Medications used in labour Flashcards
What is the Bishop’s score used for?
What does it indicate??
To clinically assess the cervix. The higher the score, the more progressive change there is in the cervix and indicates that induction is likely to be successful and indicates when an amniotomy is likely to be possible
What are the absolute contraindications of labour?
» Abnormal lie
» Known pelvic obstruction such as tumour or large ovarian cyst
» Placenta praevia
» Fetal distress
What are the relative contraindications of labour?
» Previous caesarean section = Increased risk of rupture
» Asthma (prostaglandins (including PGE2 analogues) can cause respiratory smooth muscle contraction).
How can prostaglandins induce labour?
Prostaglandin analogues encourage cervical dilatation and effacement –
they ripen the cervix and so can be used for induction of labour
Examples of prostaglandin analogues (E2)?
Dinoprostone - Propess® / Prostin E2® = Prostaglandin E2 analogues
Examples of prostaglandin analogues (E1)?
Misoprostol (Mysodelle ®) = synthetic analogue of Prostaglandin E1
What are the risk of prostaglandins in labour induction?
May lead to contractions, occasionally can lead to severe contractions / hypertonic uterus, nausea and vomiting, bowel upset, pyrexia, hypotension
How can oxytocin induce labour?
Synthetic Oxytocin (Syntocinon®) – initiates uterine contractions by attaching to uterine oxytocin receptors ; increases the frequency and force of contractions
What are prostaglandins derived from?
Eicosanoids derived from arachidonic acid
Where is oxytocin derived from?
Oxytocin is produced physiologically by the paraventricular nuclei and secreted by the posterior pituitary gland
How is oxytocin administered in labour?
IV administration
What is oxytocin?
Oxytocin is a cyclic nonapeptide
Why do women need CTG monitoring if an oxytocin infusion is administered?
There is a risk of uterine hypertonicity
What is the risk of using oxytocin in the induction of labour?
Can lead to hypotension and hyponatraemia – women usually have IV fluids alongside oxytocin infusion – need to be cautious with use and must monitor fluid balance
When is oxytocin usually administered when inducing labour?
Often used following prostaglandin treatment, once amniotomy performed for induction of labour
When is augmentation of labour required?
Augmentation of labour is required when contractions reduce in frequency or strength in active labour even after spontaneous onset of labour.
What is used to augment labour, if indicated?
Oxytocin
What does active management of the 3rd stage of labour involve?
Active management of the 3rd stage involves:
1. Early clamping and cutting of the umbilical cord (now routine practice is to allow 2-5 minutes of delayed cord clamping for all women unless contraindicated)
- Use of uterotonic medications (pharmacological management)
- Delivery of the placenta by controlled cord traction
Which medication are used within active management of the 3rd stage of labour?
1) Syntometrine:
- Combination of oxytoxin and ergometrine
- Given as an IM injection
2) Synthetic oxytocin:
- Given as IM injection or slow IV injection (5 IU)
Pharmacological management of post partum haemorrhage (PPH)?
1) Oxytocin:
- IV injection (5IU)
- IV infusion (30 IU in 500ml normal saline at a rate of 125ml/hr)
2) Syntometrine ® or ergometrine alone:
- IM 500mg
3) Carboprost (Hemabate®)
- Is a Prostaglandin F2α
- Given as IM injection (250 micrograms) at 15 minute intervals (to maximum of 8 doses (2mg)
4) Misoprostol
- A prostaglandin; sometimes given PR to help treat PPH. This is an unlicensed medication for the treatment of PPH
5) Tranexamic acid
- Is an antifibrinolytic medication therefore can be used to try to reduce the bleeding in
ongoing PPH if other pharmacological methods are not working
What should be given in threatened preterm labour, why?
Steroids should be administered to help improve neonatal outcomes
Steroid administration is thought to improve fetal lung development and improve other neonatal outcomes in preterm babies
Which drugs should be given in threatened preterm labour, why?
Betamethasone or dexamethasone is given to the woman by IM injection (2 x 12mg doses given 24 hours apart).
