Medications used in Labour Flashcards
Contraindications to induction of labour
Absaloute - abnormal lie - known pelvic obstruction such as tumour or large ovarian cyst - placenta praevia - foetal distress Relative - Previous C section (risk of rupture of uterus due to scar) - asthma
Why is asthma a relative contraindication to IOL?
Prostaglandins (including PGE2 analogues) can cause respiratory smooth muscle contraction
Function of prostaglandin analogues
Encourage cervical dilatation and effacement = ripen the cervix
Possible results of prostaglandin analogues
Contractions Severe contractions/hypertonic uterus Pyrexia Nausea and vomiting Bowel upset Hypotension
Function of oxytocin
Initiates uterine contraction by attaching to uterine oxytocin receptors; increases the frequency and force of contractions
When is oxytocin used in IOL?
After prostaglandin treatment once amniotomy Is performed
Risks of oxytocin in IOL
Uterine hypertonicity
Hypotension
Hyponatraemia
When is augmentation of labour required?
When contractions reduce in frequency and strength in active labour, even after spontaneous onset of labour
What is used in the augmentation of labour?
Oxytocin
What does active management of stage 3 of labour involve?
- Early clamping and cutting of umbilical cord
- Use of uterotonic medications (pharmacological management)
- Delivery of the placenta by controlled cord traction
Medications used in the active management of the third stage
Syntometrine
Oxytocin
What is syntometrine?
A combination of oxytocin and ergometrine
What does ergometrine do?
Causes smooth muscle (uterine) contraction
Management of PPH
Physical interventions - rubbing up a contraction - bimanual compression Surgical interventions Pharmacological interventions - Oxytocin - syntometrine or ergometrine alone - carboprost - misoprostol - tranexamic acid (if others arents working)
Function of tocolysis
To inhibit uterine contractions
When in preterm labour, what must be given ASAP?
Steriods
Why would tocolysis be used?
- Facilitate transfer of women in labour to another hospital, particularly in a hospital with an appropriate neonatal unit
- To give steroid treatment enough time to work (2 doses 24 hours apart)
Tocolysis drugs
CCBs e.g. nifedipine, orally
Oxytocin receptor antagonist e.g atosiban, IV
Beta 2 agonists e.g. salbutamol
Indomethacin
Tocolysis is ocassionally indicated if….
Foetal distress and need for emergency C section
Obstructed labour
Hypertonic uterus causing foetal distress
If emergency tocolysis needed, e.g. in obstructed labour or foetal distress etc, what can be used?
GTN
Terabutaline
Pregnant women may be on anti-hypertensives for which conditions?
Pre-existing HTN
Pregnancy induced HTN
Pre-eclampsia
Special hypertensives used in pregnancy
Methyldopa
Hydralazine
Combined alpha and beta blockers e.g. labetolol
What is the first line drug for HTN in labour?
Labetolol
What is used to treat women with symptomatic pre-eclampsia, and thought to be at risk of eclampsia, to prevent or treat seizures?
IV magnesium sulphate
Antihypertensives contraindicated in pregnancy
ACE inhibitors
ARBs
Spironolactone
Analgesics allowed in pregnancy
Paracetomal Dihydrocoedine/codeine Entonox "gas+air" Opiates (when pain is more severe) Local analgesia
Signs of local anaesthetic toxicity
Perioral tingling Paraesthesia Confusion Drowsiness Light headedness Seizures Coma, CR arrest and can be lethal
Contraindications of an epidural anaesthetic
Thrombocytopenia Coagulopathy Raised ICP Local sepsis Septic shock Allergy to local anaesthetic Lack of patient consent Anticoagulants within 12 hours of insertion
Advantages of epidural anaesthetic
Effective during labour
Can be topped up if need to go to theatre for instrumental delivery or C section
Effective after delivery if need repair of vaginal tears or manual removal of placenta (MROP)
Best for baby
Can prevent further raised BP in pre-eclampsia
Disadvantages of epidural anaesthesia
Can fail to provide adequate analgesia (1 in 10 need resisted)
Causes hypotension (1 in 50, dose dependent)
Reduces womens mobility
Dural puncture (1 in 100) leading to headache
Epidural haematoma/abscess (<1 in 10000)
Risk of respiratory depression (1 in 100 to 1 in 1000 chance)
Risk of neurological deficits (1 in 10000 to 1 in 40000 chance)
In spinal anaesthetic, where is the medication injected into?
The subarachnoid space
Advantages of spinal anaesthetic
Gives dense, anaesthetic bilateral block
Patient can stay awake and protect own airway during an operation
Disadvantages of spinal anaesthetic
2-3% risk of inadequate pain relief Shorter duration -> can wear off Causes hypotension Needs catheter Risk of dural puncture + post dural puncture headache Severe pruitis or nausea and vomiting Small risk of nerve damage
Why can general anaesthesia be more difficult in pregnancy?
Increased risk of aspiration of stomach contents
More difficult to intubate pregnant women
