Phlebotomy Chapter - 11

Specimen Requirements For Alcohol Collection

- A glass gray-top sodium fluoride tube with or without an anticoagulant (depending on the need for serum, plasma, or whole blood in the test procedure) is typically required for specimen collection - Because alcohol is volatile, the tube should be filled until the vacuum is exhausted, and the stopper should not be removed - The use of synthetic stimulants and hallucinogenic drugs continues to increase - If the phlebotomist draw specimens to test for these drugs at the same time as the BAC, the recommended tubes to draw are light blue (citrate) for the synthetic stimulants and lavender for inhalants and DNA analysis - Glass tubes are preferred for blood alcohol specimens because of the porous nature of plastic tubes

Intermediate Collection Tube

- A yellow-top sodium polyanethol sulfonate (SPS) tube is preferred as the intermediate collection tube if used - In addition to its anticoagulant properties, SPS reduces the action of a protein called complement that destroys bacteria - It also slows the ingestion 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 - Use of an intermediate tube in general is discouraged for the following reasons: - When added to the blood culture tube, SPS in the collection tube increases the final concentration of SPS - Transfer of blood from the intermediate tube to the blood culture bottles presents another opportunity for contamination - Transfer of blood to the culture presents an exposure risk to lab staff

Arterial Blood Gases

- ABGs measured by POCT include pH, partial pressure of carbon dioxide, oxygen saturation, and partial pressure of oxygen - Arterial blood pH test is a measure of the body's acid-base balance and indicates metabolic and respiratory status. The normal range for arterial blood pH is 7.35 to 7.45. Below-normal pH is referred to as acidosis and above-normal is referred to as alkalosis - pCO2 is a measure of the pressured exerted by dissolved CO2 in the blood plasma and is proportional to the pCO2 in the alveoli. Abnormal increase in pCO2 is associated with hypoventilation and decrease with hyperventilation - pO2 is a measure of the pressured exerted by dissolved O2 in the blood plasma and indicates the ability of the lungs to diffuse O2 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. A normal individual will exhibit oxygen saturation around 98%. A person with arterial sO2 below 90% is said to have hypoxemia and may be cyanotic. Inadequate oxygen in the blood can lead to the tissues not having enough oxygen, a condition called hypoxia

Donor Eligibility

- According to the American Red Cross, those who wish to donate must feel well and be in good general health - Must be at least 17 years old and weigh at least 110 lbs - A 16 yr old may donate with parent permission if allowed in the state - Those over 76 require written approval from their physicians - Hemoglobin can be no less than 12.5 g/dL and no less than 38% for hematocrit - The donor must give written permission for the blood bank to use their blood

Media Inoculation Methods

- 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 specimen collection if a syringe was used - Use of a special intermediate collection tube to collect the sample for inoculation later in the lab and not at the bedside

Platelet Function

- Allows the clinician to determine a patient's response to medication before open heart surgery or cardiac catheterization - This can help prevent excessive bleeding or blood clots - This testing can be done utilizing an automated analyzer with a single-use, disposable assays called the VerifyNow System. It uses whole-blood samples and gives measurements that correlate with lab testing - Platelet function tests can measure the ability of an individual to respond to various antiplatelet medications - The VerifyNow System Aspiring Assay, which is CLIA-Waived, provides a measurement to determine if a patient is responding to aspiring therapy

Prothrombin/International Normalized Ratio

- Also called a protime test - Used to monitor warfarin (e.g. Coumadin) therapy - Provides information on how long it takes for a patient's blood to clot - There are differences in results when using PT tests from different companies. The international normalized ratio (INR) was made a solution - The INR standardizes the differences found between the reagents in the various manufacturers' tests and allows results from different labs to be more easily compared INR = (PT of Patient / PT Normal) ^ ISI - PT of Patient = The patient's PT result expressed in seconds - PT Normal = The lab's geometric mean value for normal patients in seconds - ISI = International sensitivity index for the tissue factor in the manufacturers' reagent - Many warfarin or anticoagulation clinics use POC coagulation analyzers that perform PT and INT tests on whole blood from a fingerstick to provide timely lab results - Some POCT analyzers like CoaguChek XS Plus allow patients to perform PT tests at home and transmit their results to physicians' offices - The physician can then adjust medication over the phone, and the patient does not have to make an office visit

Hematocrit

- Also called packed cell volume (PCV) is a measure of the volume of RBCs in the patient's blood - Calculated by centrifuging a specific volume of anticoagulated blood and determining the proportion of RBCs to plasma - Blood is collected in special microhematocrit capillary tubes - The result is expressed as a percentage of cells to liquid - Hematocrits are often performed in physician office labs (POLs), clinics, and blood donor stations to screen for anemia or as an aid in the diagnosis and monitoring of patients with polycythemia

Activated Clotting Time

- Also called the activated coagulation time - Analyzes activity of the intrinsic coagulation factors and is used to monitor heparin therapy - Heparin is given intravenously to patients who have blood clots or whose blood is apt to clot too easily; also given as a precaution following certain surgeries - Once a patient's condition is stabilized, the patient is placed on oral anticoagulant therapy (such as warfarin) and monitored by PT testing - With automated ACT analyzers, the mixing and timing are done automatically - To begin the testing process with the Hemachron Signature Elite, a barcoded cuvette is scanned by a reader on the instrument ; This lets the instrument know which assay is requested and the calibration details - The cuvette is placed into the instrument, and a whole-blood sample is added to it for analysis - The instrument measures the amount of blood required for the test and performs the test automatically, without any operator interaction - The data management system allows for the results to be sent directly to the lab information system (LIS) if desired

Point of Care Testing (POCT)

- Also known as alternate site testing (AST) or ancillary, bedside, or near-patient testing- brings laboratory testing to the location of the patient - Its benefits include convenience to the patient and a short TAT for results that allow healthcare providers to address crucial patient needs, deliver prompt medical attention, and expedite patient recovery - In addition to be able to operate the analyzer according to the manufacturers instructions and possessing the phlebotomy skills required to collect the specimen, anyone who does POCT should be able to carry out the quality control and maintenance procedures necessary to ensure the results obtained are accurate - Everyone who performs POCT in a clinical setting must meet the requirements of the Clinical Laboratory Improvement Amendments (CLIA) for testing and OSHA guidelines for specimen handling

