Drugs Used in Shock
Let’s go over drugs used in shock: These are all adrenergic drugs, but you’re going to have to learn that each one of these drugs possess different properties. and you have to memorize all of them.
Epinephrine (Adrenalin) has all alpha, beta 1, beta 2 properties.
Alpha property: In the form of an eye drop it decrease intra-ocular pressure. It can also prolong the action of local anesthetic and decrease bleeding because it causes vasoconstriction.
Beta 1: Increase blood pressure in shock. Why would you want it to go up? Cause they’re in shock.
Beta 2: Relieve bronchospasm. Why would you want to bronchodilate a person? An allergic reaction. The most severe is the anaphylactic shock when all their bronchioles constrict and they can’t breathe. So you may be familiar with the Epi Pen for this reason.
Levarterenol (Levophed) has alpha and beta 1 properties.
The alpha property is VERY strong vasoconstriction.
The beta 1 speeds up the heart rate and increases blood pressure. Both are used in shock but the alpha property is too strong. In fact it’s so strong when you look at their feet they turn blue and purple, putting a lot of strain on the heart. So we don’t like the alpha property but we like the beta-1 property of this drug, so we have to add another drug: an alpha blocker. So if you’re a nurse using this drug, you’re titrating two drugs (levarterenol and an alpha blocker) trying to get the blood pressure just right.
Isoproterenol (Isuprel) has beta 1 and beta 2 properties.
Beta 1: Increases blood pressure in shock.
Beta 2: Bronchodilation used for treating asthma.
Dopamine (Intropin) has three properties but one of them we haven’t talked about yet.
We talked about dopamine when we talked about Parkinson’s disease, but there is a dopamine receptor outside the CNS, in the kidney, and when it’s stimulated it causes dilation of the renal artery. Again, we talk about shock. When someone is going into shock, we get a warning about 6 hours ahead of time by seeing that their urine output has dropped. Physiologically, when a person is about to go into shock, what you have are corticosteroids from the adrenal gland getting released and it’s there to protect only two organs in your body: the brain and heart. What happens to blood flow in the rest of the body? Constriction. The renal artery is one of those that get restricted and blood flow to the kidney is being decreased, causing decreased urine output and this can lead to kidney failure. In pre-shock therapy, we know the drug is working if the urine output is increasing.
Beta 1: increasing blood pressure in shock.
Alpha: Very strong vasoconstriction. It’s too strong. Their extremities will turn purple, but this is much easier to deal with than the levarterenol because these properties are infusion rate specific. The higher the infusion rate, the closer it’ll go to the alpha, so you have to keep the infusion rate low. Its dosed by mcg/kg/minute and as long as you keep it lower than 10 mcg/kg/min you won’t activate the alpha property. So we don’t need an alpha blocker in this case.
Dobutamine (Dobutrex) has just the Beta 1 property.
Beta 1: Utilized for cardiogenic shock.
What property do we want to utilize for bronchodilation? Beta 2. Unfortunately we don’t have any beta-2 specific drugs. They also stimulate beta-1 receptors so they’ll get a racing heart rate, shakey, jittery, etc which is all beta-1 spillover. If you want it to be as close to beta-2 specific as possible, you have to give it in the inhaled form because it’s going directly to the lungs and not in the blood stream. There can still be spillover but not as likely.
Albuterol (Ventolin, Proventil) is your rescue inhaler. It means the person can’t breath right now and you need something that will work immediately but the problem with this is that if they overuse this in allergy season, this beta-2 drug becomes a beta-1 drug and their heart races and if they keep using it, they will have a heart attack.
The other inhalers are not for rescue but are used preventively.
- Metaproterenol (Alupent)
- Pirbuterol (Maxair)
- Terbutaline (Brethine, Bricanyl)
- Salmeterol (Serevent)
These specifically target Alpha receptors.
Ophthalmic Decongestants: These constrict the blood vessels in the eye. This is how visine works. There is a warning: You never use this product for over 3 days because then you get rebound congestion and your eyes are redder than before and people get “addicted” to visine.
Nasal decongestant: These constrict the blood vessels in the nasal passages.
We have nasal sprays such as Afrin and you get instantaneous relief but same warning, you can’t use it for more than 3 days otherwise there will be rebound congestion.
There is one other option called psuedoephedrine (Sudafed) which is an oral alpha stimulant and it works as a decongestant indefinitely so if you need it for multiple days or months it’s okay, but you can’t use it with people who have hypertension cause it increases their blood pressure.