Treat or Hold? Decoding High Blood Pressure in the Emergency Room

Author: Charlotte Davies, Philippa Peto, Jasmine Lee, Kate Wesseldine / Editor: Liz Herrieven / Reviewers: Charlotte Davies, Khurram Rasool, Aadil Farooq / Codes: / Published: 23/02/2021

Introduction

A patient walks into emergency room with a sky-high blood pressure reading that makes you stop and wonder if there’s a serious problem brewing or whether it was just a temporary spike. Knowing the difference is crucial for making the right call and catching any major issues. While high blood pressure is often seen as a chronic issue that is usually best managed outside the hospital, it can also lead to emergencies that need immediate attention. So, how do you spot critical cases, and how do you handle severe hypertension in the busy ED?

Whats the big deal about high blood pressure in the ED?

This blog will help us decided whether to act, only observe, or delegate the patient to primary care when we encounter the dilemma of high numbers. Essentially, we will look at the difference between a hypertensive emergency and urgency and discuss how to handle these effectively.

What is Blood Pressure?

Medical school was a long time ago for many of us [Editor speak for yourself, Im a spring chicken]. For a refresher on BP physiology have a look at this website.

Key Points:
BP = flow X resistance

MAP = cardiac output X total peripheral resistance

Short Term Control: detected by baroreceptors in the aorta and carotid sinus. Parasympathetic fibres reduce the BP via the vagal nerve. The sympathetic fibres increase the BP.

Long Term Control: managed by the renin angiotensin aldosterone system. ANP and prostaglandins also have an effect.

The differentiation between the two systems is important as the short term control system is likely to be the predominant one affecting blood pressure in the ED, and the effect of short term control is difficult to predict.

Understanding the Basics

Hypertension is generally defined as Systolic BP 140 mmHg and/or Diastolic BP 90 mmHg in a non-acute setting. However, in the ED, Isolated elevated BP readings are common due to pain, anxiety, or acute illness. Clinicians must determine whether this elevation represents chronic hypertension, a hypertensive urgency, or a true hypertensive emergency. So, severe hypertension (Systolic BP 180 mmHg or Diastolic BP 120 mmHg) can be broadly divided into:

• Hypertensive Urgency: Severely elevated BP without acute end-organ damage, often due to non-adherence to medication.
• Hypertensive Emergency: Elevated BP with evidence of acute end-organ damage, for examples: Encephalopathy, acute pulmonary oedema, aortic dissection, acute kidney injury, papilledema.

Hypertensive Urgency vs. Emergency

First, we have hypertensive urgencies, where BP is severely elevated but without acute or impending end organ damage. This is when a patients BP might be sky-high; Let us say, systolic over 180 or even 240, or diastolic over 120; but they feel fine, and all investigations are normal. This often happens due to withdrawal or poor compliance with medications. Here, the role of the ED doctor is to give lifestyle advice and arrange timely follow-up rather than to give oral stat dose in desperation. Initiating antihypertensive medication in the ED is generally discouraged unless the patient has no access to primary care.

Finally, and most importantly, are hypertensive emergencies. This is when elevated BP is accompanied by acute organ damage, such as encephalopathy, pulmonary oedema, myocardial infarction, aortic dissection, or acute kidney injury. When the patient has clear evidence of end-organ damage, the ED team must act fast but carefully. Move the patient to a monitored bed and start intravenous treatment. The goal is not to normalize blood pressure immediately, which could cause dangerous drops in organ perfusion, but to reduce it gradually.

Management and identification of urgency and emergency hypertensive problems is covered elsewhere on RCEM Learning.

Management Strategy

While dealing with a patient with high blood pressure, ask yourself three key questions:

1. Is the measurement accurate?
   1. Use a calibrated and validated device
   2. Repeat after patient rests for at least 5 minutes
   3. Use manual measurement if automated values are suspiciously high
2. Is there any evidence of end organ damage due to high blood pressure ie is the patient truly asymptomatic?
   1. Neurological status (confusion, seizure, stroke)
   2. Cardiovascular exam (chest pain, shortness of breath, ECG)
   3. Renal function (urine output, Proteinuria, Haematuria, creatinine, urea)
   4. Fundoscopy for papilloedema or retinal haemorrhages
3. Decide if this case warrants immediate intervention to lower down the blood pressure. It is vital to stop the on-going damage and to prevent life changing damages. If there is no evidence of end-organ damage, outpatient management may be more appropriate despite how high the numbers are.

