Y khoa, dược - Collecting, processing, and testing blood specimens

48Collecting, Processing, and Testing Blood Specimens48-2Learning Outcomes48.1 Discuss the composition and function of blood.48.2 Describe the process for collecting a blood specimen.48.3 Explain the importance of confirming patients’ identities and correctly identifying blood samples.48.4 Describe how to perform venipuncture and capillary puncture procedures. 48-3Learning Outcomes (cont.)48.5 Identify the equipment and supplies required for blood-drawing procedures.48.6 Discuss the correct procedures for disposing of waste generated during blood-drawing procedures.48.7 Discuss common fears and concerns of patients and how to ease these fears.48-4Learning Outcomes (cont.)48.8 Develop techniques for helping patients with special needs, including children, the elderly, patients at risk for uncontrolled bleeding, and difficult patients.48.9 Identify common blood tests and explain their purposes.48.10 Perform certain blood tests. 48-5Introduction Medical assistantCollects blood specimensPerforms waived testingKnowledge neededUnderstand circulatory system and function of bloodAppropriate supplies and equipmentHow to perform and screen common blood tests48-6Role of the Medical AssistantPhlebotomy – insertion of a needle or cannula into a vein to withdraw bloodPut the patient at ease during procedureProcess specimens and conduct testingComplete necessary paperwork and make sure specimens are handled properly48-7Functions and Composition of BloodCirculatory system transports bloodHeart pumps 8–12 pints of blood through 70,000 miles of vessels/dayHematology – the study of blood48-8Functions and Composition of Blood (cont.)Functions of bloodDistributes oxygen, nutrients, and hormones Eliminates waste productsAttacks infecting pathogensMaintains acid-base balanceRegulates body temperature48-9Functions and Composition of Blood (cont.)Red blood cells – erythrocytes Internal respirationTransport oxygen to cellsHemoglobin – 98%Dissolved in plasma – 2 to 3 %Hemoglobin Main component of RBCsProtein containing iron48-10Functions and Composition of Blood (cont.)White blood cells – leukocytesProtect against infectionGranularBasophilsEosinophilsNeutrophilsAgranularT and B lymphocytesmonocytes48-11Functions and Composition of Blood (cont.)Platelets – thrombocytes Fragments of cytoplasmEssential for clot formationPlasma Clear, yellow liquidContains formed elements of blood90% waterSerum – clear, yellow liquid remaining after clot formation48-12Functions and Composition of Blood (cont.)Blood types or groupsPresence of antigens A and B determines type Blood also carries antibodiesTransfusions require careful matching to prevent hemolysis48-13Apply Your KnowledgeWhat is the role of the medical assistant related to collecting blood samples?ANSWER: The medical assistant will put the patient at ease during the procedure, process specimens, conduct testing, complete necessary paperwork, and make sure specimens are handled properly.48-14Apply Your KnowledgeANSWER: Functions of the blood are: (list any 3)Distributes oxygen, nutrients, and hormones Eliminates waste productsAttacks infecting pathogensMaintains acid-base balanceRegulates body temperatureWhat are three functions of blood?Very Good!48-15Collecting Blood SpecimensReading and interpreting the test orderReview orderAssemble equipment and suppliesPreparing the patientGreet and identify the patient Confirm pretest preparationExplain the procedure and safety precautionsEstablish chain of custody48-16Collecting Blood Specimens (cont.)Use Standard Precautions and PPE as neededHandling exposure incidentNeedlestick or other exposure to blood/blood productsReport to appropriate person immediatelyWash area and apply bandageDocument date, time, people involved, type of exposure48-17Drawing BloodNot all states permit medical assistants to draw bloodVenipuncture Puncture of a veinMost common sites are in the antecubital fossa and forearmCommon Sites for Venipuncture48-18Collecting Blood Specimens (cont.)Venipuncture complicationsHematomaHold needle stillHold pressure on siteafter removal of needleLatex allergyAsk patientUse non-latex gloves,tourniquet, and bandagesNerve injuryKnow anatomyInfections RareClean site prior to venipunctureMay not be evident for several days48-19Collecting Blood Specimens (cont.)EquipmentEvacuation systems – use special double-pointed needle, needle holderNeedle and syringe systemsButterfly system – winged infusion set and syringeCollection tubes Sealed to create a vacuumColor-coded to identify appropriate additive48-20Collecting Blood Specimens (cont.)Engineered safety devicesReduce the possibility of needlestick injuriesTypes Retracting needlesHinged or sliding shieldsSelf-blunting needlesRetractable lancets48-21Collecting Blood Specimens (cont.)Reagent products –chemically treated paper or dipstickSmear slidesCapillary punctureSuperficial puncture of skin with sharp point Lancets – small, disposable instrumentsAutomatic puncturing devicesMicropipettes – small, calibrated glass tubes that hold a precise volume of fluid48-22Apply Your KnowledgeWhat precautions should you take when collecting a blood specimen?ANSWER: You should use Standard Precautions and appropriate personal protective equipment.excellent!48-23Responding to Patient NeedsRespond with sensitivity and competenceFears and concerns Pain Bruises or scarsSerious diagnosisContracting a disease from the procedure48-24Special ConsiderationsChildrenTalk with parent or caregiver firstAddress child directlySpeak in a calm, soothing voiceExplain the procedure briefly in terms they can understandKeep child informed of status during the procedure48-25Special Considerations (cont.)ElderlyProne to bruisingDifficult to obtain an adequate