Evaluation of Accuracy and Precision of the Proxima 3® (Sphere Medical) Arterial Blood Gas Analysis System in Comparison With the Reference Standard Hospital ABG in a Rapidly Changing Clinical Context

In this study the investigator will test the applicability of the Proxima 3® ABG system in a heterogeneous patient population consisting of patients scheduled for hybrid atrial fibrillation surgery, patients scheduled for heart valve surgery, complex cardiac surgery with deep cooling, spine surgery or patients with expected major blood loss. The investigator will compare the ABG values obtained with the traditional ABG measurement system of the hospital.

The availability of a disposable patient-dedicated blood gas analyser allows rapid, frequent measurement of blood gases in theatre without the loss of theatre staff. As well as facilitating measurement in the unstable patient, this approach opens up the possibility for more frequent measurement to identify patient deterioration before a crisis occurs.

The conventional laboratory ABG method uses sensor technology for pH, pCO2, pO2, sodium, potassium, calcium, glucose and lactate levels. It measures hemoglobin concentration via spectrophotometry methodology at a set wavelength of 467-672 nm. The blood gas laboratory uses ABL90 Flex (Radiometer®). The optical system is based on a 138-wavelength spectrophotometer with a measuring range of 467-672 nm. The spectrophotometer is connected via an optical fiber to a combined hemolyzer and measuring chamber.