Dr Roger Browning: On Oxytocin & Obstetric Anaesthesia
If you are reading this message – then I am on a beach in Vanuatu eating fish and drinking rum from a coconut. But I have a treat for you too !
This is a guest vodcast from one of my Obstetric Anaesthesia mentors Dr Roger Browning. Roger is a great bloke [even though he is a Kiwi!] and a Consultant Anaesthetist with particular interests in Obstetric haemorrhage and thromboelastography in major haemorrhage.
I have been lucky enough to attend a few of the live teaching sessions that Roger chairs at King Edward’s Hospital for Women in Perth. This lecture was taken from that session.
Apologies it is a little longer than the usual podcast, but plenty of food for thought for anyone doing Caesars, managing labour ward or Anaesthetics out there.
For those of you who are not really into Obstetric Anaesthesia I will summarise a few key take home points for you to consider:
- In the last few decades there has been a definite increase in the incidence of postpartum haemorrhage (PPH) in developed countries
- This increase is almost entirely due to “uterine atony” after birth…. why?
- Exposure to oxytocin causes pretty rapid desensitisation of the myometrium to the effects by way of receptor down-regulation
- The use of exogenous oxytocin infusions in labour is an independent risk factor for severe PPH
- The ED95 (effective dose, 95th centile) for oxytocin in elective (non-labouring, non-desensitised women is approx. 0.35 IU
- In the woman with “arrested labour’ who is desensitised to oxytocin, this increases to 3 IU
- Oxytocin is the best drug to use in women. Adding ergometrine etc did’t add much in oxytocin-naive women [ in “in-vitro studies”]
- In women with exposure to oxytocin – there is clinical equipoise around the use of additional oxytocic agents (in addition to oxytocin). This should probably be done on a case-by-case basis – looking at contraindications and risks of these agents.
- Consider early transexamic acid early in Obstetric haemorrhage.
- Remember surgical option for PPH in women with atonic uterus and contraindications to other oxytocic agents.
- We need to think hard and anticipate treatment failure in women who have been in prolonged labour or exposed to large / long doses of oxytocin. This is especially true in the bush where resources, back-up and blood products are scant!
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