i-STAT CG4+ cartridge with the i-STAT 1 System

The i-STAT CG4+ cartridge is a single-use disposable test cartridge used with the i-STAT 1 handheld analyzer to measure pH, partial pressure of oxygen (PO2), partial pressure of carbon dioxide (PCO2), and lactate in arterial, venous, or capillary whole blood at point-of-care or clinical laboratory settings. It is intended for diagnosis, monitoring, and treatment of respiratory, metabolic, and acid-base disturbances, as well as lactic acidosis and tissue hypoxia.

The i-STAT CG4+ cartridge is substantially similar to the predicate i-STAT G3+ cartridge in design, measurement principles (potentiometric for pH/PCO2, amperometric for PO2 and lactate), calibration method (1-point on-board), sample requirements (95 µL whole blood), reportable ranges, traceability to NIST standards, storage conditions, and analyzer type (handheld). The key difference is that the CG4+ adds lactate measurement capability with product codes CHL and KHP, whereas the G3+ only measured pH, PO2, and PCO2.

CLSI EP05-A3 (precision of quantitative measurement procedures), CLSI EP06-Ed2 (linearity evaluation), CLSI EP07-ED3 (interference testing), CLSI EP17-A2 (detection capability), CLSI EP09c-ED3 (measurement procedure comparison and bias estimation), and CLSI EP35 (assessment of equivalence of specimen types).

The CG4+ demonstrates substantial equivalence because it maintains identical intended use, measurement methodology, performance characteristics (precision, linearity, accuracy), and analytical specifications as the predicate G3+ for pH, PO2, and PCO2 measurements. The addition of lactate testing uses the same amperometric measurement principle and cartridge-based format as existing i-STAT lactate tests. Comprehensive analytical and clinical studies show comparable precision across multiple sites and operators, linear performance across reportable ranges, acceptable limits of detection, minimal interference from clinically relevant substances, and strong method comparison correlations with predicate and comparative devices. Matrix equivalence studies confirm performance with both anticoagulated and non-anticoagulated specimens.