunteers had transcutaneous oxygen measurements (TCOM) performed on the chest, upper and lower limbs breathing air, with leg then arm elevated and whilst breathing 100% oxygen. RESULTS: Room-air P(tc)O(2) (mmHg, mean (95% confidence interval)) were: chest: 53.6 (48.7-58.5); upper arm: 60.0 (56.1-64.0); forearm: 52.3 (44.8-55.8); dorsum of hand: 50.2 (46.1-54.3); thenar eminence: 70.8 (67.7-73.8); hypothenar eminence: 77.9 (75.1-80.7); lateral leg: 50.2 (46.2-54.2); lateral malleolus: 50.5 (46.6-54.3); medial malleolus: 48.9 (45.6-52.1); dorsum, between first and second toe: 53.1 (49.2-57.0); dorsum, proximal to fifth toe: 58.5 (55.0 - -62.0); plantar, 1st MTP: 73.7 (70.3-77.1). Nineteen subjects had at least one room-air P(tc)O(2) below 40 mmHg (nine upper limb, 13 lower limb, four chest). Approximately 10% lower limb P(tc)O(2) were < 100 mmHg on normobaric oxygen. Only one subject at one site had an upper limb P(tc)O(2) < 100 mmHg breathing oxygen. CONCLUSION: The broad dispersion in P(tc)O(2) in our healthy cohort reflects the inherent biologic variability in dermal perfusion and oxygen delivery, making it difficult to define narrow, rigid 'normal' values. Thus, we cannot recommend a single P(tc)O(2) value as 'normal' for the upper or lower limb. A thorough patient assessment is essential to establish appropriateness for hyperbaric oxygen therapy, with TCOM used as an aid to guide this decision and not as an absolute.