Autologous Donation

- Autologous donation is the process by which a person donates blood for his or her 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 transfusions, such as diseases transmission - The minimum time between donation and surgery must be more than 72 hours - To be eligible to make an autologous donation, a person must have a written order from a physician and have a hemoglobin of at least 11 g/Dl or a hematocrit equal to or greater than 33% - If the blood is not used during surgery, it is discarded because tules for autologous donation are less strict, and therefore the blood does not meet the safety standards required for blood that is used for other patients

B-Type Natriuretic Peptide

- BNP is a cardiac hormone produced by the heart in response to ventricular volume expansion and pressure overload - It is the first objective measure for congestive heart failure (CHF) - BNP levels help differentiate between chronic obstructive pulmonary disease (COPD) and CHF - BNP blood concentrations increase with the increasing severity of CHF and have been shown to more accurately reflect final diagnosis than echocardiographic ejection fraction - BNP can be determined by using the i-STAT using a whole-blood or plasma specimen

Sepsis

- Bacteremia or Septicemia can lead to a life-threatening condition called sepsis - Sepsis is an overwhelming, unregulated response by the body to the blood infection that triggers inflammatory responses throughout the body that can lead to tissue damage, organ failure, and death - Sepsis can lead to septic shock, dangerously low blood pressure and other profound circulatory issues and metabolic abnormalities that substantially increase the likelihood of death - Sepsis is most common and most dangerous in infants, older adults, and those with weakened immune systems - Sepsis is the leading cause of death from infection

Special Identification Systems

- Blood Bank ID Bands (BBIDs) are specifically designed to protect patients and healthcare facilities form potentially fatal errors during identification and administration of blood products - All bands contain a unique ID number on each patient's band to ensure that blood specimens are correctly identified with that one person only - As testing beings, the uniquely numbered sticker is attached to the unit of blood or other blood products used for transfusion - Blood Recipient Patient ID Systems have been created to reduce common transcription errors. These systems allow for implementation of electronic ID and contain linear barcoded BBID numbers on all printed patient information - The nurse initiates the blood product validation for a patient by gathering four facts about the blood product in the presence of the patient: 1. The healthcare provider's identity, scanned from the barcode on their identification card 2. The patient's identification scanned from the barcode on the patient's wristband 3. The product's unique barcoded donor identifier on the blood unit 4. The blood product's barcode on the blood unit - A second validation may be require. Once all verification is complete, the unit is ready to be physically transfused by the clinician - Upon completion of the transfusion, the blood bank system updates to reflect that the the unit has been administered and logs the date and time of completion - This provides accurate patient records

Catheter Considerations

- Blood cultures should not be drawn through an indwelling IV or arterial catheter unless there is no other option - These kind of draws have high contamination rates and may cause a person to receive antibiotic therapy when not needed -When collecting blood cultures specimens from a vascular access device (VAD) such as a catheter or IV, one set should be drawn by venipuncture, and one drawn through the catheter. This allows for the correct interpretation of a positive result since cultures drawn through any type of VAD may indicate bacterial growth in the device, rather than in the blood - Catheter-related bloodstream infections are common causes of healthcare-associated infections. Despite their frequent occurrence, catheter-related infections are difficult to diagnose

Blood Cultures

- Blood is normally sterile - If microorganisms multiply faster in our blood faster than our body can remove them, a blood infection results - A blood infection is called bacteremia or septicemia - When a blood infection is suspected, the healthcare provider will order blood cultures to determine the presence and extent of the infection - Blood cultures can determine the organism responsible and the antibiotic to which it is most susceptible - Blood cultures are useful in assessing the effectiveness of antibiotic therapy once treatment is initiated

Syringe Inoculation

- Blood must be transferred to the bottles after draw is completed using a syringe - OSHA regulations require the use of a safety transfer device - Activate the needle safety device before or as soon as the needle is removed from the vein, and apply pressure to the site - Remove the needle from the syringe, discard it, and attach a safety transfer device to the syringe - Inoculate the anaerobic bottle first and then the aerobic - Push the culture bottle into the device until the needle inside it penetrates the bottle stopper - Allow the blood to be drawn from the syringe by the vacuum in the container, being careful only to add the amount of blood recommended - The plunger may have to be held back to keep from expelling too much blood - Never push the plunger to expel the blood into the bottle - This can hemolyze the specimen and can aerosol formation when the needle is removed - Discard the syringe and transfer device as a unit into the sharps container

Polycythemia

- Body overproduces RBCs, which is detrimental to the patient's health and the most common reason for performing therapeutic phlebotomy - RBC levels are monitored regularly, usually via hematocrit tests - Periodic removal of blood when the hematocrit exceeds a certain level is used to keep patient's RBC levels within normal range

Complete Blood Count

- CBC used to identify several concditions such as infection, anemia and low WBC count -

Cardiac Troponin T and I

- Cardiac Troponin T (TnT) and Troponin I (TnI) are proteins specific to heart musce - Blood levels of TnT rise within 4 hours of the onset of myocardial damage and may stay elevated for 14 days - Cardiac TnI levels rise within 3 to 6 hours and return to normal in 5 to 10 days - Measurement of these proteins is used in the diagnosis of acute myocardial infarction (AMI), aka a heart atack - TnT is also measured to monitor the effectiveness of thrombolytic therapy in cardiac patients - Cardiac Troponin POCT analyzers include the following: - The CARDIAC T Rapid Assay; A one-step, whole blood test for cardiac TnT that uses disposable test kits to provide results in minutes - The Triage Cardiac Panel provides results for 3 cardiac markers, TnI, CK-MB, and myoglobin

Hemochromatosis

- Characterized by excess iron deposits in the tissues, especially those of the heart, liver, and pancreas - The most common type, primary or hereditary hemochromatosis, is caused by genetic defect in iron metabolism which causes the body to absorb too much of it from the food - Secondary hemochromatosis is nonhereditary iron overload caused by other problems such as multiple blood transfusions, hemolytic disorders, iron supplements, or excess iron intake from foods - For either type, periodic removal of single units (400 to 500 cc) of blood from the patient gradually depletes iron stores, because the body uses the stored iron to make new RBCs to replace those removed - The two key tests to diagnose iron overload are transferrin saturation, also called total iron-binding capacity (TIBC), and serum ferritin - Chelating drugs that bind with iron to facilitate its removal from the body are also available for those unable to tolerate blood draws

