partial thromboplastin time principle and procedure

8/12/2019 PARTIAL THROMBOPLASTIN TIME PRINCIPLE AND PROCEDURE

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EXERCISE NO. 1

VENIPUNCTURE

OBJECTIVES

After performance of this exercise, the students must be able to:

Explain the venipuncture procedure

Give the advantages of venipuncture

Give the remedies to failure of blood to come out into the syringe/ vacuum tubes

Prepare the equipment/ materials needed to perform the venipuncture

Apply the tourniquet

Select the proper venipuncture site

Perform venipuncture

Care for a puncture site after venipuncture

List the preparations to be observed when performing the venipuncture

Enumerate the different types of anticoagulants and their uses

Define terms related to venipuncture

INTRODUCTION

The most common method of obtaining blood for laboratory examination is by

venipuncture. In venipuncture, sometimes called phlebotomy, the blood is taken directly

from superficial vein. The vein is punctured with a needle and blood is collected in a

syringe or tube. The venipuncture is the fastest way of obtaining a sample of blood form

which many different determinations/ tests can be performed.

The venipuncture is a safe procedure when performed correctly by a skilled

medical technologist. The procedure should be performed with care. Every effort should

be made to preserve the conditions of the vein. Much observation and practice are

required to become skilled and self-confident in the art of venipuncture.


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FIGURE 1 Mater ials for venipunc ture

1. Hypodermic needle

2. Syringe3. Syringe and needle assembled

The steps in venipunc ture are summarized as fol lows :

1. Preparing the equipment materials

2. Preparing the subject (patient) for venipuncture

3. Applying the tourniquet

4. Preparing the puncture site

5. Obtaining the blood

6. Care of the puncture site

Note: When performing a venipuncture, the students must be supervised by a qualified

instructor.


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PRINCIPLE

Blood specimen is obtained by puncturing the vein for examination which require more

than a few drops of blood. The venipuncture may be made by either the syringe method

or the vacutainer method.

MATERIALS/ EQUIPMENTS

1. Anticoagulated tube or bottle. Plain test tube

2. Disposable sterile dry syringe

3. Disposable sterile needles (gauge 21 or 23)

4. Tourniquet (rubber tubing, rubber bandage, flat rubber with commercial trade

names such as Veniket, Velket, etc.,)

5. Cotton balls

6. Vacutainer kit (In place of syringe and needle, if vacutainer method is to be used)

SYRINGE METHOD

Procedure

1. Assemble the equipment/ materials. Gather all the required tubes and supplies

for the procedure.

2. Identify and position the patient. Verify your patients identity and then ask him

to sit alongside the table used for taking blood. Lay his arm on the table, palmupwards and support it by placing a small cushion under the elbow.

3. Apply the tourniquet tourniquet must be placed above the elbow about 5 to

15cm away from the site of puncture. Place the tourniquet firmly but not too

tight to loose.

4. Select the vein with the tourniquet in place, use the pad of the index finger to

palpate the cubital fossa. Work across the fossa pressing up and down. The vein

will feel like an elastic tube under the skin. Select the best vein that is more

fixed and anchored better (median cubital fossa)

5. Apply the antiseptics clean and sterilize the area using cotton balls with 70%

alcohol.Let it dry.


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6. Insert the needle while holding the syringe with thumb top and the four finger

under and bringing the needle to an angle of about 15 to 30 degrees.

Puncture the vein you have selected.

7. Withdraw the blood pull the plunger with the either free hand not too fast and

not too slow until the desired volume is achieved.

8. Release the tourniquet remove the tourniquet as soon as the blood flows into

the syringe or before the desired volume is achieved.

9. Withdraw the needle place dry cotton ball in entrance of needle, ensuring no

pressure is applied. Then with one withdrawing motion, withdraw the needle,

keep the cotton ball in place and apply a little pressure to stop bleeding.

Note: ask the patient to elevate his arm for a while

10. Transfer the blood sample to anticoagulated and non-coagulated bottles or tubes

remove the needle with its cap, and let the blood flow along the side to

avoid hemolysis.

FIGURE 2 Tying a tour niqu et


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FIGURE 3 releasing the tour niqu et FIGURE 4 Veins most common ly

used for venipuncture

partial thromboplastin time principle and procedure

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