Obstetric Flashcards
What causes an increased risk of regurgitation and aspiration in pregnant woman? (8)
• Large uterus increases intra-abdominal and therefore intra-gastric pressure
• cardio-oesophageal angle changes in late pregnancy due to large uterus
• increased release progesterone cause relaxation of intestinal smooth muscle that decreases stomach emptying
• increased production gastrin which increases volume and acid content of gastric secretions
• decreased motion secretion; delayed stomach emptying
• Stomach emptying delayed due to pain, anxiety, narcotic analgesics
• anticholinergics drugs lower los tone
• antacids that contain particles can worsen pneumonitis if aspiration occurs
Why is intubation and bag mask ventilation difficult in pregnant patients? (4)
• Hyperaemia
. Friability of airway (easily collapse) and oedema
• congestion: tongue, mucosa, gum hypertrophy
• hypersecretion
Name 4 anatomical respiratory changes in pregnancy
• Airway oedema and friability
• widened anteroposterior and transverse lung diameter
• elevated diaphragm
• widened subcostal angle
Difficult airway: engorgement airway soft tissue and enlarged breasts
Name 5 functional respiratory changes in pregnancy
• Increased respiratory drive (cerebellum) resulting in reduced Paco2 and increased PaO2
• minimal change in total lung capacity but increased tidal volume, reduced functional residual capacity (low reserve while intubating) ( expiratory reserve volume decrease most, and residual volume)
• normal diaphragmatic function
• increased oxygen consumption and co2 production by foetus (quick desaturation)
Increased minute volume
Increased respiratory rate (hyperventilate) → decrease etco2
How can hypotension be prevented and treated after neuraxial block in pregnancy? (3)
• Adequate hydration by co-loading of fluids with 1L crystalloid or 500 ml colloid
• position L lateral tilt to offload aorta and IVC
•Phenylephrine: Alpha 1 receptor agonist
How can aspiration be prevented in pregnancy during surgery? (4)
• NPO guidelines
• premedication with sodium citrate (neutralise pH), metoclopramide 1 hour before surgery! (Dopamine antag, increase emptying), ranitidine (H2RB, decrease acid production)
Name 3 presentations amniotic fluid embolism
• cardiac arrest
• bronchospasm
• confusion
Variable presentation.
Which agent can be used for IM analgesia for labour?
Pethidine (meperidine)
Which agent can be used for inhalation analgesia for labour?
Nitrous oxide
Which agent can be used for iv analgesia for labour?
Remifentanil PCA
Potent ultra-short acting opioid, no foetal suppression
How should patient with cord prolapse be transported to theatre?
On all fours with assistant lifting foetal leading part off cord
Name 6 causes post partum haemorrhage
• Uterine atony: most common !
• retained products
• tears
• uterine rupture
• poor surgical techniques
• bleeding disorders
Which anaesthetic option is safest in haemorrhage?
General anaesthesia with RSI - less hypotension risk and fast
Which drugs may be used to treat post partum haemorrhage? (4)
Uterotonics (first line ! )
• oxytocin
• ergometrine (contrandicated in severe hypertension but very potent and effective for uterine atony)
• prostaglandin eg misoprostol rectally
Antifibrinolytics
• tranexamic acid
Name 5 organ -specific symptoms of eclampsia and preeclampsia
• CNS: oedema, seizures, blurry vision, persistent headache , flashing lights, light sensitivity
• CVS: severe hypertension, oedema
• git: liver capsular swelling, present as abdominal tenderness, nausea, dizzy, sudden weight gain
.Renal impairment: proteinuria , severe swelling legs, hands face
• haemolysis and low platelet counts
Trouble breathing
Treatment preeclampsia? (3)
• Seizure prophylaxis: MgSO4 best
• bp control: alpha methyldopa first line, ccb then labetolol if maxed out
• definitive management = delivery of placenta
• dexamethasone 8 hourly for foetal lung maturity
Which anaesthetic method should be used in eclampsia and why?
General anaesthesia
NOT neuraxial (contraindicated) because patient uncooperative, coagulopathy due to low platelets and raised ICP
Though general anaesthesia is the only option for the eclamptic patients, which 2 serious problems may arise?
• Seizures cause tongue biting, leading to difficult intubation
• intubation response raise bp and ICP even more
Require experienced clinicians.
Which cardiovascular component does not increase in pregnancy?
Overall BP due to decreased systemic vascular resistance
What sensory level block is needed for a C section?
T4-T6
What agent and dose is preferred for spinal anaesthesia?