Is the Patient Symptomatic?

The first challenge in blood pressure control is deciding whether the patient before you is truly asymptomatic from their hypertension.

Headache is tricky as a headache might be a sign of a hypertensive emergency and is listed as a red flag by NICE. Theres a significant nocebo effect and Im sure many of us have seen patients with a headache, who have a high BP because of the pain, or the anxiety or other things.

Epistaxis is commonly associated with hypertension but there is not enough evidence to prove causation. I would treat epistaxis related hypertension as short term control with analgesia and review.

Chest Pain is a worrying feature with hypertension as it may indicate ischaemia or an aortic dissection. We will cover treatment of hypertension associated with aortic dissection later in special situations.

Altered Consciousness and Confusion may be caused by a hypertensive emergency and consideration should be given to lowering the blood pressure.

Hypertensive emergencies are rare, and the patient normally looks very unwell, even if its triggered by a phaeochromocytoma. They should be treated with senior input and patients normally need IV treatment along with invasive monitoring in a critical care environment. For more information read the RCEMLearning reference or learning module on hypertensive emergencies, or have a listen to EMCrit.

Asymptomatic Blood Pressure Control

Look for hidden symptoms if BP >140/90mmHg. NICE Guidelines suggest looking for target organ damage:
*Papilloedema
*Retinal Haemorrhage
*New Onset Confusion
*Signs of heart failure
*Acute kidney injury

We should probably be looking at all of these factors in all patients who present with hypertension to the ED, although most of us arent very confident at looking for papilloedema. Acute kidney injury is normally defined by U&E results, but assessing for haematuria and proteinuria is also useful. Should these investigations be done by ED or by the GP? You could argue both sides, but I would say if the patients there in ED, getting an ECG and a set of bloods is easy for us to do, and easier for the patient.

Signs of heart failure can be tricky and I always consider these patients as signs of symptomatic heart failure. These are your patients with pitting oedema to their nose, or shortness of breath as their lungs are so full of fluid. The patient with a smidge of fluid in their horizontal fissure I dont count as having heart failure. Do you need an ECG? Well if youre looking for left atrial enlargement then its probably useful, as is LVH.

We should treat asymptomatic patients with any target organ damage straight away. Theres a great NICE infographic about what treatment to start first, although whether the racial differences are based on science is unclear. Blood pressure management is standardly the domain of the GP, however I think these patients should be commenced on antihypertensives in ED to prevent the target organ damage getting any worse.

Asymptomatic patients with no target organ damage should have ambulatory blood pressure readings taken before starting treatment, so they should be advised to see their GP at the next available appointment for a review. Many GP practices have a long wait for ambulatory readings so do suggest a home spyhg and recording twice daily readings – guidance here. We should take the opportunity to give healthy lifestyle advice.

But what if the BP is really really high?

The NICE guidelines no longer have treatment cut-offs above which you MUST treat, and instead they rely on target organ damage. Despite this, many of us feel really uncomfortable discharging a patient with a BP of 240/150 or similar with no treatment at all. These are patients who would benefit from SDEC or ambulatory care management to observe the effect of BP control. In acute settings, giving patients oral antihypertensives, or lowering blood pressure immediately in the absence of end organ damage, is discouraged since there is no evidence of better outcome in multiple studies. NICE does not specify a blood pressure cut-off number that mandates emergency intervention, emphasizing that clinical context matters more than the numbers alone.

Studies have shown that there is no increased short-term risk if BP is not rapidly lowered in ED. In fact, quickly dropping blood pressure can be risky, especially for patients who have lived with persistently high readings. A sudden reduction can lead to inadequate blood flow to vital organs, which may cause harm rather than help. Studies suggest that a gradual, outpatient approach leads to similar long-term results without the risks associated with rapid intervention.

The general aim is to gradually lower the blood pressure over several hours using oral agents. If the patient is reliably taking a medicine from one class, choose another in addition:

*Nifedipine MR 20-30 mg. Anecdotally people have seen hypotension as a result of nifedipine for hypertension so I always start low – and make sure treatment of the hypertension is truly indicated. I also wonder if people are prescribing the modified release dose, and then giving the immediate release dose. This calcium channel blocker can be taken twice daily for several days before switching to longer-acting equivalents such as amlodipine.

