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Dermal Heat Transport Analysis for Transcutaneous O 2 Measurement
Author(s) -
Tremper Kevin K.,
Huxtable Robert F.
Publication year - 1978
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1111/j.1399-6576.1978.tb01385.x
Subject(s) - oxygen transport , dimensionless quantity , thermal conduction , capillary action , electrode , perfusion , oxygen , thermal conductivity , oxygen–haemoglobin dissociation curve , thermodynamics , analytical chemistry (journal) , materials science , biomedical engineering , medicine , chemistry , chromatography , cardiology , physics , organic chemistry
Heat from a transcutaneous oxygen electrode is transmitted locally to the blood beneath it causing a shift in the HbO 2 dissociation curve. This increases the local PO 2 , and allows a measurable PO 2 , at the skin surface. The temperature effect on the HbO 2 , curve must be accounted for in in vivo calibration of Ptco 2 , data. To do this, the capillary blood temperature beneath the electrode must be known. A heat balance is written around the capillary blood with heat being conducted in from the electrode and carried out by two means: conduction to deep tissue; and transport away by the flowing capillary blood. The following equation is the steady state solution of the heat transport problem: T 8 = ± where Z = ± = 0.17 T 8 , = capillary blood temperature T 1 = electrode temperature T o = body temperature ρ = blood density P = cutaneous perfusion δ = dermal capillary depth k = thermal conductivity of skin C± = heat capacity of blood This solution shows the capillary blood temperature may be calculated if the T 1 and T o are measured and the physiologic constants in 2 are known. 2 is a dimensionless heat transport number which represents the relative importance of perfusion to conduction effects on the deterring T 8 , and may be used as a data correlating parameter. Z = 0.17 is obtained using literature values for the physiological constants. This analysis used in conjunction with a mass transport analysis for oxygen will produce a theoretically based correlation scheme for in vivo calibration of heated transcutaneous oxygen electrodes.