Molecular Genetic Testing

- Clinical molecular diagnostic technologies focus on: - Determining whether an individual has a certain genetic disease - Determining if an individual has an increased risk for a certain disease - Classifying an individual's genetic makeup to determine whether a drug and dosage is suitable for that individual patient - Examining the whole genome to discover genetic alterations that may cause disease - Before specimen collection, essential information must be obtained. - The patient's demographic are required, and an informed consent must be signed - Sterile whole blood specimens for molecular genetic testing are generally collected in the lavender-top EDTA tubes or tubes specially designed for this type of diagnostic study , that is, white-top gel tubes form Greiner Bio-One - Other anticoagulant tubes used for genetic testing could contain ACD, sodium citrate, or sodium heparin - When a test for RNA is ordered, the blood specimen must be sent for testing immediately or collected in a special stabilizing reagent - Blood specimens will be rejected if frozen, hemolyzed, or clotted - Ideal handling is to ship immediately at ambient temperature for overnight delivery - In hot weather, a coll pack can be enclosed. - Specimens for molecular genetic testing can be refrigerated up to seven days before shipping

T-SPOT TB

- Collected using a single standard green-top tube following standard phlebotomy specimen collection and mixing procedures - You do not need to draw a clear tube even if a butterfly needle is used to collect the specimen - The specimen can be maintained at room temperature for up to 32 hours

Specimen Collection

- Commonly collected in special bottles containing nutrient broth referred to as medium that encourages the growth of microorganisms - Specimens are typically collected in sets of two: one aerobic and one anaerobic

Principles of Donor Unit Collection

- Donor units are normally collected from a large AC 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 sterile, closed system consisting of a bag to contain the blood connected by a length of tubing to a sterile 16 to 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 unit must be used. - The anticoagulant and preservative citrate-phosphate-dextrose (CPD) or CPDA1 (CPD plus adenine) is typically used in collecting units of blood for transfusion purposes. The citrate prevents clotting by chelating calcium. A phosphate compound stabilizes the pH and dextrose provides energy to the cells and helps keep them viable

Glucose POCT Cont.

- Examples of Glucose Analyzers for Hospitals include: - Accu-Check Inform II System hemoCue Glucose 201 DM - Freestyle Precision pro - StatStrip - These devices require the use of special test materials like reagent test strips or microcuvettes that are unique to the device - Some test strips have a code that must match a code chip in the analyser - Some test materials are stored in vials that must be tightly recapped after obtaining the necessary strip or microcuvette - Other sare stored in tightly wrapped packages that must not be opened until just before they are used. All test materials must be protected from excessive heat and moisture to prevent deterioration - The HemoCue Glucose 201 DM accepts arterial specimens as well as skin puncture and venous specimens ; The test is performed using a microcuvette ; The device has a data management system that prompts the user for identification, lot numbers, and other required QC information during analysis - The StatStrip is the only glucose analyzer cleared by the FDA for use on critically ill patients using whole-blood or venous or arterial specimens ; It is not cleared by the FDA for use with fingerstick capillary blood on critically ill patients ; Capillary specimens may not represent the true glucose concentration due to insufficient peripheral blood flow caused by dehydration, shock and certain medications. Capillary specimens can be used in noncritical situations

Indications of Septicemia

- Fever - Chills - Malaise - Low blood pressure - Changes in mental status - Blood cultures are ordered based on whether the patient has a condition in which bloodstream invasion is possible, even in the absence of FUO. This is because some elderly patients and others with underlying conditions are often not capable of mounting good fever responses even though they have septicemia - Laboratory diagnosis of bacteremia of fungemia (fungus or yeasts in the blood) depends on the results of blood cultures, which are probably the most important cultures performed by the microbiology laboratory

Therapeutic Drug Monitoring Cont.

- For a drug to be beneficial, the peak level must not exceed toxic levels, and the trough level must remain within the therapeutic range - A pharmacist calculates drug dosages based on blood levels of the drug at specific times. If a specimen is collected late, it is important that the actual time of collection be recorded so that the pharmacist will be aware of the time change and can calculate values accordingly - Peak levels screen for drug toxicity, and specimens are collected when the highest serum concentration of the drug is anticipated - Peak times typically occur 30 mins after IV administration, 60 mins after intramuscular administration, and 1 to 2 hours after oral intake - Trough levels are monitored to ensure that levels of the drug stay within the therapeutic range - Trough level specimens are easiest to collect because they are collected when the lowest serum concentration of the drug is expected, usually immediately prior to administration of the next scheduled dose - Specimen collecting timing is more critical for drugs with shorter half lives - The FDA has approved gel tubes from some manufacturers for all analytes, including TDM; however, other manufacturers' gel tubes may affect TDM results

Trace Elements:

- Include aluminum, arsenic, cadmium, chromium, coper, iron, lead, mercury, selenium, and zinc - These elements are measured in such small amounts that traces of them in the glass, plastic, or stopper can leak into the specimen and cause false elevated values - For this reason, specimens for these tests must be collected in special trace element-free tubes - These tubes are typically royal-blue and contain EDTA, heparin, or no additive - The type of additive is indicated on the label (red for no additive, lavender for EDTA, and green for heparin) - Tan top tubes containing K2EDTA are available for lead analysis - When a trace element test is ordered, it is best to draw it by itself if using a needle/tube assembly, or a syringe may be used - For best results, when using a syringe to draw a trace element specimen, change the transfer device before filling the royal blue tube

Therapeutic Phlebotomy

- Involves the withdrawal of large volumes of blood usually measured by the unit (as in blood donation), or approximately 500 mL. It is performed by phlebotomists who have been specially trained in the procedure or in donor phlebotomy, since the procedure is similar to donor collection. It is used as a treatment for certain medical conditions such as polycythemia and hemochromatosis

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 these cases, the physician may order blood cultures to be collected in fastidious antimicrobial neutralization (FAN) or antimicrobial removal device (ARD) bottles - FAN bottles contained activated charcoal, which helps to neutralize the antibiotic - An ARD contains a resin that removes antimicrobials from the blood - The blood can then be processed by a conventional technique with less possibility of antimicrobial therapy inhibiting the growth of microorganisms ARDs and FANs should be delivered to the lab for processing as soon as possible

