Venipuncture PP

Chapter 20, pages 585 – 590, in CTVT
 Describe 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
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 debris
 Area is prepared properly
Blood Sample Collection
 General guidelines
 Minimum stress to patient is required
 Avoid hemolyzed sample
 Fill vacuum tube with syringe
 Anticoagulant tubes mixed gently
 Serum tubes set at an angle and allowed to clot
Patient Condition Examples
 Is the animal in Shock?
 Dehydration status
 Is the animal Breathing?
 Is the animal Normal and Healthy?
 Are all the veins blown?
 Is the animal a neonate?
Temperament Examples
 Is 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?
Venipuncture Supplies
 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)
Venous Blood Sample
 Only 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
 You must always insert the needle bevel facing up, into the
 Unlike injections – you ‘hold off’ the ENTIRE time, until you
obtain all the blood you need
Venous Blood Sample
 Performed with a needle and syringe or a vacutainer
collection system
 The method and needle gauge depend on:
Vessel size
Amount of blood required
Intended use of the sample
technician 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 need
 Time frame involved
 Your expertise
Always think about the situation before you draw blood
Simple Guidelines
 Smaller gauge needles are used with smaller or more fragile vessels,
or multiple venipunctures
 The 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
 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
 Use a quick but smooth “poke”
 Do not “jab” into the vein – you will go through it
 If 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 Venipuncture
 The cephalic vein is located on the cranial aspect of the foreleg
 The 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
 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
 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 vein
 Subsequent attempts can be made in a more cranial region
 If 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
• 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 syringe
 Remove stopper from collection tube
 Transfer blood into the tube
 If 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 ratio
 Always dispose of your needles/syringes in the “sharps” container
Marginal Ear Vein – At Home Glucose testing
Arterial Blood Sampling
•Best way to assess pulmonary function
•Blood Gasses tell us about the patient’s ability to
ventilate and oxygenate
•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

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