Accelerated hypertension and hypertensive emergencies

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

Severe BP may be cause, consequence or bystander. Pain, anxiety, hypoxia, urinary retention, cocaine/amphetamines, medication withdrawal and raised intracranial pressure can elevate BP; treat these while actively seeking organ injury.

The emergency assessment is syndrome-led: encephalopathy/seizure, stroke, ACS, pulmonary oedema, aortic dissection, AKI/haematuria, microangiopathic haemolysis and pregnancy-related disease each change drug choice and target.

Autoregulation shifts in chronic hypertension. Dropping pressure too far or too fast can reduce organ perfusion, which is why monitored titration and repeated neurological, cardiac and renal assessment matter more than achieving a normal cuff value.

Key points

Accelerated (malignant) hypertension is BP at least 180/120 mmHg with retinal haemorrhage and/or papilloedema.
A hypertensive emergency is severe BP elevation with acute, ongoing target-organ injury—not a number alone.
Same-day referral is required for BP at least 180/120 with retinal changes or life-threatening neurological, cardiac, aortic or renal features.
If BP is at least 180/120 without emergency features, investigate target-organ damage promptly and repeat clinic BP or arrange ABPM/HBPM with clinical review within 7 days.
Measure BP correctly in both arms initially, repeat after rest with a suitable cuff and assess standing BP when symptoms or treatment make postural hypotension likely.
In most hypertensive emergencies, reduce mean arterial pressure by about 20–25% over the first few hours rather than to normal immediately; specific syndromes override this rule.
Acute aortic syndrome needs rapid anti-impulse therapy; acute ischaemic stroke, intracerebral haemorrhage and pre-eclampsia/eclampsia have separate BP thresholds and targets.
Use titratable IV therapy in a monitored setting for emergency; oral loading or sublingual immediate-release nifedipine can cause dangerous, unpredictable falls and should not be used.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Chronic uncontrolled hypertension

Long-standing poorly controlled hypertension, missed treatment or medication withdrawal can permit a marked pressure rise. Chronic vascular injury also makes the brain, kidneys, retina and heart vulnerable when control deteriorates.

Sympathetic surges

Pain, anxiety, hypoxia, urinary retention and cocaine or amphetamine exposure can acutely increase sympathetic tone. These may precipitate severe hypertension or simply accompany another emergency, so organ injury must still be sought.

Renal and endocrine drivers

Acute renal dysfunction may both raise pressure and result from it. Labile hypertension with headache, palpitations, pallor or sweating suggests a catecholamine-secreting tumour and requires specialist assessment.

Pregnancy-related hypertension

Pre-eclampsia and eclampsia can produce severe hypertension with neurological, hepatic, renal or placental injury. Pregnancy changes both the relevant treatment pathway and the medicines considered safe.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
Abrupt pressure overload
A marked rise in arterial pressure increases wall stress throughout the circulation. When vascular protective mechanisms are exceeded, endothelial injury and small-vessel dysfunction begin to impair target-organ perfusion.
2
Autoregulatory failure
Cerebral autoregulation can fail at very high pressure, allowing hyperperfusion, vasogenic oedema and encephalopathy. Headache, confusion, visual disturbance or seizures may follow; fundoscopy may show retinal haemorrhages and/or papilloedema.
3
Microvascular organ injury
Damaged arterioles narrow or leak, producing renal injury, haematuria and proteinuria. Red cells and platelets may be mechanically disrupted in the microcirculation, causing thrombocytopenia and fragmented cells.
4
Cardiac and aortic stress
Increased afterload raises myocardial oxygen demand and can increase left-ventricular filling pressure, contributing to ischaemia or pulmonary oedema. Aortic wall stress may precipitate or extend an acute aortic syndrome in susceptible people.
5
Shifted perfusion range
Chronic hypertension shifts organ autoregulation towards higher pressures. An uncontrolled rapid fall can therefore reduce cerebral, coronary or renal blood flow even though the measured pressure remains above the usual range.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Accelerated hypertensionRed flag

BP at least 180/120 mmHg plus retinal haemorrhage and/or papilloedema; often accompanied by headache, visual symptoms, renal injury or microangiopathy.

Hypertensive encephalopathyRed flag

New confusion, agitation, headache, visual disturbance, nausea/vomiting or seizures with severe hypertension after excluding stroke and other causes.

Cardiac/aortic emergencyRed flag

Chest/back pain, pulse deficit, acute pulmonary oedema, myocardial ischaemia or new aortic regurgitation requires immediate syndrome-specific care.

Renal/microangiopathic injuryRed flag

Oliguria, rising creatinine, haematuria/proteinuria, thrombocytopenia or fragmented red cells supports acute organ damage.

Acute severe hypertension without organ injury

Repeated BP at least 180/120 but no retinal or life-threatening features; needs prompt investigation and 7-day confirmation/review rather than routine IV reduction.

