Anaesthesia forLower Segment Caesarian section : Anaesthesia forLower Segment Caesarian section Uvie Brigue
classification : classification Immediate threat to the life of the woman or fetus
Maternal or fetal compromise which was not immediately life-threatening
No maternal or fetal compromise but needs early delivery
Delivery timed to suit woman or staff
What is a true emergency? : What is a true emergency? Maternal
Acute deterioration in pre/co existing disease.
Massive haemmorrhage(Abruptio,Uterine rupture
Trauma(Uterine trauma)
Cardiac arrest(Perimortem C/s)
Eclampsia
Slide 4 : Fetal
Prolapsed fetal part (cord with severe bradycardia)
Failed breech delivery with fetal compromise
Compromised central circulation(Non reflex late decelerations without variability. Prolonged bradycardia
Fetal injury (blunt or penetrating maternal uterine trauma).
Regional Vs general : Regional Vs general The choice depends on factors such as expertise of anaesthetist, the degree of urgency, preexisting epidural,patients preference.
Choice may have an impact on coexisting maternal illness
Regional : Regional Venous pooling -decreased RV preload-Decreased cardiac output , reflex tachycardia
Dural puncture-Sudden decrease in ICP
Supine positioning.
OTHER COMPLICATIONS OF REGIONAL
GENERAL : GENERAL LARYNGOSCOPY –pressor response, Apnea time,Bronchospasm.
Anaesthetic agents-CVS depression, NMB hyperkalaemia in neuro muscular diseases.
Maintanance agents- CVS Depression and MH.
Other complications of GA.
Best practice (an overview) : Best practice (an overview) Category 1 and 2 –True emergencies
The 30 minute dilema : The 30 minute dilema The National Sentinel Audit of Caesarean sections defined 30 min as a standard for decision-delivery interval in the Category 1 situation.
A true Category 1 emergency, e.g. ongoing maternal antepartum haemorrhage and sustained fetal bradycardia secondary to placental abruption, realistically demands delivery in less than half this time for neonatal survival without ischaemic-hypoxic injury.
Slide 10 : On the other hand, cord prolapse is not necessarily a Category 1 emergency.
Provided the cord is decompressed and the fetus not seriously compromised, regional anaesthesia is an option.
Anaesthetic Options : Anaesthetic Options The Royal College of Anaesthetists proposed that > 85% of ‘emergency’ Caesarean sections should be under regional anaesthesia, and that fewer than 3% of regional blocks should require conversion to general anaesthesia.
The anaesthetic technique of first choice for the woman labouring with epidural analgesia will be top-up of that epidural. Unless contra-indicated,
single-shot spinal anaesthesia is appropriate for the majority of women without labour epidural analgesia who require Category 2 Caesarean section.
Epidural Top Up : Epidural Top Up Women receiving epidural analgesia in labour should be reviewed regularly to identify suboptimal block that predict potentially inadequate surgical anaesthesia if topped up for Caesarean section.
Women at risk of operative delivery, e.g. ‘trial of scar’ or non-reassuring cardiotocogram, should be given regular oral ranitidine to reduce the acidity of gastric contents. Midwives can initiate this therapy .
A high proportion of women presenting for emergency Caesarean section should have received ranitidine in labour
Slide 13 : Good multidisciplinary communication is pivotal – e.g. if an imminent fetal scalp pH result will seal an increasingly likely fate (Caesarean section for the woman with non-reassuring cardiotocogram), the anaesthetist and theatre team should be informed.
Advance warning can provide the extra time that can prove crucial in allowing successful conversion of labour analgesia to surgical anaesthesia.
What Mixture? : What Mixture? The issue of whether demonstrable benefits outweigh the risks of adding bicarbonate and ⁄ or adrenaline to a sole local anaesthetic or mixture of local anaesthetics has been explored recently .
preferred choice of local anaesthetic is levobupivacaine, the S-enantiomer of bupivacaine, which is less cardiotoxic than racemic bupivacaine in the event of accidental intravascular injection.
Opiod?
Top up Where? : Top up Where? Whether the top-up should be administered in delivery room or theatre is controversial .
