Hypertension in pregnancy

• Hypertension diagnosed prior to conception or prior to 20+0 weeks 
• Includes women entering pregnancy on antihypertensive therapy 
• Essential hypertension (no secondary cause determined)
• Secondary hypertension where causes may include:
  • renal parenchymal disease (e.g., glomerulonephritis, reflux nephropathy and adult polycystic kidney disease)
  • renal artery stenosis
  • systemic disease with renal involvement (e.g., diabetes mellitus)
  • systemic lupus erythematosus (SLE))
  • endocrine disorders (e.g., phaeochromocytoma, Cushing’s syndrome, primary hyperaldosteronism, hyper- or hypothyroidism and acromegaly)
  • coarctation of the aorta
  • obstructive sleep apnoea 
  • medications or supplements. (e.g., oral contraceptives, nonsteroidal anti-inflammatory drugs, corticosteroids, cocaine, stimulants, antipsychotic medications).

• Hypertension characterised by an elevated BP in a clinical setting and a normal BP at other times.
• Typically diagnosed by 24-hour ambulatory BP monitoring or home BP monitoring using an appropriately validated device.
• Women with white coat hypertension are at an increased risk of developing pre-eclampsia, compared with normotensive women.

• Hypertension characterised by a normal BP in a clinical setting and an elevated BP at other times.
• Typically diagnosed by 24-hour ambulatory BP monitoring or home BP monitoring using an appropriately validated device.

• New onset of hypertension arising after 20 weeks gestation
• No additional maternal or fetal features of pre-eclampsia
• Resolves within 3 months postpartum.

• Systolic blood pressure ≥ 170 mmHg and/or
• Diastolic blood pressure ≥ 110 mmHg.

• A multi-system disorder characterised by hypertension and involvement of one or more other organ systems and/or the fetus
• Proteinuria is common but is not mandatory to make the diagnosis. 
• See Appendix 3. 

• New onset systemic features of pre-eclampsia after 20+0 weeks gestation to women with pre-existing hypertension.

• Onset of seizures in a woman with pre-eclampsia.

• A variant of severe pre-eclampsia including: 
  • haemolysis 
  • elevated liver enzymes 
  • low Platelet count (Thrombocytopenia).

• Previous hypertensive disorder during prior pregnancy

• Chronic kidney disease or kidney impairment

• Multiple pregnancy

• Pre-existing chronic hypertension

• Pre-existing type 1 or type 2 diabetes mellitus

• Autoimmune disorders e.g., systemic lupus erythematosus, anti-phospholipid syndrome

• Advanced maternal age (>40)

• Obesity (BMI>35)

• Nulliparity

• Family history of pre-eclampsia

• Interpregnancy interval of 10 or more years

• Assisted reproduction technologies

• Systolic blood pressure >130mmHg and/or diastolic blood pressure >80mmHg

• At booking, consider investigations for secondary causes of hypertension, in consultation with physicians. 
• Women taking other antihypertensive medication  pre-pregnancy, should change to methyldopa, labetalol or nifedipine.
• At subsequent visits after 20 weeks gestation, monitor for signs of superimposed pre-eclampsia. Take a history of pre-eclampsia. symptoms. (e.g. headache, visual disturbance, epigastric or right upper quadrant pain) 
• Perform a general examination, including abdominal palpation (fetal lie, presentation, size) and neurological examination if required. (reflexes and clonus) 

• Where appropriate, home blood pressure monitoring (HBPM) with the use of a validated blood pressure device can be used. 
• The use of HBPM should not replace the minimum recommended frequency of antenatal reviews, according to the woman’s parity and gestation. 
• Compliance and technique with home blood pressure monitoring should be reassessed at each review, to ensure ongoing suitability.
• See Appendix 2.

• At each antenatal appointment assess for proteinuria. (Appendix 1.)

1. At booking:

• Measurement of serum electrolytes and creatinine.

1. Ongoing

• Request a pre-eclampsia screen if there is a sudden increase in blood pressure or new proteinuria. (spot urine protein:creatinine ratio (PCR), full blood examination (FBE), urea, creatinine, electrolytes, liver function tests (LFT).

