Performance evaluation of a whole blood propofol analyser.

The authors evaluated an analyser for the determination of propofol concentrations in whole blood. The Pelorus 1000 (Sphere Medical) measures propofol concentrations in around 5 min without the requirement for sample preparation. The performance of the analyser was characterised with respect to linearity, precision in control solutions and whole blood and method comparison to an HPLC based reference method. In addition, the effects of substances considered to potentially affect the assay method were investigated. The analyser was found to be linear up to 12 µg/ml (R2 = 0.9993), with a lower limit of quantification of 0.75 µg/ml. Total within device imprecision in control solutions was 0.11 µg/ml at 5.32 µg/ml and 0.17 µg/ml at 10.3 µg/ml. Within run precision in whole blood was 0.04 µg/ml at 2.84 µg/ml and 0.08 µg/ml at 6.68 µg/ml and for the reference method was 0.06 µg/ml and 0.12 µg/ml respectively. In comparison to the reference method, the overall bias of the Pelorus 1000 system over the range is estimated to be 0.15 µg/ml (95% confidence interval -0.11-0.41 µg/ml). The only cross interference of note is to a highly elevated level of conjugated bilirubin, while low haematocrit levels lead to a 0.13 µg/ml under reading with respect to the HPLC reference. The system fulfils the requirements for measurement of propofol concentrations in whole blood samples with precision and accuracy suitable for elucidating propofol pharmacokinetics at clinically relevant concentrations. With no requirement for sample preparation and a fast time to results, the analyser opens up the possibility of studies to measure and respond to blood propofol concentrations in patients in close to real time.

Comparison of time taken to obtain an arterial blood gas result at the bedside using the ProximaTM point of care machine vs. a standard remote arterial blood gas analyser: A randomized controlled trial.

Introduction: The ProximaTM point of care (POC) device enables arterial blood gas (ABG) samples to be analysed without the nurse leaving the patient. The benefits of this for work efficiency have not been evaluated. Methods: We compared the time taken to obtain an ABG result using ProximaTM versus a standard ABG sampling system. Twenty patients were randomized to ABG sampling using ProximaTM, or a standard ABG system. Nurses were observed performing all ABG sampling episodes for a minimum of 24 hours and no more than 72 hours. Results: The mean time taken to obtain a result using ProximaTM was 4:56 (SD = 1:40) minutes compared to 6:31 (SD = 1:53) minutes for the standard ABG technique (p < 0.001). Mean time away from the patient's bedside was 3.07 (SD = 1:17) minutes using the standard system and 0 minutes using ProximaTM (p < 0.001). Conclusions: Reduced time for blood gas sampling and avoidance of time away from patients may have significant patient safety and resource management implications, but the clinical and financial significance were not evaluated.