CHAPTER 11

point of care testing (POCT) blood specimens are normally collected by-

Capillary puncture or venipuncture

Typical labeling requirements for blood bank specimens

-Patient’s full name, including middle initial

-Patient’s hospital identification number

-Patients date of birth

-date and time of collection

Phlebotomist’s ID number or full name

-Room number and bed number (optional)

blood bank ID bands (BBIBs)

Specifically designed to protect patients and healthcare facilities from errors that could be fatal made during identification and administration of blood products.

Preprinted patient label with barcode that can be printed in the laboratory. All bands contain a unique ID number to ensure the specimens are correctly identified.

The additional ID numbered stickers from the bracelet or requisition are sent to the lab with the specimen to be used in the cross match process. As soon as the testing begins, the uniquely numbered sticker is attached to the unit of blood or other blood products used for transfusion

For more accuracy in the patient transfusion area-

Blood recipient patient ID systems have been created to reduce common transcription errors. These systems allow for the implementation of electronic ID and contain linear barcoded BBIB numbers on all printed patient information such as requisitions, labels, and coded specimen stickers.

Blood bank tests require the collection of

One or more lavender or pink EDTA tubes.

In some cases, non-additive glass red tubes are used.

BB tests can be rejected if they

•are not labeled exactly as described in the laboratory protocol

•are grossly hemolyzed samples

•contain IV fluids

•were collected more than 72 hours before testing

Most common BB test

Type and screen

This test determines a patients blood type (ABO) And Rh factor (positive or negative).

When a transfusion is required, a test called a crossmatch is performed using the patient’s type and screen results to help select a donor unit of blood. 🩸

During a cross-match:

The patient’s plasma or serum and the donor’s red blood cells are mixed together to determine compatibility.

A transfusion of incompatible blood can be fatal because of

Agglutination (clumping) and lysis (rupturing) of the RBCs within the patients circulatory system

Blood donor collection

Involves screening and collecting blood to be used for transfusion purposes rather than for diagnosis testing

AABB

International organization that developed standards and provides educational and accreditation programs that focus on enhancing patient and donor care and safety

Blood doner centers are also regulated by FDA bc blood and blood products are considered pharmaceuticals

Blood donor centers

Facilities that provide blood products for transfusion purposes

Donor eligibility

Helps protect the health and safety of the donor and recipient

If u wish to donate u must feel well and be in good shape, at least 17, and weight up to 110lb

there is no upper age limit as long as you are well.

A brief physical examination and medical history is needed to determine the donors health status every time no matter how many times they’ve given blood.

Hemoglobin and hematocrit checks are preformed. Hemoglobin can be no less than 12.5 and hematocrit no less than 38%

Principles of donor unit collection

-donor units are normally collected from a large anticubital vein

-the vein is selected in a manner similar to routine venipuncture and cleaned in a manner similar to blood culture collection

-the collection unit is a sterile closed system consisting of a bag to contain the blood, connected by a length of tubing to a sterile 16-18 gauge needle

-The bag fills by gravity and must be placed lower than the patient’s arm

-The collection bag contains an anticoagulant and preservative solution and is placed on a mixing unit while the blood is being drawn

-The unit is normally filled by weight but typically contains around 450 mL of blood when full. Only one needle puncture can be used to fill a unit. If the unit only partially fills and the procedure must be repeated, an entire new vein must be used.

An anticoagulant and preservative citrate-phosphate-dextrose or CPDA1 is typically used in collecting units of blood for transfusion purposes-

The citrate prevents clotting by chelating calcium, A phosphate compound stabilize the pH, and dextrose Provides energy to the cells and helps keep them viable

Lookback

The tracing and testing of blood donors and recipient when a blood product has been determined to be potentially contaminated with a blood-borne pathogen. Can only occur when the blood service is made aware of the possibility of a transfusion related infection. At that time, notification to all blood recipients is required and verification for all blood components previously collected and currently in inventory is retrieved.

