Hypertensive emergency

High blood pressure without symptoms is NOT hypertensive emergency (see asymptomatic hypertension)

Background

• Definition: end-organ damage due to hypertension
  • Blood pressure is generally >180/120 (usually > 220/130), but presence of end-organ damage defines disease (not absolute blood pressure number)

Etiology

• Idiopathic
• Sympathomimetic drug use
• Preeclampsia
• Acute glomerulonephritis

Prehospital

• Prehospital BP measurements should be considered reliable
• Acute lowering of BP is not typically recommended
• Focus on ABCs (assess need for Intubation or respiratory support)
• Provide care of treatable etiologies
  • CHF
  • Respiratory Failure from Pulmonary Edema
  • Acute Pain

Clinical Features

End-Organ Dysfunction

• Brain - Hypertensive encephalopathy (altered mental status), seizure, ICH, ischemic stroke
• Eyes - Retinal hemorrhage, papilledema
• Heart - ACS, CHF/LV failure/pulmonary edema
• Vascular - Dissection, Microangiopathic hemolytic anemia
• Renal - Acute failure, hematuria, proteinuria, Glomerulonephritis
• OBGYN - Eclampsia

Differential Diagnosis

Hypertension

• Asymptomatic hypertension
• Hypertensive urgency
• Hypertensive emergency
  • ACS
  • Hypertensive encephalopathy
  • Acute renal failure
  • Nontraumatic thoracic aortic dissection
  • PRES
• Preeclampsia/Eclampsia
• Autonomic dysreflexia
• Drug use or overdose (e.g stimulants or Synthroid)
• Tyramine reaction
• Pheochromocytoma
• Hyperthyroidism
• Anxiety

Evaluation

Consider any of the following based on the patient's clinical presentation

• CBC - assess for hemolytic anemia
• Chem 8 - assess renal failure and possible secondary causes
• Cardiac enzymes
• Urinalysis - Assess renal failure, glomerulonephritis, preeclampsia
• Chest Xray - evaluate for pulmonary edema or dissection
• ECG - LVH, ischemia

Treatment

• Goal: Lower diastolic pressure to 105 mmHg within 2-6 hours
  • Maximum initial fall in BP should not exceed 25% of presenting value in 1st hour
• Be careful of lowering BP in patients with CVA

By Drug

Drug	Dose	Mechanism	Pros	Cons	Notes
Nitroprusside	0.3-0.5 mcg/kg/min IV initial infusion Incr by 0.5mcg/kg/min up to 2mcg/kg/min	Arterial > veno-dilator	1. Very effective 2. Immediate onset/offset	1. Cyanide Toxicity 2. Coronary steal? 3. Incr HR	1. Avoid in liver/renal failure 2. Avoid with increased ICP 3. Avoid in pregnancy
Nitroglycerin	Start 5-100 mcg/min	Veno>arteriodilation	1. Rapid on/offset 2. Increases coronary flow	Causes Tachycardia	Drug of choice in patients with cardiac ischemia, LV dysfunction, or pulmonary edema
Labetalol	20-80mg IV bolus q10min OR 0.5-2mg/min IV infusion or 200mg to 400mg PO BID	Beta>alpha blocker	1. No change in HR, cerebral flow 2. Rapid onset	Avoid in COPD, CHF and heart block	1. Consider in ACS 2. Consider in ischemic CVA
Esmolol	Load 250-500 mg/kg/ over 2min Infuse 50mcg/kg/min over 4min - if ineffective repeat load, increase infusion rate by  50mcg/kg/min up to 200mcg/kg/min	Beta selective	Rapid on/offset	Avoid in COPD, CHF bradycardia	Consider in ACS
Nicardipine	Start 5mg/h If ineffective after 15min increased in 2.5mg/hr interval up to 15mg/hr	Decreases PVR	Good for intracranial pathology	Slower onset/offset	Avoid in CHF, ACS
Phentolamine	5-10mg IV bolus q5-15min OR 0.2-5mg/min IV infusion	Alpha blocker			Used for catecholamine-induced hypertension
Enalaprilat	Bolus 1.25mg over 5min q6hr, titrate at 30min intervals to max of 5mg q6hr	Decreases HR, SV, systemic arterial pressure	Does not impair cerebral flow	Variable response	1. Used in patients at risk for cerebral hypotension, CHF 2. Avoid in pregnancy
Clonidine	0.1 - 0.3 mg PO q12 scheduled; For hypertensive emergency, 0.2 mg x1, then 0.1 mg q1 hr prn, max 0.6 mg total	Alpha-2 agonist, BP effects within 30-60 min after PO dose			Reduced CNS sympathetic flow, decreasing SVR, HR, BP; no renal blood flow changes; tolerance/tachyphylaxis develop quickly
Hydralazine	10 - 20 mg slow IV/IM bolus q4-6 hr prn, max 40 mg/dose	Peripheral vasodilator, with fall in BP beginning within 30 min, lasting 2-4 hrs			Decrease in DBP > SBP; has increased HR, stroke volume and cardiac outpt; preferential vasodilation > venodilation

By Disease

Aortic Dissection

• Rapidly reduce sys BP to 100-120; HR 60-80 within 20min
• Avoid volume depletion
• Prevent reflex tachycardia
  • Labetolol alone
  • Nitroprusside or nicardipine AFTER metoprolol or esmolol

Pulmonary Edema

• Reduce BP by 20-30%
• Promote diuresis AFTER vasodilation

ACS

• No more than 20-30% reduction for SBP >160
• Consider NTG, beta-blocker

Cocaine/Amphetamine Toxicitiy

• Benzos
• Mixed alpha + B blockade
  • Phentolamine OR nitroprusside AND beta blocker

Renal Failure

• Reduce BP by no more than 20%
• Avoid nitroprusside (renal metabolism)
• Labetalol or nicardipine

Eclampsia/Pre-eclampsia

• Goal BP <160/110
• Labetalol or nicardipine
• Magnesium

Encephalopathy

• Decrease MAP by 15-20%
  • Avoid overly aggressive lowering
• Nicardipine or labetalol

CVA

• SAH
  • See Subarachnoid Hemorrhage (SAH)
• ICH
• See current guidelines for best practice
  • Labetalol or Nicardipine or Esmolol
• Ischemic
  • If thrombolytic treatment is planned then goal systolic blood pressure 185 mm Hg
  • If no thrombolytics then consider blood pressure control if SBP >220 mmHg or DBP >120 mmgHg
  • Labetalol or Nicardipine are both effective and safe

Pheochromocytoma

• Phentolamine OR (nitroprusside AND beta blocker)

See Also

• Hypertension (main)
• Asymptomatic hypertension
• IV nitroglycerine alternatives

References

Authors

Ross Donaldson