What are tocolytic medications used for?
1) Tocolytic drugs (known as “tocolysis”) aim to inhibit uterine contractions.
2) Usually used in women in threatened preterm labour from 24 weeks and 35 weeks of gestation.
3) Can be used to facilitate transfer of woman in labour to another hospital, particularly a hospital with an appropriate neonatal unit
4) Can be used to try to give steroid medication enough time to work (to derive maximum benefit of steroid treatment for neonate and allow 2 doses to be given 24 hours apart)
Which drugs can be used for tocolysis?
1) Calcium channel blocker e.g. Nifedipine, can be given orally
2) Oxytocin receptor antagonist e.g. Atosiban , is given IV
3) Beta2 agonists e.g. Terbutaline, salbutamol – act by causing relaxation
of smooth muscle
4) Indomethacin
Which drugs (tocolytics) can be used in an acute setting (emergency CS, obstructed labour, or hypertonic uterus causing fetal distress)?
Terbutaline or GTN can be used.
They act to cause smooth muscle relaxation and stop the uterus contracting.
Why may antihypertensives be prescribed during pregnancy?
> Pre-existing hypertension
> Pregnancy-induced hypertension
> Pre-eclampsia.
Which antihypertensives are used during pregnancy?
» Methyldopa
» Hydralazine
» Combined alpha & beta-blockers e.g. labetolol
Which antihypertensives are contraindicated during pregnancy?
> ACE inhibitors
Angiotensin receptor
Blockers
Spironolactone
In terms of antihypertensives in pregnancy when may labetolol be contraindicated?
> Asthmatics
> Some cardiac conditions (Bradycardias, cardiac failure)
What is the 1st line and 2nd line antihypertensives treatment options during labour?
1st line = Labetolol
2nd line = Hydralazine
In women with symptomatic pre-eclampsia, and thought to be at risk of eclampsia, obstetricians may commence IV what to prevent seizures?
In women with symptomatic pre-eclampsia, and thought to be at risk of eclampsia, obstetricians may commence IV magnesium sulphate treatment to prevent or treat seizures.
Analgesia during pregnancy - Non-pharmacological?
• Breathing exercises, aromatherapy, warm baths,
acupuncture, hypnotherapy
• TENS machine
» transcutaneous electrical nerve stimulation – good for early labour, but may lose effect in advancing labour
Analgesia during pregnancy - Simple analgesia?
• Paracetamol
– Safe throughout pregnancy; may be used in latent (early) phase of labour for pain relief
• Dihydrocodiene / Codiene (mild opiates)
– Make sure patient aware of side effects (nausea, constipation, drowsiness); may be useful in latent (early) phase of labour; risk of neonatal respiratory depression
• Aspirin
– Avoid in labour as increases bleeding risk
– can be used - only low dose - for other medical indications in pregnancy on specialist advice only, but definitely not for acute pain relief in labour
Which simple analgesics should not be used un pregnancy?
NOT: Ibuprofen / Diclofenac
NSAIDs can cause premature closure of the fetal ductus arteriosus, fetal oliguria, oligohydramnios after 30 weeks gestation, and risk of bleeding in fetus.
However, commonly used post partum for pain relief.
May not be suitable in asthmatics or patients with hx of GI disease such as GORD, peptic ulcers or inflammatory bowel disease.
Analgesia during pregnancy - Analgesia - Entonox?
Entonox “Gas & Air” = nitrous oxide:
- Patient can self-administer - Usually reserved until in active labour - Patient can feel “giddy” or intoxicated, can feel nauseated or may vomit
Analgesia during pregnancy - Analgesia - Opiates, examples?
1) Morphine
2) Pethidine
3) Diamorphine
4) Remifentanyl (Patient controlled analgesia)
Analgesia during pregnancy - Analgesia - Opiates, patient controlled?
Remifentanyl = Patient controlled analgesia, which can be self-administered bolus dose via a hand held button; syringe driver attached to IV cannula
Analgesia during pregnancy - Analgesia - Opiates, antidote?