Autologous donation

The process by which a person donates blood for their own use. This is done preoperatively for elective surgeries when it is anticipated that a transfusion may be needed.

Using one’s own blood eliminates many risks associated with transfusion such as diseases and incompatibilities

The minimum time between donation and surgery must be more than 72 hours

In order to do this, a person must have a written order from a physician and have a hemoglobin of at least 11 or a hematocrit equal to or greater than 33

If the blood is not used during surgery, it is discarded because it does not meet the safety standards required to donate to another person

Cell salvaging

Medical procedure designed to recover blood lost during surgery to re-infuse it back into the patient. It is a form of autologous blood transfusion. It is recommended that the salvaged blood be tested for residual free hemoglobin prior to re-infusion

A high free hemoglobin level indicates that too many red blood cells were destroyed during the salvage process and renal dysfunction can result if the blood is re-infused

Free hemoglobin can be detected using point of care instruments, such as the homoCue Plasma/Low Hb analyzer

Blood is normally sterile however

Bacteria or other microorganisms may enter the circulatory system from extravascular sites via lymph vessels.

Usually, Microorganisms that find their way into the bloodstream are cleared from the Blood by the bodies immune system. However-

If microorganisms multiply faster than the body can remove them a bloodstream infection results (BSI)

The presence of microorganisms or their toxins in the blood is called

Septicemia

Bacteremia

Refers to an infection caused by bacteria in the blood

Fungemia

The presence of fungi, such as yeast or mold in the blood

When a BSI is suspected-

A healthcare provider will order blood cultures to determine the presence and extent of infection.

Blood cultures can also identify the type of organism responsible and the anabiotic to which it is most susceptible. In addition, blood cultures are useful in assessing the effectiveness of antibiotic therapy once treatment is initiated.

Sepsis

An overwhelming, unregulated response by the body to the BSI that triggers inflammatory responses throughout the body which can lead to tissue damage, organ failure, and death

Septic shock is dangerously low blood pressure and other profound circulatory issues and metabolic abnormalities that substantially increase the likelihood of death.

Sepsis is most common in

Infants, older adults, and those with weakened immune systems

Bloodstream infection (BSI) symptoms

Fever, chills, malaise, low blood pressure, and changes in mental status.

Fever of unknown origin (FUO)

A persistent fever with no obvious cause has long been recognized as an indication of a BSI.

However, blood cultures are ordered based on whether the patient has a condition in which bloodstream invasion is possible, even in the absence of FUO.

How many blood culture bottles

2 or 4

CLSI blood culture guidelines recommend collecting paired aerobic and anaerobic blood culture bottles for routine blood culture collection.

One blood culture consist of blood from a single Venipuncture inoculated Into two separate bottles referred to as a set which are filled to the optimal blood to broth ratio

Recommendations for the number of blood cultures to collect include the following:

• For signs and symptoms of sepsis, Two sets of blood cultures should be collected ASAP before antimicrobial agents are administered

• For critical situations in which rapid administration of antibiotics is important, 2 to 3 sets of cultures, One right after another from different sites are usually required

• for FUO, 2 to 3 sets of cultures one right after another from different sites are usually required. If these are negative after 24 to 48 hours two more cultures from different sites are typically collected

• If bacteremia or fungemia are suspected but blood cultures are persistently negative, alternative media bottles may be required to optimize the recovery of mycobacteria and fungi

The timing of blood cultures is important and

They should be collected as close to the time ordered as possible. Collection time generally depend depends on the status of the patient (The patient is in critical condition or an anabiotic must be given right away)

Time in considerations include:

• When more than one set is ordered for a collection at the same time, the second set should be obtained from a separately prepared site on the opposite arm

• in some cases “second site” Blood cultures are more useful when drawn 30 to 60 minutes apart

• If timing is not specified on the requisition, the phlebotomist should follow laboratory protocol

Volume of blood for blood cultures

20-3mL for adults

For infants and children, the blood volume drawn should not exceed 1% of their blood volume

Blood culture specimens are most commonly collected in special bottles that contain-

Nutrient broth, Referred to as medium, That encourages the growth of microorganisms.

