I-STAT PORTABLE BLOOD ANALYZER IN AUSTERE LOCATIONS

MAJOR UPDATES

1. The frequency of performing an electronic simulator check for quality assurance.

GOAL

The goal of this CPG is to present the proper use and maintenance of use of the i-STAT portable blood analyzer, with a focus on the en-route care environment. This guideline outlines the expectations and instructions for maintenance, calibration, quality control, and use of the i-STAT portable blood analyzer. Updates include how to mitigate the negative impact of harsh environmental conditions found in deployment on the equipment and analyzer results. The series is developed by the Center for Sustainment of Trauma and Readiness Skills, University of Cincinnati Medical Center.

BACKGROUND

Point-of-care (POC) testing is defined as a pathology or laboratory test that is performed at the site of clinical interaction allowing immediate decision regarding treatment.1 Because POC tests are performed in a non-laboratory setting, they are designed to be as simple as possible and produce reliable results when used by non-laboratory health-care professionals.2 In this sense, POC testing is ideal for the En-Route Critical Care (ERCC) environment, however, austere ERCC conditions can affect the POC test results. One of most important environmental factors that medics must always be cognizant of are extremes in ambient temperature; exposure to extreme temperatures can render results inaccurate.

Critical Care Air Transport Teams (CCATTs) use the i-STAT (Abbott Point of Care, Princeton, NJ, USA) as their POC device (Figure 1).3 CCATT must therefore understand how to use the equipment, be able to troubleshoot and calibrate the analyzer, and also provide quality assurance with controls and simulators (the function of controls and simulators will be defined below). In addition, teams must be aware of the specific drugs and environmental conditions that alter test accuracy. Finally, teams are also responsible for protecting POC testing equipment from the elements.

The i-STAT analyzer can measure multiple different lab values: cardiac troponin I, electrolytes, blood gas, urea, creatinine, glucose, ionized calcium, and international normalized ratio (INR).

Test results from the i-STAT are generally available in 10 minutes or less. The results displayed on the screen depend on the type of cartridge inserted into the analyzer

Figure 1. i-STAT Analyzer

The cartridges that are typically stocked for use by CCATT are the CHEM8+, CG8+, EG7+, and CG4+. Cartridges are each loaded with a sample of the patient’s blood and inserted into the bottom port of the analyzer for analysis.

The CG8+ cartridge (Figure 2) measures glucose, sodium, potassium, ionized calcium, hemoglobin, and hematocrit. The blue arrow just to the right of “CG8+” defines the fill mark when blood is loaded into the cartridge; this indicates the volume of blood necessary to perform the test.

The EG7 cartridge measures sodium, potassium, ionized calcium, hemoglobin, hematocrit, pH, PaCO2, PaO2, TCO2, HCO3, base excess, SO2.

The CHEM8+ cartridge (Figure 3) measures creatinine, Blood Urea Nitrogen (BUN), glucose, ionized calcium, anion gap, TCO2, chloride, potassium, and sodium. The fill mark is at the beginning of the blue segment.

The CG4+ cartridge measures lactate, pH, PaCO2, PaO2, TCO2, HCO3, base excess, SO2.

The quality controls for the i-STAT system are simulators and controls. There are two types of simulators for the i-STAT: internal and external. Internal simulators are built into the analyzer and external simulators (Figure 4) must be inserted into the analyzer in the same port that receives the cartridge. Both types of simulators mimic the signals that a cartridge, loaded with blood, would send to the analyzer; simulators validate the analyzer. Controls are liquids that are injected into the cartridge (instead of blood); the cartridge is then inserted into the analyzer and run to validate the cartridge. CCATT members are tasked to perform these quality checks to ensure lab tests are accurate.