[CG] GTN Nitroglycerin (Glyceryl Trinitrate) for emergency cervico-uterine relaxation
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Rapid and transient relaxation of the cervix and uterus is occasionally required to allow obstetric manoeuvres during emergencies.
A number of case reports and trials have shown nitroglycerin (Glyceryl Trinitrate) to provide rapid and transient cervico-uterine relaxation (albeit unlicensed).
The therapeutic effect is seen within 1-2 minutes of administration and lasts for 3-5 minutes.
- Fetal head entrapment during vaginal breech delivery.
- When uterine relaxation is required during a difficult caesarean section.
- Management of uterine inversion
Maternal IV cannula requires to be sited prior to administration of GTN (the drug may cause profound drop in BP)
Sublingual via metered pump:
Nitrolingual pump spray should be primed before using it by pressing the nozzle once.
1-2 sprays (400-800 micrograms) administered as spray droplets beneath the tongue (do not inhale). Ask woman to close her mouth after spray administered.
Repeat after 5 minutes if hypertonus sustained.
- Nitrates may increase intraocular pressure and so should be used with caution in glaucoma.
- Uncorrected hypovolaemia
- Severe anaemia (Hb<60 g/L)
- Increased intracranial pressure
- Constrictive pericarditis / pericardial tamponade
- Hypersensitivity to GTN. Nitrates, coconut oil, ethanol, glycerol monocaprylocaproate, peppermint oil
Due to vasodilating effects –
Reflex tachycardia or bradycardia
Rarely nausea, vomiting,flushing
(For complete list cautions,contraindications and side-effects see BNF)
Haemodynamic monitoring, a rapidly running I.V. infusion and immediately available ephedrine and phenylephidrine are mandatory prior to the use of Nitroglycerin (Glyceryl Trinitrate).
Once the third stage is complete, a Syntocinon infusion should be commenced.