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Intravenous Techniques

Learning Objectives

Upon completion of this lesson the student should know how to:

  • Use proper judgment in restraint, positioning, vein selection, and equipment selection for venipuncture technique in animals

  • Perform venipuncture technique using peripheral veins of the dog and cat

  • Perform blood collection technique using a needle and syringe

  • Perform blood collection technique using the vacutainer collection system

  • Perform intravenous injection technique using the peripheral veins of the dog and cat

  • Be familiar with intravenous injection technique using the jugular vein of the horse

  • Know the commonly used venipuncture sites for ruminants and pigs

  • Troubleshoot technical problems with venipuncture techniques

  • Recognize, understand, and prevent the potential complications of venipuncture and intravenous injection

Reading assignment

Readings in Clinical Textbook for Veterinary Technicians 7th ed. by McCurnin and Bassert

Venipuncture techniques for sample collection or injection: pp. 586-591, 606-607, 623-633, 649-655

Introduction

Venipuncture is the technique of puncturing a vein with a needle device to enter the venous circulation. In this lesson, we will review the basic techniques of venipuncture for blood sampling and intravenous injection. Intravenous catheterization technique will be covered in a separate lesson.

Indications for venipuncture:

  • venous blood collection
  • to administer medication, blood, fluids, or test substances via an intravenous
  • injection
  • for intravenous catheterization

Restraint and Positioning

The restraint used depends on the choice of vein and is very important to the success of the procedure. Venipuncture requires a more exacting technique than subcutaneous or intramuscular injection techniques, as you are targeting a narrow structure that is also near other important structures such as arteries or nerves, depending on the vein. Be sure you are familiar with the anatomy for whatever vein you are using.

During venipuncture, the vein is distended by compressing it at a spot between the venipuncture site and the heart. When using the cephalic, lateral saphenous, medial saphenous, and femoral veins, the handler is responsible for both restraining the animal and distending the vein while the technician performs the venipuncture. When using the jugular vein, the handler restrains the animal while the technician compresses the vein and performs the venipuncture.

Vein selection

The choice of vein depends on the reason for venipuncture and the species with which you are working.

For small animals such as the dog or cat, the jugular, cephalic, saphenous, and femoral veins are used for blood sampling and intravenous catheterization. For intravenous injection, without using a catheter, the cephalic, saphenous, and femoral veins are used. When working with the hind leg veins, the lateral saphenous is preferred over the medial saphenous and femoral in dogs, and the medial saphenous and femoral is preferred over the lateral saphenous in cats.

For large animals such as the horse and ruminants, the jugular is generally preferred for many techniques.

Site preparation

Restrain and position the animal for venipuncture, then distend the vein by applying digital pressure between the heart and the venipuncture site. If the vein cannot be seen or palpated, clipping the hair may be necessary. Always get the ownerís permission to clip the hair before doing so.

Once the vein has been isolated, dampen the area is with alcohol. This aids in visualization of the vein, flattens the hair, and removes gross contamination from the skin and hair. Alcohol does not sterilize the site.

Basic Blood Collection techniques

Note that the smaller diameter needles will tend be more comfortable for the animal, but may increase hemolysis or clotting of your blood sample.

Basic Blood collection technique using syringe and needle

Equipment

  • Choose an appropriately sized needle- the larger diameter needles are usually used in 1 to 1 1/2" lengths while the smaller diameters are used in shorter lengths
  • Choose an appropriately sized syringe-determined by the size of the animal and vein, the size of the sample desired, and the size of the needle used. Large samples should not be collected through a small diameter needle as this increases the chance of hemolysis and clotting.
  • Alcohol swab or equivalent
  • Optional- clippers with no. 40 blade
  • Bandage material if needed- cotton or gauze and bandage tape

Technique

  • Select vein and prepare site
  • Equipment set up

-Select blood collection tubes and write animal identification on tubes

-Select needle and syringe

-Attach needle to syringe and move the syringe plunger back and forth to make sure it moves freely, then replace it to a closed position

-Prepare bandage for cephalic, saphenous, or femoral vein with dry cotton ball or gauze pad and bandage tape

  • Apply pressure to distend vein either digitally or with a tourniquet
  • Insert needle at a 20-30 degree angle, with the bevel facing up or away from the vein, through the skin into the lumen of the vein. With the bevel up, you can observe the bevel cutting the skin and also the lumen of the needle entering the skin and subcutaneous tissues. When a small amount of blood is visible in the hub of the needle or syringe, you are likely in the vein. Try to have some of the needle length threaded into the vein (about 1/2 inch).
  • Aspirate desired amount of blood into the syringe by slowly and steadily withdrawing the plunger using the third or fourth fingers while maintaining the same needle position

iv1.jpg (80533 bytes) Typical hand and finger position on syringe during blood collection

