Obstetric Anaesthesia Flashcards
What is the definition of labour pain?
Intermittent periods of pain, which continues for many hours
What is the first stage of labour pain?
Uterine contraction, cervical effacement and dilatation. This acts on T10 - L1 uterine sympathetic nerves via paracervical ganglia and effects the S2-S4 pelvic splanchnic nerves
What is the second stage of labour pain?
Pain occurs due to vagina and perineum stretching as well as extra uterine pelvic structures, pain is due to affecting the S2 - S4 pudendal nerve and L5 - S1
What are non-pharmacological therapies for labour pain?
- trained support
- acupuncture
- hypnotherapy
- massage
- TENS - Transcutaneous nerve stimulation
- Hydrotherapy
- homeopathy
- aromatherapy
What systemic analgesia can be taken?
- simple - paracetamol, codeine ( can be slf-administered in early stages of labour)
- opioids - single shots, usually IM (morphine, diamorphine, pethidine)
- IV meds - Fentanyl, Alfentanil, Remifentanil
What is entonox composed of?
50% N2O AND 50% O2
What is entonox?
Rapid onset analgesia, self-limiting with minimal side effects.
What are the potential downsides of entonox?
Theoretical risk of bone marrow suppression
Greenhouse gas - so bad fr environment
What regional techniques of anaesthesia may be used?
Epidural
Spinal
Combines spinal - epidural
Where is the epidural space?
Between the foramen magnum to the sacrococcygeal membrane ~5mm wide.
What runs through the epidural space?
Fat. veins, lymphatics and nerve roots
What level is an epidural inserted at and why?
Inserted at the level of L3/4 as the spinal cord terminates at L2 and tries to prevent damage.
What are the indications for an epidural?
- maternal request
- pre-eclampsia toxaemia (PET)
- pregnancy-induced hypertension (PIH)
- Cardiac/other medical disease
- augmented labour
- multiple births
- instrumental/operative delivery likely
What are the absolute contraindications for an epidural?
- maternal refusal
- local infection
- allergy to local anaesthetic
What are relative contraindications for an epidural?
- coagulopathy
- systemic infection
- hypovolaemia
- abnormal anatomy
- fixed cardiac output
What are potential adverse effects to CVS?
hypotension
bradycardia
What are potential adverse effects to respiratory system?
blocked intercostal muscles
poor cough
(if very high block)
What are potential adverse effects - drug related?
anaphylaxis
allergy
neurotoxicity
What are potential adverse effects to neurological system?
RARE - related to haematoma or abscess
headache
What are the different regimes of an epidural?
Traditional (intermittent bolus), given at high concentrations, labour intensive, gives intermittent inadequate analgesia and can cause haemodynamic instability
Continuous infusion – low dose local anaesthetics + opioid, less labour intensive, gives constant analgesia and keeps haemodynamically stable
Continuous infusion and bolus – greater maternal satisfaction
Combined spinal-epidural – is rapid onset, high maternal satisfaction, significant reduction in local anaesthetic dose
How may anaesthetic be given for a Caesarean section?
General or local (epidural top up spinal, combined)
When is GA indicated in c-section?
- imminent threat to mother +/- foetus
- contraindication to LA
- maternal preference
- failed regional technique
What are the disadvantages of GA for c-section?
- increased risk associated with altered physiology
- aspiration
- failed intubation
- awareness
What are the additional needs for a patient who will have GA for a c-section?
- antacids pre-op
- adequate preoxygenation
- rapid sequence induction
- cricoid pressure
- adequate anaesthesia
- extubation awake, left lateral position
- post-op analgesia requied