These specimens are typically collected in sets of two-

One aerobic (with air) bottle

One anaerobic (without air) bottle

The bottles typically have different colored caps so that it is easy to tell them apart

The antiseptic procedure used to minimize the risk of contamination of the blood culture collection site by microorganisms is referred to as a.

Sterile technique

The major difficulty in the interpreparation of blood cultures is contamination by normal microbial flora on the skin

Sterile means free from all living microorganisms. It is not possible to completely sterilize a blood culture site but sterile blood culture technique goes beyond the aseptic technique used for routine venipuncture to reduce the likelihood of contamination as much as possible

To minimize the risk of contamination by skin flora

Collection sites require a 30 to 60 second friction scrub to get the bacteria beneath the dead skin cells on the surface of the arm.

Tincture of iodine, chlorhexidine gluconate, and a providone-iodine 70% ethyl alcohol combination have all been shown to be effective antiseptic for cleaning blood culture collection sites

If an iodine preparation is used-

Clean it from the site using alcohol or another suitable cleanser after the specimen has been collected. If the patient has a known iodine sensitivity, use chlorhexidine gluconate Or an acceptable alternate antiseptic to clean the site

Many healthcare facilities use this the majority of the time to clean blood culture sites

Chlorhexidine gluconate in isopropyl alcohol solution and 70% isopropyl alone instead of iodine preparations considering many people are allergic to iodine solutions.

Both antiseptic techniques are equally effective.

initial specimen diversion device (ISDD)

Has been shown to reduce and sustain 0-1% blood culture contamination rates.

Sterile vein-to-bottle or vein-to-syringe closed-system device.

Adding the blood to the culture bottle is called

Media inoculation.

Inoculation can occur in several different ways: directly into the bottle during specimen collection, or after collection, when blood has been collected in a syringe. A third way is to use a special intermediate collection tube to collect the sample for inoculation later in the laboratory and not at bedside

Direct inoculation

Use only blood culture bottles for direct filling. Use a butterfly and specially designed blood culture bottle holder.

Prepare the bottles white antiseptic is drying, mark the required volume on the bottle, clean the tops with 70% isopropyl alcohol or alcohol prep pads, connect the special holder to the luer connector of the butterfly collection site. Fill aerobic bottle first bc the butterfly tubing has air in it. Keep bottle upright as it fills. Mix each container after removing it from the needle holder

Syringe inoculation

Blood is transferred to the bottles after blood has been drawn.

Fill aerobic bottle first because sometimes it is difficult to obtain the 8-10mL of blood per bottle and the aerobic bottle is the most critical. The reasoning is that aerobic and facultative bacteria cause the most cases of bacteremia and almost all yeast recoveries are from aerobic bottles.

Be carful when filling that you only add the recommended volume of blood to the bottle, you may have to hold the syringe back to obtain the right amount of blood.

Intermediate collection tube

A yellow top tube containing sodium polyanethol sulfonate (SPS) is preferred for this method.

In addition to its anticoagulant properties, SPS reduces the action of a protein called compliment that destroys bacteria. It also slows down ingesting of bacteria by leukocytes and reduces the activity of certain antibiotics. Other anticoagulants such as citrate, heparin, EDTA, and oxalate may be toxic to bacteria and are not recommended.

The use of an intermediate tube is discouraged for the following reasons

-When added to the blood culture bottle, SPS in the collection tube increases the final concentration of SPS.

-Transfer of blood from the intermediate tube to the blood culture bottle presents another opportunity for contamination

-Transfer of blood to the culture bottles presents an exposure risk to laboratory staff

Antimicrobial Neutralization products

It is not unusual for patients to be on antibiotic or antimicrobial therapy at the time blood culture specimens are collected. Presence of the antimicrobial agent in the patient’s blood, can inhibit the growth of the microorganisms in the blood culture bottle. In such cases, the physician may order blood cultures to be collected in fastidious antimicrobial neutralization (FAN) or antimicrobial removal device (ARD) bottles.