Principles of Lactose Tolerance Testing

- It is suggested that a 2-hour GTT be performed the day before the lactose tolerance test - A 2-hour lactose tolerance test is performed in the same manner as the GTT; however, an equal amount of lactose is substituted for the glucose - Blood samples for glucose testing are drawn at the same time used in the previous GTT test Results: - If the person has mucosal lactase, the resulting glucose curve will be similar to the GTT curve - If the patient lacks the enzyme, glucose levels will rise only slightly from the fasting level, resulting in a "flat" curve - False-positive results have been demonstrated in patients with small bowel restrictions and disorders such as slow gastric emptying, Crohn disease, and cystic fibrosis

Lookback Program

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

Electrolytes

- Minerals with an electric charge that are present in blood and body fluids - The most commonly electrolytes measured by POCT are sodium, potassium, chloride, bicarbonate ion, and ionized calcium - Sodium (Na+) is the most plentiful. Plays a major role in maintaining osmotic pressure and acid-based balance and in transmitting nerve impulses. A decreased sodium level is called hyponatermia. An excess level is called hypernatermia - Potassium (K+) is concentrated within the cells with very little found in the bones and blood. It is released into the blood when cells are damaged. Plays a major role in nerve conduction, muscle function, acid-based balance, and osmotic pressure. Low potassium is called hypokalemia. high potassium is called hyperkalemia - Chloride (Cl-) exists mainly in extracellular spaces where it joins with sodium to make sodium chloride (NaCl) and with hydrogen in the stomach to make hydrochloric acid. Plays a role in fluid and pH balance. Chloride must be supplied along with potassium when hypokalemia is being corrected - Bicarbonate (HCO3-) plays a role in transporting CO2 to the lungs and in regulating blood pH. Formed when carbonic acid is dissociated into H+ and HCO- ions. Hypoventilation results in higher CO2 levels and the production of more H+ ions and can lead to acidosis. Hyperventilation decreases CO2 levels and can lead to alkalosis - Ionized Calcium (iCa2+) accounts for 45% of calcium in blood; the rest is bound to protein and other substances. Only ionized calcium can be used by the body for such critical functions as muscular contraction, cardiac function, transmission of nerve impulses, and blood clotting

Coagulation Specimens

- Most coagulation tests are collected in light blue-top citrate tubes - Some coagulation tests such as anti-factor Xa are collected in a light blue top called a CTAD (because it contains citrate, theophylline, adenosine, and dipyridamole) - CTAD tubes are used to inhibit thrombocyte activation between collection of the specimen and testing - A discard tube for PT/INR, PTT/aPTT and some special coagulation assays is no longer needed - All anticoagulation tubes must be gently inverted 3 or 4 times immediately after collection to avoid formation of microclots, which can invalidate test results

Blood Alcohol (Ethanol) Specimens

- Normally a physician orders a blood alcohol, or ethanol (ETOH), test on a patient for medical reasons related to treatment or clinical purposes - In such situations, there is no requirement for chain of custody, but the results of such analytes can ultimately become evidence in court - For that reason, they need standard protocol and well-documented handling becomes very important - Blood alcohol determinations may be required because of on-the-job injury, employee insurance programs, and employee drug screening - Occasionally, a law enforcement agency may request a blood alcohol content (BAC) also called blood alcohol concentration, test on an individual who has been involved in a traffic accident - Both industrial and legal samples require that chain-of-custody protocol be strictly followed

Arterial Blood Gases and Electrolytes

- Often ordered in emergency situations because of the critical balance in which these analytes must be maintained - ABG readings are used to determine the pH of blood -Balance of electrolytes is essential for normal function of cells and organs

Glucose Testing

- One of the most important POCT procedures - Most often performed to monitor glucose levels in patients with diabetes mellitus - Predominantly use whole-blood specimens obtained by routine skin puncture - Some will accept a heparinized venous or arterial specimens - To perform the test, a drop of blood is applied to a reagent test strip or microcuvette. The analyzer determines the level of glucose in the blood, and the result appears on a display screen - Regulatory agency guidelines and CLSI recommend that a person receive institution authorization to perform POCT glucose testing only after completing formal training in facility-established procedures, including maintenance and quality control There are two types of analyzers: 1. One for personal use 2. Use in healthcare settings - Hospital-approved glucose analyzers are equipped with data management systems and require various QC checks to monitor the performance of the meter and the operator - Glucose analyzers for home do not have the same level of QC checks. It is common practice in hospitals to not use a patient's personal glucose analyzer for treatment decisions All analyzers approved for hospital use have the following characteristics in common: - Sample types may be venous, arterial, or capillary - They allow data to be downloaded from the device and transmitted to the LIS or electronic health record (EHR) - They require the use of a patient and/or authorized operator identification number - The require QC - QC must be repeated if the analyzer is dropped, the battery is replaced, or patient results or analyzer functioning are questioned

Paternal/Paternity Testing

- Paternal testing uses DNA profiling (also called genetic fingerprinting) to determine the probability that two specific individuals have a genetic parent-child releationship - DNA profiling can also be used to determine the probability of other genetic relationships such as grandparent-to-grandchild and sibling-to-sibling relationships - The most common parental testing is paternity testing to determine whether a man is the father of a specific child - Results are usually reported as a percentage, with a 99.9% being the highest - In general, paternity test results exclude the possibility of parentage rather than prove parentage - Testing may be requested by physicians, lawyers, child support enforcement bureaus, or individuals - Paternity testing requires a chain-of-custody protocol and specific identification procedures that may include fingerprinting - A photo identification document such as a passport is usually required - The mother, child, and potential father are all tested - Blood samples are preferred for testing; however, buccal swabs are increasingly being used

Typical Labeling Requirements for Blood Bank Specimens

- Patient's full name (including middle initial) - Patient's hospital identification number (or other unique identifier) - Patient's date of birth - Date and time of collection - Phlebotomist's ID number of full name - Room number and bed number (optional)

Lactate

- Patients who are critically ill can exhibit metabolic acidosis - The accumulation of lactic acid (lactic acidosis) in the blood as been identified as a cause of acid-based disorder (metabolic acidosis) - Lactic acidosis is associated with major metabolic issues and is due to hyperlactatemia. Hyperlactatemia is usually present in patients with severe sepsis or septic shock - Patients who have arterial lactate levels of more than 5 mmol/L have a very poor prognosis; consequently it is important to be able to obtain lactate results within minutes to effectively treat severe sepsis - If the test is performed in the lab, the sample must be transported on ice without delay and analyzed as soon as it arrives in the lab - The test can be performed bedside within a few seconds using the i-STAT or Nova Biomedical's StatStrip lactate analyzer

