To much effort needed, high costs for an academic study

Evaluate the precision and accuracy of the Proxima 3® System by obtaining quantitative clinical data at various time points. Compare the methods associated with obtaining blood gas results using the Proxima 3® System device versus a conventional ABG analyse. The aim of the investigator is to evaluate the precision and accuracy of the Proxima 3® ABG system parameters (pH, pCO2 pO2, hematocrit and potassium) in clinical practices with rapid changing 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.

Inclusion Criteria:

• Male and female patients ≥18 years old
• Patients who have (or will have) an arterial line, which was (will be) inserted for clinical - need, will be considered for inclusion in this study
• Patients who give informed consent (or their personal/nominated consultee) to participate in the study
• Patients who are likely to have an arterial line for at least 6 hours.

Exclusion Criteria:

• Patients contraindicated for an arterial line
• Refusal of consent by a patient
• Not for use with patients with uncorrected hyperphosphataemia, hypocalcaemia or hypercalcaemia.
• The patient is considered to be unsuitable for the study by the investigator