Determination of ideal PtcO2 measurement time in evaluation of hypoxic wound patients
Shah, J.B.; Ram, D.M.; Fredrick, E.; Otto, G.H.; Sheffield, P.J.
Undersea and Hyperbaric Medicine Journal of the Undersea and Hyperbaric Medical Society Inc 35(1): 41-51
2008
ISSN/ISBN: 1066-2936 PMID: 18351126 Document Number: 622043
Shah JB, Ram DM, Fredrick E, Otto GH, Sheffield PJ. Determination of ideal PtcO(2) measurement time in evaluation of hypoxic wound patients. Undersea Hyperb Med 2008; 35(1):41-51. Objective: Evaluation of ideal time for baseline PtcO(2) readings in air, elevation test, and oxygen challenge during evaluation of hypoxic wound patients. Design: Retrospective analysis. IRB APPROVAL: Western IRB deemed this study exempt from requiring IRB approval. Patients. 202 patients with lower extremity wounds. Method: Patients had PtcO(2) measurements using 6 electrodes positioned in 3 paired locations along the limb (above the knee: AK; below the knee: BK; and foot). Measurements were made from each electrode at 7 different time-event occasions: position of limb (supine or elevated), type of breathing gas (sea level air or oxygen), and time of measurement. A total of 8,484 measurements were analyzed by first examining each electrode's data, and then pooling the data for each location pair. Main Results: PtcO(2) readings for air (10 minutes) were less than air at 20 minutes. Maximal readings were close to the 20-minute mark for AK and BK measurements, and closer to 30 minutes for the foot. Elevation test at 3 versus 5 minutes showed a continuing decline in PtcO(2) values. Oxygen challenge readings at 5 and 10 minutes were significantly different: the latter always larger than the former. Conclusion: Ideal times for baseline readings, leg elevation test, and oxygen challenge test are at least 20, 5, and 10 minutes, respectively.