Fastidious antimicrobial neutralization bottle

Contain activated charcoal, Which helps to neutralize the antibiotic

Antimicrobial removal device

Contains a resin that removes antimicrobials from the blood

How to transport blood culture specimens

Transport at room temperature, and as soon as possible after collection. If not received by the lab within two hours, the delay of processing the specimens could hinder the detection of microbial growth

Pediatric blood culture

It is recommended that in place of the iodine step the site should be cleaned two additional times with separate preparation pads saturated with 70% isopropyl alcohol or ethyl alcohol

Collected in smaller bottles with a different formulation of the broth

Volume should be no more than 1% of the patient’s total blood volume per collection.

Catheter considerations in blood culture draws

Do not draw blood cultures through an IV or arterial catheter unless there is no other option.

Draws from vascular lines are known to have a higher contamination rate and may cause a person to receive antibiotic therapy when not needed

When collecting blood cultures from a vascular access device such as a catheter or IV draw one set by venipuncture and one through the catheter. This allows for the correct interpretation of a positive test result because cultures drawn through any type of VAD may indicate bacterial growth in the device rather than in the blood.

Coagulation specimens

most coagulation tests are collected in light blue sodium citrate tubes.

Some special coagulation tests, such as anti-factor Xa are collected in light blue top tubes called a CTAD (Citrate, Theophylline, adenosine, and dipyridamole)

CTAD tubes are used to

Inhibit platelet activation between collection of the specimen and testing.

You might have to draw this before collection of light blue tops but it is not required

A clear discard tube

Light blue top tubes must be filled until the normal vacuum is exhausted to obtain a 9:1 ratio of blood to anticoagulant which is critical for

Accurate test results.

This ratio can be altered if the patient’s hematocrit exceeds 55%, even if the tube is correctly filled. In such cases, laboratory personnel may request specimen collection in a special tube that has had the anticoagulant volume adjusted.

If a light blue top is the first or only tube to be drawn using a blood collection set with tubing (butterfly)-

A discard tube must still be collected first to prime the tubing. Otherwise, the air in the tubing will take the place of blood in the tube and result in an incomplete draw and an incorrect blood-to-additive ratio.

Coagulation factors V and VIII are highly unstable. If these specimens cannot be tested within four hours-

They must be centrifuged and the plasma frozen

Drawing a coagulation specimen from a VAD is not recommended. Coagulation specimens drawn from VADs require-

A discard volume of blood that is 6 times the dead space volume of the tubing or approximately 5mL

Two hour Postprandial glucose

Postprandial (pp)- After a meal

glucose levels in blood specimens obtained two hours after a meal are rarely elevated in normal persons, but may be significantly increased in diabetic patients. Therefore, a glucose test on a specimen collected two hours after a meal is an excellent screening test for diabetes and gestational diabetes

A 2-hour PP test is also used to monitor

Insulin therapy

Correct timing of specimen collection is very important. Glucose levels and specimens collected too early or too late may be

Falsely elevated or decreased leading to misinterpretation of results. If test results are abnormal, other tests might be ordered

Glucose tolerance test

Used to diagnose carbohydrate metabolism problems.

The major carbohydrate in the blood is glucose, the body source of energy. The GTT elevates the bodies ability to metabolize glucose by monitoring the patient’s tolerance to high levels of glucose without adverse effects.

The two major types of disorders involving glucose metabolism: hyperglycemia (Blood glucose level is increased) and hypoglycemia (Blood glucose levels are decreased)

Used in the diagnosis of glucose metabolism problems after a screening test has identified a potential problem.

The GTT evaluates the insulin response to a measured does of glucose by

Recording glucose levels on specimens collected at specific time intervals. GTT length is typically 1 hour for gestational diabetes and 3 hours for other glucose metabolism evaluations. Results are plotted on a graph called a GTT curve

There are several variations of the GTT procedure, each involving different doses of glucose and timing of collections. The glucose is contained in a special-

Beverage (glucola). The method used to collect the blood should be Consistent for all specimens, that means that if the first specimen is collected by venipuncture, all succeeding specimen should be venipuncture.