• Dating scan to ensure accurate dates. 

1. Fetal assessment may include:
   • Serial ultrasound scans performed 4 weekly after 28 weeks
   • fetal biometry
   • amniotic fluid assessment
   • fetal umbilical artery Doppler studies. 
   • If clinically indicated, CTG if > 28 weeks gestation e.g., abnormal fetal growth, decreased fetal movement.

• Consider antihypertensives when systolic blood pressure persistently exceeds 140 mmHg and/or diastolic pressure exceeds 90 mmHg.
• Blood pressure target is ≤135/85mmHg.

• See prophylaxis above. 

• Frequent review by an Obstetrician/GP Obstetrician and by a physician familiar with the management of hypertension in pregnancy, is recommend. 
• Early referral to Obstetric led care at a health service of Maternity Capability Level 4 or higher, as required. 
• Depending on Health Service capability, women needing two antihypertensive agents during pregnancy to manage blood pressure should be considered for further management referral, if not already done.

•  Take a history of pre-eclampsia symptoms. (e.g., headache, visual disturbance, epigastric or right upper quadrant pain)  
• General examination, including abdominal palpation. (fetal lie, presentation, size) and neurological examination. (reflexes and clonus)

• Triage to severe or non-severe hypertension (SBP <160 mmHg and DBP <110 mmHg) by measuring BP over several hours. 
• In consultation with the Obstetrician/GP Obstetrician, consider admission, day stay assessment or transfer with PIPER to a health service with appropriate capability. 
• First line agents in pregnancy are methyldopa, labetalol or nifedipine. See Pharmacological Management for stable Hypertension.
• Blood pressure target is ≤135/85mmHg. 
• Women presenting with new onset severe hypertension ≥160mmHg systolic or ≥110mmHg diastolic. (see severe HT) 

• Assess for proteinuria at each visit. (Appendix 1.) 
• Absence of proteinuria does not exclude a diagnosis of pre-eclampsia. 
• See Diagnosis of Pre-eclampsia for diagnostic criteria of pre-eclampsia. (Appendix 3.)

• Consider performing bloods for Pre-eclampsia screen four weekly, or as indicated.   
  • FBE 
  • creatinine and U&E 
  • LFT’s 
  • coagulation profile only if evidence of thrombocytopenia or significant abnormalities in LFT’s. 

• If features of pre-eclampsia are present, see ‘Pre-eclampsia’. 

• Fetal assessment may include:
  • serial ultrasound scans performed 4 weekly after 28 weeks. 
  • fetal biometry
  • amniotic fluid assessment
  • fetal umbilical artery Doppler studies. 
  •  If clinically indicated, CTG if > 28 weeks gestation e.g., abnormal fetal growth, decreased fetal movement.

• Management after initial assessment will be based on results of investigations and ongoing blood pressure levels.
• Some women referred for assessment of new onset hypertension will have normal blood pressure and investigations. This could be ‘White Coat Hypertension’ and they may go on to develop Gestational Hypertension or/and Pre-eclampsia. Repeat assessment within 7 days.

Outpatient Care and Management

• Outpatient management is usually suitable for women with gestational hypertension, without severe features. 
• The timing and frequency of assessment will be determined by the gestation, the severity of disease and patient factors. 
• An individualised care plan should be developed in the antenatal clinic by the obstetrician or GP obstetrician.

• Frequent review by an obstetrician/GP obstetrician and by a physician familiar with the management of hypertension in pregnancy, may be required. 
• Early referral to obstetric led care at a health service of Maternity Capability Level 4 or higher, as required. 
• Depending on the Health Service capability, women who require 2 or more antihypertensive agents to control blood pressure should be considered for referral for further management.

• 15 minutely blood pressure until below <160/110 mmHg.
• Maternal report of fetal movements. 
• Hourly Heart rate and Oxygen saturation.
• Neurological assessment of reflexes and presence of clonus. 
•  Fluid balance charted with review of urine output 4 hourly to ensure >80mL/4 hours.

