Venipuncture

The Procedure

1. Wash your hands and get your equipment ready – DO NOT FORGET THE SHARPS BIN! There are two types of alcohol wipe found around the hospital. You should try and use the red wipe for equipment and the blue wipe for skin, but if only one type is available, then don’t worry. You should clean out the blue tray with the red wipe. Start on the inside, then do the outside. Then collect together the rest of your equipment – a blue wipe for the skin, cotton wool, tape, needle, syringe and tourniquet. Twist the needle onto your tourniquet so it is ready (but leave the needle sheathed). If you are to take more than one sample, make sure you have enough syringes. There are different coloured syringes that are for taking samples for different purposes: [note – these will vary in different Trusts / regions / countries]
   1. Red top – haem
   2. Brown top – urea/electrolytes
   3. Yellow top – glucose
   4. Green top – coagulation
   5. Blue top – blood transfusion
   6. NOTE – you don’t have to wear gloves for this procedure – is it just a matter of choice. If you do wear them, make sure you change them where indicated.
2. Introduce yourself – go and see your patient – check they are the right person; check their name on their wristband and their date of birth. Tell them what you are going to do and why, ask if this is ok.
   1. Check for allergies, and anti-coagulant medication
   2. if they are on anti-coagulant therapy, tell them it might bleed a little bit more than normal, but that this is nothing to worry about.
3. Find the vein – expose the patient’s arm, and put the tourniquet on about 2-3cm above the cubital fossa. If you can’t see much, then ask the patient to clench and open their fist a few times. You should FEEL for a vein. You want one that feels bouncy, and that you can palpate both edges of. When you are happy,  (take off your gloves), wash your hands, (put new gloves on) and then wash the patient arm. Use either the blue wipe, or one of the swab things that you have to crack open. Wash the area for 30 seconds and let it dry completely. When you are washing, do it firmly both along the direction of the arm, and at 90’ to this. Do a firm hard scrub.
4. Stick the needle in! – anchor the vein just below where you are going to puncture it with your non-needle (left) hand. Do not touch the actual entry site after you have cleaned it. With the needle at 20’ to the arm, push it into the vein, with the hole of the needle pointing upwards. Push it in about 2-3mm. Pull back the syringe just a little to see if it fills with blood (i.e. to check you are actually in the vein). Make sure you keep the needle fixed and secure all the time. You should ideally hold the base of the needle with your left hand, to keep your right hand free to do other things. If you are confident you are in a vein then you can pull the syringe all the way back. You can do this as quickly or as slowly as you want. When it clicks in place, you can’t pull it back anymore. Make sure you fill up the syringe to past the filling line. If you need to take more samples, then you can remove the syringe but keep the needle in place and just attach a new syringe.
   1. Flashback – this is the first bit of blood that comes into the syringe. It shows you that you are actually in the vein. If you see flashback, but are then unable to withdraw anymore blood, you have probably gone all the way through the vein and out the other side! In this case, pull the needle out a bit and try to withdraw a bit more blood.
   2. when you have filled your syringe, make sure you tilt/shake the bottle, to ensure that any preservatives in the syringe will mix properly with the blood.
5. Take the tourniquet off! – as soon as you have finished, and BEOFRE you remove the needle, take the tourniquet off!! Then put cotton wool over the needle entry site, and then withdraw the needle and press on with the cotton wool. Get rid of your needle quickly – straight into a sharps bin! You can ask the patient to hold down the cotton wool if they are able to. If not then you should hold it down until it stops bleeding. Never leave the patient if it is still bleeding.
   1. When you do leave, stick a plaster over (if not allergic), or if they are, just tape down some cotton wool.
6. Label up your blood samples, and then put them in their packets, and label up the packets. Students are not allowed to sign off blood samples – i.e. you are not allowed to send the sample off to the lab; you will have to get someone else to check it over first.
7. Clean up – throw everything away that should be thrown away, and clean your blue tray. Thank the patient, and don’t forget to wash your hands.

General tips

• If you have to take lots of samples, start with the largest sample and work your way down – its easier to get more blood at the beginning.
• Straight after you have taken your sample, turn it upside down, swill it around a bit. The different coloured tubes each have different substances inside them that react with the blood. You should make sure the blood is well mixed with these substances.
• You don’t have to fill the samples to above the line, except those for coagulation.
• If you can’t easily see a vein, then you can leave the tourniquet on for up to 2 minutes to see if one becomes visible/palpable. Watch out for the arm turning blue though! You could also try asking the patient to lower their arm, as this reduces venous return from the arm to the heart. Also ask them to do this fist thing. If all else fails you can try the hand – but this is more difficult and painful for the patient. You are more likely to rupture the vein, and its unlikely you can collect more than 10ml from here do to the reduced perfusion in this regions
• Always be polite, courteous and enthusiastic! If you make a mistake, patients are much less likely to complain if you were nice to them than if you were rude.
• You should not take blood from an arm when:
  • There is an obvious AV fistula. This is where there is an abnormal connection between an artery and a vein. It make be the result of a congenital defect, pathological, or most likely it will be surgical.
  • There has been a mastectomy (removal of breast) on that side of the patient.
  • The arm is damaged from stroke
  • The arm has a drip going into it.
• You should never take blood from a vessel that has a pulse!

Complications

• Haematoma (a collection of blood in the subcutaneous tissues) – this is relatively common, and will most likely be seen as a lump under the needle site after you remove the needle. It is normally the result of going all the way through the vein (and consequently you may also have not collected any blood at all.). They are more likely to occur if you leave the tourniquet on as you remove the needle because this causes increased pressure, thus forcing blood out of the hole you have just made. If you cause a haematoma, then press down on it firmly with a swab for about 2 minutes.
• Bruising – relatively common but can be unsightly and painful for patient.
• Nerve Damage – you always run the risk of getting a nerve when you perform this procedure. Just be aware of where the nerves are and be careful. Never perform Venipuncture near the wrist (particularly the inner aspect) as there are a lot of nerves in this region.

References

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