Blood gas measurements using the Bayer Rapid Point 405: are we basing our decisions on accurate data?

Therapeutic decisions in the Operating Room (OR) are often made based solely upon results obtained from arterial blood gas machines. We evaluated how precise and accurate the results obtained from Bayer Rapid Point 405 (RP405) were vis-à-vis those of our blood gas laboratory and if they met the standards of the members of the anesthesia department.

About 3 ml of blood from an indwelling arterial catheter were drawn into a heparinized syringe (FIMS Portex Inc.) from each of 90 patients and immediately analyzed by two RP405 and the hospital's main blood gas machines (Instrumentation Laboratories GEM 3000). The remaining 2.8 ml of blood was used to measure Hematocrit and sent to the hospital's main biochemistry laboratory for electrolyte measurement using an indirect ion selective method (Roche Diagnostics Modular ISE Module). A survey was distributed to each of the 19 anesthesiologists at the Sir Mortimer B Davis Jewish General Hospital (JGH). Their opinions for accuracy and treatment thresholds for each of the 12 variables measured by the RP405 were sought.

For all measured variables, including pH, pCO2, pO2, potassium and Hematocrit, the correlation between the measurements from the RP405 and the gold standard were all above 95.5% with a p < 0.001. The survey results demonstrate that the machine gives results that are accurate within the acceptability frame expected by our staff anesthesiologists.

Anesthesiologists must be confident that the information they receive is accurate in the context of rapidly changing clinical status. Our results show that the RP405 analyzers produce reliable measurements.