  • Release pressure on the vein
  • Remove the needle from vein and immediately apply pressure on the venipuncture site
  • Place blood promptly and gently into collection tubes. If an anticoagulant is used, gently rock the tube to disperse the reagent in the blood. Note : Many practitioners use sealed vacutainer tubes in which to dispense the blood sample:

Method 1: The needle, with the syringe still attached, is forced through the rubber stopper so that it enters the tube. The vacuum in the tube causes the blood to be automatically drawn into the tube through the needle from the syringe. If the blood is rapidly squirted into the tube with this technique, hemolysis may occur.

iv2.jpg (51454 bytes) Method 1: Transferring blood into blood specimen tube through needle

Method 2: The needle is detached from the syringe and the stopper removed from the collection tube before transferring the blood to the tube. Close the stopper on the tube after filling. The stopper will tend to come out again unless the pressure in the tube is equalized by inserting an 18 gauge needle into the tube through the stopper. You may hear a small hiss as air passes through the needle. Blood that clings to the inside surface of the stopper can be aerosolized through the needle out into the air, so some think that using this technique to equalize pressure is not appropriate. Remove the needle before sending to the lab.

iv3.jpg (50048 bytes) Method 2: Transferring blood into blood specimen tube through syringe

  • Maintain pressure on the venipuncture site for at least 60 seconds, apply bandage if appropriate.
  • Remove bandage after 1/2 to 1 hour.

Basic blood sampling technique using the Vacutainer system

Equipment-

  • Instead of a needle and syringe, a device known as the vacutainer is used. The Vacutainer collection system (Becton-Dickinson Co., Rutherford, NJ) consists of a double ended needle, a plastic holder, and a sealed collection tube with a rubber stopper. The needle is screwed into the top of the holder, while the collection tube is placed into the bottom of the holder.

iv4.jpg (55632 bytes) Vacutainer set up with needle, holder, and collection tube

iv5.jpg (36160 bytes) Some Vacutainer set ups utilize a "butterfly" attachment.

Once the vein is entered with the needle, the other end of the needle is allowed to pierce the collection tube. The vacuum in the tube causes the blood to be automatically drawn into the tube.

The vacutainer needles come in the same gauges as hypodermic needles. Use the same guidelines in choosing vacutainer needles as you would for regular needles. The holders also come in different sizes depending on the size of the collection tube that is being used. Generally the small holder and tubes would be used for cats and small dogs, while the large size holder and tubes would be used for larger animals.

iv6.jpg (40752 bytes) Vacutainer holders and tubes come in different sizes and types.

  • The rest of the equipment is the same as for blood collection with a syringe and needle.

Technique

  • Select vein and prepare site
  • Equipment set up

-Select blood collection tubes and write animal identification on tubes

-Select Vacutainer needle and appropriate sized holder

-Attach Vacutainer needle to holder, set blood collection tube into holder, but do not force the blood collection tube onto the needle yet

-Prepare bandage for cephalic, saphenous, or femoral vein with dry cotton ball or gauze pad and bandage tape

  • Apply pressure to distend vein either digitally or with a tourniquet
  • Insert the needle with attached holder at a 20-30 degree angle, with the bevel facing up directed or away from the vein, through the skin into the lumen of the vein. Have a blood collection tube ready. You will have to use your fourth or fifth finger as a brace at the end of the blood collection tube to keep the tube from falling out of the holder since it is not attached yet. Once you are in the vein, you may see a small amount of blood at the distal end of the vacutainer needle inside the holder.
  • Force the blood collection tube stopper onto the needle by pushing the tube farther up into the holder. This action takes a fairly firm push. Be careful to keep the needle steady in position as you do this.

iv7.jpg (62559 bytes) Blood collection with the Vacutainer system

iv8.jpg (42986 bytes)   iv9.jpg (48657 bytes)
Blood collection with the Vacutainer system using the butterfly attachment

  • Allow the blood to fill the tube to the desired volume. If other blood tubes are required, leave the needle in position and change to other tubes, filling as needed.
  • Release pressure on the vein
  • Remove needle from the vein and immediately apply pressure on the venipuncture site
  • Maintain pressure on the on the venipuncture site for at least 60 seconds, apply bandage if needed.
  • Remove any bandage after 1/2 to 1 hour

Basic intravenous injection technique using syringe and needle

Equipment

Equipment set up is the same as that for any venipuncture. It is very important to aseptically attach the needle to the syringe when setting up. The choice of needle and syringe depends on the volume and characteristics of the medication to be injected and the size of the vein being used. Always choose the smallest diameter needle as possible, but some medications are very viscous and require a larger diameter needle than you would normally like to use.

