Gestational hypertension

• hypertension in pregnancy is defined as a diastolic BP more than 110 mmHg on any one occasion or more than 90 mmHg on 2 occasions 4 or more hours apart (ISSHP classification)
• severe hypertension is a single diastolic BP more than 120 mmHg on any one occasion or more than 110 mmHg on 2 occasions 4 or more hours apart
• some authorities also consider an incremental diastolic rise of more than 25 mmHg above booking to be significant

Gestational proteinuria          

• 300mg or more/24hours, or
• two clean catch specimens at least 4 hours apart with more than or equal to  “++” protein, or more than or equal to “+” if the urine SG is less than 1.030 (ie dilute) and pH less than 8 (higher false positives with alkaline urine, overall false positive with dipstick approx 10+ %]

Pre-eclampsia

• pre-eclampsia is gestational hypertension with proteinuria

The aim is to reduce diastolic BP to less than 100 mmHg, prevent pulmonary oedema, prevent convulsions and maintain the urine output.

• gain initial IV access with grey venflon
• Check U&Es, LFTs, albumin, urate, Hb, H'CRIT and platelets. Clotting should only be checked if the platelets are less than 100 x10⁹/l.
• perform a CTG and then give consideration to the method and timing of delivery
• catheterize, test and measure hourly urine volumes
• Anti-hypertensive therapy as below. Use automatic blood pressure recorder initially quarter hourly - the aim is to reduce the BP slowly.
• consider inserting an epidural if the clotting is normal
• also consider labetolol, hydralazine (or nifedipine) as below

Labetalol

Labetolol is the drug of choice and treatment is generally started if the diastolic blood pressure is 110 mmHg or greater.

Labetalol (Trandate) comes as ampoules of 100 mg in 20 ml. Give an initial:

• bolus of 50 mg (10 ml) slowly IV over 2-5 minutes and then set up an
• infusion: add the ampoules undiluted to a syringe driver (5 mg/ml) starting at 4 ml/hour, doubling every 30 minutes to a maximum of 32 ml/hour (160 mg/hour)

Side-effects: if the patient becomes symptomatically hypotensive, give atropine 600 mg IV stat. Caution is required with asthma and its use is contraindicated with AV-block.

Hydralazine

Hydralazine can be given as an alternative to Labetalol.

Hydralazine (Apresoline) comes as ampoules containing 20 mg in powder form. Dissolve in 1 ml of water and make it up to 20 ml with N Saline. Give a:

• bolus: 5-10 mg (5-10 ml) slowly over at least 2 minutes, then start an
• infusion: make this up as 80 microgram/ml (i.e. 40 mg hydralazine to 500 ml Hartmann's solution). Start at 30 ml/hour (40 microgram/min) increasing by 30 ml/hour every 30 minutes to 120 ml/hour (160 microgram/min) or until the BP is controlled. Wean off by reducing 30 ml/hour every 30 minutes.

Side-effects: tachycardia and severe headache (therefore there may be confusion with eclamptic symptoms). If the patient becomes hypotensive give atropine 600 microgram IV stat.

Nifedipine:

If either of the above do not control blood pressure despite being on the maximum dose, then it is reasonable to consider using Nifedipine. Use of more than one agent, however, markedly increases the risk of profound hypotension.

Give a 5-10 mg capsule of sublingually, repeated if required to a maximum of 40 mg.

Side-effects: headache (therefore it may be confused with eclamptic symptoms).

• magnesium sulphate should be used following an eclamptic seizure (see section titled 'Eclampsia')
• the use of magnesium sulphate in pre-eclampsia halves the risk of eclampsia and may reduce the incidence of maternal death
• its use may be considered after discussion with the consultant and the dosing regimen is the same as that for use in eclampsia. (Lancet 2002, 359:1877-90)

Criteria for magnesium sulphate:

• hypertension (equal to 140/90 mmHg) with proteinuria (equal to 0.3 g/day or equal to 2+ on urinalysis) and at least one of the following:
  • headache, visual disturbance, epigastric pain
  • clonus (equal to 3 beats)
  • platelet count less than 100 x 10⁹, ALT more than 50 IU/litre
• severe hypertension (systolic equal to 170 mmHg or diastolic equal to 110 mmHg) with proteinuria (equal to 0.3 g/day or equal to 2+ on urinalysis)

