Objective: To determine the accuracy of a new, portable battery-powered blood gas analyzer when used by nonlaboratory-trained clinicians in the critical care setting.
Design: Prospective analysis of blood samples from critically ill patients.
Setting: Large tertiary critical care unit.
Patients: Heterogeneous group of medical and surgical critically ill patients.
Measurements and main results: Two hundred thirty-nine split blood samples from intensive care patients were analyzed by clinicians in the critical care environment using a new, portable, battery-powered blood gas analyzer (Immediate Response Mobile Analyzer [IRMA], Diametrics Medical, St. Paul, MN). Near-patient measurements were compared with measurements obtained by laboratory technologists using an IL-1312 blood gas analyzer (Instrumentation Laboratories, Lexington, MA) in an established near-patient critical care laboratory. Precision and coefficients of variation were also determined using repeated testing of quality control samples at three levels of pH, PO2, and PCO2. There was good agreement between IRMA determinations and the laboratory. Correlation coefficients ranged from 0.96 to 0.99. Bias and precision (+/-2 SD), respectively, were 0.02 and 0.036 units for pH, -0.3 torr (1.8 kPa) (-0.04 kPa) and 7.2 torr (0.96 kPa) for PCO2 and -3.9 torr (0.52 kPa) and 13.8 torr (1.8 kPa) for PO2. Precision on repeated testing of quality control samples ranged from 0.022 to 0.04 units for a pH of 7.2 to 7.6, 1.2 to 4.6 torr (0.16 to 0.61 kPa) for a PCO2 of 20 to 60 torr (2.7 to 8 kPa), and 3.0 to 7.4 torr (0.40 to 0.99 kPa) for a PO2 of 70 to 160 torr (9.3 to 21.3 kPa). Coefficients of variation ranged from 0.15% to 0.28% for a pH of 7.2 to 7.6, 2.0% to 3.7% for a PCO2 of 20 to 60 torr (2.7 to 8.0 kPa), and 1.7% to 3.6% for a PO2 of 70 to 160 torr (9.3 to 21.3 kPa). Mean turnaround time was 16.5 +/-10.1 mins for the near-patient laboratory and 2+/-0.5 mins for IRMA.
Conclusions: IRMA is accurate and reproducible when used in the clinical setting by nonlaboratory-trained individuals. Nonlaboratory-trained individuals can obtain laboratory results in the critical care setting comparable with the results obtained by trained laboratory technologists. Bedside laboratory testing decreases turnaround time compared with a near-patient laboratory.