Maternal:

• Blood tests are ordered 2-3 times per week, depending on severity and rate of change in the woman’s condition
  • FBE, U&E and LFT’s
  • coagulation profile ONLY if platelets <100x10⁹ or significant transaminase abnormality
  • blood Group and Hold if planning birth
  • urine PCR every 3-4 days, if proteinuria has not previously been detected.

Fetal:

• Fetal heart rate or CTG from 28 weeks gestation, as indicated by the woman’s overall clinical condition.
• Ultrasound for fetal growth, amniotic fluid , UA Doppler. Frequency as clinically indicated.

• Refer to Pharmacological management for stable hypertension and Pharmacological management for severe hypertension.

• Recommended from viability to 34⁺⁶ weeks gestation if  birth is considered likely within the next 7 days
• Give 11.4 mg by intramuscular injection of betamethasone (Celestone Chronodose^®) daily for two doses.

• See Timing of Birth

• Minimum daily review by GPO, obstetric registrar or consultant.
• Notify paediatric team of all preterm antenatal inpatients. Paediatric consultation to discuss neonatal care, depending on gestation. 
• Anaesthetic review if delivery is planned. 
• If transfer is required, seek assistance from regional partners or PIPER.

• Consider thromboprophylaxis with non-pharmacological and / or pharmacological measures during the antenatal and postnatal period. 
• Refer to your local Adult Venous Thromboembolism (VTE) Prevention guidelines.

Pharmacological Management for stable Hypertension. (Chronic, gestational and non-severe pre-eclampsia)

and

Pharmacological Management for Severe Hypertension. 

• Medications may be required for stabilisation while awaiting transfer to a higher capability level service.
• Blood pressure target is ≤135/85 mmHg. 

• Clinical progression is unpredictable, so close clinical surveillance is required for all women with pre-eclampsia Increasing severity may be indicated by:
  • difficult to control BP 
  • maternal symptoms
  • deteriorating biochemical or haematological investigations
  • eclampsia.
• Deteriorating fetal status -The definitive treatment is birth of the fetus and placenta. 
• See Timing of Birth. 

• Care in the antenatal period depends on the gestation and severity of disease.
• Ensure ongoing obstetric review and medical review if required.
• Initial inpatient management is usually required, but there may be a role for outpatient management after senior review
• Maternal observations while an inpatient will depend on disease severity.
• See Vital signs as per Severe Hypertension. 
• See Investigations as per Severe Hypertension. 

• If transfer is required, seek assistance from regional partners or PIPER.
• Refer women with severe early onset pre-eclampsia to a Level 6 Maternity Service – consult with PIPER as indicated.

• Pre-eclampsia is an independent risk factor for venous thromboembolism (VTE) Refer to your local Adult Venous Thromboembolism (VTE) Prevention guidelines.

• Administration of intravenous fluids may contribute to a risk of pulmonary oedema. Consider IV fluid administration only after senior consultation.
• Hourly fluid balance and an indwelling urinary catheter maybe required.
• Diuretics are usually not recommended.

• Consider MgSO4 for fetal neuroprotection for planned birth less than 30 weeks gestation.

• See Care in Labour.

• Refer to Postpartum for management post birth. 

250-750 mg

Two to three times daily

• Alpha blocker.
• Slow onset of action over 24 hours.
• May cause dry mouth, sedation, dizziness, blurred vision.
• Use with caution in women with a history of depression.

100-400 mg 

Three to four times daily

• beta blocker.
• Contraindicated in women with asthma, chronic airway limitation.

• Calcium channel blocker.
• Avoid in women with aortic stenosis.
• May cause peripheral oedema.

Good Practice Points 

• Oral hydralazine can be used as a second line agent.
• Angiotensin converting enzyme (ACE) inhibitors and angiotensin receptor blockers are contraindicated in pregnancy but are safe to use postpartum in breastfeeding women. 

• Repeat after 30 minutes.
• Maximum dose: 45 mg in 24 hours.

• See appendix 4.

• See appendix 5. 

• Terminate the seizure.
• Prevent recurrence.
• Control hypertension.
• Prevent maternal and fetal hypoxia.

• Follow the basic principles of resuscitation.
• Call for help using emergency codes.
• Protect the woman from harm and move her to a left lateral position to decrease risk of aspiration.
• Ensuring a patent airway, oxygen by mask and intravenous access. 