Topping-up in the delivery room might gain time, but maternal monitoring is suboptimal when the risk of high block or systemic local anaesthetic toxicity is greatest.
Waiting until arrival in theatre before starting to top-up can invoke obstetrician impatience and a call for general anaesthesia. A compromise is to administer a small initial dose in the delivery room (e.g. 5 ml levobupivacaine 0.5%) and further 5-ml increments as required in theatre.
The efficacy of epidural anaesthesia is consistently reported as inferior to that of spinal anaesthesia in both elective and emergencies
Slide 16 : Blockade of light touch sensation from S5 to T5 should avoid the need for supplementation or conversion to general anaesthesia.
Drops of ethyl chloride allow evaluation of both cold and light touch sensation.
The addition of epidural fentanyl 50 ug minimises pain from visceral traction.
On account of the imprecision in determination of dermatomal levels, it has been proposed that block height be recorded on a diagram .
Spinal : Spinal Active bleeding, cardiac disease, uncorrected coagulopathy and a high suspicion of bacteraemia are contra-indications to single-shot spinal anaesthesia. An adequate block for starting surgery should be conferred by a majority of de novo single shot spinals within 10–20 min
Hyperbaric bupivacaine 0.5%, 2.5 ml is a midrange dose, appropriate for most women; the addition of diamorphine probably enhances blockade of visceral pain, and certainly provides postoperative analgesia..
When there is pressure of time, fentanyl 25 lg is an alternative opioid that requires no dilution.
However, this short-acting opioid does not confer postoperative analgesia.
Spinal cont. : Spinal cont. Preservative-free morphine is also available at an appropriate dilution (2 mg in 10 ml); 0.1 mg (0.5 ml of this solution) provides comparable postoperative analgesia to diamorphine 0.25 mg .
Obsessive maintenance of left-lateral tilt to offset aortocaval compression and prompt use of phenylephrine (now widely regarded as the vasopressor of choice) should mitigate the slight fetal acidosis that has been observed after spinal compared with epidural or general anaesthesia .
Spinal cont. : Spinal cont. Pre load before spinal anaesthesia has been superseded by ‘coload’ – a fluid bolus coinciding with the sympathetic blockade. Although phenylephrine can be given by infusion , 50–100 ug boluses are as efficacious.
Phenylephrine 100 ug is equivalent to ephedrine 8 mg . Timing is everything; the first dose of phenylephrine should be given preemptively rather than waiting for arterial pressure to decrease.
Subsequent doses are best given in response to symptoms (nausea or light-headedness), which tend top recede hypotension. Reflex bradycardia (heart rate 45– 50 )
Spinal Cont. : Spinal Cont. Women with preterm babies require more rather than less intrathecal local anaesthetic, presumably because of less engorgement of the inferior vena cava and therefore epidural veins, and consequently less compression of the thecal sac .
The incidence of hypotension (a 30% decrease in mean arterial pressure) after single-shot spinal anaesthesia in women with treated pre-eclampsia has been shown to be less than that in healthy parturients
Eclamptic women who have regained consciousness and received intravenous magnesium can safely undergo regional anaesthesia, provided coagulation indices are acceptable
CSE : CSE In the event of failure of a topped-up labour epidural to produce bilateral loss of light touch sensation from S4 to T5, single-shot spinal anaesthesia using a dose appropriate for a de novo spinal is not an inherently safe option because of the risk of excessively high block.
Combined spinal-epidural anaesthesia is a useful recourse. A conservative spinal dose (hyperbaric bupivacaine 0.5% 1 ml) might well suffice and can be safely augmented by subsequent increments of epidural local Anaesthetic.
GA : GA Arguably, historical and contemporary evidence does not suggest that ‘traditional’ rapid sequence induction (thiopental, succinylcholine, cricoid pressure, intubation) is necessarily the safest approach to general anaesthesia for Caesarean section .
The most recent Report on Confidential Enquiries into Maternal Deaths in the United Kingdom cited six deaths attributable to general anaesthesia, and featured the unwelcome reappearance of oesophageal intubation as a cause of mortality.