*Doxazosin 4-8 mg immediate release
*Metoprolol 25-50 mg (three times daily, can be replaced later)

Youll note that amlodipine and review is NOT a strategy recommended. It wasnt recommended in 2018, and wont be recommended now. Amlodipine is a calcium ion influx inhibitor of the dihydropyridine group (slow channel blocker or calcium ion antagonist) and inhibits the transmembrane influx of calcium ions into cardiac and vascular smooth muscle. After oral administration of therapeutic doses, amlodipine is well absorbed with peak blood levels between 6-12 hours post dose with absolute bioavailability of between 64% and 80%. Theres more discussion around this on X (previously Twitter).

When you feel comfortable to discharge, the patient can be discharged to their GP with a prescription of the medication that achieved the improved control. If control is incomplete, the patient will need a review.

Why dont we just give everyone IV and send them home?

Lowering the blood pressure too quickly can trigger cerebral or myocardial ischaemia. The BP should be lowered gradually to minimise this risk against the potential risk of cardiovascular events. There is no proven benefit from rapid reduction of blood pressure in patients with severe asymptomatic hypertension and most such patients can be managed as outpatients.

Why dont we treat everyone regardless of whether theres target organ damage?

There are risks associated with over medicalising everything, and with inducing hypotension. Confirming hypertension and trying lifestyle modifications before pharmaceutical management is preferred and the GP is the expert in managing this.

A retrospective cohort where elevated BP in ED not associated with adverse cardiovascular outcome at 2 years. https://t.co/z5nZXY64lf

chris connolly (@chrisconnolly83) February 15, 2021

Discharging Patients Safely: The Importance of Follow-Up

For patients not requiring admission, safety netting is crucial. This means giving clear advice about their condition, symptoms to watch for, and when to seek help. Ensuring they have a reliable pathway to follow-up care, whether through their GP or a specialist hypertension clinic, is essential to avoid future complications. Last but not the least; do not forget to document your assessment, the discussions with the patient, and the follow-up plan clearly in the notes, to protect both patient safety and medico-legal standards.

Special Considerations

Hypertension in Pregnancy – follow the latest NICE guidelines and liaise with your obstetrician. This may be a sign of pre-eclampsia – do an urgent urine dip before discussion with O+G.

Hypertension with Acute Aortic Dissection – Reducing the blood pressure is a mainstay of treatment for aortic dissection. You want the blood pressure to be around 100 -120mmHg systolic – the lowest tolerated (i.e. still perfusing brain). Stage one is reducing the heart rate with beta blockers like labetalol. Stage two is vasodilation with things like GTN. Stage one must be initiated before stage two as otherwise as the BP drops, short term BP control mechanisms senses the BP drop causing a reflex tachycardia.

Autonomic Dysreflexia is an uncontrolled sympathetic response in patients with spinal cord injury, normally above T6. It can be triggered by correctable causes like constipation and urinary retention and these should always be looked for and treated before prescribing medication. For more details have a look at this review article here.

Autonomic dysreflexia: quick thread

An important condition to be aware of and be prepared for in any patient with a spinal cord injury or malignant compression at the level of T6 or above pic.twitter.com/dsJryAQIyM

Tony Duffy (@Existential_Doc) April 9, 2021

Hypertension and Acute Stroke – it is unclear whether treating hypertension acutely is beneficial, but as hypertension is generally considered a contraindication to thrombolysis, many thrombolysis centres treat it aggressively. Hypotension risks ischaemic injury after acute stroke so hypertension should only be managed under close monitoring, ideally by the hyperacute unit. I suggest seeking specialist advice from the stroke unit before starting anything.

Sub arachnoid haemorrhage requires swift blood pressure control to prevent the risk of re-rupture. Your neurosurgeon probably has a preferred agent.

Head Injury and Raised ICP may present with hypertension as part of Cushings triad. Treatment with mannitol or hypertonic saline may be indicated.

Hypertension and the Elderly is often a balancing act to manage. There are now less specific targets and in the elderly this is particularly important as the high blood pressure could be all that sustains them from falling over because of their very stiff vasculature. The MDTea podcast has covered this well.