• Control of severe hypertension to levels below 160/100 mmHg.

• Intravenous MgSO4 Administration. (Appendix 6)

• Where a seizure has not resolved within 2-3 minutes or recurs prior to commencing MgSO4, it is reasonable to administer one of the following agents intravenously over 2-3 minutes whilst commencing the MGSO4 infusion. 
• Note: these agents are NOT first line treatment agents, nor can they replace MgSO4 infusion.
• Diazepam 5–10 mg IV.
• Clonazepam 1–2 mg IV.
• Midazolam 5–10 mg IV.

• Plan timing and mode of birth with senior staff once the woman’s condition is stable.
• Consult with Regional Partners /Paediatric team/PIPER to consider the most suitable place for birth.
• At preterm gestations, the differential diagnoses of eclampsia should be considered prior to proceeding with elective birth.

• Provide close clinical surveillance in an appropriately staffed area.
• Provide woman centred care including postnatal debriefing.

• Consult early with a multidisciplinary including obstetric midwifery and anaesthetics
• Care to be provided in Birthing with one-to-one midwifery care.

• If ≥ 34 weeks gestation, vaginal birth is preferable, if possible.
• If <32 weeks' gestation, the success of induction is reduced and a caesarean section is likely to be necessary.
• If vaginal birth is planned and the cervix is unfavourable, consider cervical ripening. 

• Blood pressure, pulse, respiratory rate, oxygen saturations and conscious state every 15 minutes until stable.
• Refer to your local guideline/SCV Guideline - Care in Labour.
• Assess the woman for and report immediately, any of the following signs or symptoms:
  • altered mental state
  • sudden rise in BP or BP≥160/110mmHg
  • oliguria, (urine output <80 mL in 4 hours) 
  • oxygen saturations <94%
  • persistent frontal headache
  • visual disturbances
  • epigastric or right upper quadrant pain
  • hyperreflexia
  • sustained clonus.

• Women should continue to receive their prescribed oral antihypertensive therapy during labour if hypertension is not adequately controlled during labour with oral antihypertensives, intravenous therapy may be required.
• For women receiving Labetalol intravenously. (Appendix 4)
• For women receiving hydralazine intravenously. (Appendix 5) 

• Fluid balance charting.
• Caution is advised with IV fluids.
• Insert large bore intravenous cannula – more than 1 may be required if a MgSO4 infusion is used x2.
• Prevention or treatment of hypotension with drugs such as ephedrine, phenylephrine or metaraminol is effective and appears safe in preeclamptic women if required but can cause rebound hypertension.

• Insert large bore intravenous cannula – more than 1 may be required if a MgSO4 infusion is used.
• Caution with use of iv fluids.
• Strict fluid balance charting. 
• Fluid loading is not usually essential prior to epidural anaesthesia.
• Restrict total fluid intake including intravenous therapy to 80mL/hour.
• Where oxytocin is used for labour induction or augmentation, use low volume dosing of oxytocin infusion. 
• Insert an indwelling urinary catheter with urometer and measure urine hourly.
• Observe for oliguria - <80mL /4 hours. 
• Observe for pulmonary oedema.

• See MgSO4 for seizure prophylaxis. (Appendix 6)

• Refer to your local care in labour or SCV Care in labour guidelines.
• If at risk of an eclamptic seizure and/or emergency caesarean section during labour, restrict intake to clear fluids or nil orally.

• Continuous CTG if ≥28 weeks. (or at consultant discretion at earlier gestations)

• Regional analgesia may be preferred to manage blood pressure.
• Discuss with anaesthetic team regarding platelet thresholds.
• Refer to your local Epidural Analgesia in labour guidelines.

• Do not routinely limit the duration of the second stage of labour if BP is within target range - refer to SCV Care in Labour guideline for management of second stage.
• Consider operative birth in the second stage of labour for women where hypertension has not responded to initial treatment.

• Active management of the 3rd stage with 10mg of Oxytocin by IM or IV injection. Refer to SCV Care in Labour policy Management of the Third Stage of Labour guideline 
• Avoid Syntometrine/ Ergometrine in women with hypertension.

