Okay, we were just talking about vasoconstrictors. Now,
let's talk about vasodilators.
Right? When we need to decrease the blood pressure and
the arterial side, what medications do we have? Well, the
first one that we have is nitroglycerin.
Okay. Its primary job is vasodilation and it vasodilates
arterial and the venous vasculature, but it does at
different rates. Okay.
When you're under 100 mcg/min, the primary effect is just on
the venous side.
Then when you're above 100 mcg/min, your primary effect is
vasodilating the arterial side.
So, I've had a lot of nurses have patients that are
hypertensive and they start
nitroglycerin and they say "Hey, I'm up to 50 mcg/min or
even 75 mcg/min and
I'm not touching my blood pressure." Well that's because we
have vasodilated the
arterial side enough so we may need to use a different
medication rather than nitroglycerin.
This doesn't have a secondary job. When I'm starting it, I
know I want to vasodilate the patient.
It does have adverse effects of hypotension and it
could really cause a headache because you're vasodilating
the arteries in the
brain and that increased perfusion can cause a headache.
Now, remember with
nitroglycerin we can't use normal tubing, we have to use
polyethylene line tubing.
It looks like blue tubing, we just usually call it nitro
tubing. The range on this is 5–200 mcg/min.
Now, our second medication for vasodilation is
This is the big daddy to nitroglycerin. Okay. Its primary
job is a powerful vasodilator.
It's going to vasodilate both the arterial and the venous
side almost instantaneously
when you start it. Okay, so it's got an immediate reduction
in preload and afterload
when you start it. It doesn't have a secondary job. Okay?
The adverse effect is hypotension.
Its greatest adverse effect over anything else is
So, anticipate a rapid reduction in blood pressure when you
start it. Okay.
With that in mind, there is a special consideration that we
need to titrate slowly and with caution.
Also a special consideration that this medication needs to
be protected from light.
Other institutions protect medications like nitroglycerin
epinephrine and levophed from light but nitroprusside
especially needs to be
protected from light because it deteriorates under light
really really rapidly.
A second special consideration is that when you have a
patient in renal or liver failure
and you're starting nitroprusside, you can cause cyanide
So, it probably should not be used in patients with renal or
With this medication, we're going to have a range of 0.1–3
mcg/kg/min and you are going to probably
want to start it at 0.1 mcg/kg/min because we want to see
how it's going to affect the patient.
That maybe all you need to reduce the blood pressure.
Our third medication that causes vasodilation is
nicardipine. Its primary job again is
vasodilation of both the arterial and the venous vasculature
and it doesn't have a secondary job.
It's got an adverse effect of hypotension. Now, nicardipine
calcium channel blocker, but it's selective just to smooth
muscle and not to the heart tissue. Right?
So, it's going to cause vasodilation of both the vasculature
the venous side and the arterial side, but it also
vasodilates the pulmonary vasculature.
So it can help with pulmonary hypertension, but it may cause
negative inotropic effect with patients that have severe
heart failure. So keep that in mind.
Range of about 5–20 mg an hour and you're going to titrate
it by 5.
So you're going to start at 5 mg/hour and then increase it
by 5 mg every time you titrate it.