Anaesthetics and the Pregnant Woman Flashcards
How does the maternal CV system adapt to pregnancy?
CO increases 40%
HR increases 15%
SV increases 35%
Peripheral resistance decreased 35%
What is the effect of aorto-caval compression?
Hypotension
Supine hypotension syndrome in 15% of women at term
How much does the blood volume change?
TBW - increases 40%
Plasma volume by 50% and RBC by 30% therefore there is physiological dilution
Why are women hypercoaguable?
Clotting factors increase by 800%
Why are pregnant more prone to reflux?
Increase acid production
Lower LOS pressure - due to reduced diaphragmatic closure of LOS
Why do women get oedematous?
Decrease in concentration of total protein, albumin, and globulin therefore decrease in oncotic pressure
What happens to sensitivity to narcotics in pregnancy?
Increases
Why does the afterload increase after delivery?
Loss of placenta - loss pressure shunt
Why does preload increase after delivery?
Uterus contraction
When is the high risk time for cardiac failure? and VTE?
Cardiac failure - immediately after delivery
VTE - 5 days after delivery
Why might it be difficult to intubate?
Weight gain and fluid retention
Laryngeal oedema
Breast enlargement
What are the risk with pregnant airways?
More difficult to intubate
Higher risk of aspiration
Low saturations
What causes pain in labour?
First stage - visceral pain from dilatation of cervix
Second stage - somatic pain from distension of outlet, vagina, vulva, perineum
How must you take NO?
Hyperventilate in the first 30s of a contraction
Immediately stop at end of contraction
When is pethidine used?
No longer at all due to metabolic side effects in the fetu
What is are opioids of choice? What is the dose?
Morphine, IM, 100mg 2-3 hourly
Fentanyl, IV 50-100ug, PCA, used in epidurals
Remifentanil, PCA
What is remifentanil? What are the difficulties with it?
Ultra short acting synthetic opioid
Narrow therapeutic window
What proportion of women get epidurals?
50% in first pregnancies
40% in multiparous
Why do an epidural in someone with cardiac disease?
Because the pain itself causes increased cardiac stress
What are the contraindications for epidural use?
Relative
- Hypovolaemia
- Coagulopathy
- Sepsis
- Active neurological
- Obstetrical
What are the indications for epidurals?
Pain
Cardiac disease
Pre-eclampsia
What are the advantages of epidural use?
Very effective pain relief
Allows instrumental delivery
More synchronised contractions
What are some complications?
Immediate
- Hypotension, dural puncture, high block, total spinal, intravascular injection
Delayed
- PDPH
- Backache
- Neurological
- Infective complications
- Haematoma
How do you treat post epidural headache?
Blood patch
What agents are used in epidurals?
Ropivacaine + fentanyl
Bupivacaine
What anaesthetics are used in caesareans?
Spinal - majority of electives
Epidural top up - if already in labour with one
GA - if emergency and no time for epidural placement
What is used post delivery?
Multimodal
