Platelet Limbo

Two cases of pregnancy-thrombocytaenia last week brought out the old discussion about the use of regional anaesthesia when the platelet count is low. The first case was HELLP syndrome: unwell, RUQ pain, and platelet count of 25,000. She had no petechiae on her mucosa, or under the sphygomanometer cuff, and the venepuncture sites had healed well. Her airway looked alright for intubation. After dexamethasone and several hours of magnesium infusion overnight Caesarean delivery of the 34 week baby was successfully undertaken with general anesthesia (with isoflurane of course!) without a platelet transfusion. Clots formed in the operative field and the estimated loss was less than average. She was extubated and tranferred to HDU and did well. The strategy here was to treat the patient rather than a number: there was no clinical sign of thrombocytopenia and there was no bleeding- thus no platelets were given and the ones that were going around seemed to do the job enough.

The other case was one of moderately severe preeclampsia for cesarean delivery; her platelet count was 79,000. Again there was no overt sign of low platelets and spinal anesthesia was successsfully used without a problem. She presented a good scenario for discussion because her oedema and adiposity would have made for a worrying attempt intubation, and this is often the case because obese, older and oedematous patients are the ones with more severe forms of preeclampsia and the more difficult looking airways. It is a nonsense that a neuraxial block is safe at 50,000 but not at 49000. In these cases induction of general anaesthesia can result in a failed airway and awake intubation can provoke a marked hypertensive response which, ironically in a preeclamptic, could precipitate an intracranial hematoma. So how low can you go with a platelet count and a spinal? Probably lower than we would normally like. Look at the patient and consider the alternatives and the circumstances. Even if a spinal hematoma does develop, the disaster is if it unrecognised and untreated, not if it occurs. It is better to be calling for a neurosurgeon rather than a forensic pathologist.

CSE for Labour : Creating Silly Extras?

Combined spinal epidural analgesia for labour pain has been the sexy product of obstetric anaesthesiology over the last decade. It was trumpeted in the Lancet, of all places, in the early 1995, and there was associated cover in the general media about this technique of labour analgesia which gives rapid relief and allows ambulation. But this study compared CSE and dilute (0.1% bupivacaine) epidural topups with epidural boluses of 0.25% bupivacaine so it is not surprising there were the differences observed. The later COMET trial, also published in Lancet, concluded there were no differences in obstetric outcomes between dilute epidural by infusion and CSE with intermittent dilute epidural topups. There were analgesic differences between the two techniques, but they can be explained by the differences in epidural management rather than the use of a spinal dose at the start of the neuraxial analgesia. The strongest argument for CSE in labour seem to be its rapid onset, but this onset only starts when the drug is injected into the CSF. The anaesthetists has to get there first (why not run faster?) assess the situation, and the get informed consent. In my experience I am always asked a to come to place an epidural; I have never been specifically asked by a parturient for a CSE. An obstetrician may occasionally suggest a spinal dose, but that is always for anaesthesia for delivery, rather than analgesia for labour pain. Is there an extra layer of consent needed for a spinal dose, thus making the time to achieve analgesia longer? In my view there seems to be an extra, albeit small, risk of meningitis, nerve root trauma, conus trauma, local anaesthetic toxicity to nerves, and in my hands, headache. If the dura is not breached there will not be a CSF leak. Even with a 27 G non-cutting needle there will be a chance of CSF leak that may rarely cause headache or cranial nerve symptoms (such as hearing loss or tinnitus). I have not had a epidural needle dural puncture in over 2000 cases, using a technique which uses forced loss of resistance to fluid and the lateral position. CSE seems easier in the sitting position, but this increases lumbar CSF pressure. Even in the sitting position finding CSF from the spinal needle can be tricky, increasing the time for some parturients to get their relief. And infection control in the dirty environment of a delivery room (visitors, street clothes, wandering partners, etc) and a possibly bacteraemic labouring woman is another dissuader from the use of CSE as a routine method of labour analgesia. The mentioned complications have and do occur. We can only speculate if for any case the complication would not have happened if it was epidural-only analgesia, but the breach of dura or the point of the long spinal needle often seem to be the likely culprit. Dilute, low dose bupivacaine and fentanyl epidural doses are an effective and safe means of analgesia for labour, and are effective and appropriate in the great majority of cases when “an epidural” is requested by a labouring patient.