Intrapartum Care: Drugs in Labour Flashcards
What is oxytocin?
A hormone secreted by the posterior pituitary gland but produced in the hypothalamus.
What role does oxytocin play in labour (3 things)?
1) stimulates the ripening of the cervix
2) stimulates contractions of uterus during labour and delivery
3) role in lactation during breastfeeding
What are oxytocin infusions used for in labour?
1) induce labour
2) progress labour
3) improve the frequency and strength of uterine contractions
4) prevent or treat postpartum haemorrhage
What is Syntocinon?
Syntocinon is a brand name for oxytocin produced by one drug company.
What class of drug is Atosiban?
An oxytocin receptor antagonist.
What can be used as an alternative to nifedipine for tocolysis in premature labour (when nifedipine is contraindicated)?
Atosiban
What is ergometrine?
It is derived from ergot plants.
Role of ergometrine in labour?
It stimulates smooth muscle contraction, both in the uterus and blood vessels so:
1) useful for delivery of placenta (3rd stage of labour)
2) reduce postpartum bleeding
When is ergometrine ONLY used?
After the delivery of the baby (not in the 1st or 2nd stage of labour)
Side effects of ergometrine?
Due to action on smooth muscles in blood vessels and GI tract:
1) HTN
2) Diarrhoea
3) Vomiting
4) Angina: causes coronary artery spasm
Who should ergometrine be avoided in?
1) Pre-eclampsia
2) HTN: use with significant caution
What is Syntometrine?
Syntometrine is a combination drug containing oxytocin (Syntocinon) and ergometrine.
Indication of Syntometrine in labour?
It can be used for prevention or treatment of postpartum haemorrhage.
Often used as an alternative to oxytocin in the active management of third stage of labour.
Indications for syntocinon in labour?
1) stimulates the contraction of the uterus
2) reduces risk of postpartum haemorrhage
3) induce labour
Mechanism of Ergometrine?
stimulates alpha-adrenergic, dopaminergic and serotonergic receptors
Role of prostaglandins in labour?
1) Stimulate contraction of uterine muscles
2) Have a role in ripening the cervix before delivery
What is one key prostaglandin to be aware of in labour?
Dinoprostone (prostaglandin E2)
Indication for dinoprostone?
Induction of labour
What 3 forms can dinoprostone come in?
1) vaginal pessaries (Propess)
2) vaginal tablets (Prostin tablets)
3) Vaginal gel (Prostin gel)
What class of drugs inhibit prostaglandins?
NSAIDs e.g. ibuprofen, naproxen
Impact of prostaglandins on BP?
Act as vasodilators and lower BP
How do NSAIDs affect BP?
Cause raised BP due to inhibiting prostaglandins
Why are NSAIDs generally avoided in pregnancy?
Can raise BP
Why are NSAIDs particuarly useful for dysmenorrhoea (painful periods)?
Block prostaglandins - reduce painful cramping of the uterus during menstruation.
What is misoprostol?
Misoprostol is a prostaglandin analogue: i.e. binds to prostaglandin receptors and activates them
Indication of misoprostol in labour?
1) It is used as medical management in miscarriage, to help complete the miscarriage.
2) Used alongside mifepristone for abortions
3) Induction of labour after intrauterine fetal death
What is mifepristone?
An anti-progestogen medication that blocks the action of progesterone, halting the pregnancy and ripening the cervix.
Indication of Mifepristone in pregnancy?
1) abortions (used alongside misoprostol for abortions)
2) induction of labour of labour after intrauterine fetal death
Mechanism of mifepristone?
1) anti-progestogen
2) halts the pregnancy and ripening the cervix
3) enhances effects of prostaglandins to stimulate contraction of uterus
When is mifepristone NOT used?
It is not used during pregnancy with a healthy living fetus.
What class of drug nifedipine?
Calcium channel blocker
Mechanism of nifedipine?
Calcium channel bloker that acts to reduce smooth muscle contraction in blood vessels and uterus.
2 main indications of nifedipine?
1) HTN and pre-eclampsia: reduce BP
2) Premature labour: tocolysis, where it suppresses uterine activity and delays the onset of labour
What class of drug is terbutaline?
Beta-2 agonist (similar to salbutamol)
Mechanism of terbutaline?
Stimulates beta-2 adrenergic receptors. It acts on the smooth muscle of the uterus to suppress uterine contractions.
Indication for terbutaline?
Tocolysis in uterine hyperstimulation, notably when the uterine contractions become excessive during induction of labour.
What class of drug is carboprost?
A synthetic prostaglandin analogue (i.e. binds to prostaglandin receptors)
Mechanism of carboprost?
Binds to prostaglandin receptors and stimulates uterine contraction.
Indication of carboprost?
Given as deep IM injection in postpartum haemorrhage where ergometrine and oxytocin have been inadequate
Contraindication of carboprost?