Technique

  • Check medication for the 5 Rís, for the presence of any impurities, expiration date
  • Select vein and prepare site
  • Equipment set up

-Prepare bandage with tape and cotton or gauze

-Select needle and syringe and assemble aseptically

-Clean the rubber stopper on the medication vial with an alcohol swab

-Remove needle cover and aspirate a volume of air into syringe to equal the volume of the injection

-Inject the air into the medication vial

-Aspirate proper medication volume by withdrawing the plunger

-Remove needle with syringe, some technicians like to replace the needle with a new one at this point

-Remove air bubbles by pointing the needle towards the ceiling and tapping the syringe barrel, then release the air by pushing on the plunger slightly

Important note: some medications, such as cancer chemotherapy agents, require special precautions in handling and it would not be safe to remove air bubbles by this technique in certain situations

-Verify that the correct volume is present in the syringe without air bubbles

  • Apply pressure to distend vein either digitally or with a tourniquet
  • Insert the needle through the skin into the vein and thread the needle into the vein. When using the jugular vein of large animals such as the horse, the needle is usually introduced into the vein without the syringe attached at first.
  • Aspirate a small amount of blood into the syringe to verify intravenous placement

iv10.jpg (50388 bytes) The presence of blood in the syringe indicates intravenous placement.

  • Release pressure on the vein
  • Inject medication by pushing on the plunger while maintaining the same needle position. Use the rate of injection recommended by the drug manufacturer. For large volumes, some technicians pause just before and during injection and reaspirate to confirm intravenous placement before continuing.

iv11.jpg (54090 bytes) Intravenous injection.

  • Remove needle from vein
  • Apply pressure to the venipuncture site immediately for at least 60 seconds
  • Apply bandage if indicated
  • Note the injection on the medical record
  • Remove bandage in 1/2 to 1 hour

Troubleshooting venipuncture technique problems

  • You canít find the jugular. If the animal is not too heavily furred or fat, this may be due to positioning problems:

1. Sometimes the neck is in a position that causes the jugular vein to flatten, making it hard to find-- Try repositioning the head so that the nose is higher or lower, or that the nose is tilted a little more away from you or closer to you.

2. Sometimes the shoulder position interferes with proper digital pressure on the jugular so that it does not distend with blood, making it hard to find--Try repositioning the front leg to change the shoulder position.

3. You apply pressure on the jugular furrow near the thoracic inlet, but nothing seems to happen. Try applying digital pressure across the entire jugular furrow more cranial to the thoracic inlet and directed somewhat against the trachea. As you apply digital pressure and release, observe for movement of the skin surface or hair that occurs as the vein fills and empties with the change in pressure. You can also palpate this movement as it occurs. Many dogs have a change in hair pattern, a "cowlick", at the jugular furrow where the vein resides so this will give you an additional clue as to where to look.

  • The rolling vein: Some veins will tend to bounce away from the needle as you go through the skin and attempt to enter the vein directly; this is called "rolling".

You can stabilize the vein in place by placing your thumb on the side opposite to the needle, and placing tension on the surrounding skin to tighten its position. Or try inserting the needle under the skin just lateral to the vein, then puncture the vein from the side by a slight redirection of the needle. You might feel a slight pop as you enter the vein.

Note: The needle is often redirected once the needle has been inserted under the skin, but there has not been success in entering the vein. An attempt can be made to reposition the needle while it is still under the skin so that additional skin punctures are not performed. If you choose to reposition the needle during venipuncture, do not change the angle of the needle while you are moving the needle in or out at the same time. To change the angle of the needle, pull the needle back so that it is just under the skin and away from deeper structures, then change the angle of the needle, and then direct it towards the vein at the new angle.

  • Losing the vein: When blood flow suddenly stops during blood collection, check for the following:

           1. The bevel of the needle is lodged against the wall of the vein. Rotate the needle slightly within the  vein to position the bevel towards the center of the vein lumen in the mainstream of blood flow

           2. There is a loss of blood pressure in the vein. If the rate of aspiration was too rapid, blood will be depleted from the vein and blood flow into the syringe or vacutainer tube will cease.

           -Make sure that digital pressure is still present

           -Stop aspiration, continue digital pressure, and see if the vein will redistend so that you can    continue drawing blood.