• Consider placental histopathology if earlyonset pre-eclampsia.

• Hypertensive disorders of pregnancy may develop for the first time during the postpartum period.
• Postnatal care should be individualised according to the severity of pre-eclampsia and the rate of resolution.

• Where MgSO4 has been given for seizure prevention, the infusion should usually continue for 24 hours after birth or the last eclamptic seizure (whichever is the later) in Critical Care Unit or in Birth Suite 
• Transfer to the postnatal ward only after consultation with senior obstetric staff.

• Continue close monitoring. 
• Record observations on the Maternity Observations chart until:
  • BP is stable
  • urine output has normalised
  • blood investigations are stable or improving
• Ask woman if she has symptoms such as severe headache and epigastric pain.
• Accurate fluid balance charting may be required for women with moderate or severe disease using an indwelling urinary catheter with hourly urometer. Observe for oliguria - <80 mL/4 hours.
• Reduce frequency of monitoring only after discussion with the treating obstetric/medical team.

• Reassessment of proteinuria is not required.
• Women requiring ongoing treatment with MgSO4 may need reassessment of blood tests in the first 24 hours following birth.
• For women not requiring MgSO4, who have clinical resolution and antenatal blood tests were normal, further investigations are not required.
•  If haematological or biochemical abnormalities do not resolve, consider further specific investigations. 

•  Postpartum Hypertension with systolic BP >160mmHg and /or diastolic BP >110mmHg requires escalation of care to Obstetric Consultant, GP Obstetrician, Regional Partners or PIPER.

• If hypertensive (SBP >140 mmHg or DBP > 90 mmHg), consider commencement/continuation of antihypertensive therapy.
• The agents recommended for antenatal treatment can be used for the postnatal treatment if breastfeeding.
• Consider therapy with enalapril to reduce dosing frequency.
• If women are NOT breastfeeding, standard anti-hypertensive therapy can be used. 
• For women prescribed beta blockers, refer to your local Neonatal Hypoglycaemia for BGL monitoring of the neonate.
• Non-steroidal anti-inflammatory drugs (NSAIDs) should be avoided in the immediate post-partum period. 
• In the absence of an alternative analgesic agent, the use of NSAIDs should be limited to short-term inpatient usage.

• Assess for risk of VTE and institute non-pharmacologic and pharmacologic prophylactic measures if required.
• Refer to your local Adult Venous Thromboembolism (VTE) Prevention guidelines.

• Suitability for discharge to community care should consider blood pressure control, evidence of resolving biochemical derangement and usual postpartum issues. 
• Women with a blood pressure reading of <150/100mmHg or lower are suitable for discharge and follow-up in the community.
• Consider the risk of late seizures and the peak postpartum BP when timing discharge. 
• Domiciliary midwife should review all women with hypertensive disorders after discharge. 
• Send a discharge summary to the GP and MCHN reflecting the pregnancy complications, management and specific recommendations for follow up.
• Women with new onset hypertension during pregnancy who are discharged on antihypertensives or with persisting hypertension should be advised to have their blood pressure checked weekly or fortnightly with the GP, depending on blood pressure levels, to allow reduction and cessation of antihypertensives when possible. 
• Women with pre-eclampsia with severe features (e.g., early onset pre-eclampsia or evidence of significant end organ effects (eclampsia, stroke etc) may benefit from postnatal follow up with the obstetric or obstetric medicine team. 

•  Postnatal counselling should include a discussion about: 
  • future risk of recurrence in subsequent pregnancies, and to consider aspirin in future pregnancies if at risk of preterm pre-eclampsia
  •  hypertension and cardiovascular disease risks in later life
  • further information is available at: https://www.heartfoundation.org.au/bundles/for-professionals/fp-pregnancy-and-heart-disease

At booking: 

• If proteinuria is present on urine dip stick, or the woman has renal disease, or risk factors for renal disease eg SLE, chronic hypertension, perform a spot urine protein: creatinine ratio. (PCR) 

During pregnancy:

• Spot urine PCR greater than 30 mg/mmol is diagnostic of proteinuria in pregnancy (in the absence of an alternative explanation. (e.g., UTI)
• Once proteinuria has been detected, there is no established role for serial testing. 
• 24-hour urine collection is no longer used.
• Absence of proteinuria does not exclude a diagnosis of pre-eclampsia. (Appendix 3) 

Renal

• Random urine protein to creatinine ratio greater than or equal to 30 mg/mmol7 from an uncontaminated specimen. 
• Serum or plasma creatinine greater than or equal to 90 micromol/L. or
• Oliguria (less than 80 mL/4hours or 500 mL/24 hours).

