POINT-OF-CARE BLOOD TESTS

POCT

Also known as alternate site testing or bedside near patient testing

Brings laboratory testing to the location of the patient.

Uses a small, portable, and often handheld devices. It’s benefits Include convenience to the patient and a short turnaround time for results that allow healthcare providers to address critical patient needs, deliver prompt medical attention, and expedite patient recover recovery.

POCT quality control

It is important to have processes and systems in place to ensure that POCT is preformed properly and that results correlate with the same test when performed in the main lab.

Waived tests do not require the same level of quality checks as tests classified as non-waived

CLIA regulations for waived tests require QC to be performed as specified by the manufacturers instructions. And most cases this means performing liquid controls upon receipt of a new shipment of test kits and with all new testing personnel

POCT infection control

Handheld POC analyzer carried between patients in a healthcare institution can be fomites for disease. To reduce the possibility of accidental transmission of infectious microorganisms to patients, Device manufacturers have developed recommendations for disinfecting their instruments.

Use 1:10 bleach or bleach wipes to clean POC instruments

POC coagulation monitoring

Several different types of POC coagulation analyzers can be used to monitor patients on warfarin and heparin therapy. Some of the more common POC coagulation tests that involve monitoring: PT and INR, aPTT or PTT, ACT, and platelet function

POC Instruments for coagulation:

CoaguChek XS PLus- PT/INR

Hemochron signature elite-ACT

I-STAT- ACT, PT/INR

VERIFYNOW- platelet function

Activated clotting time (ACT)

This test analyzes activity of the intrinsic coagulation factors and is used to monitor heparin therapy.

Heparin is given to patients who have blood clots, or whose blood is apt to clot easily. It is also given as a precaution following certain surgeries. Affects on IV heparin administration are immediate, but difficult to control. Too much heparin can cause internal bleeding therefore Heparin therapy is closely monitored.

Once a patient’s condition is stabilized, the patient is placed on an oral anticoagulant therapy (such as warfarin) And monitored by PT testing.

Prothrombin PT

A test that is used to monitor warfarin therapy. It provides information on how long it takes for a patient’s blood to clot. Several manufacturers produce PT tests, And the tests are slightly different. Consequently, there can be a difference in the results obtained on the same patient if PT tests from different companies are used

International normalized ratio

Was created to solve the problem of different manufacturers having different test results for PT tests.

a standardized laboratory measurement used to determine how long it takes for a person's blood to clot.

INR is a mathematical calculation derived from your PT result to standardize values across different laboratories.

ISI

International sensitivity index for the tissue factor in the manufacturers reagent

Many warfarin or anticoagulant clinics use POC coagulation analyzers that perform PT and INR tests on

Whole blood from a finger stick to provide timely lab results

Platelet function

Allows the clinician to determine a patients response to medication before open heart surgery or cardiac catheterization. This can help prevent excessive bleeding or blood clots. This testing can be done using an automatic analyzer with single use disposable essays called the verifynow. It uses whole blood samples and gives measurements that correlate with laboratory test testing.

Platelet function tests can measure the ability of an individual to respond to various

Antiplatelet medications.

Patient’s respond differently to this type of medication, some are very resistant.

The verifyNow System aspirin essay, which is CLIA waived, provides a measurement to determine if a patient is responding to aspirin therapy

Arterial blood gasses and electrolytes

Arterial blood gases and electrolytes are panels of tests that are often ordered in emergency situations.

ABG readings are used to determine the pH of blood, which threatens the patients survival if it is outside the very narrow normal range.

Balance of electrolytes is essential for normal function of cells and organs

ABG and electrolyte testing with POC analyzers has proven to be invaluable in critical care situations

Arterial blood gases

Evaluate respiratory function.

These tests measured my POCT include pH, partial pressure of carbon dioxide (PCO2), oxygen saturation (SO2), and partial pressure of oxygen (PO2)

pH

An abbreviation for potential hydrogen, A scale representing the relative acidity or alkalinity of a solution.

The arterial blood pH test is a measure of the bodies acid base balance and indicates metabolic and respiratory status. The normal range for arterial blood pH is 7.35-7.45.

