Chapter 20, pages 585 – 590, in CTVT

VENIPUNCTURE

OBJECTIVESDescribe patient preparation, positioning, and

procedures for blood collection from peripheral veins

Describe indications and procedures for collection of arterial blood samples in small animals

Become familiar with blood collection techniques and protocols

3

General Principles for Collection Of Samples for Laboratory Testing

Blood and urine samples should be obtained before treatment

Supplies are appropriate for the sample and gathered before collection is started

Site of collection is free of disease and debrisArea is prepared properly

4

Blood Sample CollectionGeneral guidelines

Minimum stress to patient is requiredAvoid hemolyzed sampleFill vacuum tube with syringe Anticoagulant tubes mixed gentlySerum tubes set at an angle and allowed to clot

Patient Condition ExamplesIs the animal in Shock?Dehydration statusIs the animal Breathing?Is the animal Normal and

Healthy?Are all the veins blown?Is the animal a neonate?

Temperament ExamplesIs the animal trying to take your head

off?Is the animal calm and laid back?Is the animal conscious?Is the animal dying?Remember “flight or fight” syndrome?

Needles (Get more than one) Syringes (Get more than one) Cotton balls (or gauze) in alcohol Vet Wrap, gauze or dry cotton balls

(Band-aid) Muzzle or muzzles (E-collars can also act

as great restraint devices) Proficient person to restrain the animal Hydrogen Peroxide (optional and if

available)

Venipuncture Supplies

Venous Blood SampleOnly through experience does one learn to

collect a blood sample quickly with minimal trauma to the vessel and minimal stress and discomfort to the patient

Proper RESTRAINT is as important as the venipuncture technique

You must always insert the needle bevel facing up, into the vein

Unlike injections – you ‘hold off’ the ENTIRE time, until you obtain all the blood you need

Venous Blood SamplePerformed with a needle and syringe or a

vacutainer collection systemThe method and needle gauge depend on:

Vessel sizeAmount of blood requiredIntended use of the sampletechnician preference

You should use the largest needle possible for the vein chosen and direct the bevel upward

Blood Collection

The reason you are drawing blood will dictate: Limb to be used Amount of blood you will needTime frame involved Your expertiseAlways think about the situation before you draw blood

Simple GuidelinesSmaller gauge needles are used with smaller or

more fragile vessels, or multiple venipuncturesThe amount of negative pressure applied to

aspirate the blood into the syringe must not be excessive

Forceful retraction of the plunger may result in hemolysis of the red blood cells as they pass through the needle. Remember these little guys are fragile. Not only can you collapse the vein but your lab results may be effected

Guidelines Before venipuncture, the hair and skin over the

vessel are wiped with a cotton ball saturated with 70% isopropyl alcohol (or you can shave the hair)

This helps to remove dirt, causes vasodilation, and improves visualization of the vein

In animals with dense hair coats, the vessel may be easier to identify if the hair over the vessel if parted with an alcohol ball or shaved

Peripheral Vein Blood Collection

Introduce the needle into the occluded vessel as far distally as possible.

Use a quick but smooth “poke”Do not “jab” into the vein – you will go through

itIf your first attempt is unsuccessful reinsert

the needle more proximal to the previous entry site. In other words, make your first attempt to draw blood as far down the leg as possible. If you miss or damage the vein you can always make other attempts moving upward along leg

Cephalic VenipunctureThe cephalic vein is located on the cranial aspect

of the forelegThe animal is restrained in sternal recumbency or

in a standing position. Your larger breed dogs prefer to remain standing or be seated with the foreleg in extension

If you are utilizing the right cephalic vein the restrainer is positioned on the animal’s left side

Use your thumb to help stabilize the vein so it does not roll

Lateral Saphenous Vein

Medial Saphenous Venipuncture in the Cat

This vein is located on the medial aspect of the rear leg, and is used to obtain small volumes of blood, primarily in felines

If the right vein is used place the cat in right lateral recumbency with the left rear leg abducted

The vein is occluded with pressure applied by the restrainer’s left hand in the right marginal region (kitty karate chop)

Wipe the leg with alcohol and part the fur until you see the vein

Blood is collected with a 22- to 25- gauge needle attached to a 1- or 3-ml syringe

Medial Saphenous Venipuncture in the Cat

Firm pressure is applied to the puncture site for at least 60 seconds after venipuncture. It is extremely important to do this because the medial saphenous veins are especially prone to hematoma formation

Even the best phlebotomist can cause a hematoma on a cat

Medial Saphenous Vein

Jugular Venipuncture Collection

Patient's head is raised exposing the neck Your initial attempt should be made in the caudal third of the

jugular veinSubsequent attempts can be made in a more cranial regionIf the vessel is damaged in the distal portion of the vein, a

more proximal region is still patent and usable for blood collection

The jugular furrow can be palpated just lateral to the trachea

Person drawing the blood must “Hold Off”

• Palpation of the jugular vein in lieu of visualization may be necessary in some animals

• Wiping the neck with alcohol helps to visualize the vein. In cats, water is sometimes used because

the smell of alcohol is often repugnant to them.

The smell sometimes makes them gag

After the Blood Collection; With a sense of urgency!

Detach needle from your syringeRemove stopper from collection tubeTransfer blood into the tubeIf utilizing a anticoagulant tube, gently invert the tube a few times to mix the contents. Do NOT SHAKE it!Your tube must be filled at least half way to achieve the appropriate blood/anticoagulant ratioAlways dispose of your needles/syringes in the

“sharps” container

Marginal Ear Vein – At Home Glucose testing

Arterial Blood Sampling

WHY? •Best way to assess pulmonary function•Blood Gasses tell us about the patient’s ability to ventilate and oxygenate

WHAT?•Measure CO2 (ventilation) and O2 (oxygenation)•Performed on a Blood Gas analyzer

Common errors with blood collection and handling

Rapid or forceful aspiration of the blood, especially through a needle less than 22g

Traumatic aspiration of blood Spraying the blood through the needle into a second vial. The

needle and tube stopper should be removed and the blood runs gently down the inside of the vial

Water present in the syringe, needle, or tube, causing osmotic damage to the cells

Collecting too little or to much blood for the amount of anticoagulant present, resulting in dilution error or direct cellular damage from concentration anticoagulant

Slow collection or delayed transfer to anticoagulant, allowing clumping of platelets and clot formation

Improper or incomplete mixing of anticoagulant. The tube should be gently but thoroughly rotated by hand or on an automatic tube rotator or it may be rolled across a flat surface

Excessive physical force, such as shaking, jarring, or dropping

VIDEOS ON VENIPUNCTUREhttp://www.youtube.com/watch?

v=AND813sHUkshttp://www.youtube.com/watch?

v=ofw6pnP04zY&feature=relatedhttp://www.youtube.com/watch?

v=iUnabo1KmgI