Peripartum hyponatraemia: an overview of physiology, prevention and management TOG 2022 Flashcards
When should you monitor Na in labour?
- Oxytocin
- Dextrose for variable insulin regime
- +ve FB of >1500mls
- Na <130
What should be done if Na >130 in labour
No fluid restriction
Repeat Na of still RF in 8 hours
If +1500mls fluid balance
What should be done if Na 125-130 in labour
Fluid restrict to 80ml/hr
Repeat Na in 4 hours
Inform senior obs team, neonatal team
What should be done if Na <125 +/- Sx in labour
- Fluid restrict <30mls/hr
- Repeat Na in 2 hours
- Stop oxytocin
- MDT - obs, anaesthetics, neonatal, medical/renal
If severe symptoms or worsening hyponatramia in labour
CCu involvement
Following MDT consider
- 2.7% saline 200ml in 30 mins
- 20mg furosemide IV, if sign fluid overload
After delivery what to do:
Na >130
No further action unless clinically Idx
What should be done if Na 125-130 after delivery
No fluid restriction unless clinicallt indicated
Repeat Na if risk factors present in 8 hours
Discuss obs/aamesthetics
What should be done if Na >130 after delivery
Fluid restrict to 30mls/hr
Repeat Na if RF still present in 4 hours
MDT discussion
Flow diagram explaining above
Average accumulation of how much fluid by 3rd trimester?
6.5-8L
Effect of pregnancy on plasma osmolality?
Falls by 10 to 280 from 10 weeks until 1-2 weeks PP
Normal serum sodium in pregnancy?
130-145 (135-145 outside pregnancy)
RF for permpartum hyponatrarmia
Lower baseline sodium in pregnancy
* Labour-related nausea, vomiting, stress, pain, starvation and increased antidiuretic hormone (ADH) secretion
* Physiological oliguria and antidiuresis
* Prolonged labour
* Oxytocin augmentation protocols
* Excess of oral/intravenous fluids/positive fluid balance >1500 ml
* Neuraxial analgesia
* Dextrose infusion
Oxytocin is structurally similar to what hormone?
ADH
Is a mild anti-diuretic effect.
Risk of dilution hyponatraemia with 1L IVI vs 2.5L
1L <1%
2.5L 26%