1.8ml (9mg!) bupivacaine 0.5% with dextrose intra-thecally
(With 0,2 ml (10 micrograms!) fentanyl for total volume 2ml)
Name 5 cardiovascular changes during pregnancy
• Increased cardiac output
• increased heart rate
• increased blood volume and dilutional anaemia
• aorto -caval compression
Systemic vascular resistance remains the same!
Name 4 neurological physiological changes during pregnancy
Increased CSF
engorgement epidural veins
Decreased MAC
Decreased local anaesthetic volumes required
Name 3 musculoskeletal physiological changes during pregnancy
Increased ligamentous laxity
Increased risk dislocation
Increased lumbar lordosis
Name 6 cardiac physiological changes during pregnancy
Increased CO (stroke vol)
Increased SV
Increased HR
LV hypertrophy
Regurgitant murmurs
Decreased SVR
Increased intravascular volume
Diastolic BP decrease mid-pregnancy then back to normal at term
Cardiac oxygen consumption increase
Dilutional anaemia
Name 5 GIT physiological changes during pregnancy
decreased LES sphincter tone
Reflux
Increased risk aspiration
Liver enzymes AST, ALT, GGT decrease
Increased ALP
Nausea and vomiting (hyperemesis gravidarum)
Increased appetite
Decrease GIT mobility - delayed stomach emptying (uterus, decreased sphincter tone due to hormones)
Name 5 renal physiological changes during pregnancy
Increased renal blood flow, arterioles vasodilation
Increase GFR
Increase risk UTI
increase urinary protein and glucose
Decrease plasma urea and creatinine
Systemic: decreased sensitivity to RAAS, more water retention, decrease plasma osmolality
Structural: pelvicalyceal dilatation, hydronephrosis, increase GBM pore size contribute to phys proteinuria
Increase calcium excretion and reabsorption or Uric acid
Name 6 endocrine physiological changes during pregnancy
Increased progesterone and oestrogen
Placenta secrete relaxin, human placental lactogen, hCG
Thyroid hyperplasia
Transient hyperthyroid
Insulin resistance
Increase cortisol secretion by adrenals
Pituitary enlarge causing increase GH, prolactin, ACTH but TSH normal
Parathyroid hyperplasia
What drug and dose should be given after delivery of baby?
2,5 iu oxytocin iv over 1 minute
And 17,5 iu in 1 litre ringers over 8 hours
(To prevent post partum bleeding )
Name 3 signs spinal/epidural haematoma
• Motor or sensory block not regressing as expected with complete paralysis and sensory deficit (within 6 hours)
• severe pain in lumbar nerve distribution (back pain)
• loss bowel/bladder control - cauda equina syndrome
Name 3 pre-operative drugs given to obstetric patients
• Aspiration prophylaxis
_Metoclopramide (prokinetic dopamine antagonist most commonly used) (also anti-emetic)
- sodium citrate ( antaCID)
- ranitidine (h2r antagonist)
• antibiotic: kefzol
• preload with ringers or voluven
Avoid benzo and opioid, give paracetamol or pethidine for analgesia. If anxious use ga.
Can give ketamine if emergency because doesn’t cross placenta
Dose MgSO4 for eclampsia?
4g IV diluted in 200ml normal saline 20% over 20minutes
5g 50% solution with 1ml 2% lignocaine in each buttock IM 4hrly for 24h
Name 3 pharmacokinetic and pharmacogenetic changes in obstetric patients
• Decreased MAC
• decreased requirements for local anaesthesia in spinal block
• decreased requirements of high lipid soluble drugs (induction agents)
Name 4 reasons that regional anaesthesia is preferred over general for C section
• Risk failure to intubate for Ga
• risk aspiration
• risk suppression of foetus by Ga drugs
• mother can bond with baby and breastfeed earlier
• atonic uterus with PPH (don’t exceed 1 MAC)
Name 6 pharmacological effects of my mgs04
•Anticonvulsant (Use in severe pet/eclampsia)
• sedative
• skeletal muscle relaxation (enhances effects of all muscle relaxants)
. Tocolytic (may cause atonic uterus with PPH)
• negative inotropic (decrease bp-used in pet/eclampsia)
• bronchodilator ( effective treatment bronchospasm)
Name 3 fluid management options for post partum haemorrhage
• Crystalloid’s: replace blood loss 3:1 - up to 20% blood loss
• colloids: replace 1 : 1- up to 20%
• packed red cells when hb < 10 g/ dL or loss> 20% (1,5x weight x (hct2-hct1))
At what point in pregnancy should anaesthetist be worried about aspiration?
≥ 16 weeks