Below normal pH is referred to as acidosis and above normal pH is referred to as alkalosis

PCO2 (partial pressure of carbon dioxide)

A measure of the presence exerted by dissolved CO2 in the blood plasma and it’s proportional to the PCO2 in the alveoli; therefore, it is an indicator of how well air is being exchanged between the blood and the lungs. An abnormal increase in PCO2 is associated with hypoventilation and a decrease with hyperventilation

PO2 (partial pressure of oxygen)

A measure of the presence exerted by dissolved oxygen in the blood plasma and indicates the ability of the lungs to diffuse oxygen through the alveoli into the blood. It is used to evaluate the effectiveness of oxygen therapy

SO2

is a measure of the percentage of hemoglobin binding sites occupied by oxygen in the bloodstream. It is used to determine a patient’s oxygenation status. A normal, healthy individual will usually exhibit oxygen saturation around 98%. A person with an arterial oxygen saturation below 90% is said to be hypoxemia (an abnormal low level of oxygen in the blood) and may be cyanotic. Inadequate oxygen in the blood can lead to the tissues not having enough oxygen, A condition called hypoxia

Electrolytes

Minerals with an electric charge that are present in blood and body fluids. They are important because they help carry electrical Impulses across cell membranes. They are especially important to heart, nerve, and muscle function.

Electrolytes are monitored in a wide variety of illnesses. The most common electrolytes measured by point of care testing are sodium, potassium, Chloride, bicarbonate ion, and ionized calcium.

Sodium (NA)

Is the most plenty full electrolyte in the blood. It plays a major role in maintaining osmotic pressure and acid-base balance and in transmitting nerve impulses.

A decrease or low level in the blood is called hyponatremia, an excessive or high blood level is called hypernatremia

Potassium (K)

Is primarily concentrated within the cells with very little found in the bones and blood. It is released into the blood when cells are damaged.

Place a major role in nerve conduction, muscle function, acid base balance, and osmotic pressure. A low level is called hypokalemia, high level is hyperkalemia.

Chloride (CI)

Exists mainly in the extracellular spaces where it joins with sodium to make sodium chloride And with hydrogen in the stomach to make hydrochloric acid (stomach acid). It also plays a role in fluid and pH balance. Must be supplied along with potassium when hypokalemia is being corrected

Bicarbonate ion (HCO3)

Play a role in transporting CO2 to the lungs and in regulating blood pH. It is formed when carbonic acid is dissociated into H and HCO3 ions. Decreased ventilation results in higher CO2 levels and the production of more hydrogen ions and can lead to acidosis. Hyperventilation decreases CO2 levels and can lead to alkalosis

Multiple test panel monitoring by point of care testing

Several small portable, and in some cases, handheld analyzers are available that measure multiple commonly ordered stat tests.

Examples of analyzers that can perform several different tests: ABL90 FLEX PLUS, AVOCimeter, GEM premier, I-STAT, STATE PROFILE PRIME

These analyzers can measure tests such as sodium, potassium, chloride, bicarbonate ion, pH, PCO2, PO2, SO2, BUN, glucose, Hgb, HCT, ACT, lactate, and troponin

B-type natriuretic peptide (BNP)

A cardiac hormone produced by the heart in response to ventricular volume expansion and pressure overload. It is the first objective measurement for congestive heart failure. BNP levels help physicians determine chronic obstructive pulmonary disease and CHF. Can be determined by the I-STAT using whole blood or plasma

Cardiac troponin T and I

Proteins specific to heart muscle.

Blood levels of the these proteins rise within four hours of the onset of myocardial damage and may stay elevated for up to 14 days. Measurement of these proteins is a valuable tool in the diagnosis of acute myocardial infraction or heart attack. TnT is also measured to monitor the effectiveness of thromboytic therapy in cardiac patients.

Analyzers include: CARDIAC T Rapid assay and the Triage Cardiac Panel.

Complete blood count (CBC)

Can be used to identify several conditions that require immediate medical intervention, such as infection, anemia, and low white blood cell count.

Analyzer used- XW100 automated hematology analyzer

C-reactive protein

Is a B-globulin (a type of protein) made by the liver. It Is released into the blood as a response to inflammation, which can have various causes such as tissue injury, or the beginning of an infection. It is measured as a sensitive but nonspecific marker of systemic inflammation disorders and associated diseases.