Haematological

• Thrombocytopenia. (platelets under 150 x 10/L)
• Haemolysis. (schistocytes or red cell fragments on blood film, raised bilirubin, raised lactate dehydrogenase (LDH), decreased haptoglobin)
• Disseminated intravascular coagulation. (DIC)

• New onset of raised transaminases (over 40 IU/L) with or without epigastric or right upper quadrant pain.

Neurological

• Headache.
• Persistent visual disturbances. (photopsia, scotomata, cortical blindness, retinal vasospasm)
• Hyperreflexia with sustained clonus.
• Convulsions. (eclampsia)
• Stroke.

• Pulmonary oedema.

Uteroplacental

• Fetal growth restriction. (FGR)
• FDIU.

Resources required

• One to one midwifery care in birthsuite or highdependency unit for the duration of therapy
• IV access should be secured with two large bore IV cannulas (16g)
• Consider triple lumen connection port
• A fluid bolus of sodium chloride 0.9% or compound sodium lactate (Hartmann’s solution) is not necessarily required prior to labetalol administration but may be considered according to the patient’s fluid status.

• Severe or uncontrolled asthma. 
• Uncontrolled congestive cardiac failure. 
• History of allergic disorders with a predisposition to bronchospasm.
• Second- or third-degree atrioventricular block. (AV block)
• Sick sinus syndrome. (without pacemaker)
• Shock. (cardiogenic or hypovolaemic)
• Bradycardia with a heart rate <60bpm.

1. Bolus doses can be administered:

• Using a controlled infusion device over 2 minutes; Note: This is the preferred method of administration

1. Or 

• Manual IV injection over 2 minutes

1. Note: An obstetric registrar/consultant or GPO must remain present during ALL bolus doses of labetalol.

• Controlled infusion device. 
• The line is required to be primed with labetalol prior to loading the syringe into the controlled infusion device and connecting to the giving set.
• Label the line with ‘Labetalol’.
• Each individual bolus dose is drawn up and administered via a separate syringe.
• Ensure only the prescribed dose for the bolus dose is loaded into the syringe driver pump.
• Label syringe with ‘Labetalol (5 mg/mL)’.
• Load syringe into syringe driver pump.
• Connect to cannula.
• Manual IV injection.
• Withdraw only the required dose for each individual bolus dose undiluted from the ampoule. 
• Label the syringe as above.

• Up to two bolus doses may be administered after which a labetalol infusion should be commenced if the blood pressure remains above the target range (systolic BP≥160mmHg and / or diastolic BP ≥110mmHg).
• The maximum daily dose of labetalol should not exceed 300 mg in 24 hours.

• Bolus doses of IV labetalol must be administered under the direct supervision of medical staff, whether via syringe driver or manual bolus.
• The woman should be nursed in supine with lateral tilt, lateral position or semi-recumbent during and up to three hours after IV labetalol administration due to the potential side effects of orthostatic hypotension.
• CTG monitoring should always be undertaken for pregnant women >28 weeks receiving labetalol boluses.
• The maximum daily dose of labetalol should not exceed 300 mg in 24 hours.

• 20mg (4mL) administered by slow IV injection over two (2) minutes.
• One further bolus can be administered at 10 minutes if necessary.
• Syringe Driver/controlled infusion device.
• Follow your local guidelines on how to administer the bolus dose via your local pump/syringe driver device.

OR

•  When performing a manual IV injection:
  • flush cannula with 10 mL sodium chloride 0.9%
  • inject 20 mg (4 mL) over 2 minutes
  • flush cannula with 10 mL sodium chloride 0.9%.

