The i-STAT is a handheld blood analyzer that can test for over 30 different values from a few drops of blood, delivering results in about two minutes. Made by Abbott, it covers blood gases, electrolytes, kidney function, blood sugar, cardiac markers, clotting times, and even traumatic brain injury biomarkers. The specific tests depend on which cartridge is loaded into the device.
How the i-STAT Works
The i-STAT uses small, disposable cartridges that each contain miniaturized sensors for a specific set of tests. A clinician loads a blood sample (venous, arterial, or from a finger stick) into a cartridge, inserts it into the handheld device, and gets results at the bedside. There’s no need to send blood to a central lab and wait. This makes it especially useful in emergency departments, intensive care units, operating rooms, ambulances, and remote clinics where time matters.
Different cartridges use different detection methods. Electrolytes and kidney markers rely on tiny electrodes similar to traditional lab equipment. Cardiac markers like troponin use an immunoassay with electrochemical detection. Clotting tests detect the endpoint of the coagulation process electrochemically rather than optically. The result is a single portable device that covers a surprisingly wide range of lab work.
Electrolytes and Basic Chemistry
The most commonly used cartridge is the CHEM8+, which gives a broad snapshot of your blood chemistry. It measures nine values directly: sodium, potassium, chloride, ionized calcium, total CO2, glucose (blood sugar), blood urea nitrogen (BUN), creatinine, and hematocrit (the percentage of your blood made up of red blood cells). From those, it also calculates hemoglobin and anion gap.
This panel tells clinicians a lot in a short time. Sodium and potassium levels reveal fluid balance and can flag dangerous heart rhythm risks. BUN and creatinine show how well the kidneys are filtering waste. Glucose catches dangerously high or low blood sugar. Ionized calcium matters for heart and muscle function. A standalone glucose cartridge and a creatinine-only cartridge are also available when the full panel isn’t needed.
Blood Gases and Oxygen Levels
Several cartridges focus on how well the lungs are exchanging oxygen and carbon dioxide, which is critical in emergency and intensive care settings. The CG4+ cartridge measures pH, the partial pressures of oxygen and carbon dioxide, oxygen saturation, total CO2, bicarbonate, base excess, and lactate. Lactate is particularly important because rising levels can signal that tissues aren’t getting enough oxygen, a hallmark of sepsis or shock.
The CG8+ and EG7+ cartridges combine blood gas measurements with electrolytes and hematocrit, giving clinicians a more complete picture from a single sample. During cardiac surgery or when monitoring critically ill patients in the ICU, these combination cartridges let care teams track both oxygenation and blood chemistry without multiple lab draws.
Cardiac Markers
The i-STAT offers three cartridges for evaluating heart-related emergencies. The most significant is the cardiac troponin I (cTnI) cartridge, which detects a protein released when heart muscle is damaged. Troponin I is the gold standard for diagnosing heart attacks and for assessing risk in patients with chest pain. The i-STAT cTnI test can detect levels as low as 0.02 ng/mL, with a measurement range up to 35 ng/mL.
A BNP (B-type natriuretic peptide) cartridge helps evaluate heart failure. When the heart is under strain, it releases BNP into the bloodstream, so elevated levels can distinguish heart failure from other causes of shortness of breath. A CK-MB cartridge is also available, measuring another enzyme associated with heart muscle injury, though troponin has largely replaced it as the primary cardiac marker.
Clotting and Coagulation
Three cartridges address blood clotting. The PTplus cartridge measures prothrombin time and reports it both in seconds and as an INR (International Normalized Ratio), the standardized scale used to monitor patients on blood thinners like warfarin. It covers an INR range of 0.8 to 8.0, which spans normal clotting through severely thinned blood.
Two additional cartridges measure activated clotting time (ACT) using either celite or kaolin as the activating agent. ACT is primarily used during surgeries and procedures that involve blood-thinning medications like heparin, especially cardiac surgery and catheterization, where clinicians need to confirm that clotting is adequately suppressed before and during the procedure.
Traumatic Brain Injury
One of the newer additions to the i-STAT menu is the TBI cartridge, which measures two brain-specific proteins: GFAP (released from support cells in the brain) and UCH-L1 (released from damaged neurons). This test is FDA-cleared and helps clinicians evaluate whether a patient with a head injury may have bleeding or bruising in the brain, potentially reducing the need for CT scans. Both whole blood and plasma versions of the cartridge are available.
Pregnancy Testing
A total beta-hCG cartridge provides a quantitative pregnancy hormone measurement from a blood sample. Unlike a urine pregnancy test that gives a simple yes-or-no answer, the i-STAT version measures the actual hormone level, which is useful for confirming early pregnancy, monitoring pregnancy complications like ectopic pregnancy, or checking hCG levels before certain medical procedures.
Where the i-STAT Is Typically Used
The device was designed for situations where waiting for a central lab would delay treatment. Emergency departments use it to rapidly assess patients arriving with chest pain, breathing difficulty, or altered consciousness. ICUs rely on it for frequent monitoring of blood gases and electrolytes in critically ill patients. It’s used during cardiac surgery to track clotting times and blood chemistry in real time. Ambulance crews and flight medics use it during patient transport between hospitals, and it has a role in remote or rural facilities that lack a full laboratory. In all these settings, the two-minute turnaround can directly change how quickly a patient receives the right treatment.