Rapid Syphilis Test

- Rapid syphilis tests detect antibodies to Treponema Pallidum, the bacterium that causes syphilis - The rapid tests are performed on serum, plasma, or whole blood, but they are typically performed using whole blood collected by fingerstick - Results are available within 15 minutes. - A positive test result must be confirmed with a second more complex test performed by a clinical lab

Specimen Requirements

- Require the collection of lavender or pink-top EDTA tubes. Sometimes a nonadditive glass red-stoppered tube is used - Specimens collected for blood bank testing can be rejected if they: - Are not labeled exactly as described in the lab protocol - Are grossly hemolyzed samples - Contain IV fluid (note if drawn from opposite arm or below IV) - Were collected longer than 72 hours before testing

Timing Considerations

- Should be collected as close to the time ordered as possible Other timing considerations include: - When more than one set is ordered for collection at the same time, the second set should be obtained from a separately prepared site on the opposite arm if possible - In some cases, "second-site" blood cultures are more useful when drawn 30 to 60 minutes apart. Follow laboratory protocol - If timing is not specified on the requisition, the phlebotomist should laboratory protocol - Blood cultures are typically ordered immediately before or during fever spikes when bacteria are most likely to be present. Timely collection is important, but volume is more important than timing in detecting the causative agent of septicemia

Skin Antisepsis

- Skin antisepsis, the destruction of micoorganisms on the skin, is a crucial part of the blood culture collection procedure - Failure to clean properly can introduce skin-surface bacteria into the blood culture bottles and interfere with interpretation of results - The best way to overcome this problem is by meticulous antiseptic technique during preparation of the skin with the appropriate bactericidal agent

Oral Glucose Challenge Test

- Some pregnany women develop gestational diabetes - The oral glucose challenge test (OGCT), also called the one-hour glucose screen test or gestational glucose screen tests, screens for gestational diabetes, and is a modified version of the OGTT - To perform the test, the patient is given a drink containing 50g 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 suggested that the patient have a follow-up OGTT within one week

Blood Bank Specimens

- Specimens yield information that determine which blood products can be transfused safely into a patient

Antiseptic or Sterile Technique

- Sterile means free from all living microorganisms - It is not possible to completely sterilize a blood culture site, but sterile blood culture technique reduces 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 the get to the bacteria beneath the dead skin cells on the surface of the arm - Tincture of iodine, chlorhexidine gluconate, and a providone / 70% ethyl alcohol combinations have all been shown to be effective antiseptics for cleaning blood culture collection sites - Research has shown that cleansing the patient's skin with chlorhexidine or tincture of iodine is superior to using iodophors such as providone-iodine in reducing contamination rate at blood culture collection sites - When using an ampule swab of chlorhexidine gluconate or tincture of iodine, the swab should be placed at the site of the needle insertion and move outward in concentric circles without going over any area more than once. The area covered should be at least 2.5 x 2.5 inches in diameter - If an iodine preparation is used, it should be cleaned from the site using alcohol or another suitable cleanser after the specimen has been collected - Chlorhexidine gluconate is the recommended blood culture site disinfectant for infants two months and older and patients with iodine sensitivity

Therapeutic Drug Monitoring

- Tests drug levels in the bloodstream at specific intervals and is used: - To manage patients being treated with certain drugs in order to help establish a drug dosage - While adjusting the dosage when in combination with other drugs taken - In identifying noncompliant patients - In maintaining the dosage at a therapeutic level - To avoid drug toxicity

Blood Donor Collection

- The American Association of Blood Banks (AABB) is an international organization that develops standards and provides educational and accreditation programs that focus on enhancing patient and donor care and safety - Blood centers are also regulated by the FDA since blood and blood products and considered pharmaceuticals - All potential blood donors must be interviewed to determine their eligibility to donate blood and to obtain information for records that must be kept on all blood donors

Bilirubin Testing

- The Bilichek Analyzer is a noninvasive, transcutaneous bilirubin (TcB) measurement system for newborns - The meter directs light into the skin of an infants head or sternum and measures the intensity of the specific wavelengths that are reflected back to determine the bilirubin concentration

Lipid/Cholesterol Testing

- The Cholestech LDX System can perform total cholesterol (TC), LDL and HDL cholesterol tests, and non-HDL and TC/HDL ratios - HDL cholesterol is good - LDL cholesterol is bad - Blood can be obtained by venipuncture or fingerstick and collected in a lithium heparin capillary tube for transfer into the testing cartridge - A quantitative result is obtained by the instruments evaluation of the intensity of a colored bar

Type, Screen, and Cross-Match

- The Type and Screen determines a patient's blood type (ABO) and Rh factor (positive or negative) - When a transfusion is required or there is a possibility that one may be required, a test called a cross-match 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 RBCs are mixed together to determine compatibility - A transfusion of incompatible blood can be fatal do to agglutination and lysis of the RBCs within the patient's circulatory system

Skin Preparation

- The antiseptic used to clean the venipuncture site must not contain alcohol or other volatile organic substances that might compromise results - Therefore, 70% isopropyl alcohol used for routine venipuncture site preparation or other alcohols such as methanol and ethyl alcohol must not be used for a BAC collection - Tincture of iodine contains alcohol and likewise should not be used - The most frequently used antiseptics for ETOH specimen collection are aqueous benzalkonium chloride (BZK) and sometimes aqueous providone-iodine - If alternate antiseptic is not available, regular soap and water can be used

Interferon-Gamma Release Assays

- The interferon-gamma release assay (IGRA) detects TB infection by measuring an individual's immune response to mycobacterium tuberculosis (M. tuberculosis or M-TB) - Performed by mixing a patient's WBCs with M-TB antigens - Most WBCs will release a substance called interferon-gamma (INF-y) that can be measured - A positive test means that the person has been infected with M-TB - An IGRA that is negative does not necessarily rule out active TB infection - Two IGRA tests approved aby the FDA are the QuantiFERON-TB Gold plus In-Tube Test (QFT-Plus) and the T-SPOT TB test

Hemoglobin

- The measurement of hemoglobin levels is an important part of managing anemia - An example POCT analyzer is Hemocue HB 201+ Analyzer - This device can determine Hgb levels in arterial, venous, or capillary blood specimens - A small amount of blood is placed in the microcuvette and inserted into the machine for a reading - As part of electronic QC, the analyzer automatically verifies the performance of the optics every time it is turned on and every two hours while the analyzer is left on

