FRCA Notes

Maternal Cardiac Arrest

Resources

  • Maternal cardiac arrest is mercifully rare, with a prevalence of 1 in 20,000 - 30,000 pregnancies
  • The definitive resource is the Resus Council/OAA/MBRRACE guideline (see above)

Common obstetric causes

  • Amniotic fluid embolism
  • Eclampsia
  • Haemorrhage
  • Drug toxicity e.g. magnesium, spinal anaesthesia

  • Cardiac disease
    • Cardiac disease is the leading indirect cause of maternal death
    • Cardiomyopathy, arrhythmias and MI may cause or contribute to cardiac arrest

4H's and 4T's

  • Hypovolaemia e.g. haemorrhage, relative hypovolaemia from sepsis
  • Hypoxia
  • Hypothermia
  • Hypo/hyper-kalaemia, -calcaemia, -magnesaemia

  • Tamponade
  • Toxins e.g. LA toxicity, remifentanil, high/total spinal
  • Tension pneumothorax
  • Thrombus e.g. pulmonary embolus
    • Interestingly, one would normally thrombolyse individuals with cardiac arrest from suspected PE
    • Yet pregnancy is an absolute contra-indication to thrombolysis
    • Major surgery within 14 days is also an absolute contra-indication to thrombolysis
    • This would appear to exclude all parturients yet to deliver and all who had a LSCS from receiving thrombolysis...

  • For patients <20 weeks' gestation, no modifications are required
  • For those >20 weeks' gestation, standard ALS applies but with two major modifications
    • One minor potential modification is consideration of bi-axillary pad placing

Tilt

  • Patients should be resuscitated with either:
    • Manual displacement of the uterus to the left, or
    • Left lateral tilt of at least 15° (but <30°)

Perimortem caesarean section

  • Perimortem caesarean section should begin within 4 min of arrest and be accomplished by 5 min

  • The primary reason for perimortem caesarean is to maximize the chance of maternal survival by relieving aortocaval compression
  • Doing so both improves venous return and promotes transfusion of blood from the placental bed
  • Foetal survival is also optimized by rapid delivery; the best chance of survival occurs when delivery occurs within 5 min of maternal arrest
  • Overall the evidence base for doing this is fairly limited (see the above-linked Deranged Physiology page), but I can't envisage an RCT anytime soon...