• hypovolaemia (caused by loss of plasma proteins into interstitial space and the urine) is an important feature of pre-eclampsia
• Under-replacement may lead to acute renal failure, over replacement may lead to pulmonary and cerebral oedema
• give sodium lactate as IVI
• the total fluid input (including oral intake and infusions) should not exceed 80 ml/hour
• if the urine output is less than 120ml in 6 hours, inform obstetric consultant and consider senior anaesthetic review
• a CVP line is important if considering more than a small fluid challenge and is usually managed in ITU - the normal range is 2–8 cm of H₂O, although the change of the right ventricular pressure to a fluid challenge is also important
• repeat U&E twice daily
• do not give NSAIDS

• mild coagulation abnormalities, particularly a low platelet count, are not uncommon
• occasionally, particularly in severe cases, disseminated intravascular coagulation occurs with elevated fibrinogen degradation products, low fibrinogen levels, reduced platelet count, elevated prothrombin index and reduced factor VIII activity
• treatment involves replacement of coagulation factors with fresh frozen plasma, cryoprecipitate and platelets as advised by the haematologist
• early delivery of the fetus in these cases is essential

• the choice lies between parenteral narcotics or epidural anaesthesia
• an epidural is contraindicated in the presence of a coagulopathy
• great care must be taken if using narcotics not to cause respiratory depression, which will increase CO₂ retention and exacerbate cerebral oedema plus lowering the convulsive threshold
• if vaginal delivery is contemplated it is preferable that Syntocinon is given via a syringe pump to reduce the total fluid load to the patient and at delivery Ergometrine should be withheld unless specifically requested for post-partum haemorrhage
• in the third stage Syntocinon 10 IU IM may be safely given intramuscularly to assist separation and expulsion of the placenta

Principles of treatment

1. Call for help.
2. Left lateral tilt and protect the patient from injury.
3. Check ABC (airway usually not required, but have suction available).
4. Give high flow oxygen (15 l/min).
5. Establish an intravenous line for magnesium sulphate.

                                                                                          .

Magnesium sulphate is available on the labour ward emergency trolley:

Notes

• if the patient is anuric, do not administer further MgSO₄ until urine is produced
• providing there is urine production, infuse 1g hourly (5 ml/hr) via a syringe pump, continuing for 24 hrs after the last fit
• if a further convulsion occurs, give a further 2g of 20% magnesium sulphate (10ml) IV over 5 mins (infuse at 120ml/hr), or 4g (20ml) if more than 70 Kg (infuse at 120ml/hr)
• routine checking of magnesium levels is not required but, if levels are measured, levels of 2.0-4.0 mmol/l are expected
• the infusion should be discontinued if the level is more than 4.0 mmol/l

All patients with eclamptic seizures should be seen as soon as possible by the consultant on-call from both obstetric and anaesthetic disciplines. Monitor with a critical monitoring chart. Measure the respiratory rate and confirm that the patellar reflex is present (or forearm reflex in a patient with an epidural) every hour. Although MgSO4 is not sedative, it can depress neuromuscular transmission. Reduced patellar reflexes usually precede respiratory depression.

• if respiratory arrest intubate, ventilate, stop the infusion and give calcium gluconate(10 ml of 10% solution) over 10 mins
• if respiratory depression give high flow 02 (e.g. 15 l/min), stop the infusion and give calcium gluconate (10 ml of 10% solution) over 10 mins (if using an IVAC, run at 60ml/hr)
• if urine output less than 120 ml in 6 hrs, reduce MgSO4 infusion to 0.5 g/hr (2.5 ml/hr) and review fluid balance
• if reflexes are absent, stop infusion and restart once reflexes have returned
• reduce infusion rate (e.g. to 0.5 g/hr = 2.5 ml/hr) unless there have been further fits

• titrate the intravenous Labetalol against blood pressure and once blood pressure is stable convert to oral therapy
• oral therapy should be given for up to 6 weeks following discharge from hospital to be discontinued by the General Practitioner
• full blood count (and clotting if platelets less than 100 x109/l), urea and electrolytes and liver function tests may need to be checked, but the frequency of measurements will depend on the clinical situation, particular care being taken if the patient develops HELLP Syndrome
• if however, the patient is clinically well, passing good volumes of urine and blood tests were previously either normal or showing a trend to improvement, further testing is probably unnecessary
• If Syntocinon is required postnatally, a low fluid volume regimen is recommended:
  • 40 units of Syntocinon may be made up to 40 ml using Hartman’s solution
  • This gives a solution with a concentration of 1 IU in 1ml. This may be run at 5-10 ml/hour and the existing Hartman’s line, which usually runs at 80 ml/hour, should be reduced to 70 ml/hour.