Preparation requirements for a GTT

Eat a balanced meal containing 150 g of carbs for three days before the test

Fast for at least eight hours, but no more than 16

Drink water during the fast and during the test to avoid dehydration because urine specimens may be collected as a part of the procedure

Do not exercise, smoke, or chew gum for at least eight hours before or during the test

In normal patient’s, blood glucose levels peak within

30 min to 1 hour following glucose ingesting. The peak in glucose levels triggers the release of insulin, Which brings glucose levels back down to fasting levels within about two hours and no glucose spills over into the urine.

Diabetic patients have in inadequate or absent insulin response; Consequently, Glucose levels, peak at higher levels and are slower to return to fasting levels. If blood is not drawn on time, it is important for the phlebotomist to note the discrepancy so that the physician can take this into consideration.

Oral glucose challenge test

Some pregnant women develop high blood glucose levels during pregnancy, A condition called gestational diabetes. This test, also called a 1 hour glucose screening test or gestational glucose screening test screens for gestational diabetes, and is a Modified version of the GTT.

To preform this test, the patient is given a drink containing 50 g of glucose. A blood glucose specimen is collected one hour after the patient finishes the drink. If the glucose result on the specimen is greater than 140 mg/dL, It is suggestion that the patient have a follow up OGTT within one week.

Lactose tolerance test

Used to determine if a patient lacks the mucosal enzyme lactase, Which is necessary to convert lactose, or milk sugar, into glucose and galactose.

A person lacking the enzyme suffers from gastrointestinal distress and diarrhea following the ingestion of milk and other lactose containing foods.

The test is typically performed in the same manner as a two hour GTT, However, An equal amount of lactose is substituted for the glucose.

Blood samples are drawn at the same time as for a GTT. If the patient has mucosal lactase, The resulting glucose curve will be similar to a GTT curve and the result is considered negative

If the patient is lactose intolerant, the glucose curve will be flat.

Preferred lactose Tolerance test is the hydrogen breath test- This test requires the patient to drink a special beverage with a measured dose of lactose

Molecular genetic testing

Includes a comprehensive list of laboratory tests performed to analyze the genetic information in DNA and RNA from tissue samples such as blood, saliva, urine, feces, and organ tissue to detect specific markers using biochemical, cytogenetic, or molecular methods or a combination of these methods

Sterile whole blood specimens for molecular genetic testing are generally collected in the lavender top EDTA tubes or white top gel tubes (PPT). Other anticoagulant tubes used for genetic testing could contain ACD, Sodium citrate, Or sodium heparin.

Blood specimen will be rejected if frozen, Hemolyzed, Or clotted

Prenatal/Paternity testing

Prenatal testing uses DNA profiling (Also called genetic fingerprinting) To determine the probability that two specific individuals have a genetic parent-Child Relationship.

Paternity test- The tested determine if a man is the biological father of a specific individual (most common)

Maternity test- The test to determine if a woman is the biological mother of a specific individual

Results are usually reported as a percentage with a 99.9% probability being the highest.

Blood samples are preferred for testing, however cheek swabs are increasingly being used

Therapeutic drug monitoring

The testing of drug levels in the bloodstream at specific intervals.

•Used to Manage patients being treated with certain drugs in order to help establish a drug dosage

• While adjusting the dosage when drugs are being taken in combination with other drugs

• In identifying noncompliant patients

• In maintaining the dosage at a therapeutic level

• To avoid drug toxicity

Examples of drugs that typically require therapeutic monitoring

Antibiotics and antifungals, Anticonvulsants, Bronchodilators, cardiac drugs, Chemotherapy drugs, Immunosuppressants, Protease inhibitors, Psychiatric drugs

For a drug to be beneficial, The peak level (Maximum) Must not exceed

Toxic levels, And the through level (Minimum) must remain within the therapeutic range

Timing of specimen collection in relation to dosage administration Is critical for

Safe and beneficial treatment, and it must be consistent

Peak levels screen for

Drug toxicity, and specimens are collected when the highest serum concentration of the drug is anticipated. Peak times are influenced by many factors, but typically occur approximately 30 minutes after IV administration, 60 minutes after intramuscular Administration, And one to two hours after oral intake.