           -Gently squeezing or pumping the paw will also increase venous return.

           -Decrease the rate of aspiration

- If you are using a Vacutainer set up, a Vacutainer system may be inappropriate for this vein because the rate of aspiration cannot be controlled manually

          3. The needle became dislodged from the vein. Reposition the needle carefully. Keep the same angle of needle position you had when you were in the vein and move the needle slightly deeper or more shallow, depending on the circumstances. With each change in needle position, aspirate patiently to see if you are back in the vein.

          4. If a hematoma starts to form, stop the procedure and apply pressure.

  • Extravascular injection: As you are injecting intravenously, you notice a swelling develop around or slightly proximal to the venipuncture site, and the animal becomes restless. Even if the needle was properly in the vein at the time of injection, extravasation of the medication may have occurred because of excess pressure inside the vein during injection: administration was too rapid or proximal digital pressure was not released before injection.

Stop the injection procedure and notify the veterinarian. If an irritating substance has been injected extravascularly, immediate treatment to prevent tissue damage is warranted.

  • Hemolysis of blood sample: The serum or plasma is red tinged. Hemolysis is usually caused by rough handling of the specimen, and less likely by some pathology of the red blood cells.

You may have:

-used too small a needle diameter

-forcefully squirted the blood into the collection tube

-shaken the blood sample in the tube too much

  • Undesired clotting of blood sample: Inappropriate clotting of the sample is also usually caused by improper handling of the blood sample or venipuncture technique, and less likely by some disease process.

You may have:

-taken too long to perform the blood draw so that the blood started to clot in the syringe or needle

-not properly inverted the blood collection tube to disperse the anticoagulant in the sample

-performed a traumatic venipuncture, releasing tissue thromboplastin in your sample so that it clotted prematurely

  • Reentering the same vein on the same day:

Most technicians prefer to use a completely different vein for subsequent venipunctures on the same day.

If you entered the vein but were unsuccessful in your mission and had to completely remove the needle to start over again, only reenter the same vein where you can see that it is properly distended. Use new equipment. You may have to wait a few minutes before making another attempt on the same vein, otherwise distending the vein too soon can cause additional hemorrhage from the first venipuncture site. Generally, if you have to use the same vein, subsequent venipuncture should be attempted proximal to the previous sites.

  • You are in exactly the right place but you canít get into the vein and itís not a "roller": You may be too deep or too shallow to the vein or you may have gone through the vein and ended up in an extravascular space.

Use redirection techniques. Keep the same angle of needle position and move the needle slightly deeper or more shallow, depending on the circumstances. With each change in needle position, aspirate patiently to see if you are in the vein.

  • Bending the needle before venipuncture

Bending the needle is often purposely done to change the angle at which cat and small dog venipuncture is performed, making it easier sometimes to obtain the right position. But remember that when you prebend a needle, it narrows the lumen of the needle and weakens the needle, increasing the chance of problems. Use the correct equipment that allows you to obtain the proper angle during venipuncture rather than bending the needle.

  • Cleaning blood stains from fur: Most technicians find that over the counter 2% hydrogen peroxide works very well, copiously applied with a cotton ball.

Complications of venipuncture

Complications of venipuncture donít happen very often if you follow proper technique and good judgment in handling the animal. However, sometimes problems occur despite your best efforts:

  • Hematoma- This is a fluctuent non-painful swelling containing clotted blood that leaked out of the venipuncture site and collected into a surrounding tissue space before hemostasis occurred. Owners will notice it as a soft lump or swelling, and because blood has leaked into the tissues underneath the skin, purple or reddish discoloration to the skin may develop. Owners will recognize the discoloration as a bruise. Normally within a few days time, the blood is absorbed by the body and the swelling resolves. The bruise will change color from purple to green as the blood is metabolized from the area.
  • Hemorrhage- Blood leaks from the venipuncture site before hemostasis occurs, and a small amount of blood is often seen on the skin and fur at the site. Mild hemorrhage that occurs into the surrounding tissues will create a bruise. More dramatic hemorrhage from a venipuncture site is unusual but you should immediately notice it as blood draining or dripping from the venipuncture site onto the skin and fur. There may be an enlarging hematoma as well if the blood is leaking rapidly into the tissue spaces as it also exits through the skin. This kind of event will give you a special moment. Such dramatic hemorrhage may indicate a clotting defect or vein laceration.
  • Thrombosis- This is a blood clot that occurs inside the vein and may actually occlude venous blood return. The vein may collapse down temporarily as a result. If the blood clot is large and becomes dislodged, it could travel intact through the circulation and become an embolism.
  • Phlebitis- This is inflammation of the vein and takes a day or so to develop after the venipuncture. There would be edema, swelling, redness, and the area would be warm and painful to the touch. An infection of the vein may be the source of inflammation. This is a serious complication and if these signs are seen, the animal should receive immediate veterinary care.
  • Skin irritation- Sometimes the skin at the site of the venipuncture becomes irritated, usually by the preparation of the site before the venipuncture. The animal may respond afterward by licking or scratching the site excessively, even to the point of causing hair loss.