Check vital signs:

• Every 5 minutes for 15 minutes. 
• Then every 15 minutes for 1 hour.
• Then every 30 minutes for 3 hours.
• Continuous CTG for a minimum of 3 hours after completion of bolus dose.

• All infusions to be administered using a syringe driver pump or large volumetric pump with syringe adapter.
• IV labetalol infusion should be commenced if the blood pressure remains elevated (systolic BP≥160mmHg and / or diastolic BP ≥110mmHg) after three bolus doses.
• As individual responses to labetalol will vary, medical staff must determine the infusion rate.
• Infusion rates will vary from 20 mg/hour (4 mL/hour) to 160 mg/hour (32 mL/hour).

• 200mg in 40mL (5mg/mL) drawn up undiluted into a 50mL syringe. 
• Label syringe with ‘Labetalol 200 mg in 40 mL (5 mg/mL)’.
• If not already primed, ensure the line is primed with labetalol prior to commencing infusion. 
• Follow your local guidelines on how to administer the bolus dose via your local pump/syringe driver device.

• Commence at 20 mg/hour (4 mL / per hour): Infusion may be used up to 160mg/hour.
• Follow your local guidelines on how to administer the bolus dose via your local pump/syringe driver device.
• Confirm 200 mg in 40 mL.
• Input VTBI: 40 mL.
• Input rate: 4 mL/hr. (dose 20 mg/hr)
• Ensure line is labelled appropriately.

• Infusion to be titrated according to blood pressure every 15 minutes. 
• A medical order is required for each rate change. 
• Discontinue by weaning over 1-2 hours when blood pressure is consistently less than 155 / 95 mmHg. 
• In some clinical scenarios, ceasing without weaning may be more appropriate.
• If the systolic blood pressure consistently <140mmHg or diastolic <90mmHg, notify medical staff regarding cessation of infusion and review.

• Use Maternity Track and Trigger Observations chart or high dependency chart.
• BP Every five minutes for 15 minutes after commencement of an infusion then every 15 minutes. 
• HR 30 minutes.
• Temperature 2 hourly.
• Continuous CTG >28 weeks gestation, while on treatment.

• The BP should be monitored every 15 minutes throughout an infusion.
• The woman should be placed supine with lateral tilt, lateral position or semi-recumbent during and up to three hours after IV labetalol administration, due to the potential side effects of orthostatic hypotension.
• The maximum daily dose of labetalol should not exceed 300 mg in 24 hours.

• IV labetalol infusions can be used until oral treatment can be commenced
• Breastfeeding:
• Labetalol is considered safe to use in breastfeeding, observing for signs of hypotension and/or bradycardia.

Contraindications

• Known hypersensitivity.
• SLE.
• Severe tachycardia. (greater than 125 bpm)
• Myocardial insufficiency.
• Right ventricular heart failure.

Precautions

• Suspected/confirmed coronary artery disease.
• Renal impairment.
• Hepatic impairment.
• Cerebrovascular disease.

• Intravenous.

• Reconstitute the hydralazine 20 mg vial with 1 mL of water for injection to make a 20 mg/mL solution.
• Dilute 1 x 20 mg/mL reconstituted ampoule of hydralazine with 19 mL sodium chloride 0.9% (to obtain 1 mg per mL) in a 20 mL syringe. (final volume is 20 mL)
• Label as ‘Hydralazine 1mg per ml’.

Intermittent IV bolus

• The bolus dose is 5mg.
• The IV bolus is given by slow intravenous injection (pushed by hand) over 3-5 minutes.
• The initial response should occur within 5-15 minutes.
• Dose can be repeated every 20 minutes to a maximum of 3 bolus doses, each drawn up in a separate syringe.
• Commence a hydralazine infusion if the BP is still outside of target range following 3 x 5mg boluses.
• Maximum cumulative dose is 30 mg over24 hours.

• Dissolve 40 mg hydralazine powder (2 ampoules) in 2 mL of water for injections in a 50ml syringe. (40 mg in 2 mL) 
• Add 38 mL of sodium chloride 0.9% to syringe 40 mg in 40 mL. (1 mg in 1 mL) 
• Administer via syringe pump.