Principles of 2-Hour PP Specimen Collection

- The patient fasts prior to the test. This means no eating, smoking or drinking other than water for at least 10 to 12 hours before the start of the test - The patient is instructed to eat a high-carbohydrate breakfast (typically one containing the equivalent of 75 to 100 g of glucose) or given a measured dose of glucose beverage on the day of the test - After a meal, nothing else should be consumed before the test. The patient should rest during the 2-hour waiting period; no exercise - A blood glucose specimen is collected 2 hours after the patient finishes eating - A two-hour PP can also be performed by having the patient drink a beverage containing 75g of glucose and collecting the blood specimen two hours after their finish the beverage

Forensic Specimens

- The tests most frequently requested are breath or blood for alcohol - Other tests include urine drug screens and blood specimens for drugs and DNA analysis - When forensic specimens are collected, a special protocol, referred to as the chain of custody, must be strictly followed - Chain of custody requires detailed documentation that tracks the specimen from the time it is collected until the results are reported - 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 include the time, date, and place where the specimen was obtained, along with the signature of the person whom the specimen was taken - Patient identification and specimen collection take place in the presence of a witness, frequently a law enforcement officer, in which case protocol and packaging are completed by the officer before the specimen is sent to a crime lab for analysis - Any person who is involved in drawing a blood alcohol specimen for legal reasons can be summoned to appear in court

POCT Infection Control Issues

- The transferral of microorganisms from the environmental surfaces to patients is largely via hand contact with the surface. Although hand hygiene is important to minimize the impact of this transfer, cleaning and disinfecting environmental surfaces routinely is fundamental in reducing their potential contribution to the incidence of healthcare-associated infections - Several manufacturers recommend cleaning the device with 10% bleach - It has been proven that a 1:10 bleach solution can effectively clean and disinfect POC instruments, but to be effective, such a solution must be prepared daily - Bleach wipes are also available - The wipes are found to encourage cleaning due to convenience

Recommended Volume

- The volume of blood drawn is the most important variable in detecting the causative agent - It has been shown that the identification of pathogens increases in direct proportion to the volume of blood cultured NICU patient: - 1 mL for Pink Cap - 1 mL total <18 lbs: - 1 mL for Pink Cap - 1 mL total 18-29 lbs: - 3 mL for Pink Cap - 6 mL total ( 3 per 2 bottles) 30-88 lbs: - 10 mL for Blue Cap Aerobic - 20 mL total (10 per 2 bottles) >88: - 10 mL for Blue Cap Aerobic - 10 mL for Purple Cap Anaerobic - 20 mL total volume - According to CLSI, most bacteremia is caused by aerobic and facultative (able to live with or without oxygen) bacteria - In addition, pathogenic yeasts are recovered almost exclusively from aerobic bottles. Consequently, if less than the recommended volumes of blood is collected, the blood should be added to the aerobic bottle first; any remaining blood should then be added to the anaerobic vial

Direct Inoculation

- To collect the specimen directly into the blood culture medium, use a butterfly and specially designed holder - Connect the holder to the Luer connector of the butterfly collection set - Fill the aerobic vial first, because the butterfly has air in it - Avoid backflow by keeping the culture bottle lower than the collection site and preventing the culture medium from contacting the stopper or needle during blood collection - Mix each container after removing it from the needle holder - After filling both containers and collecting blood for any other tests, remove the needle from the patient's arm, activate the safety device, and hold pressure over the site

TB tests

- Traditionally a skin test that requires 2 visits ; One to administer the test and the second 48 to 72 hours later to have the results interpreted - TB blood tests require only one visit, which eliminates compliance issues with return visits that are sometimes a problem with the TB skin tests

Lactose Test

- 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, rising nor more than a few mg/dL from the fasting level - Some individuals normally have a flat GTT curve (resulting in a false-positive result) ; it is then suggested that they have a two-hour GTT performed the day before the lactose tolerance test so that results can be evaluated adequately - The noninvasive, preferred lactose tolerance test is the hydrogen breath test - This test also requires the patient to drink a special beverage with a measured dose of lactose that if not properly digested will ferment in the colon and release larger than normal levels of hydrogen in the breath samples that are taken at regular intervals during the test

Lactose Tolerance Test

- Used to determine if a patient lacks lactase - A person lacking the enzyme suffers from gastrointestinal distress and diarrhea following the ingesting of milk and other lactose-containing foods - Symptoms are relieved by eliminating milk from the diet

POC Coagulation Monitoring

-Some of the more common POC coagulation tests that involve monitoring are listed here: - Prothrombin time (PT) and international normalized ratio (INR) - Activated partial thromboplastin time (aPTT or PTT) - Activated clotting time (ACT) - Platelet function Among the POC instruments available to perform various coagulation tests are: - CoaguChek XS Plus - PT/INR - Hemochron Signature Elite - ACT - i-STAT - ACT, PT/INR - VerifyNow- Platelet Function

GTT Procedure

1. Follow normal ID protocol, explain the procedure, advise the patient that water is allowed by drinking other beverages, eating food, smoking, or chewing gum is not allowed 2. Draw the fasting specimen and check for glucose 3. Ask the patient to collect a fasting urine specimen if urine testing has been requested 4. Give patient the determined dose of glucose beverage 5. Remind the patient to finish the beverage within five minutes 6. Note the time the patient finishes the beverage, start timing for the test, and calculate the collection times for the rest of the specimens based on this time 7. Give the patient a copy of the collection times 8. Collect blood (and urine specimens if applicable) as close to the computed times as possible 9. Label all specimens with the exact time collected and time interval in addition to patient information 10. Deliver or send specimens to the lab as soon as possible

Blood Culture Collection Procedure

1. Identify the patient, explain the procedure, obtain consent 2. Sanitize the hands. Put on gloves 3. Apply tourniquet, identify venipuncture site, release tourniquet 4. Aseptically select and assemble equipment 5. Perform friction scrub 6. Allow site to dry 7. While site is drying, inspect bottles for defects, check expiration dates, remove flip-off caps 8. Cleanse the culture bottle tops while the site is drying 9. Mark the minimum and maxiumum fill on each of the culture bottles 10. Reapply tourniquet, perform venipuncture without touching or repalpating the site 11. Direct draw: Fill the bottles, and invert them several times 12. Withdraw needle, place the gauze, activate the needle safety feature, apply pressure 13a. Direct draw: Discard the blood collection unit 13b. Syringe Draw: Remove and discard the needle, attach the transfer device and fill and mix the bottles 14. Clean the patient's skin if an iodine preparation was used to clean the site 15. Label the bottles with patient's ID and other required information, including blood collection site 16. Dispose of used and contaminated materials 17. Thank the patient, remove gloves, and sanitize the hands 18. Transport specimens to the lab as quickly as possible

