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The i-STAT CG4+ cartridge with the i-STAT 1 System is intended for use in the in vitro quantification of pH, partial pressure of oxygen (PO2), and partial pressure of carbon dioxide (PCO2) in arterial, venous, or capillary whole blood in point of care or clinical laboratory settings.

The i-STAT CG4+ cartridge with the i-STAT 1 System is intended for use in the in vitro quantification of lactate in arterial or venous whole blood in point of care or clinical laboratory settings.

pH, PO2, and PCO2 measurements are used in the diagnosis, monitoring, and treatment of respiratory, metabolic, and acid-base disturbances.

Lactate measurements are used in (1) the diagnosis and treatment of lactic acidosis in conjunction with measurements of blood acid/base status, (2) monitoring tissue hypoxia and strenuous physical exertion, and (3) diagnosis of hyperlactatemia.

The i-STAT CG4+ cartridge is used with the i-STAT 1 analyzer as part of the i-STAT 1 System to measure pH, partial pressure of oxygen (PO2), and partial pressure of carbon dioxide (PCO2) in arterial, venous or capillary whole blood and to measure lactate (Lac) in arterial or venous whole blood.

The i-STAT 1 System is an in vitro diagnostic (IVD) medical device intended for the quantitative determination of various clinical chemistry tests contained within i-STAT cartridges using whole blood. The i-STAT 1 System consists of a portable blood analyzer (i-STAT 1 analyzer), single-use disposable test cartridges (i-STAT cartridges), liquid quality control and calibration verification materials, and accessories (i-STAT 1 Downloader/Recharger, i-STAT Electronic Simulator and i-STAT 1 Printer). The i-STAT 1 System, including the i-STAT CG4+ cartridge, is designed for use by trained medical professionals in point of care or clinical laboratory settings and is for prescription use only.

The i-STAT CG4+ cartridge contains the required sensors, a fluid pack (calibrant pouch), a sample entry well and closure, fluid channels, waste chamber, and the necessary mechanical features for controlled fluid movement within cartridge. The i-STAT cartridge format allows all the tests in the cartridge to be performed simultaneously. All the test steps and fluid movements occur within the i STAT CG4+ cartridge. The i-STAT 1 analyzer interacts with the i-STAT CG4+ cartridge to move fluid across the sensors and generate a quantitative result. Cartridges require two to three drops of whole blood applied to the cartridge using a transfer device, by the trained user before the cartridge is placed within the analyzer.

The i-STAT 1 analyzer is a handheld, in vitro diagnostic analytical device designed to run only i-STAT test cartridges. The analyzer functions as the main user interface and the electromechanical interface to the test cartridge. All within-cartridge fluid movements, as well as the timing and heating of the test cycle, are automated and controlled without user intervention by system software embedded within the analyzer.

Since the provided text describes a medical device (i-STAT CG4+ cartridge with the i-STAT 1 System), it is an in vitro diagnostic (IVD) device, not an AI/ML diagnostic system. Therefore, many of the typical acceptance criteria and study components for AI/ML devices (e.g., number of experts, adjudication methods, MRMC studies, training set details) are not applicable to this type of device.

This clearance is based on demonstrating substantial equivalence to a predicate device (i-STAT G3+ cartridge) through analytical performance studies, rather than a comparative effectiveness study against human readers or specific performance benchmarks tied to a disease outcome.

Here's an organized breakdown of the acceptance criteria and study information provided for the i-STAT CG4+ cartridge, focusing on what is relevant for an IVD device and clearly indicating where AI/ML-specific criteria do not apply:

Acceptance Criteria and Device Performance for i-STAT CG4+ Cartridge

The acceptance criteria for this in-vitro diagnostic device are based on demonstrating robust analytical performance and substantial equivalence to a legally marketed predicate device (i-STAT G3+ cartridge). The studies focus on precision, linearity, traceability, detection limits, and analytical specificity (interference and oxygen sensitivity), as well as method comparison with established laboratory methods.

1. Table of Acceptance Criteria and Reported Device Performance

The "acceptance criteria" for an IVD device like this are generally implied by the successful demonstration of performance characteristics within clinically acceptable ranges and alignment with the predicate device. The tables below summarize the reported device performance, which implicitly met the internal acceptance criteria for substantial equivalence.

Precision/Reproducibility (Aqueous Materials - Sampled Performance Ranges)

Linearity/Assay Reportable Range (Regression Summary)

Detection Limits (LOQ and LOD)

Analytical Specificity (Interference): A substance was identified as an interferent if the difference in means (or medians) between the control and test samples was outside of the allowed error (±Ea) for the i-STAT test.

• Bromide: Interferent at 37.5 mmol/L (decreased lactate results >10.0 mmol/L).
• Glycolic Acid: Interferent at 10.0 mmol/L (increased lactate results >0.8 mmol/L).
• Other substances listed (Table 11) showed No Interference.

Altitude Study (Correlation Coefficient and Slope Acceptance)

Method Comparison (Bias at Medical Decision Levels)
Bias at medical decision levels (MDL) needs to be clinically acceptable.