GA cont. : GA cont. The rarity of general anaesthesia for elective Caesarean section has meant that training opportunities have diminished.
There is an increasing likelihood that a trainee’s first experience of Caesarean section under general anaesthesia will be an emergency case .
There is a strong argument for rehearsal in a high-fidelity simulator . Best practice demands competency-based training and assessment of all anaesthetists covering obstetric units.
Depth of anaesthesia : Depth of anaesthesia The effects on the fetus of anaesthetics and opioid analgesics are ‘innocuous and reversible’ .
The choice of drug regimen or doses used for women with cardiac or cerebrovascular disease should not be restricted on account of concerns for the fetus .
Dose-dependent respiratory depression is predictable and readily treatable by a neonatal paediatrician, who should be present
Slide 25 : There is no justification for administration of low inspired vapour concentrations that risk awareness.
To maintain bispectral index (BIS) values < 60 for ‘adequate’ depth of anaesthesia during Caesarean section, end-tidal vapour concentration > 0.75 MAC (+ 50% nitrous oxide) has been recommended .
There is no evidence that neonatal ‘outcome’ is adversely influenced by greater depth of maternal anaesthesia; the relaxant effect of modern, insoluble vapours on uterine tone is readily reversible.
In the event of severe hypovolaemia, anaesthesia can be induced and maintained with intravenous ketamine, which has a useful sympathomimetic effect.
Pre-Eclampsia : Pre-Eclampsia In pre-eclampsia, general anaesthesia is indicated for uncorrected coagulopathy or symptoms (piercing headache, in particular) or signs consistent with impending eclampsia.
An exaggerated pressor response to intubation, which would threaten the integrity of the cerebral circulation, will be averted reliably by a neuro-anaesthetic
Slide 27 : induction regimen (thiopental supplemented by alfentanil or remifentanil ).
The threat of dangerous hypertension remains at extubation; antihypertensive pretreatment (e.g. labetalol in 10–20-mg increments) is effective.
Non-depolarising neuromuscular blockade is significantly enhanced by therapeutic serum magnesium concentrations, and monitoring by peripheral nerve stimulation is essential.
Placenta Praevia and Accreta : Placenta Praevia and Accreta The commonly held obstetric view that placenta praevia dictates general anaesthesia is not supported by available evidence.
Guidelines from the Royal College of Obstetricians and Gynaecologists state that the choice of anaesthetic lies with the anaesthetist .
The difference between the mother who is actively bleeding (in whom sympathetic blockade might be disastrous) and the stable, volume-replete mother is sometimes not appreciated.
Slide 29 : Reducing the depth of general anaesthesia to treat intraoperative hypotension is not a substitute for addressing the problem of hypovolaemia, which requires aggressive management regardless of the type of anaesthetic.
Placenta praevia overlying a previous Caesarean section scar raises the possibility of placenta accreta (abnormally firm attachment of the placenta to the uterine wall) and a particularly high risk of massive haemorrhage .
General anaesthesia with invasive monitoring, rapid fluid warming ⁄ infusion device, cell salvage facility, and provision for postoperative ICU admission might be considered prudent.
Conclusion : Conclusion Good multidisciplinary communication is crucial; the categorisation of urgency should be discussed.
Anaesthetists should participate actively in resuscitation of the fetus in utero; relief of aortocaval compression is paramount.
Epidural top-up with levobupivacaine 0.5% and fentanyl is the anaesthetic of choice for the women receiving labour epidural analgesia who require Caesarean section.
Combined spinal-epidural is useful if epidural top-up has failed to provide bilateral light touch anaesthesia from S5 – T5.
Single-shot spinal anaesthesia is appropriate for most Category 2 emergencies (in women without labour epidural analgesia)pre –eclamsia is not a contraindication.
Slide 31 : Phenylephrine is the vasopressor of choice. Phenylephrine 100 ug= ephedrine 8 mg.
Induction and maintenance doses of general anaesthesia drugs should not be reduced in the belief that the baby will be harmed.
General anaesthesia is not indicated by default for placenta praevia