Complications of intravenous injection

  • Extravascular injection- If a medication intended for intravenous use is injected outside the vein, the immediate consequence would be that the medication will not have the desired effect as the blood level of the drug will not be achieved. Also, some medications can be very irritating to tissues. There may be edema, inflammation, or even necrosis and loss of tissue later if the tissue reaction is severe enough. Always notify the veterinarian if you inject something extravascularly.
  • Adverse reactions to the medication being injected: Allergic reactions take many forms and may include respiratory difficulty, vomiting, facial edema, urticaria, piloerection, erythema, or strange behavior. Some of these reactions are immediate, some take a few minutes to manifest. Adverse reactions can also occur if the injection is given too rapidly or with side effects inherent to the medication. Notify the veterinarian immediately and donít forget to record any adverse reactions on the medical record.

Links to websites of interest

How to use the transverse facial venous sinus in the horse-- you may need to register with IVIS first to get into the site- don't worry it is free and well worth having as a resource, then you will have to scroll down the list of articles to the "How To" section  http://www.ivis.org/proceedings/AAEP/2003

Intravenous techniques in pigs http://oslovet.veths.no/teaching/pig/pigbleed 

Blood sampling from mice http://www.uib.no/vivariet/mou_blood/Blood_coll_mice_.html 

Getting blood from chickens http://www.arbovirus.health.nsw.gov.au/areas/arbovirus/about/chickenmethods.htm 

References

McCurnin DM and Bassert JM: Clinical Textbook for Veterinary Technicians 5th ed WB Saunders Company, Philadelphia, 2002, pp. 67-71, 78-79, 89-92, 95-97

Crow SE and Walshaw SO: Manual of Clinical Procedures in the Dog and Cat JB Lippincott Company, Philadelphia, 1987, pp. 15-42

McCurnin DM and Poffengarger EM: Small Animal Physical Diagnosis and Clinical Procedures WB Saunders Company, Philadelphia, 1991, pp.129-137

Venipuncture technique photos using dog leg phlebotomy model

Writing assignment

When you have completed your study of the lesson, please answer the following questions and submit your answers via e-mail.  You may answer the questions directly in an e-mail or you may download the Word file, fill in your answers and return the Word file as an attachment.

Send to Dr. Bidwell: abidwell@nvcc.edu

Venipuncture Lesson Writing Assignment MS Word file

1. Name two veins other than the jugular that could be used for blood collection in cattle. Which of these two do you think you would or should prefer?

2. Name the veins that are used for blood collection in the pig.

Which one would you prefer to use?

Which one would you prefer least?

Which one do you think would be best for intravenous injection?

3. Name 3 possible situations when venipuncture would be contraindicated, and why.

4. Name the size ranges of the needles you would use for the jugular vein in the cat, dog, and large animals.

5. Name the size ranges of the needles you would use for the peripheral leg veins in the cat and dog.

6. What size range of syringe is usually used for blood collection in animals?

7. Why is the needle inserted with the bevel up?

8. What are the 5 Rís in medicating animals?

9. When using the jugular vein for intravenous injection in the cow, do you enter the vein with the needle pointing towards the head (upward) or towards the heart (downward) ?

10. How does intravenous technique for injection using the jugular in the horse differ from other species and why?

11. Why should subsequent venipuncture be attempted proximal to the previous sites?

12. To change the angle of the needle so that the tip of the needle moves more to the right, which way would you move the end of the syringe?

13. What problems with your venipuncture technique could cause hematoma?

14. What problems with venipuncture technique would increase the chance of hemorrhage?

15. What breeds of animals are at risk for hemorrhage?

16. In what organ would embolism most likely occur from a peripheral vein thrombus and why?

17. What problems with venipuncture technique would predispose an animal to phlebitis?

18. What problems with venipuncture technique would increase skin irritation?

19. What handler mistake during intravenous injection technique would increase the possibility of the medication gaining access to the perivascular space even if you are in the vein?

20. How can you tell you are injecting something extravascularly?

21. What is the minimum time for which you should apply pressure to the venipuncture site when you are done?