Hypertension: Urgencies and emergencies

Definitions

• A fair bit of crossover!
• Hypertensive emergency
  • • BP > 180/120 with new or worsening target organ damage
    • 40% previous HTN diagnosis, 60% de novo
    • 30% have secondary cause
• Hypertensive urgency / uncontrolled HTN
  • • BP > 180/120 without target organ damage
• Malignant / accelerated HTN
  • • Severe HTN (>180/120) + grade 3 or 4 hypertensive retinopathy
    • May progress to hypertensive emergency
    • Rare
    • 80% mortality at 2 years without treatment. Survival 90% at 5 years with treatment
    • If not an emergency – give oral agents and don’t lower BP too quickly

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Assessment

• Use large cuff for large patient, check both arms and check for postural drop (especially in the elderly)
• Ask about vision, headaches, chest/back pain, vomiting
• Examine CV, respiratory system, neurological system (document GCS) and fundi
• Look for secondary causes and signs of end organ damage
  • • Urine – dip for blood/protein (send urine PCR if present), pregnancy test
    • ECG
    • CxR
    • Eyes – changes can be absent in presence of organ damage elsewhere. Can be unilateral.
    • Bloods – U&Es (creat, K+), BNP, trop, TSH, clotting, blood film if haemolysis
    • Consider
      • • CT head / CTA (for CVA, bleeds, PRES). Always if depressed GCS.
        • Full renal screen
        • Echo
        • Metanephrines, autoantibodies
• Consider secondary causes (more here)
  • • Drugs (recreational, withdrawal, OCP, steroids, psychiatric, immunosuppressants, anti-cancer drugs)
    • CNS (head injury, CVA, raised ICP)
    • Renal (primary, renovascular)
    • Endocrine (hyperaldosteronism, phaeo, cushings, thyroid)
    • Other (coarctation, eclampsia)
• Consider urgent management in the absence of end organ damage, emergency management if present
• However… Isolated hypertensive retinopathy, renal dysfunction, LVH on ECG, proteinuria or cerebral microbleeds does not constitute an emergency

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Complications (defines hypertensive emergency)

• CV
  • • Aortic dissection
    • ACS
    • Acute LV failure / pulmonary oedema
• Neuro
  • • Hypertensive encephalopathy
    • Intracranial haemorrhage
    • Acute ischaemic CVA
• Other
  • • AKI
    • Pre-eclampsia
    • Thrombotic microangiopathy (low platelets, fragments on film)
• Notes on hypertensive encephalopathy
  • • Headache, vomiting, confusion, seizures, visual disturbance
    • Insidious onset
    • Can be evidence of PRES on imaging (often on CT, though MRI is better)
    • Causes vasogenic oedema secondary to failure of cerebral autoregulation
    • More common in lupus, cryoglobulinaemia, haemolytic uraemic syndrome, cyclosporine, cisplatin and tacrolimus tx, CKD
    • Aim to reduce BP by 20% during first hour, and to 160/100 by 4 hours

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Lowering the Blood Pressure in A Hypertensive Emergency

