Brandon, a guy comes into your hospital with a chief complaint of a lac to his finger. In triage his BP is 240/120. He states that he has not been taking his BP meds in months. He has not other medical history and has no other immediate complaints.
Your MD, your nurses, and the medic who brought him to the hospital all think he should get SL nitro and IV hydralazine to quickly lower his BP.
How do you convince them that treating asymptomatic hypertension is a usually a bad idea.
An interesting question, but as we see, one with many other questions embedded.
Many of us have tried to consign to the ash heap of history the idea of "hypertensive urgency." This is essentially the "scary high blood pressure that doesn't seem to be causing any problems." Although many humans (EMS and nursing humans among them) seem genetically disposed to be alarmed by high numbers, the operative part of that sentence is probably the part about no problems. As famed cardiologist Dr. Will Smith wrote, "Don't start nothing, won't be nothing."
Obviously, hypertension as a chronic condition is bad for you, causing nastiness like cardiac and renal disease. But a condition it probably took the patient years to develop need not necessarily be corrected in an hour, and in fact this may cause signs and symptoms of hypoperfusion, as their system has regulated itself to maintain flow at much higher pressures.
True hypertensive emergency is another matter. This is the "scary high blood pressure that is causing problems," i.e. end organ dysfunction. This should be corrected briskly, usually to about a generic goal of a 25% reduction in MAP, unless you care to make up a different arbitrary goal, or unless disease-specific targets are present (made-up or not; see previous discussion on intracranial hemorrhage). There is also a middle ground of hypertension with no real organ injury but predisposing factors that seem to make it unusually risk, such as a known aortic aneurysm.
So the easy answer is to fix hypertensive emergencies and ignore hypertensive urgencies. (Well, refer them to outpatient management.) That's well and good for an ivory tower discussion. But if you claim you'd be happy ignoring a blood pressure of 180 or 200, all we'll have to do is keep running it up like an auctioneer and eventually you'll crack. 240? 280? 300? At some point your basic animal instincts will brush aside your evidence-based parts and concede to lowering the blood pressure.
What most of us will shoot for, partially based on expert consensus (unsupported, natch) is a SBP <180 and perhaps a DBP <110. Some go a bit more aggressive and say <160/100. Since this is purely based on fear, you can really pick your threshold. In the ICU I say <180 unless there are special circumstances. Like treating fever with antipyretics, I frankly care very little, but the nurses will keep calling.
To summarize, there is not much evidence that treating asymptomatic hypertension does any good. However, we all do it if it's high enough, and probably will until there is a study proving that X blood pressure is safe to ignore.