copyright © 2010 delmar, cengage learning. all rights reserved. chapter 40 phlebotomy: venipuncture...

Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED.

Chapter 40

Phlebotomy: Venipuncture and Capillary Puncture


Why Collect Blood?

• Phlebotomy used to determine disease and treatment

• Bloodletting dates back to ancient Egyptians

• Phlebotomy historically used to cure patients with “bad” blood


The Medical Assistant’sRole in Phlebotomy

• To collect blood as efficiently as possible for accurate and reliable test results

• Role varies

• Direct contact with patient


The Medical Assistant’sRole in Phlebotomy

• Provide high-quality care

• Focus on safety


Anatomy and Physiologyof the Circulatory System

• Blood forms in body’s organs and bone marrow

• Blood carries oxygen and nutrients to cells and removes waste products and carbon dioxide

• Click here to see an animation



• Veins– Usually carry deoxygenated blood, containing carbon

dioxide and other cellular wastes

– Thin-walled (thinner than arteries)

– Carry blood back to the right side of the heart from the cells

– No pulse

• Capillaries connect most arteries and veins



• Arteries– Usually carry oxygenated blood

– Thick-walled

– Branch to form arterioles, which branch to form capillaries

– Have pulse

– Path of blood away from the heart



• Body contains about 6 liters of blood

• Forty-five percent of blood is formed elements– Erythrocytes

– Leukocytes

– Thrombocytes (platelets)



• Two mL of blood will yield about 1 mL of fluid– Liquid part of blood is plasma

• Clotting converts fibrinogen into fibrin



• Centrifuge separates serum from blood

• Anticoagulant prevents blood from clotting to produce plasma specimen

• Buffy coat



• How to obtain blood sample– Antecubital area

– Median cubital vein

– Superficial veins in hand

– Veins in wrist

– Veins in feet or legs

– Arteries of arms


Venipuncture Equipment

• Syringes and needles– Do not destroy integrity of vein

– Syringes vary in volume from 1 mL to 50 mL

– Pull plunger of syringe to create vacuum within barrel



• Syringes and needles– Avoid causing vein collapse

– Use with butterfly collection set

– Recommended length of needle



• Safety needles– Required

– Protects patient and health care worker



• Vacuum tube system– Vacuum tube system

– Closed system

– Tube with vacuum already in it attaches to needle• Tube’s vacuum is replaced by blood

– Double-pointed needle with different-length needle on each end and screw hub near center



• Vacuum tube system– Needle acts as pipeline to deliver blood from patient to

tube

– Bevel of needle should face upward when inserted into vein

– Insert at 15° angle

– Safety tube holders



• Additives, anticoagulants, and gels– Different tests require different types of blood

specimens

– Anticoagulants prevent clotting of blood

– Steps to a clot

– Basic anticoagulant tubes

– Other additives improve quality of specimen



• Additives, anticoagulants, and gels– Thixotropic separator gel >>

– Separator gel tube: centrifuging process

– Glass particles activate clotting



• Tourniquets– Constrict flow of blood in arm

– Make veins more prominent

– Rubber or elastic strip 1 inch wide by 15–18 inches long

– Blood pressure cuff may be used instead



• Specimen collection trays– Hold all equipment necessary– Carts also used


Venipuncture Technique

• Approaching the patient– Social skills

– Technical skills

– Administrative skills



• Preparing supplies and greeting the patient– Prepare before venipuncture

– Keep spare tubes

– Put patient at ease



• Patient and specimen identification– Ask patient to state full name

– Check wristband if applicable

– Label sample tubes before leaving examination room

– Check paperwork against tubes



• Patient and specimen identification– Computer label >>

– Aliquot specimen



• Positioning the patient

• Selecting the appropriate venipuncture site– Order of preferred sites

• Antecubital

• Back of hand

• Wrist (difficult)

• Ankle or foot (needs a doctor’s written order)

– Use of tourniquet



• Performing a safe venipuncture– Find site that will give best blood return

– Palpate vein with tip of finger

– Differentiating between veins, tendons, and nerves

– Use the tourniquet appropriately

– Avoid scars and compromised arms



Click Here to play the video



• Syringe specimen collection– Identify patient

– Verify paperwork and tubes

– Assemble equipment

– Situate patient in comfortable position

– Wash hands



• Syringe specimen collection– Select vein

– Tie tourniquet

– Don gloves

– Clean site and allow to air-dry

– Palpate for vein



• Syringe specimen collection– Hand position to hold syringe >>



• Syringe specimen collection– Place blood in appropriate containers

– Fill tubes according to recommended order

– Activate safety device immediately

– Place empty syringe and needle into sharps container



• Vacuum tube specimen order of draw– Procedure follows syringe method with only slight variations

– Proper hand position >>

– Order of draw



• Butterfly collection system– Combines benefits of syringe and vacuum methods

– Used for small or fragile veins that are difficult to draw

– Winged needle inserted at about 5° angle then threaded into vein



• Blood Cultures– Use a surgical solution rather than alcohol– Use sterile techniques– Blood is collected into special transport bottles

• Aerobic bottle is filled first, then anaerobic



• Patient reactions– Vary

– Stop if pain persists



• The unsuccessful venipuncture– Try another tube

– Change position of needle by rotating needle half a turn

– Advance further into vein



• The unsuccessful venipuncture– Pull back a little

– Methods of vein stimulation

– Probing of vein not recommended

– After two attempts, have someone else try



• Criteria for rejection of a specimen– Quality assurance for specimen collection and

processing

– Another specimen often obtained to recheck results



• Factors affecting laboratory values– Incorrect specimen handling and storage

– Patient factors• Not fasting

– Drawing procedure incorrect• Alcohol in specimen

• Tourniquet on too long

• Wrong tube


Capillary Puncture

• Method of obtaining one to several drops of blood

• Tests that use blood obtained by capillary puncture– CBC, RBC, and WBC

– Hemoglobin and Hematocrit

– Glucose testing

– Phenylketonuria testing


Capillary Puncture

• Puncture sites


Capillary Puncture

• Preparing the puncture site– Promoting circulation

– Cleaning and disinfecting >>


Capillary Puncture

• Performing the puncture– Wear appropriate PPE

– Perform the puncture in one steady motion >>

– Wipe away the first drop of blood

– Collect in capillary tubes or other capillary collection device >>

copyright © 2010 delmar, cengage learning. all rights reserved. chapter 40 phlebotomy: venipuncture...

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