Cell Salvaging

A Medical procedure designed to recover blood lost during surgery and reinfusing it back into the body - It is a form of autologous blood transfusion - Prior to reinfusion, it is recommended that the salvaged blood be tested for residual-free hemoglobin - A high free hemoglobin level indicates that too many red cells were destroyed during the salvage process and renal dysfunction can result if the blood is reinfused - Free hemoglobin can be detected using point-of-care instruments such as the HemoCue Plasma/Low Hemoglobin analyzer

Drug Detection Times

Alcohol: 2 - 12 hours Amphetamines: 1 - 3 days Barbiturates: 24 - 52 hours Benzodiazepines: - Up to 1 week - Metabolites up to 3 weeks Cocaine: - Less than 12 hours Cannabinoids: 1 - 2 days - Metabolites up to 7 days Methadone: 24 - 36 hours Heroin: 4 - 12 hours Morphine: 6 - 12 hours Codeine: 10 - 12 hours Dilaudid, hydrocodone: 12 - 24 hours Oxycontin (extended release tab): 24 - 30 hours Aerosols: 30 minutes - 6 hours Volatile Solvents: 2 - 72 hours Anesthetic gases: 5 - 60 mins Phencyclidine: 3 - 5 days

Examples of Categories of Drugs that Typically Require Therapeutic Monitoring

Antibiotics and Antifungals - Aminoglycosides (e.g., gentamicin, tobramycin, amikacin), amphotericin, cholaramphenicol, vancomycin Anticonvulsants - Carbamazepine (Tegretol), ethosuximide, phenobarbital, phenytoin, valproic acid Bronchodilators - Theophyline, caffine Cardiac drugs - Digitoxin, digoxin, procainamide, quinidine Chemotherapy Drugs - Methotrexate. 5-FU Immunosuppressants - Azathioprine, cyclosporine, sirolimus, tacroliumus Protease Inhibitors - Atazanavir, indinavir, lopinavir, nelfinavir, ritonavir, boceprevir, telaprevir Psychiatric drugs - Antidepressants (e.g., imipramine, amitriptyline, nortriptyline, doxepin, desipramine), lithium, valproic acid

C-Reactive Protein

CRP is a type of Beta-globulin made by the liver and released into the blood after tissue injury, the beginning of an infection and other causes of inflammation - Measured as a sensitive but nonspecific marker of systemic inflammation disorders and associated diseases - Traditional CRP detects concentrations of 3 to 5 mg/L - High sensitivity CRP (hs-CRP) can detect low-grade inflammation even in asymptomatic individuals; It is typically used as an independent marker to identify individuals at risk for future heart disease, in which case it is sometimes called cardiac CRP - healthcare providers can use the Stratus CS analyzer to measure hs-CRP within 14 minutes using whole blood or plasma

QuantiFERON

Commonly called the TB-Gold test - Collected by drawing 1 mL blood into each of four special tubes - Tubes should be at room temperature at the time of collection - 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 10 times immediately after filling to ensure the entire surface of the inside of the tube is coated with blood - Do not overshake as this can result in gel dislodgment and lead to inaccurate results - Tubes must be transferred to an incubator as soon as possible within 16 hours of collection - There is no order of draw but this is commonly used: 1. Gray-top tube: Nil or negative control (has no additive) 2. Green-top tube: TB1 antigen tube (primarily detects CD4 T-cell response) 3. Yellow-Top Tube: TB2 Antigen tube (detects CD4 and CD8 T-cell responses) 4. Purple-Top Tube: Positive Control (contains mitogen, a nonspecific T-cell stimulator) - An alternate collection method is to draw the specimen in a single room temperature 5-mL lithium-heparin tube for later transfer to the special TB-Gold tubes - The specimen can be held up to 12 hours before transfer to the TB-Gold

Glycohemoglobin / Hemogloin A1c

Glcyohemoglobin, also called glycated hemoglobin, is glucose, which is chemically bound to hemoglobin A, the primary form of hemoglobin in adult - This combination is more commonly called hemoglobin A1c (HbA1c) - The rate of formation of HbA1c is directly proportional to plasma glucose levels - Glucose stays attached to the hemoglobin for the life of the RBC, which is around 120 days - HbA1c levels reflect the average blood glucose levels over the past 2 to 3 months and can be used to evaluate long-term effectiveness of diabetes therapy - The American Diabetes Association recommends measurement of HbA1c levels at least 2 times per year and quarterly in patients who are not meeting their glycemic targets - DCA Vantage Analyzer provides flexible data management and the convenience of an on-board printer. In addition, the clinician can see a patient's trend graph on the display screen for immediate review of previous results; this also facilitates a discussion of compliance issues with the patient

GTT

In normal patients, blood glucose levels peak within 30 mins to one hour following glucose ingestion - The peak of glucose results in the release of Insulin, which brings glucose levels back down to fasting levels within about 2 hours and no glucose spills into the urine - Diabetic patients have 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

POCT Quality Control

Many, but not all, POC tests are waived tests. POC tests that are not waived cannot be performed by phlebotomists - Waived tests do not required the same level of quality checks as tests classified as nonwaived, or sometimes referred to as moderately or highly complex tests - The College of American Pathologists (CAP) requires that external liquid control b e performed only as specified by the manufacturer's instructions on many of the waived tests - In most cases, that means performing liquid controls upon receipt of a new shipment of test kits and with each new testing personnel - If the kit is not stored properly or if the patient results are questionable, then controls must be performed before proceeding - POCT regulations from CAP serve as a minimum guide that must be instituted - Manufacturers of POCT devices have enhanced them to include internal QC checks that can detect problems with the specimen (i.e, clotting, short samples, air bubbles) and internal electronic checks that can determine if the instrument is functioning properly

Two-Hour posprandial Glucose

Postprandial (PP) means after a meal - Glucose levels in 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 (2-hr PP) 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 in specimens collected too early or late may be elevated or decreased, repsectively, leading to misinterpretation of results - If results are abnormal, other tests that might be ordered are HbA1c or a glucose tolerance