Is typically used as an independent marker to identify individuals at risk for future heart disease

Analyzer used- Stratus CS, use whole blood or plasma.

Glucose

One of the most common POCT procedures and is most often performed to monitor glucose levels of patients with diabetes mellitus. glucose analyzer are small, portable, and relatively inexpensive. They use whole blood specimens obtained by routine skin puncture. Symbol will also accept harmonized venous or arterial specimens.

Hospital glucose analyzers: Require QC, Require the use of a patient authorized operator identification number, allow data to be downloaded from the device and transmitted to the LIS or electronic health record.

Analyzers: accu-Chek inform ii system, Hemocue glucose 201 DM, statstrip, freestyle precision pro.

Test strips or microcuvettes are unique to the particular device used and have to match the device. Some have a code that chip that can be matched to the analyzer.

StatStrip is the only FDA approved glucose test

Glycohemoglobin/hemoglobin A1c

Glucose which is chemically bound to hemoglobin A, The primary form of hemoglobin in adults.

The combination of hemoglobin A and glucose is more commonly called hemoglobin A1c.

The rate of formation of this is directly proportional to plasma glucose levels. Glucose stays attached to the hemoglobin for the life of the red blood cell (120 days). Hemoglobin A levels reflect the average blood glucose level over the previous 2 to 3 months and can be used to evaluate the long-term effectiveness of diabetes therapy.

This test has been accepted as a more accurate predictor of the likelihood of a Diabetic patient developing complication’s from the disease. Recommended that this test be done twice a year or 4 times a year in patients who are not meeting their glycemic targets

Analyzer- DCA Vantage

Hematocrit

Also called packed cell volume (PCV)

A measure of the volume of red blood cells in a patient’s blood. It is calculated by centrifuging a specific volume of anticoagulated blood, and determining the proportion of red blood cells to plasma.

Blood is collected in a special microhematocrit capillary tube. The tubes are sealed at one end with a clay or special stopper and placed in a special hematocrit centrifuge. Hematocrits are often performed in a physicians office, clinic, or donor stations to screen for anemia or as an aid in the diagnosis and monitoring of polycythemia.

Analyzer- StatSpin CritSpin

Hemoglobin

The measurement of this is an Important part of managing patients with anemia.

Analyzer- HemoCue 201 analyzer. It can determine hemoglobin levels in arterial, venous, or capillary blood.

Lactate

The accumulation of lactic acid (lactic acidosis) in the blood has been identified as a of cause of acid-base disorder (metabolic acidosis). Lactic acidosis is associated with major metabolic issues and is due to hyperlactatemia (increased lactate in the blood). Hyperlactatemia is usually present in patients with severe sepsis or septic shock.

The lactate level can be used as a marker of the severity of the condition and the patients stress response. Patients who have an arterial lactate level of more than five have a very poor prognosis. Consequently, it is important to be able to obtain lactate results within minutes to effectively treat severe sepsis. If It is transported to the laboratory the sample must be on ice without delay and analyzed as soon as it arrives.

Analyzer- I-STAT or nova StatStrip

Lipid/cholesterol testing

Lipids are fats and fat like waxy substances the body uses for energy. They include cholesterol and triglycerides. High levels can contribute to atherosclerosis and heart disease.

Analyzer- The Cholestech LDX system can preform total cholesterol (TC), Low-density lipoprotein (LDL), and high-density lipoprotein (HLD) cholesterol tests.

Can be obtained by venipuncture or finger stick and collected in a lithium heparin capillary tube

LDL

Low density lipoprotein

“Bad” cholesterol because it contributes to atherosclerosis

HDL

High density lipoprotein

“Good” cholesterol because it is believed to Carry LDL away from the arteries.

Rapid syphilis test

detect antibodies to treponema pallidum, the bacterium that causes syphilis. The rapid test can usually be performed on serum, plasma, or whole blood, but they are typically performed using whole blood collected by finger stick. Results are available within 15 minutes. A positive test result must be confirmed with a second more complex test performed by a clinical laboratory