Through levels are monitored to ensure that levels of the drug-

Stay within the therapeutic range. Third level specimens are easiest to collect because they are collected when the lowest serum concentration of the drug is expected, Usually immediately before administration of the next scheduled dose

A half life

Is the time required for the body to metabolize half the amount of the drug

When a single dose is administered for every half-life of a drug, Half of the initial dose will be cleared from the body before the next dose is given

TDM for most drugs require a

Serum specimen

whole blood EDTA specimens are typically require for

Immunosuppressive drugs

Therapeutic phlebotomy

Therapeutic (Pertaining to treatment) Phlebotomy involves the withdrawal of large volumes of blood, Usually measured by the unit, Or approximately 500 mL.

It is used as a treatment for certain medical conditions, such as polycythemia and hemochromatosis

Polycythemia

A disease involving the bodies overproduction of red blood cells which is detrimental to the patient’s health and the most common reason for performing the therapeutic phlebotomy.

The patient red blood cell levels are monitored regularly usually by the hematocrit test. Blood is removed periodically when the hematocrit exceeds a certain level to help keep the patient’s red blood cell levels within the normal range

Hemochromatosis

Also called iron overload

A disease characterized by excessive iron deposits in the tissues, especially those of the heart, liver, and pancreas.

The most common type is caused by a genetic defect in iron metabolism that causes the body to absorb too much iron from food.

Secondary hemochromatosis is non-hereditary iron overload caused by other problems such as multiple Blood transfusions, hemolytic disorders, iron supplements, or excessive iron intake from foods.

For either type, periodic removal of single units of blood from the patient gradually depletes iron stores, because the body then uses the stored iron to make new red blood cells to replace those removed

Two key tests to diagnose iron overload (hemochromatosis) are:

Transferrin saturation (also called total iron-binding capacity) and serum ferritin

Toxicology specimens

Toxicology is the scientific study of toxins (poisons).

Clinical toxicology is considered with the detection of toxins and treatment for the effects they produce

Forensic toxicology is concerned with the legal consequences of toxin exposure, both intentional and accidental, these tests examine

Blood, hair, urine, and other body substances for the presence of toxins

Forensic specimens

Increasingly, law-enforcement officials request the collection of a toxicology specimen for forensic or legal reasons. The tests most frequently requested are breath or blood for alcohol.

Other requests include urine drug screens and blood specimens for drugs and DNA analysis.

Chain of custody

When forensic specimens are collected, a special protocol, Referred to as the chain of custody must be strictly followed.

Requires detailed documentation that tracks the specimen from the time it is collected until the results are reported. The specimen must be accounted for at all times. If documentation is incomplete, legal action may be compromised.

A chain of custody form is used to identify the specimen and the person or persons who obtained and processed it. Information on the form also includes the time, date, and place where the specimen was obtained along with the signature of the person from whom the specimen was taken

Blood alcohol (Ethanol) Specimens

Normally a physician orders this test on a patient for medical reasons related to treatment or other clinical purposes. In such situations, there is no requirement for chain of custody, but the results of such analyses can ultimately become evidence in court.

Blood alcohol determinations for industrial purposes are becoming more common and may be required because of on the job injury, employee insurance programs, and employee drug screening.

Blood alcohol content (BAC)

Also called blood alcohol concentration test

Occasionally a law-enforcement agency may request this on an individual who has been involved in a traffic accident. Chain of custody protocol must be strictly followed

Skin prep for blood alcohol specimens

Must not contain alcohol

Aqueous benzalkonium chloride and sometimes aqueous providone-iodine are used for these specimens as well as soap and water sometimes.