Hypertension in Children is increasing in frequency. Make sure you look carefully for renal causes and occult head injury, and refer to your friendly paediatric team – even if they don’t need acute management, these cases will need follow up.

Oh Ive already given them 5mg amlodipine. Im just going to keep them in the ED for another hour or so while I wait for it to work. pic.twitter.com/ptMWkSobxW

Anu Mitra (@AcmeDR) June 2, 2022

How to Treat Hypertensive Emergencies in the ED

When you spot a hypertensive emergency, it’s really important to act quickly and carefully. You want to bring down the blood pressure at just the right pace – not too fast and not too slow – to avoid making matters worse or causing new issues. Generally, you want to lower the mean arterial pressure by about 20-25% within the first hour. A rapid crash in blood pressure risks depriving vital organs of blood flow, so gradual reduction is the key.

The choice of medication depends on the clinical picture. However, in hypertensive emergencies, parenteral drugs are better for their immediate effect, titration control and safety profile. Nicardipine and Labetalol are usually preferred for first line treatment.

Feature	Nicardipine	Labetalol
Drug class	Calcium channel blocker (CCB)	Alpha-1 + non-selective beta blocker
Onset	515 min	25 min
Duration	46 hours	26 hours
Titration	Continuous infusion only	IV bolus or infusion
Effect on HR	May cause reflex tachycardia	May cause bradycardia
Cerebral perfusion	Maintains or improves	Maintains
Pregnancy use	Not first-line	Preferred (preeclampsia)
Airway/CHF patients	Safer in asthma/COPD	Caution: bronchospasm, CHF
Preferred in	Stroke, neuro-emergencies	Aortic dissection, pregnancy, ACS

Labetalol is usually preferred in most hypertensive emergencies because of its efficacy, safety profile, and it is less likely to cause reflex tachycardia or sudden drops.

Clinical Choices at a Glance

Conditions	Recommended Drugs	Notes
Acute Cerebral Hemorrhage (Confusion, Seizure)	Nicardipine, Labetalol, Esmolol, fenoldopam, clevidipine	Reduce significantly elevated mean arterial pressures by 20% to 25%. Careful titration to avoid cerebral ischemia. Target systolic blood pressure to 160 mm Hg or lower
Acute coronary Syndrome (Chest pain)	Nitroglycerine	Limit ischemia and reduce the mean arterial pressure by no more than 25%
Aortic Dissection (Tearing chest pain radiating to back)	1st: Esmolol, Labetalol, diltiazem 2nd: alpha antagonist, benzodiazepine, Nicardipine, sodium Nitroprusside	Reduce HR to 60 and systolic BP 100-140mmHg Beta blockers before vasodilators.
Acute Pulmonary Oedema (Crackles, Gallop rhythm)	Sodium Nitroprusside, Furosemide, Nitroglycerin, Nicardipine	Goal: reduce afterload by 20-30%
Acute renal failure (proteinuria and haematuria)	Nicardipine, Fenoldopam, Clevidipine	Reduce systemic vascular resistance with acute blood pressure reductions of less than 20% to help preserve renal blood flow
Pheochromocytoma crisis (episodic palpitations and headache)	Phenoxybenzamine, Phentolamine, Sodium Nitroprusside	Pre-treatment with alpha-blockers before beta-blockers
Pre-eclampsia	Hydralazine, Labetalol	Prevent progression to eclampsia. Monitor for seizures and foetal well-being

Final Thoughts

Managing high blood pressure in an ED room depends fully on your clinical judgment rather than numbers and fears. High blood pressure readings can be scary but not every patient needs emergency treatment. The main role of an emergency physician is to rule out end-organ damage, expedite lifestyle advice, arrange appropriate follow-up, and make judicious use of medications if required. SDEC and ambulatory care follow-up can always be considered for alarmingly high numbers of otherwise well patients. Consider diving deeper into the topic through reading from RCEM Learning and reading guidelines from NICE NG136.

Examples in Cases

Summary of Managing Severe Hypertension in ED

Further resources

The Resus Room
CoreEM

About the Authors

Charlotte Davies and Liz Herrieven are ED Consultants, and members of the RCEMLearning blog editorial team. Phillipa Peto and Jasmine Lee are Acute Medicine and Renal Consultants. Kate Wesseldine is a GP trainee.