• Usual strategy
  • • Lowering BP too fast can be life-threatening
    • In first hour aim to reduce MAP by 15% or 20% (or to maybe 160-180 systolic – then keep it there)
    • Over next 23 hours, aim to gradually reduce MAP by 10%
    • Can give IV treatment initially, then oral at 6 hours and then wean IV (but must give an oral agent at some point or you won’t be able to wean the IV)
    • Should be on HDU with arterial line ideally
• Exceptions
  • • Acute ischaemic stroke – only lower acutely if BP > 220 systolic (or > 180 if candidate for thrombolysis) to prevent watershed infarction. Aim 15% reduction in MAP
    • Aortic dissection – you should rapidly lower BP, aim systolic of 120 within 20 minutes and HR < 60. Use betablocker first, then a vasodilator.
    • Acute intracerebral haemorrhage – decrease BP to 150 systolic within an hour and < 140 in 6 hours. Maybe don’t drop BP by > 60 (risk of AKI). If large haematoma and signs of raised ICP, can reduce BP more slowly
    • ACS or heart failure – some guidelines suggest decrease systolic BP to 140 within an hour
• Labetalol infusion
  • • Usually first line
    • Infusion 200mg in 200ml. 0.5-2mg/min, or 30-300mg/hr. Start at 120mg/hour and double rate every 15 mins to 480mg/hr max.
    • Don’t give more than 200mg
    • Can give 20mg IV bolus first if need to bring BP down faster in first hour
    • Can be used in aortic dissection, CVA and encephalopathy especially
    • Increase by 15-30mg/hr every 15-30 minutes
    • Can cause bradycardia and bronchoconstriction
    • Lasts 3-6 hours
    • Not recommended in
      • • Uncontrolled heart failure
        • 2^nd or 3^rd degree HB, bradycardia, sick sinus syndrome
        • Asthma
        • Severe peripheral artery disease
        • Untreated pheochromocytoma
        • Metabolic acidosis
        • Be cautious if already on betablocker, digoxin or CCB
• IV GTN
  • • An alternative (but could also be used with labetalol)
    • Best in aortic dissection and ACS
    • 50ml GTN in 50ml normal saline. Rate is 2mg/min, titrating to max 10mg/min. Increase rate every 15 mins
    • Lasts minutes so easier to titrate
    • Then once controlled, wean rate and add in oral antihypertensives.
    • Side effects – headache, reflex tachycardia
    • Becomes less effective over time
    • Not recommended in
      • • PRES (can increase oedema)
        • RV infarct
        • Severe aortic stenosis
        • Mitral stenosis
        • Tamponade / constrictive pericarditis
        • HOCM
        • Marked anaemia or severe volume depletion
        • Cerebral haemorrhage
        • Use of sildenafil
        • Raised ICP
• Other IV options
  • • Nitroprusside – option in heart failure, avoid in liver and renal dysfunction or acute MI
    • Nicardipine – useful in encephalopathy
    • Esmolol – useful for aortic dissection. Very short acting
    • Phentolamine – alpha blocker, useful for phaeo, cocaine, clonidine withdrawal. Can cause reflex tachycardia
• If using oral agents as well, choose long-acting ones Amlodipine, bisoprolol, bendroflurazide, ramipril
• For cocaine toxicity – diazepam. Avoid betablockers.
• For pre-eclampsia – magnesium and labetolol. See PET

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Lowering BP in hypertensive urgency (or ‘uncontrolled HTN’)

• No acute end organ damage with BP > 180 systolic (Ensure normal ECG, urine dip, fundi, no symptoms)
• Can often be managed as outpatient but seen in ambulatory care within 48 hours of starting therapy
• Consider referral to complex HTN clinic – esp if young, or already on 3 agents
• Aim to reduce MAP by no more than 20% in first 48 hours (or to 160/100). Aiming to control BP in days to weeks.
• Check postural BP
• Drug treatment
  • • Consider
      • • Diltiazem (Tildium LA) 200-300mg OD
        • Doxazocin 8mg BD
        • Nifedipine MR 10mg BD (not s/l prep which can be dangerous and drops BP too fast). Can increase to 20mg BD
    • Then
      • • Metoprolol 12.5mg initially, then up titrate to 25mg BD
    • Then
      • • Add in ACE-I or alpha blocker or diuretic
    • Amlodipine – takes 8 hours to reach peak concentration, and about 1 week to reach steady-state effect. Therefore not recommended in this scenario (although often given)
    • Might avoid diuretics – can exacerbate volume depletion and hypokalaemia
    • Can use ACE-I and betablockers but be careful, patients can be very sensitive, start at a low dose
    • Avoid betablocker if suspected pheochromocytoma
    • Avoid ACE-i if suspected bilateral RAS