It needs to be avoided or used with particular caution in patients with asthma, as it can cause a potentially life-threatening exacerbation of the asthma.
How is carboprost given?
Deep IM injection
What is tranexamic acid?
An antifibrinoyltic medication that reduces bleeding
Mechanism of tranexamic acid
1) Binds to plasminogen and prevents it from converting to plasmin.
2) Plasmin is an enzyme that works to dissolve the fibrin within blood clots.
3) Therefore, by decreasing the activity of the enzyme plasmin, tranexamic acid helps prevent the breakdown of blood clots.
What is fibrin?
Fibrin is a protein that helps hold blood clots together.
Indication of tranexamic acid?
Tranexamic acid is used in the prevention and treatment of postpartum haemorrhage.
What is failure to progress?
Failure to progress refers to when labour is not developing at a satisfactory rate.
This increases the risk to the fetus and the mother.
Who is failure to progress more common in?
Women in labour for the first time compared with those that have previously given birth.
Progress in labour is influenced by the three P’s.
What are they?
Power (uterine contractions)
Passenger (size, presentation and position of baby)
Passage (shape and size of the pelvic and soft tissues)
The first stage of labour has 3 phases.
What are they?
1) latent phase
2) active phase
3) transition phase
What dilation of the cervix is the latent phase of the 1st stage of labour?
0 to 3cm dilation
What rate does the latent phase of the 1st stage of labour progress at?
0.5cm per hour
Describe the contractions in the latent phase of the 1st stage of labour progress at?
Irregular
What dilation of the cervix is the active phase of the 1st stage of labour?
3cm to 7cm dilation
What rate does the active phase of the 1st stage of labour progress at?
1cm per hour
Describe the contractions in the active phase of the 1st stage of labour progress at?
Regular
What dilation of the cervix is the transition phase of the 1st stage of labour?
From 7cm to 10cm dilation
What rate does the transition phase of the 1st stage of labour progress at?
1cm per hour
Describe the contractions in the transition phase of the 1st stage of labour progress at?
strong and regular
When is delay in the first stage of labour is considered?
Either:
1) Less than 2cm of cervical dilatation in 4 hours
2) Slowing of progress in a multiparous women
What is a partogram?
Function: to monitor the progress of labor and identify and intervene in cases of abnormal labor.
Central feature: a graph where cervical dilatation is plotted.
What features are recorded on a partogram?
1) Cervical dilatation (measured by a 4-hourly vaginal examination)
2) Descent of the fetal head (in relation to the ischial spines)
3) Maternal pulse, blood pressure, temperature and urine output
4) Fetal heart rate
5) Frequency of contractions
6) Status of the membranes, presence of liquor and whether the liquor is stained by blood or meconium
7) Drugs and fluids that have been given
How are uterine contractions measured?
In contractions per 10 minutes
When the midwife says “she is contracting 2 in 10”, it means she is having 2 uterine contractions in a 10 minute period.
There are two lines on the partogram that indicate when labour may not be progressing adequately.
What are these labelled?
‘Alert’ and ‘action’
The dilation of the cervix is plotted against the duration of labour (time). When it takes too long for the cervix to dilate, the readings will cross to the right of the alert and action lines.
What is crossing the ‘alert’ line on a partogram an indication for?
Amniotomy (artificially rupturing the membranes) and repeat examination in 2 hours.
What does crossing the ‘action’ line on a partogram indicate?
Care needs to be escalated to obstetric-led care and senior decision-makers for appropriate action.
What is the 2nd stage of labour?
Lasts from 10cm dilatation of the cervix to delivery of the baby
What does success of the 2nd stage of labour depend on?
The three P’s: power, passenger and passage
When does delay in the 2nd stage of labour occur?
When the active 2nd stage (pushing) lasts over:
1) 2 hours in nulliparous women
2) 1 hour in multiparous women
What does ‘power’ refer to in labour?
Strength of uterine contractions
When there are weak uterine contractions, what can be given to stimulate the uterus?
An oxytocin infusion
What does ‘passenger’ refer to in labour?
Passenger refers to the four descriptive qualities of the fetus:
1) size
2) attitude
3) lie
4) presentation
How can the size of the baby affect delivery?
Large babies (macrosomia) will be more difficult to deliver, and there may be issues such as shoulder dystocia.
The size of the head is important as this is the largest part of the fetus.
What does ‘attitude’ of the fetus refer to?
The posture of the fetus e.g. how rounded the back is, how the head and limbs are flexed.
What does the ‘lie’ of the fetus refer to?
The position of the fetus in relation to the mother’s body:
- transverse
- longitudinal
- oblique
What is a longitudinal lie?
The fetus is straight up and down
What is a transverse lie?
