Comparison of tissue oxygen-tension measurements by different devices. An experimental study in pigs

Abstract

The aim of this study was to evaluate measurements of subcutaneous oxygen tension (PscO₂) generated by three different monitors and to compare measurements obtained with and without the tonometer technique in a standardized animal model. Seven domestic pigs weighing 20-28 kg were anaesthetized and mechanically ventilated. A pulmonary artery catheter was inserted for haemodynamic monitoring and temperature measuring. An external carotid artery was cannulated for blood pressure monitoring and blood sampling. A peripheral venous line was used for fluid and drug infusion. The animals were then subjected to hyperoxia and hypoxia by varying the inspiratory oxygen fractions (FiO₂) between 0.1 and 0.8. Arterial and central venous blood gases were analysed at each step of FiO₂. Cardiac output was determined using a thermo­dilution technique. Central, subcutaneous and skin surface temperatures were measured. Three different devices for subcutaneous tissue oxygen-tension (PscO₂) measurements were compared: (1) Biogenesis, (2) Continucath and (3) Paratrend 7. Continucath was used both with and without tonometer simultaneously. Inter Class Coefficient of Correlation between PscO₂ values obtained by the two Continucath sensors was 76% and between Paratrend 7 and Biogenesis 88%. Absolute values generated by Biogenesis and Paratrend 7 were not different. PscO₂ values obtained with the Continucath devices were on average 50% higher than those generated by Biogenesis and Paratrend 7 (p<0.05). Conclusions: The new Paratrend 7 and the old Biogenesis sensors generate almost equal tissue oxygen-tension values in response to changes in arterial oxygen tension. The Continucath sensor generates almost 50% higher values compared with the Paratrend 7 and Biogenesis sensors, both with and without tonometer.

• Hyperoxia Hypoxia Perfusion Polarographic Electrode Tissue Oxygen Tension Tonometry