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Paediatrics: Venepuncture & Cannulation

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As an FY1 it is likely that you will manage paediatric patients during their admission, often in other specialties like general surgery. Particularly in general surgery you will find you will have to bleed or cannulate these patients as general phlebotomy rarely covers paediatric patients.

Bleeding or cannulating children can cause a lot of anxiety for Junior Doctors, but with the right help, it is no different from any adult.

Find the right place & people
Paediatric wards often have treatment rooms specifically for taking bloods and small procedures. There are games, books, lights and plenty of fun toys to distract the children so it is a great place to do the bloods.

Ideally take someone with you. Ideally two extra people, one to distract the child and one to help hold the limb and pass you equipment. Paediatric wards often have play specialists who are trained to help distract children and they are a fantastic help for taking bloods.

Use the right equipment
It is important you familiarise yourself with the equipment as it is often different. 

Local anaesthetic creams like emla can be applied in advance to minimise the discomfort patients encounter. Nursing staff can often apply this if you request it over the phone if you know you're going to need to bleed a patient later. 

Paediatric blood tubes are much smaller & therefore you require far less blood (great for a clotting!). Consider using a vein finder (found on most paediatric wards) which are handheld devices that shine a light to identify veins. 

Avoid multiple punctures by considering a cannula. It is an easy way to take blood as you insert the cannula and then let the blood drop into the tubes. In case you find you need more blood, as long as you have not flushed the cannula you can draw another sample. It also saves the child from another puncture if you need a cannula in the future. Do remember to bandage it well as paediatric cannulas have the habit of falling out.

Capillary bloods
If you absolutely cannot find a vein, then you can use capillary bloods. A lance (slightly larger than the diabetic finger prick) on a heel or finger can be used with the blood being dropped into a tube. It isn't ideal though as bloods can easily haemolyse giving you skewed U&Es. 

Blood gas analysis can be performed on a capillary blood sample. Again heel or finger prick is used to draw blood into a capillary tube. These can then be analysed on the same machines as syringe samples. These are very useful for pH, Bicarb and lactate etc, however, the CO2 and O2 should be interpreted with caution. Furthermore, cold peripheries can cause the lactate to be falsely elevated. Electrolytes (although sometimes inaccurate) are also included on the results.

Dr A Przystupa (FY3 Paediatrics: DGH in the East of England)

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