Analgesia + anaesthesia in labour Flashcards
Spinal nerve roots of body and fundus of uterus
T1-L1
Spinal nerve roots of cervix and birth canal
S2-S4
What analgesia can be inhaled in labour?
entonox - 50% oxygen, 50% nitrous oxide
Side effects of entonox
loss of control
nausea
vomiting
What analgesia can be given parenterally in labour?
pethidine
1mg/kg up to 150mg IM
Maternal side effects of pethidine
confusion
loss of control
sedation
nausea
vomiting
respiratory depression
pruritis
delayed gastric emptying
Foetal and neonatal effects of pethidine
readily crosses placenta by diffusion
HR variability changes after 40 mins
When can remifentanil PCA be given in labour?
alternative to epidural when contra-indicated
What is an epidural?
epidural space = potential space between ligamentum flavum and dura mater
motor and sensory nerves pass through epidural space
epidural = placement pharmacologically active drugs into epidural space to work on nerves
What is a spinal?
unlike epidurals, spinals go through dura mater
holes in dura can cause severe headaches
more rapid onset than epidurals
block is more predictable than epidural
What is a combined spinal epidural (CSE)?
both spinal and epidural techniques used
Types of regional anaesthesia
single shot spinal:
- rapid onset
- quick to perform
- limited duration
- single shot
epidural top up:
- need good epidural in situ
- slower onset
- large doses of local anaesthetic
combined spinal epidural:
- rapid onset
- slower to perform
- can top up epidural in prolonged procedures
- can use epidural for post op analgesia
Contents of epidural space
nerve roots covered by dura
veins, fat, lymphatics
Borders of epidural space
superior - foramen magnum
inferior - sacral hiatus
anterior - posterior longitudinal ligament
posterior - ligamentum flavum
lateral - intervertebral foraminae
Which level are spinals or CSE not placed above?
L2 due to presence of solid spinal cord
Epidural analgesia advantages
excellent analgesia
continuous
avoids parenteral opioids and their side effects
can be extended for anaesthesia for lower segment caesarean section
improved pulmonary function
minimise pulmonary and venous thrombosis
decrease in cardiovascular complications
Disadvantages of epidural analgesia
complications - failure, post dural puncture headache, nerve damage
can prolong labour
side effects - hypotension, pruritus, shivering, back ache, pyrexia, decreased mobility
Indications for epidural analgesia
maternal request
to permit augmentation of labour
pre-eclampsia
maternal disease
anticipated difficult airway (obesity)
anticipated difficulty getting rapid regional anaesthesia (obesity)
expectation of operative delivery (twins, malpresentation)
cardiac disease (regurgitant valvular lesions)
specific neuro conditions (AV malformations)
Absolute contraindications epidural analgesia
patient refusal
local anaesthetic allergy
infection at site of insertion
Relative contraindications epidural analgesia
hypovolaemia
coagulopathy
anatomical abnormalities
systemic sepsis
valvular heart disease
neurological disease
back problems
Caesarean section categories and time from decision to delivery
A - 20 mins
B - 30 mins
C - 75 mins
D - 360 mins
elective
Reasons for general anaesthesia for caesarean section
urgency of surgery - Cat A when spinal not easy
contraindications to regional anaesthesia (coagulopathy, thrombocytopaenia, hypovolaemia)
maternal request
failed regional anaesthesia