Possible phaeochromocytomaRed flag

Labile/postural hypertension with headache, palpitations, pallor, diaphoresis or abdominal pain merits same-day specialist assessment under NICE.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
Repeat validated BP in both arms and fundoscopyFirst step
Why
Confirm severe BP, identify inter-arm clues and diagnose accelerated retinal injury.
Interpretation and limitations
Retinal haemorrhage or papilloedema with BP at least 180/120 triggers same-day specialist review; absence does not exclude another hypertensive emergency.
02
Urinalysis, urine ACR, U&E/eGFR and FBC/blood film
Why
Detect renal injury, proteinuria/haematuria and microangiopathic haemolysis.
Interpretation and limitations
Acute creatinine rise, haematuria/proteinuria, thrombocytopenia or schistocytes supports organ injury and higher-acuity management.
03
ECG and high-sensitivity troponin when cardiac symptoms/signs
Why
Assess ischaemia, strain and arrhythmia.
Interpretation and limitations
Troponin must be interpreted with symptoms, serial change and ECG; severe hypertension can cause type 2 injury but ACS still needs its own pathway.
04
Chest imaging, BNP and echocardiography when heart failure suspected
Why
Confirm pulmonary oedema and LV/valve pathology.
Interpretation and limitations
Acute pulmonary oedema is target-organ injury requiring monitored IV treatment, not outpatient medication adjustment.
05
CT brain/CTA aorta or other syndrome-specific imaging
Why
Identify stroke, haemorrhage, dissection or another structural emergency.
Interpretation and limitations
Select imaging from symptoms; do not delay aortic/stroke-team activation while waiting for routine hypertension tests.
06
Pregnancy test and toxicology/secondary-cause tests when indicated
Why
Identify pregnancy hypertensive disease, sympathomimetics or endocrine triggers.
Interpretation and limitations
Pregnancy changes thresholds/drugs; plasma/urine metanephrines are arranged with specialist input when phaeochromocytoma is suspected.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Severe hypertension without acute injury

Repeated severe readings can occur without acute target-organ injury. Accurate measurement after rest, no retinal or life-threatening features, and no acute renal, cardiac or neurological injury favour prompt outpatient confirmation and review rather than routine intravenous reduction, provided the person remains clinically stable.

Acute stroke or intracranial haemorrhage

A focal neurological deficit or abrupt severe headache favours a structural cerebrovascular event over diffuse hypertensive encephalopathy. Brain imaging is needed because hypertension may be a consequence as well as a cause.

Acute aortic syndrome

Abrupt chest, back or abdominal pain maximal at onset, a pulse or pressure difference, new aortic regurgitation or malperfusion raises concern for an acute aortic syndrome. This requires immediate aortic-team assessment and appropriate imaging; haemodynamic treatment should follow the aortic protocol and preserve organ perfusion.

Sympathomimetic or catecholamine crisis

Stimulant exposure or episodic headache, palpitations, pallor and sweating suggests a sympathetic cause. The history may be labile or paroxysmal, but acute organ injury still determines emergency status.

Pain or raised intracranial pressure

Severe pain, agitation, urinary retention or raised intracranial pressure can drive a reactive pressure rise. Treating the precipitant and observing the trend helps, while syndrome-specific tests assess for concurrent target-organ injury.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01same dayNICE emergency referralFirst stepBP at least 180/120 plus retinal haemorrhage/papilloedema or life-threatening neurological, cardiac, aortic or renal features.

1First: repeat accurate BP while beginning ABC, neurological, cardiac, volume and fundal assessment; obtain IV access and monitoring.
2Next: refer/admit same day to the appropriate acute team and investigate the organ syndrome in parallel.
3Next: use titratable IV therapy with a documented syndrome-specific target; in many emergencies aim for MAP reduction around 20–25% over several hours.
4EscalationEscalation: aortic dissection, stroke/ICH and pregnancy follow their dedicated rapid targets and specialist protocols.

02no acute injuryBP at least 180/120 without red flagsRepeated severe BP but no retinal haemorrhage/papilloedema or life-threatening symptoms.

1First: check adherence, recent medicines/substances, pain/anxiety and perform target-organ tests as soon as possible.
2Next: if target-organ damage is found, consider starting treatment immediately without waiting for ABPM/HBPM and arrange close review.
3Next: if no damage is found, confirm diagnosis by repeat clinic BP within 7 days or ABPM/HBPM, with clinical review within 7 days.
4EscalationEscalation: any new confusion, chest/back pain, breathlessness, oliguria or visual/retinal sign converts to same-day emergency care.

03monitored reductionGeneral hypertensive emergencyAcute organ injury without a condition requiring a different dedicated target.

