Anaesthesia for Circumcision
I use 1% lignocaine plain. Ensuring there is NO ADRENALINE. You can buffer the lignocaine just prior to injection with 0.05ml of 8.4% Sodium Bicarbonate made up to 1 ml 1% Lignocaine. I use a luer lock 1ml Syringe and draw the bicarbonate first.
1% lignocaine contains 10mg lignocaine per 1 ml. Maximum dose of lignocaine is 4.5mg/kg = 0.45ml/Kg.
So a 5 kg baby can have maximum 27.5mg lignocaine =2.75 ml 1% lignocaine
However effective anaesthesia can be obtained at a much lower dose.
My recommended maximum dose for circumcision is 0.3ml of 1% lignocaine per Kg eg 1.5ml of 1% lignocaine for a 5kg infant. However my usual dose is approx 0.5 - 0.7ml of buffered 1% lignocaine total.
I do an injection at 10 and 2 o'clock with a bleb, going through buck's fascia - the deep fascia, as the dorsal nerve supplying the glans is under that structure, being careful to avoid the vessels. Choose a point to inject the ring block approximately 1/2 way down the shaft for maximum effect, particularly to cover pain from tying the string to the ring.
With the common situation of rotation in the penis, the dorsal vein should be regarded as 12 o’clock, to avoid the dorsal arteries which lie either side of the vein. Some is injected superficial and some is just deep to the fascia.
I also do a ventral ring injecting superficially to avoid the urethra, about 1/2 way down the shaft to pick up the innervation from the superficial perineal nerve. Total dose given need not exceed about 1 ml of 1% lignocaine plain.
This may seem a lot of areas, but I have discovered that if I do this, I will almost always have total anaesthesia of the penis, and a relaxed baby. They are also given paracetamol and Lignocaine cream (EMLA) to the injection area 30 mins before surgery.
Don’t bother withdrawing to check for vessels - if you hit a vessel the syringe flashes back blood. If that happens, just reposition the needle and keep going. After injecting local, get your nurse to gently pinch the penis gently at the site of the flashback to reduce bruising.
Wait 4 minutes for effective anaesthesia.
EMLA applied for 60 to 90 minutes whih lessens the pain of the lignocaine injection. EMLA does not adequately anaesthetise the internal foreskin layer, and is inadequate as the sole anaesthetic for the procedure
Tootsweet is 24% sucrose and is useful to both settle and distract the baby. we use one 2 minutes before local is injected and another just before surgery 4 minutes later.
Inspect the penis to avoid blood vessels
Injection of 1% lignocaine at 10 O'Clock
Inject some each side at the subpubic space to collect the dorsal penile nerve branches before they enter the penis.
Inject at 2 O'Clock
Inject the left subpubic space.
Inject the ventral margin of scrotum/penile junction, to complete a ring block
Make sure you inject superficially over the urethra so it is not injured
A ring of lignocaine picks up the branches of the superficial peroneal nerve coming from the scrotum.