The Pre-brief
It’s another busy day in the Emergency Department and your next patient is a 48-year-old man with no past medical history who began experiencing chest pain and headache after watching the Cleveland Browns lose to the Pittsburgh Steelers at a local bar. The nurse was alarmed by his triage blood pressure which was 240/120, so she immediately moved him to a bed from the waiting room. As you begin to consider a list of differential diagnoses, you wonder about your management strategy for his blood pressure.
More than just a numbers game
Hypertensive Emergency (HE) is defined as severe blood pressure elevation (MAP>135 OR BP≥180/120) accompanied by evidence of end-organ injury. Acute pulmonary edema, cardiac ischemia, and neurologic emergencies are the most common types of organ injuries secondary to HE. It is estimated that 1-2% of patients with chronic hypertension will end up developing HE. A more alarming statistic is that up to 16% of patients with no prior history of hypertension can present in HE. (29261994)
It is not the degree of blood pressure that correlates with the severity of organ injury. More importantly, is the rate of development of a blood pressure spike that strongly correlates with the likelihood of organ dysfunction.
The pathophysiology of HE is complicated and involves multiple physiologic processes as well as many neuronal and hormonal pathways. The abrupt increase in systemic vascular resistance (SVR) leads to an increase in vascular permeability, platelet activation, and fibrin deposition. Microvascular thrombi caused by fibrin deposition result in vessel occlusion, organ ischemia, and organ injury.
How low do I go?
Current recommendations advocate for lowering the mean arterial pressure (MAP) by approximately 25% within the first one or two hours of HE diagnosis. (23817082)
However, the target reduction in blood pressure depends on the disease process and the specific organ involved. (Table 1 lists a few of the disease processes that can present with HE and their blood pressure targets.)
Some conditions that are also characterized by harmful increases in blood pressure demand a more aggressive MAP reduction in a shorter time period. Examples include aortic dissection, preeclampsia/eclampsia, and intracerebral hemorrhage. For these conditions, clinicians may find it necessary to reduce the MAP by more than 25% within the first two hours in order to prevent significant morbidity and mortality. In other circumstances, it may be preferable to avoid aggressive blood pressure reduction in patients with acute ischemic stroke, except in cases of severe hypertension (>220/110 mmHg) or before initiating thrombolysis (>185/110 mmHg).
The Debrief
- Hypertensive Emergency is a spike in blood pressure resulting in organ injury
- Focusing on the rate of blood pressure elevation is more important than fixating on a certain value
- Certain pathophysiology conditions require careful monitoring and management of the blood pressure. Consider starting an arterial line in this critically ill patient cohort to help guide clinical decision-making and antihypertensive therapies.
Coming Next in Part 2: Pharmacological Management of Hypertensive Emergencies