The fetus is straight side to side
What is an oblique lie?
the fetus is at an angle
What does the ‘presentation’ of the fetus refer to?
The part of the fetus closest to the cervix:
- cephalic
- shoulder
- breech
What is a cephalic presentation?
Head is first
What is a shoulder presentation?
The shoulder is first
What is a breech presentation?
The legs are first. This can be:
- complete
- frank
- footling
What is a complete breech?
With hips and knees flexed (like doing a cannonball jump into a pool)
What is a frank breech?
With hips flexed and knees extended, bottom first (i.e. like a pike)
What is a footling breech?
With a foot hanging through the cervix
What does ‘passage’ refer to?
The size and shape of the passageway, mainly the pelvis.
When there are problems in the second stage of labour, interventions may be required depending on the situation.
Name some possible interventions
1) changing positions
2) encouragement
3) analgesia
4) oxytocin
5) episiotomy
6) instrumental delivery
7) caesarean section
What is the 3rd stage of labour?
From delivery of the baby to delivery of the placenta
When does delay in the 3rd stage of labour occur?
1) >30 minutes with active management
2) >60 minutes with physiological management
What does active management of the 3rd stage of labour involve?
1) IM oxytocin
2) Controlled cord traction
What are the main options for managing failure to progress?
1) amniotomy, also known as artificial rupture of membranes (ARM) –> for women with intact membranes
2) oxytocin infusion
3) instrumental delivery
4) caesarean section
What is used 1st line to stimulate uterine contractions during labour?
Oxytocin
It is started at a low rate and titrated up at intervals of at least 30 minutes as required.
What is the aim for contractions per 10 minutes?
4-5 contractions per 10 minutes
Complications of too few vs too many contractions during labour?
Too few: means that labour does not progress
Too many: can result in fetal compromise, as the fetus does not have the opportunity to recover between contractions
What are non-medical options that can improve symptoms in labour?
1) Antenatal classes help prepare women for what to expect in labour
2) Understanding what to expect
3) Having good support
4) Being in a relaxed environment
5) Changing position to stay comfortable
6) Controlled breathing
7) Water births may help some women
8) TENS machines may be useful in the early stages of labour
What simple analgesia can be used in early labour?
Paracetamol (codeine may be added for additional effect).
What analgesics are avoided in labour?
NSAIDs (due to increase in BP)
Give some options for medical pain relief in labour
1) simple analgesia
2) gas and air (entonox)
3) IM pethidine or diamorphine
4) patient controlled analgesia
5) epidural
What is gas & air (Entonox)?
Gas and air contains a mixture of 50% nitrous oxide and 50% oxygen.
Indication for gas and air in labour?
Used during contractions for short term pain relief.
How is gas and air given in labour?
The woman takes deep breaths using a mouthpiece at the start of a contraction, then stops using it as the contraction eases.
Side effects of gas and air in labour?
Lightheadedness, nausea, or sleepiness
What are pethidine and diamorphine?
Opioid medications
How are pethidine and diamorphine usually given in labour?
IM injections
Indications for pethidine and diamorphine in labour?
- pain
-anxiety - distress
Side effects of pethidine and diamorphine in labour?
1) can cause respiratory depression in neonate if given too close to birth
2) the effect on the baby may make the first feed more difficult
During labour, patients may be offered the option of patient-controlled analgesia.
What drug is offered?
IV remifentanil
This involves the patient pressing a button at the start of a contraction to administer a bolus of this short-acting opiate medication.
What class of drug is remifentanil?
Short acting opiate
What must be in place if a patient is offered patient-controlled remifentanil?
There needs to be input from an anaesthetist, and facilities in place if adverse events occur.
This includes access to naloxone for respiratory depression, and atropine for bradycardia.
What 2 medications must be accessible if giving a patient patient-controlled remifentanil?
1) naloxone: for respiratory depression
2) atropine: for bradycardia
What does an epidural involve?
1) An epidural involves inserting a small tube (catheter) into the epidural space in the lower back.
2) Local anaesthetic medications are infused through the catheter into the epidural space
3) Medications diffuse to the surrounding tissues and through to the spinal cord, where they have an analgesic effect
Where is the epidural space located?
his is outside the dura mater, separate from the spinal cord and CSF.
What are the 2 anaesthetic options for an epidural?
1) levobupivacaine
2) bupivacaine
These are usually mixed with fentanyl
Adverse effects of an epidural?
1) Headache after insertion (post-dural puncture headache)
2) Hypotension
3) Motor weakness in legs
4) Nerve damage
5) Prolonged 2nd stage
6) Increased probability of instrumental delivery
Women need urgent anaesthetic review if they develop significant motor weakness (unable to straight leg raise) after an epidural.
What would this indicate?
The catheter may be incorrectly sited in the subarachnoid space (within the spinal cord), rather than the epidural space.