Should not be used- tincture of iodine, 70% isopropyl, methanol, ethyl alcohol

Specimen requirements for blood alcohol specimens

A glass grey top sodium fluoride tube with or without an anticoagulant is typically required for specimen collection. Because alcohol is volatile (easily evaporated or Vaporized), the tube should be filled until the vacuum is exhausted and the stopper should not be removed

Drawing specimens to test synthetic stimulants and hallucinogenic drugs

Draw light blue (citrate) for synthetic stimulants

Draw lavender for inhalants and DNA analysis

Drug screening

For these screenings, chain of custody protocol is required even if the test is not being performed for legal reasons

Testing for drugs in the blood involves sophisticated methods, such as gas chromatography-mass spectrometry (GCMS) and liquid chromatography-mass spectrometry (LCMS).

Detection times for drugs in the blood are dependent on many factors, including genetics, body size and composition, Age, Gender, History, and tolerance of the user.

Drugs commonly detectable at blood drug screening

Alcohol, Amphetamines, barbiturates, benzodiazepines, cocain, cannabinoids, inhalants, methadone, opiates, and phencyclidine

Trace elements

Trace elements or metals, include aluminum, arsenic, cadmium, chromium, copper, iron, lead, mercury, selenium, and zinc. These elements are measured in such small amounts that traces of them in the glass, plastic, or stopper material of evacuated tubes may leach into the specimen, causing falsely elevated test values.

For this reason, specimens for these tests must be collected in special trace element free tubes (royal blue stoppers that contain EDTA, heparin, or clot activator). Tan-Top tubes containing K2 EDTA are available for lead analysis.

When a trace element test is ordered, it is best to draw it by itself using a needle tube assembly or a syringe.

Tuberculosis blood test

The traditional TB test is a skin test that requires two visits to a healthcare provider one to administer the test and the second 48-72 hours later to have the results interpreted. Other is a blood test (quantiFERON-TB GOLD PLUS)

Interferon-gamma release assays

The TB blood test is a type of test called an interferon-gamma release essay (IGEA). IGEAs Detect TB infection by measuring an individuals immune response to mycobacteria tuberculosis. An IGRA test is performed by mixing the patient’s white blood cells with M-TB Antigens. When they are mixed with the TB antigens the white blood cells of most individuals who have been infected with M-TB Will release a substance called interferon-gamma that can be measured. A positive test means that a person has been infected with the M-TB. An IGRA That is negative does not necessarily rule out active TB infection

This is a blood test

Quantiferon TB gold plus

Collected by drawing 1 mL blood into each of four special tubes. The tube should be at room temperature. The tubes draw slowly, so keep each tube in place for several seconds after it stops filling to make certain it is completely filled. The tube has a black mark on the side to indicate the 1 mL volume. If a butterfly needle is used for the draw, draw a clear tube first to ensure proper filling of the first specimen tube. Shake each tube firmly 10 times immediately after filling to ensure that the entire surface of the inside of the tube is coded with blood. Do not shake the tubes too energetically because this can cause gel dislodgment and lead to inaccurate test results.

The filled tubes must be transferred to an incubator as soon as possible, within 16 hours of collection

Although there is no specific order of draw for filling the tubes, the following order of draws commonly used

1. Gray-top tube: Negative control tube- does not contain and additive

2. Green-top tube: TB1 antigen tube- Primarily detect CD4 T-cell response

3. Yellow-top tube: TB2 antigen tube- The tech CD4 and CD8 T-cell response

4. Purple-top tube: Positive control tube- contains mitogen, a nonspecific T-cell stimulator

Venous blood gases

If there is no respiratory component to an illness, VBG Analysis can be an alternative to arterial blood gases to estimate CO2, PH, Lactate, And potassium levels.

Can be used for initial assessment of ICU and ED patients. They are also especially helpful in gathering key variables of pH, lactate, and potassium and diagnosing diabetic ketoacidosis

Collected in a green top lithium Heparin tube or a Heparin based syringe. They can also be collected by capillary puncture into a green top lithium capillary tube