i STAT CG4+ and CHEM8+ cartridges for point-of-care testing in the emergency department

The i‑STAT is an in vitro whole‑blood analyser that uses single‑use cartridges for critical care tests at the point of care, such as blood gases, electrolytes, metabolites and coagulation.

The CG4+ and CHEM8+ cartridges could be used as a component of the patient pathway in the emergency department, as an alternative to laboratory-based or other point‑of‑care tests, where the speed of access to test results is a limiting factor in improving patient throughput.

Seven studies using i‑STAT with findings relevant to the emergency department setting are included in this briefing. Five used the CG4+ cartridge, 1 used the CHEM8+ cartridge and the other used both CG4+ and CHEM8+ cartridges.

A prospective cohort study in 1 US emergency department assessed the diagnostic test accuracy of lactate in serum measured using the CG4+ cartridge for predicting mortality in 669 patients with suspected sepsis. Analysis showed that the lactate measurement using the i‑STAT was accurate for clinical decision‑making compared with the laboratory test.

One prospective cohort study in a US medicine and pathology laboratory assessed the correlation between 5 different systems used for lactate analysis, including the i‑STAT CG4+ cartridge. The Vitros system was used as a reference standard. Of the 90 samples tested, the i‑STAT lactate values of 85 samples (94%) fell within the same risk category as the Vitros value.

Two studies evaluated the i‑STAT CG4+ cartridge in non‑emergency department settings. A before‑and‑after study found that post‑operative mortality rates in young children and babies changed from 6.2% before i‑STAT CG4+ lactate testing was introduced to 2.4% after. Test turnaround time was 2 minutes using the i‑STAT CG4+. A prospective cohort study in 446 intubated intensive care adult patients found that partial pressure of oxygen and carbon dioxide as measured by the CG4+ cartridge could be considered acceptable surrogates to laboratory measurements.

One before‑and‑after study in a US emergency department compared bedside lactate testing using i‑STAT CG4+ with laboratory testing in patients with suspected sepsis. Eighty patients in the i‑STAT CG4+ group were compared with 80 patients in the laboratory group. There was a statistically significant reduction in time to intravenous fluid administration in the i‑STAT group compared with the laboratory group. No statistically significant difference was found in time to intravenous antibiotics between the 2 groups.

In the only UK‑based reports, 2 before‑and‑after studies assessed the impact of a redesigned emergency department service, including the addition of point‑of‑care testing using the i‑STAT, on the amount of time patients spent in the department. Both found a statistically significant reduction in the median time for patients to be declared ready to leave when the i‑STAT CHEM8+ and CG4+ cartridges were used. In the context of the overall service redesign, the contribution of the point‑of‑care testing to the reduced turnaround time cannot be evaluated separately. Both studies were supported by the manufacturer.

i‑STAT is a handheld battery‑operated, reusable analyser. Samples are processed automatically and results are provided in 2 minutes.

The CG4+ cartridge measures lactate, pH, bicarbonate, base excess, oxygen saturation, the partial pressures of oxygen and carbon dioxide and total carbon dioxide.

The CHEM8+ cartridge measures sodium, potassium, chloride, total carbon dioxide, anion gap, ionised calcium, glucose, urea nitrogen, creatinine, lactate, haematocrit and haemoglobin.

The i‑STAT cartridges are single‑use and each cartridge requires 2 to 3 drops of blood.

The CG4+ cartridge costs £12.49 per test, excluding VAT.

The CHEM8+ cartridge costs £19.54 per test, excluding VAT.

The i‑STAT analyser costs £5191, excluding VAT.