1First: treat hypoxia, pain, agitation, seizures and other precipitants while monitoring arterial pressure and organ perfusion.
2Next: titrate IV labetalol or nicardipine according to contraindications and the organ syndrome, generally reducing MAP 20–25% over the first few hours.
3Next: reassess neurology, urine output, creatinine, ECG/heart failure and avoid hypotension.
4EscalationEscalation: transition cautiously to oral therapy after organ injury and BP are stable; investigate secondary causes once the acute state allows.

04exceptionsTargets that need a dedicated pathwaySuspected aortic dissection, acute stroke/ICH, pre-eclampsia/eclampsia, ACS or pulmonary oedema.

1First: activate the relevant specialist protocol rather than applying a generic target.
2Next: aortic dissection requires rapid heart-rate/impulse control followed by BP lowering, usually aiming SBP below 120 mmHg if perfusion tolerates it.
3Next: stroke reperfusion/ICH teams set BP thresholds; pregnancy uses obstetric drugs/targets; pulmonary oedema often needs vasodilation and respiratory support.
4EscalationEscalation: intensive monitoring when IV therapy, neurological change, shock or rapidly changing physiology is present.

Key medicines and prescribing safety2 treatments · regimens, roles and cautions

Titrated BP reduction in many hypertensive emergencies and anti-impulse therapy when beta-blockade is appropriate.

Labetalol IV

50 mg IV over 1 minute; repeat at 5-minute intervals if needed to a total maximum 200 mg. Alternatively infuse a 1 mg/mL solution, commonly around 160 mg/hour titrated to response.

Avoid with asthma/bronchospasm, marked bradycardia, heart block or decompensated systolic failure; monitor supine because postural hypotension can persist. Syndrome-specific dosing may differ.

Titrated arterial vasodilator when beta-blockade is unsuitable or additional BP control is needed.

Nicardipine IV

Start 3–5 mg/hour by continuous IV infusion for 15 minutes, increase by 0.5–1 mg/hour every 15 minutes to response; maximum 15 mg/hour, then reduce to about 2–4 mg/hour maintenance.

Continuous monitoring required; may cause tachycardia, headache or hypotension. In acute aortic syndrome, control heart rate/impulse first to avoid reflex shear stress.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Hypertensive encephalopathy

Loss of cerebral autoregulation causes oedema, headache, confusion, visual disturbance and seizures. Without controlled treatment, neurological injury may progress and airway protection can become necessary.

Stroke and haemorrhage

Small-vessel rupture or vascular occlusion can produce intracerebral haemorrhage or ischaemic stroke. These syndromes require their own pressure targets because excessive reduction may worsen threatened brain perfusion.

Acute cardiac injury

Afterload and oxygen-demand mismatch may cause myocardial ischaemia, while rising filling pressure can produce acute heart failure and pulmonary oedema. In a patient with severe hypertension, either represents clinically important acute target-organ injury, although the cardiac cause still needs syndrome-specific assessment.

Acute kidney injury

Renal arteriolar injury reduces filtration and can cause oliguria, rising creatinine, haematuria and proteinuria. Kidney dysfunction also complicates fluid management and selection of antihypertensive treatment.

Microangiopathic injury

Severe small-vessel damage can fragment red cells and consume platelets, producing haemolytic anaemia and thrombocytopenia. This pattern signals extensive vascular injury and higher-acuity management.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

Use continuous or very frequent BP monitoring during IV therapy; consider an arterial line for unstable or tightly targeted cases.
Repeat neurological state, pupils/vision and fundoscopy findings when clinically useful.
Track ECG/telemetry, oxygenation, chest symptoms and pulmonary oedema response.
Monitor urine output, creatinine/eGFR, potassium, urinalysis and blood count/haemolysis markers.
After stabilisation, document secondary-cause work-up, oral regimen, home BP plan and early specialist/primary-care follow-up.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

The retina defines accelerated hypertension

The term is not synonymous with any BP above 180/120; retinal haemorrhage and/or papilloedema is the defining NICE feature.

No emergency does not mean no urgency

Severe BP without organ injury still needs prompt target-organ testing and a 7-day confirmation/review plan.

Treat the syndrome, not the cuff

Aortic dissection and stroke require different rates and destinations even at the same starting BP.

Pain can drive pressure

Analgesia and relief of urinary retention, hypoxia or withdrawal can reduce BP and prevent unnecessary drug escalation.

Avoid oral shortcuts

Sublingual/immediate-release nifedipine can cause abrupt hypotension and organ ischaemia; monitored titration is safer.

11Common pitfallsFrequent interpretation and management errors.

01
Calling every BP above 180/120 a hypertensive emergency without looking for acute organ injury.
02
Discharging severe asymptomatic hypertension without target-organ tests and a 7-day review plan.
03
Trying to normalise chronic severe BP within minutes in a generic emergency.
04
Giving vasodilator before heart-rate/impulse control in suspected aortic dissection.
05
Missing papilloedema because fundoscopy was omitted.