Continuous IV infusion

• Loading dose: Administer hydralazine at 1mg/min (i.e. 1mL/min of the prepared solution) for 10 minutes.
• Titrate infusion by 1 mg/hour, every 20 minutes until the optimum BP is achieved or the maximum rate is reached. (5mg/hour)
• If the blood pressure has reached the target range after 5 minutes administration of the loading dose (i.e. 5mg), the loading dose may be ceased.
• Maintenance dose: Continue infusing hydralazine at 1-10mg/hr (1-10mL/hr) to maintain a diastolic BP of 90 - 100mmHg.

Side effects

• Tachycardia.
• Headache.
• Flushing.
• Palpitations.

• Monitor BP, pulse and oxygen saturations:
  • every 5 minutes during administration and until stable,then
  • hourly for 4 hours
• Continuous CTG if ante/intrapartum.

• Monitor BP every 15 minutes untilstable, then;
• Hourly for duration of infusion. (unlessotherwise instructed)
• Continuous CTG if ante/intrapartum.

Additional considerations during monitoring

• Maintain strictfluid balance monitoring
• Monitor, as clinically appropriate:
  • full blood count
  • liver function test
  • urea and electrolyte levels
  • coagulation profile.

• One to one midwifery care in birth suite or high dependency unit for the duration of therapy.
• Dedicated IV line for MgSO4 using a controlled infusion device.
• Resuscitation support available.
• Calcium gluconate 10% (0.22 mmol/mL) 10 mL vial available in case of respiratory depression/overdose.

• Maternal cardiac conduction defects. (heart block)
• Hypermagnesaemia.

• Myasthenia gravis.
• If impaired renal function, monitor plasma magnesium levels.

• 4g (8ml) is given over 20 minutes at a rate of 24mL/hour via controlled infusion device.

1 g/hour (2ml/hr) IV for 24 hours.

If impaired renal function:

• reduce loading dose to 2g over 20 minutes and maintenance infusion rate to 0.5 g/hour.

If new onset seizure or persistent seizures during MgSO4 infusion. (loading or maintenance)

• give a further 2 g IV over 5 minutes
  • if seizures persist, may be repeated in a further 2 minutes.

• Related to hypermagnesaemia.
• Common (greater than 1%): nausea and vomiting, sensation of heat/flushing.
• Infrequent (0.1–1%): headache, dizziness.

• BP, pulse, respiratory rate, level of consciousness.
• Oxygen saturation. (SpO2)
• Deep tendon reflexes.
• If antepartum: FHR/CTG depending on gestation.

• BP, pulse and respiratory rate every 5 minutes (for minimum 20 minutes) until stable.
• Continuous SpO2.
• Continuous CTG if greater than 28+0 weeks gestation.
• Under 28 weeks' gestation, individualise assessment of fetal wellbeing.
• Observe for side effects.
• Check deep tendon reflexes (patellar; if epidural insitu, biceps) after completion of loading dose, notify obstetrician if absent and do not commence maintenance dose.

• BP, pulse, respiratory rate and SpO2 every 30 minutes.
• Temperature every 2 hours.
• Continuous CTG if greater than 28+0 weeks gestation.
• Under 28 weeks gestation, individualise assessment of fetal wellbeing.
• Strict fluid balance monitoring and documentation.
• indwelling urinary catheter is recommended.
• Hourly urine measurements - Observe for oliguria - <80mL /4 hours.
• Hourly Deep tendon reflexes.
• Record as: A=Absent, N=Normal, B=Brisk.
• If renal function is normal, serum monitoring is not required. 
• Therapeutic serum magnesium levels are 1.7–3.5 mmol/L.

• Respiratory rate less than 12 breaths/minute.
• Absent deep tendon reflexes.
• Urine output less than 80 mL/4 hours.
• Magnesium serum levels greater than 3.5 mmol/L.
• Use Maternity Observations chart.

• Where MgSO4 has been given for seizure prevention, the infusion should usually continue for 24 hours after birth or the last eclamptic seizure.
• Before discontinuing therapy, ensure clinical improvement of blood pressure and diuresis is evident and condition is stable.