• pH: Biases ranging from -0.0080 to -0.0166 at various MDLs.
• PO2: Biases ranging from -0.6 to -3.3 at various MDLs.
• PCO2: Biases ranging from 0.67 to 3.49 at various MDLs.
• Lactate: Bias of -0.140 at 5.00 mmol/L MDL.
  These biases met the implicit acceptance criteria for substantial equivalence to the comparative methods.

2. Sample Size Used for the Test Set and Data Provenance

For an IVD device, there isn't a "test set" in the AI/ML sense, but rather a series of analytical performance studies using different types of samples.

• Precision (Aqueous Materials):
  • 20-Day Precision: 83-84 replicates (N) per fluid level per test.
  • Multi-site Multi-day Precision: 90-91 replicates (N) per fluid level per test across 3 point-of-care sites.
• Precision (Whole Blood):
  • Clinical Precision: N varied by sample range and test, ranging from 3 to 154 for various analytes and sample types (venous, arterial, capillary).
  • Within-Sample (Native Capillary): 60 test results (30 subjects, duplicate tests).
  • Within-Sample (Contrived Capillary): N=32 for L1 pH/PO2/PCO2, N=22 for L2 pH/PO2/PCO2 (from 27 subjects, duplicate tests).
• Linearity: Whole blood samples of varying analyte levels. Specific N not provided per sample, but regression analysis was performed.
• Detection Limit (LoQ/LoB/LoD): Whole blood samples (altered to low/blank analyte levels).
• Interference: Whole blood samples (spiked with potentially interfering substances).
• Oxygen Sensitivity: Whole blood samples (altered to 4 lactate levels).
• Altitude: Whole blood samples (relevant analyte levels).
• Method Comparison:
  • Arterial/Venous/Capillary pooled for pH, PO2, PCO2: 551-557 specimens.
  • Arterial/Venous pooled for Lactate: 345 specimens.
  • Capillary only for pH, PO2, PCO2: 184-193 specimens (native and contrived).
  • Native Capillary (Bias at MDL): 175-178 specimens.
• Matrix Equivalence: 228-289 specimens (arterial/venous whole blood, with and without anticoagulant).

Data Provenance:

• The studies were conducted by Abbott Point of Care Inc. and at "multiple point of care sites" for clinical precision and method comparison.
• The exact country of origin is not specified but implied to be across various clinical settings where the device might be used.
• The studies appear to be prospective analytical studies designed to evaluate device performance under controlled conditions, not retrospective real-world data collection.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications

Not Applicable. For an IVD device, the "ground truth" is established through the measurement by a comparative/reference method (e.g., RAPIDPoint 500/500e, or the i-STAT G3+ predicate device), not through human expert consensus or labeling. The device's performance is compared against these established analytical methods.

4. Adjudication Method for the Test Set

Not Applicable. Adjudication methods (like 2+1, 3+1) are for establishing ground truth from multiple human readers/experts, which is not relevant for calibrating the analytical performance of an IVD device.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done

No. MRMC studies are typically performed for AI/ML diagnostic aids where the AI is intended to assist a human reader, and the study measures the improvement in human reader performance (e.g., diagnostic accuracy, sensitivity, specificity) with and without AI assistance. This device is an analytical instrument for quantitative determination of blood gases and lactate, not an AI/ML diagnostic aid.

6. If a Standalone (i.e., Algorithm Only Without Human-in-the-Loop Performance) Was Done

Yes (in principle). The listed performance studies (precision, linearity, detection limits, interference, method comparison) assessed the analytical performance of the device itself (i-STAT CG4+ cartridge with the i-STAT 1 System) independent of a human's interpretative role. The device measures and provides a numerical output for pH, PO2, PCO2, and Lactate. The "human-in-the-loop" here is the operator performing the test, not interpreting an AI-generated image or signal.

7. The Type of Ground Truth Used

The "ground truth" for the performance evaluation of this IVD device was established in two primary ways:

• Reference Materials: Traceability to NIST SRMs (for pH, PO2, PCO2) or a manufacturer's working calibrator (for Lactate). These are analytical standards.
• Comparative Methods: Established and legally marketed laboratory instruments (e.g., RAPIDPoint 500/500e for pH/PO2, and the i-STAT G3+ predicate device for PCO2 and the i-STAT CG4+ (K200492) for Lactate).
• Defined Concentrations: For linearity, LoQ, LoB, LoD, interference, and oxygen sensitivity studies, samples were prepared with known or targeted analyte concentrations.

This is distinct from clinical diagnostic "ground truth" which might come from pathology, long-term outcomes, or expert consensus in fields like radiology.

8. The Sample Size for the Training Set

Not Applicable. This is an IVD device that does not use AI/ML, so there is no concept of a "training set" for an algorithm. The device measures chemical analytes via established electrochemical principles.

9. How the Ground Truth for the Training Set Was Established

Not Applicable. As there is no training set for an AI/ML algorithm, this question is not relevant.

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