澳纽考题2001B08:Anesthesia for manual removal of placenta

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2001B08:

After 10 hours labour, a healthy 28 year old primiparous woman at term requests epidural analgesia. Her cervix is 8cm dilated. She reaches full dilatation and delivers before any block is performed. Following delivery she has a retained placenta. Justify your choice of anaesthetic technique for manual removal of placenta.

The choice of anaesthetic technique for manual removal of retained placenta involves similar issues as for caesarean section.

• IV access should be established. If there is significant active bleeding, bilateral large bore (16G or greater) cannulae should be placed.

• Check for valid group and screen. Cross-match blood if there is continuing rapid blood loss.

• Aspiration prophylaxis (sodium citrate 30 mL orally; ranitidine 50 mg IV;
  metoclopramide 20 mg IV) should be given to all patients, regardless of technique.

• If blood loss is minimal (under 1000 mL) and there is no cardiovascular instability (tachycardia, hypotension, postural drop), regional anaesthesia is suitable and the preferred technique – a spinal in this case.

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Check for recent platelet levels / exclude history of coagulopathy or thrombocytopenia.
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Establish informed consent.
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Insure close cardiovascular monitoring and adequate fluid filling.
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Establish with 2.0 to 2.2 mL of 0.5% heavy bupivacaine. Fentanyl 10-15 mcg will improve density of the block, but is less important than for caesarean section.
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Previously considered only to require a block to T10, but now evidence suggests block needs to reach T7 for adequate anaesthesia.

• If blood loss is large and ongoing, particularly if cardiovascular instability is present, general anaesthesia may be safer than regional anaesthesia and it’s associated peripheral vasodilation. There is also a risk of requiring greater surgical intervention in such case, for which a regional anaesthetic may be unsuitable.

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Rapid sequence induction (pre-oxygenation, cricoid, suxamethonium or other rapid acting relaxant, cuffed endotracheal tube).
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Fluid filling.
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Access to vasopressors.

• Uterine relaxation if required can be provided by either small aliquots of glycerol trinitrate 50 mcg IV or deepening of the volatile anaesthetic.

• Following removal of placenta, oxytocinon 5 IU x2 should be provided after consultation with the obstetrician. An ongoing infusion of 30-40 IU oxytocinon in 1000 mL Hartmann’s/NS 250 mL/h is commonly also required. Second and third line oxytocics (ergometrine, PGF-2alpha) should also be readily available.

Reference:

• Oxford Handbook of Critical Care. Singer & Web. 2000.