Caring for patients in the Hypertension Clinic at Toronto Western I have had the opportunity to talk with my preceptors about the long-term clinical manifestations and complications of high blood pressure. In this blog post, I wanted to explore further what can happen acutely in the case of a hypertensive emergency.
What is a Hypertensive Emergency?
Hypertensive emergencies don’t refer to a specific elevated blood pressure number, but rather an elevated blood pressure that leads to end organ damage. For each individual patient this can happen at a different number. For example, a patient who regularly has blood pressures of ~180/90, a blood pressure of 200/90 may not trigger a hypertensive emergency. However, a pregnant woman with pre-eclampsia might have a baseline blood pressure of ~110/70, and therefore a blood pressure spike to 165/85 might trigger a hypertensive emergency. Examples of end organ damage include both micro and macrovascular damage. Microvascular complications involving small vessels can include encephalopathy, pre-eclampsia/eclampsia and local inflammatory events. Macrovascular damage can include CHF, MI, aortic dissection, stroke or subarachnoid hemorrhages.
What workup should be done in a suspected Hypertensive Emergency?
Look for the end organ damage.
· Heart: ECG, CXR, troponin, CT chest with contrast or transesophageal echo
· Brain: CT or MRI Brain
· Kidneys: Urinalysis, serum lytes and creatinine
When to Suspect Hypertensive Emergencies (not exclusive):
· Hypertensive Encephalopathy: High blood pressure and…
o Severe headache +/- vomiting
o Confusion/altered mental status
o Seizures
o Retinal changes
· Pre-eclampsia/Eclampsia: Pregnant or post-partum + high BP and…
o Headaches
o Blurring of vision, flashing lights
o Pain below the ribs
o Nausea/vomiting
o Fluid retention, flash edema
· CHF:
o Dyspnea
o Peripheral edema
o Fatigue
o Weight gain
· Myocardial Infarction:
o Chest pain/chest discomfort/chest pressure
o Diaphoresis
o Nausea/vomiting
o Anxiety
o Pain in the arm, jaw, abdomen
· Aortic Dissection:
o Tearing chest pain, radiates to the back
o Unilateral arms weakness, pulse deficit, bilateral BPs deficit
o Stroke symptoms
· Stroke:
o Motor or sensory disturbances
o Speech disturbances
o Dizziness, diplopia, dysarthria, ‘dystaxia’, dysphagia
· Subarachnoid Hemorrhage:
o Head trauma
o Meningismus
o Nausea/vomiting
o Stroke symptoms
o Sudden onset headache
Approach to Management of Hypertensive Emergencies:
Blood pressure management in the setting of a hypertensive emergency will vary based on the specific hypertensive emergency. For the most part, we don’t want to lower blood pressures too quickly, as end organs and vascular beds have become used to these higher pressures by way of a process called autoregulation. Therefore, we should reduce the blood pressure slowly (~10-20% in the first hour, and then a further 5-15 over the next 23 hours).
Some notable exceptions to this approach are:
o Ischemic Stroke: in the early stages of an ischemic stroke, we do not want to lower blood pressure too much, as the perfusion of the penumbra (area of the brain at risk for infarct) could be compromised. We therefore don’t typically lower blood pressure unless it is >185/110mmHg (if a candidate for reperfusion), or >220/120mmHg (if not a candidate for reperfusion therapy).
o Aortic Dissection: in this hypertensive emergency, we want to lower the blood pressure QUICKLY to reduce the shearing forces on the already damaged aorta. The target blood pressure is 100-120mmHg systolic and should be achieved in ~20 minutes.
o Intracerebral Hemorrhage: this condition is a tricky one, where a balance has to be struck between competing priorities of ensuring that the blood pressure is high enough that the brain is maintaining its perfusion, but not too high so as to induce re-bleeding. A target of ~160 systolic is a reasonable approach, according to AHA guidelines.
What is Used to Lower Blood Pressure in Emergencies?
The classes of drugs used in hypertensive emergencies are beta-blockers, vasodilators and calcium channel blockers. Depending on the hypertensive emergency in question one of these medications (or a combination of these antihypertensives) can be used.
~KD~
References:
1. Hypertensive Emergencies. Emergency Medicine Cases. https://emergencymedicinecases.com/episode-41-hypertensive-emergencies/
2. Evaluation and Treatment of Hypertensive Emergencies in Adults. UpToDate. https://www.uptodate.com/contents/evaluation-and-treatment-of-hypertensive-emergencies-in-adults?search=hypertensive%20emergencies&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1#H1
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