Obstetric Considerations
This covers the key considerations when anaesthetising the obstetric patient for both obstetric and non-obstetric surgery. Other physiological factors are covered under physiology of pregnancy.
Physiological Changes of Pregnancy
- A
- Airway oedema
MP score ↓ both during pregnancy and during labour.- Avoid nasal airways
- Airway oedema
- B
- Compensated respiratory acidosis
Due to ↑ MV. - ↓ O2 store
↓ FRC and ↑ VO2. - ↑ V/Q mismatch
- Compensated respiratory acidosis
- C
- ↑ HR and CO
- ↓ SVR and BP
- ↑ Circulating volume
- Note hypertension of pregnancy
Regional is more stable than GA if not intravascularly deplete.
- F
- ↑ RBF, GFR, and creatinine clearance
- G
- ↑ Aspiration risk
Combination of ↑ intragastric pressure and ↓ oesophageal sphincter tone.- Suggest premedication with:
- Ranitidine 150mg
- Sodium Citrate 30ml
- Metoclopramide 10mg IV
- Suggest premedication with:
- Mildly deranged LFTs
- ↓ Plasma protein concentration
↑ Unbound drug levels.
- ↑ Aspiration risk
- H
- Dilutional anaemia
- Potential for massive maternal haemorrhage from uterine surgery
- Crossmatch required
Indications for Antenatal Anaesthetic Assessment
Anaesthetic Indications: * Previous anaesthetic complication * Difficult or failed intubation * Anaphylaxis * Malignant hyperthermia * Suxamethonium apnoea * Complications from previous neuraxial * Previous obstetric analgesia complication * Painful labour/delivery despite anaesthetic involvement * Painful caesarian
Patient Indications:
- Respiratory disease
- That impairs ADLs
- Cardiac disease
- Valvular disease
- Arrhythmias
- Congenital cardiac disease
- PPM/ICD
- Pulmonary hypertension
- Neurological disorder
- MS
- MG
- Intracranial lesions
- Spinal cord problem
- Spinal cord injury
- Previous back surgery
- Congenital abnormalities
- Spinal anatomy that may limit neuraxial options
- Haematological disorder
- Bleeding abnormalities or disorders
- Other
- Severe systemic disease
- Morbid obesity
- Refusal of blood products
- Patient request