sampleSpeak clearly in a low-pitched voiceAllow adequate time for patient to respond to questions48-26Special Considerations (cont.)Risk of bleedingHemophilia or taking blood-thinning medicationHold site for at least 5 minutesContact physician if bleeding does not stop48-27Angry or violent patients Explain need for testingAvoid arguingDo not force patientDocument behavior and if patient refusesSpecial Considerations (cont.)Difficult patientsDifficult venipuncture – do not stick more than twiceFainting patients –Reaction to blood drawPosition to avoid injuryDifficult patientsDifficult venipuncture – do not stick more than twiceFainting patients –Reaction to blood drawPosition to avoid injury48-28Apply Your Knowledge ANSWER: After drawing blood on a patient taking anticoagulants, you should hold a cotton ball over the puncture site for at least 5 minutes, monitor the site carefully, and notify the physician if bleeding does not stop.What is one precaution you can take when drawing blood from a patient who is taking anticoagulants?Correct!48-29Performing Common Blood TestsResults aid in diagnosisPOLs often only perform waived testsKnow office policy48-30Performing Common Blood Tests (cont.)Chemicals in labAnticoagulants – keep blood in uncoagulated stateSerum separators – form a gel-like barrier between serum and clot in coagulated sampleStains – color particular cells48-31Hematologic TestsBlood countsRBC countWhite blood cellsDifferential white blood cell PlateletHematocritHemoglobinCentrifuged Capillary Sample48-32Hematologic Tests (cont.)Morphologic studiesMorphology – study of shape and form of objects Requires special trainingCoagulation testsIdentification of potential bleeding problemsMonitor therapeutic drug levels for anticoagulantsPT and PTT48-33Hematologic Tests (cont.)Erythrocyte sedimentation rateMeasures rate of RBCs falling to the bottom of the blood sampleMust be performed on a fresh sampleTube must contain an anticoagulantRead after one hourRecorded as mm/hr48-34Chemical TestsRarely performed in the POLWaived tests Blood glucose monitoringHemoglobin A1cCholesterol tests48-35Serologic TestsIntroduction of an antigen or antibody into a specimen and detection of a reaction to itImmunoassays Western blotRadioimmunoassay (RIA)Enzyme-linked immunosorbent assay (ELISA)Immunofluorescent antibody (IFA) testRapid screening testsInfectious mononucleosisHIVHelicobacter pylori48-36Apply Your KnowledgeMatching:___ Hemoglobin A1c A. ESR___ Lysing RBCs/evaluating the color B. Serology test___ Shape or form of objects C. Coagulation tests___ Identify bleeding problems D. Chemical test___ Rate at which RBCs fall E. Differential___ Percentage of each type of WBC F. Morphology___ ELISA G. HemoglobinANSWER:GFEDCBASuper!48-37In Summary48.1 Blood is composed of plasma (the liquid portion) and formed elements. Blood serves as a transport medium for oxygen, nutrients, hormones, and waste products and also attacks infecting organisms, maintains acid-base balance, and regulates body temperature. 48.2 Blood is collected by one of two means: venipuncture or capillary puncture. Venipuncture is the process of obtaining a blood sample from a vein, and capillary puncture is the process of obtaining blood from a superficial skin puncture.48-38In Summary (cont.)48.3 It is essential that a patient’s identity be confirmed before a blood sample is collected. Correctly identifying the blood sample with the patient’s name ensures that the correct test will be done for the correct patient. 48.4 Venipuncture is performed by cleansing the skin in the antecubital space, applying a tourniquet above the space, inserting a needle into the vein in the space, and withdrawing blood by way of an evacuated tube. Capillary puncture involves cleansing the skin on the finger, sticking the finger with a safety lancet, and applying the drop of blood to a slide or in a small tube. 48-39In Summary (cont.)48.5 The supplies needed to perform a venipuncture include VACUTAINER components (safety needle, needle holder/adapter, collection tubes), antiseptic and cotton balls or antiseptic wipes, tourniquet, sterile gauze squares, and sterile adhesive bandages. Capillary puncture requires capillary puncture device (a safety lancet or an automatic puncture device such as Autolet or Glucolet), antiseptic and cotton balls or antiseptic wipes, sterile gauze squares, sterile adhesive bandages, reagent strips, micropipettes, and smear slides.48-40In Summary (cont.)48.6 All waste generated during blood-drawing procedures should be disposed of immediately. Sharps should be placed in the sharps container after activating the safety device, and gloves, gauze, and other disposable supplies should be placed in a biohazard container. 48.7 Patients are often concerned about pain, bruising, and scarring when having blood drawn. They are sometimes afraid that they may have a serious disease, especially if large amounts of blood are drawn. Good communication by the medical assistant is the key to easing these fears.48-41In Summary (cont.)48.8 There are always patients who will have special needs, including children, the elderly, patients who have bleeding disorders, and difficult patients. Each patient will present a special set of challenges and should be treated with the utmost care and concern.48.9 The most common tests performed in a physician’s office laboratory include hematologic tests, chemical tests, and serologic tests. 48-42In Summary (cont.)48.10 Hematologic, chemical, and serologic tests require special care when performing them. The medical assistant should review the manufacturer’s instructions carefully for important information about correctly performing each test.48-43End of Chapter 48Blood will tell, but often it tells too much. ~ Don Marquis