Naloxone = Opioid antagonist
Analgesia during pregnancy - Analgesia - Opiates, negative side-effects/risks?
Mother:
- Nausea
- Drowsiness
- Respiratory depression
- Vomiting (Co-prescribe antiemetic)
Neonate:
- Respiratory depression
Analgesia during pregnancy - Analgesia - benefits of using remifentanyl?
1) Patient controlled analgesia
2) Fast metabolism and redistribution
3) Does not cross the placenta
Before general anaesthesia is administered what are options for injectable analgesia?
When else may it be used?
Local anaesthetic injected intradermally
May be administered after delivery to suture an episiotomy or vaginal tear
Analgesia during pregnancy - Analgesia - local anaesthetic example?
Usually Lignocaine is used – you get different strengths.
Analgesia during pregnancy - Analgesia - local anaesthetic, how do they work?
Local anaesthetic agents temporarily block action potentials
at nerve endings.
Analgesia during pregnancy - Analgesia - local anaesthetic, risks?
1) Patients can be allergic to local anaesthetic.
2) Local anaesthetic toxicity can occur. Signs include:
- Perioral tingling, paraesthesiae, confusion, drowsiness, light-headedness, seizures
- Can lead to coma, cardiorespiratory arrest and be lethal
What type of anaesthesia is an epidural?
Epidural anaesthesia is a form of regional anaesthetic block
How are epidural anaesthetics administered?
Involves injection of local anaesthetic + opiate medications into the epidural space using a catheter.
Contraindications of epidural anaesthesia?
1) Thrombocytopaenia
2) Coagulopathy
3) Raised intracranial pressure
4) Local sepsis
5) Septic shock
6) Allergy to local anaesthetic
7) Lack of patient consent
8) Anticoagulants with 12 hours of insertion
Advantages of epidural anaesthesia?
Advantages:
» Effective analgesia during labour
» Can be topped up if need to transfer to theatre for instrumental or caesarean section delivery
» Effective after delivery if need repair of vaginal tears or manual removal of placenta (MROP)
» Best for baby
» Can prevent further raised blood pressure in pre-eclampsia
Disadvantages of epidural anaesthesia?
Disadvantages:
» Can fail to provide adequate analgesia (1 in 10 need re-sited)
» Causes hypotension (1 in 50 chance; dose-dependent)
» Reduces woman’s mobility
» Dural puncture (1 in 100 chance) – post dural puncture headache (worse on sitting up or standing; (can be treated using a epidural blood patch)
» Epidural haematoma / abscess (<1 in 10000 chance)
» Risk of respiratory depression (1 in 100 to 1 in 1000 chance)
» Risk of neurological deficits (1 in 10000 to 1 in 40000
chance)
What are spinal anaesthetics often used for?
Most Caesarean sections
How are spinal anaesthetics administered?
Usually a local anaest.hetic + opiate medication are injected into the
subarachnoid space.
What are the advantages of spinal anaesthetics?
Advantages:
» Gives dense, anaesthetic bilateral block
» Patient can stay awake & protect own airway during operation – woman can stay awake to meet her baby!
What are the disadvantages of spinal anaesthetics?
Disadvantages:
» 2-3% risk of inadequate pain relief – may need other analgesics or may require general anaesthetic
» Shorter duration – can wear off! May be problem if surgery takes longer than expected (>60-90mins)
» Causes hypotension (due to blockade of the sympathetic nerves) similar to epidural and general anaesthetic
» Patient needs urinary catheter (though many other indications for a catheter too!)
» Risk of dural puncture – post dural puncture headache (worse on sitting up or standing)
» Patient may suffer from pruritus or nausea and vomiting
» Small risk of nerve damage
When may general anaesthetics be required for a pregnant woman?
Outside of other acute surgery, if an emergency Caesarean section is needed and there is not enough time to site a spinal block or a regional anaesthesia fails.
What are the risks of using general anaesthesia?
General anaesthesia can be more difficult in pregnancy due to increased risk of aspiration of stomach contents and more difficult intubation in pregnant women
