Clinical Case 048: We Ask an Epidural Expert

This case is an opportunity for us to learn from an expert.  Epidural analgesia in labour can be rewarding and infuriating.  So I have enlisted the help of Dr Roger Browning – Consultant Anaesthetist at Fremantle and King Edward Memorial Hospitals {tertiary maternity centre in WA}.  I put a few questions to Roger based around a real case to see how the expert goes about troubleshooting common epidural problems. Here we go:

26 yo primigravida, induced for postdatism @ 41 weeks.  She is now ~ 6cm dilated with slowish progress.  You have been called to put in an epidural after she has tried nitrous and a dose of IM morphine.  As you arrive she is clearly very distressed with each contraction.  They are coming every 4 minutes on an Oxytocin infusion.  She is otherwise fit and well, normotensive.
Practitioners should use the technique they have learnt and are most familiar with. I would place a lumbar epidural using a 16G tuohy kit and loss of resistance to saline, and thread the catheter in leaving 4-4.5 cm in the space and secure it to her back using a “lockit”, medium tegarderm and surrrounding fixomull dressing for reinforcement. I would aspirate the catheter to check for blood or CSF and then test the catheter with a 7-8 ml injection of bupivacaine 0.125% + fentanyl 5mcg/ml. If there is no major motor block within 5min (ie indicating subdural or intrathecal catheter) I would then give another 5-8ml of solution ie 15ml in total to get initial analgesia.
At KEMH we use bupivacaine 0.0625% + fentanyl 2.5mcg/ml background infusion of 5ml/hr and PCEA 10ml with 20min lockout, via a CADD pump. In a rural hospital (and other metro hospitals like osborne park) I would prescribe intermittent topups: bupivacaine 0.125% + fentanyl 5mcg/ml 10-15ml hourly PRN, for breakthrough bupivacaine 0.25% 5ml hourly prn, rectal pressure pethidine 50mg/5ml hourly prn, and instrumental delivery / suturing ligonocaine 2% + adrenaline 1:20000 4ml + 4ml one dose only.
3 hours later….
You are called by the midwife for help.  She states that the epidural you put in worked great initially, but… now it is not so good.  She hasn’t made much progress up to 8 cm now.  We are still expecting a few hours of pain at best….
You need to assess whether or not you think the epidural cathetter is still in the epidural space. Check the patient’s back & dressing, if the catheter is now less than 3cm in the space, or there is a lot of fluid under the dressing don’t waste time trying more drugs etc, it has come out, take it out and place another epidural. If everything looks ok then carefully titrate in more bupivacaine 0.125% + fentanyl5mcg/ml solution, larger volumes will often “spread further” and tend to be better than small volumes of more concentrated LA. I will give up to another 20-25ml in increments over 10-20min. If this doesn’t work you should probably take it out and place a new epidural catheter.
Our 26 yo primi has made it to fully, but not really descending well.  The CTG trace has been getting ugly…  some decelerations at first, but now it has become flat / unreactive.  The Obs team call you for a Csection.  It is not Cat 1 urgent, but you want to get her ready ASAP.
Before starting an epidural topup for a CS once again you want to be sure the catheter is in the epidural space and it is working. Look at her back is the catheter < 3cm in the space? is there a lot of fluid under the dressing? has it been working well down in labour ward? If the answer is no to any of these you are probably better off taking it out and doing a spinal.  At KEMH to topup a epidural we use lignocaine 2% + adrenaline 1:200000 (which comes in a 20ml ampoule) and fentanyl 50-75mcg. You should aspirate the catheter to check for csf / blood and then give 5ml as a test dose, check for early profound block (?intrathecal) or tachycardia, perioral tingling (?iv). You should titrate in the lignocaine in 5ml increments every 5min, to max of 7mg/kg (in the average female this is around 25ml) checking the block height regularly, aiming for loss of cold sensation to T4 (nipples) and signs of sacral spread also (difficulty lifting legs off the bed). If after the maximal dose you have an inadequate block you should consider doing a CSE or spinal (using a smaller dose than usual as there is a risk of a high spinal) rather than causing local anaesthetic toxicity with even more lignocaine. I often also give pethidine 50mg (personal practice not dept) as it decreases the severity / incidence of shivering.
You give your top-up, get her ready and the Obs team start cutting.  As soon as they hit the peritonela layer she winces and says she feels sick.  A minute later and she is crying in pain – her husband is looking very scared.
And how do you go about making this decision?]  This description suggests she has an inadequate block and you should stop the surgeons before they proceed to making a uterine incision. The critical issue here is that once the surgeons incise the uterus they are commited to continuing, placental perfusion and foetal oxygenation is impaired and maternal haemorrhage starts, the surgeons cannot / should not be asked to stop for 15min whilst you try to “fiddle with your block”! You need to make a decision prior to this point. Clarify with the patient are they feeling pain or merely touch, believe them if they say it is pain. Check the dermatomes with ice and get the surgeons to “check with forceps etc in the surgical field. If the patient has significant pain at the point of peritoneal incision as in this scenario, and the block appears to be obviously inadequate I would err on the side of converting to a GA before then letting the surgery proceed. If you have already “topped up” with a decent volume of lignocaine 2% + adr (ie 15-25ml) and given this time to work (15-30min) it is unlikely that stopping for another 10min and giving another 5-10ml will make it into a working block. Having said that if they have a difficult airway or look high risk for a GA and you think some more time and more drugs will make a difference then it might be worthwhile to persist, this is an individual risk/benefit decision and you need to talk to the patient /surgeon and explain all of these issues. The most common scenario for pain during a caesarean occurs post delivery, is usually only mild, and related to temporary surgical stimulation whilst swabbing high in the abdomen or fiddling with the ovaries etc. Often you can get a patient through this with iv opioids, inhaled N20, some surgical infiltration of LA (beware max dose if you used alot in the epidural) and distraction with the baby! Sometimes you still need to do a GA to allow the surgery to finish though…
OK – that is epidurals through the eyes of an expert.   Big thanks to Dr Browning for taking the time to answer my questions. This is certainly a part of medicine with plenty of art, less science and a lot of inter-individual variation.  I am keen to hear your tricks and techniques.  Let us know on the comments.

Add a Comment

Your email address will not be published. Required fields are marked *