Validation of oxygen saturation measurements in a canine model of hemoglobin based oxygen carrier (HBOC) infusion

The study was designed to validate oxygen saturation measurements from the NOVA CO-Oximeter, the i-STAT System, and the Corning 170 blood gas analyzer under conditions similar to the clinical application of a hemoglobin-based oxygen carrier.

A canine model was used for both in-vitro and in-vivo experiments.

Canine laboratory for in-vivo, and tonometry laboratory for in-vitro sets.

6 mixed-breed canines, 30 kg; canine remainder sample blood.

In the first set of experiments, the target blood pO2 levels were reached by tonometry. In the second set of experiments, quantitative measurements of total oxygen content with the LEXO2Con-K, were performed immediately followed by measurements with the NOVA CO-Oximeter and the i-STAT system. HBOC was added in concentrations of 16.2, 32.5, 65.0, and 97.5 g/L. To analyze the clinical significance of the differences in the results obtained with the different investigated instruments; blood samples from dogs treated with HBOC after acute hemorrhagic shock were used.

There was a strong correlation between the oxygen saturation values measured with the investigated instruments in samples after tonometry and known oxygen partial pressure. The total calculated O2 content varied by 5% based on results generated by calculations based on the investigated instruments. The results did not change with different oxygenation of the sample. The differences among methods were not significant when HBOC concentration was 16.2 g/L. Higher concentrations of HBOC increased the difference between calculated and measured oxygen content; i-STAT system demonstrated a greater deviation from the results of the other two instruments. Systemic oxygen uptake based on investigated instruments showed high correlation with values based on LEXO2CON-K measurements (r=0.97 for CO-Oximeter, 0.96 for gas analyzer, and 0.79 for i-STAT). Systemic oxygen uptake values based on CO-Oximeter and blood gas analyzer data showed a 75% accuracy; i-STAT accuracy was 63% for control samples and 50% for samples after HBOC infusions.

The NOVA CO-OXimeter is an accurate analyzer for measurement of oxygen saturation after HBOC infusion in the canine model. Use of the i-STAT system should be limited to arterial samples or for samples with a low HBOC concentration.