Blood Culture Specimen Requirements

Recommendations for the number of blood cultures to collect include the following: - For critical situations in which rapid administration of antibiotics is important, 2 to 3 cultures, one right after another from different sites is usually required - For FUO, two to three cultures, one right after another from different sites are usually required. If these are negative 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 (e.g., Myco/F Lytic media) bottles may be required to optimize the recovery of mycobacteria and fungi

Other POC Tests

See Below

Multiple-Test-Panel Monitoring by POCT

Several small, portable, and in some cases handheld, analyzers are available that measure multiple commonly ordered STAT tests. - Analytes that may be includede are Na+, K+, Cl-, and HCO3-, as well as gas blood values for pH, pCO2, pO2, and sO2, BUN, glucose, Hgb and Hct, ACT, lactate, and troponin - Any uncorrected imbalance can quickly turn life threatening - POCT instruments in the ER or ICU play an important role at these times because of the immediate test result availability Examples of Analyzers that can perform several different tests are: - ABL 80 Flex - AVOXimeter - GEM Premier - i-STAT - STAT PROFILE Prime - ABL80 Flex is used in clinics and full-service hospitals. Analytes measured include blood gases, electrolytes and glucose - The AVOXimeter diagnoses carbon monoxide toxicity and methemoglobin status of patients ; Aids in diagnosing and detecting intracardiac and great-vessel shunts; Can offer evaluation of blood gases in about 10 seconds - The GEM Premier 5000 measure critical chemistry analytes such as lactate, potassium, BUN and creatinine, allowing for near-patient screening for renal disease

Toxicology Specimens

Study of toxins - Clinical toxicology is concerned with detection of toxins and treatment for the effects they produce - Forensic toxicology is concerned with legal consequence of toxin exposure, both intentional and accidental - Toxicology tests examine blood, hair, urine, and other body substances for the presence of toxins, which often exist in very small amounts

Drug Screening

Testing for drugs involves sophisticated methods such as gas chromatography-mass spectrometry (GCMS) and liquid chromatography-mass spectrometry (LCMS) that must be done at a forensic or clinical laboratory - Drug detection times in blood are dependent on things like genetics, body size and composition, age, gender, history and tolerance of the user - A user's disease state and the drugs used to treat it that may remain in the user's system affecting detection times - There are legal implications to drug screening, and a chain-of-custody protocol is required even if the test is not being performed for legal reasons

Coagulation Specimens Cont.

The following are a number of important things to remember when collecting specimens for coagulation tests - Light blue-top tubes for coagulation tests must be filled until the 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, a discard tube must 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 - Never pour two partially filled tubes together to create a full tube, as the anticoagulant-to-blood ratio will be greatly affected - Coagulation factors V and VIII are highly unstable. If these specimens cannot be tested within 4 hours, they must be centrifuged and the plasma frozen - Drawing a coagulation specimen from a VAD is not recommended. However, if there is no other choice, the specimen can be drawn by a specially trained healthcare personnel . Coagulation specimens drawn from VADs require a discard volume of blood that is six times the dead-space volume of the tubing, or approximately 5mL

Cont.

The handheld i-STAT makes use of test cartridges that contain sensitive biosensors on a silicon chip made to perform specific tests. After choosing the appropriate cartridge, two to three drops of either venous or arterial blood is applied and then the cartridge is inserted into the iSTAT - the STAT PROFILE has a menu of 10 critical care tests (pH, pCO2, pO2, Na, K, Cl, iCa2+, glucose, lactate, and Hct) that can be performed using arterial, venous, or capillary samples ; It only takes 3 steps (pressing start, scanning or entering patient ID, and pressing aspirate)

Pediatric Blood Culture Considerations

There are additional challenges presented with pediatric blood culture specimen collection - The critical nature of pediatric pathogens such as Streptococcus Pneumoniae and Neisseria meningitidis and children commonly having previously received broad-spectrum antibiotics - Because of these considerations, special blood culture bottles must be used for pediatric populations. They are different from adult blood culture bottles in both the formulation of the broth and the volume - The same methods for skin antisepsis for adults apply to pediatric patients unless the antiseptic is tincture of iodine. It is recommended that in place of the iodine step, the site should be cleansed two additional times with separate preparation pads saturated with 70% isopropyl alcohol or ethyl alcohol - In general, for infants and younger children, the volume of blood collected for culturing should be from 1% to 4$ of the patient's total blood volume - Pediatric blood culture bottles are designed to accommodate an inoculation of up to 4mL of blood

Initial Specimen Diversion (ISD)

This technique has been shown to reduce blood culture contamination rates down to 0.2% sustained for 12 months in the Emergency Department - This uses a novel closed-system device which includes an integrated butterfly safety needle and transfer adapter, which is used to divert, sequester and isolate the first 1.5 to 2.0 mL of blood flow - The diverted blood contains skin plugs, cells, and microbes that could result in contamination of blood culture - The device then opens an independent, second sterile blood flow path for specimen collection into the blood culture bottles

Glucose Tolerance Test (GTT)

Used to diagnose problems of carb metabolism - The major carbohydrate is glucose - GTT evaluates the body's 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 are those in which the blood glucose level is increased (hyperglycemia), as in diabetes mellitus, and those in which blood glucose levels are decreased (hypoglycemia) - GTT evaluates the insulin response to a measured dose of glucose by recording glucose levels on specimens collected at specific time intervals. Insulin levels are sometimes measured also - GTT length is typically one hour for gestational diabetes and three hours for other glucose metabolism evaluations - The test rarely exceeds 6 hours - Results are plotted on a graph, creating a GTT curve - The method used to collect blood should be consistent for all specimens. If the first specimen was venipuncture, so should the subsequent collections. If the first was capillary, so should the other collections

GTT Preparation and Procedure

While preparing for a GTT test, the patient must: - Eat balanced meals containing approximately 150 g of carbohydrate for 3 days before the test - Fast for at least 8 hours but not more than 16 hours prior to the test - Be allowed to drink water during the fast and during the test to avoid dehydration and because urine specimens may be collected as part of the procedure; no other foods or beverages are allowed - Be discouraged from engaging in excessive exercise for 12 hours before the test - Not smoke or chew gum for at least 8 hours before or during the test, as these activities stimulate the digestive process and may cause erroneous test results - Receive both verbal and written instructions to ensure compliance