Emergency Pharmacology: A Highlight on Vasopressors (Dopamine)

Vasopressors are life-saving drugs that are commonly seen in an emergency setting. But what are vasopressors, and what are their mechanisms of action?

Vasopressors Defined

Vasopressors are types of medications that exert pressure on the veins, on the vascular beds to promote vasoconstriction. When this happens, there is an increase in blood flow to the heart, lungs, and the brain. Aside from these organs, the kidneys are also directly affected by vasopressors.

Upon administration of vasopressors, the kidneys are alerted to hold all the fluid in the body or what is also known as fluid retention, causing dilation in the renal cavity or arteries; this will be explained further as we go along.

Examples of Vasopressors

There are many examples of vasopressors available in the market, but there are only two that are commonly utilized inside the hospital, especially in emergency scenarios. These drugs are:

  • Norepinephrine (Levophed)
  • Dopamine

Between the two, we’ll focus our attention on dopamine.

Dopamine

Dopamine is usually the first line of drug given to anyone who is suffering from hypotension.

Much like any other vasopressors, the introduction of dopamine is going to prompt vasoconstriction, putting pressure on the vessels. The primary goal for the administration of dopamine is to increase blood pressure. Aside from boosting blood pressure, dopamine can also inadvertently increase heart rate.

As mentioned, the kidneys are also going to be affected through perfusion, holding the fluid in to retain blood and distribute it to the rest of the body.

Hypotensive Crisis

Vasopressors are given especially during a hypotensive crisis. A hypotensive crisis is a situation wherein the body is losing a lot of blood drastically, which can either be caused by the following:

  • Trauma, example: gunshot wound
  • Excessive vomiting
  • Diarrhea

Any of these events can lead to hypovolemic shock, which is a deficiency of blood or fluids within the vascular spaces. If there is the extremely low amount of blood perfusion, it will compromise the distribution of oxygen. Remember, without oxygen, the body will eventually expire.

The Function of the Kidneys

So, during a hypotensive crisis, the kidneys will swoop in to save what is left of the little blood in the body by ceasing the mechanism of urination. The kidneys will not allow pee to go out of the body, keeping it inside the vascular spaces until blood pressure will rise naturally.

Route of Dopamine

Dopamine is usually given with an intravenous infusion as a piggyback or slow infusion; this will help increase blood pressure and dilate the renal arteries. This is true during emergencies.

Dopamine and ARF

Dopamine is also given to clients who are suffering from acute renal failure (ARF). When the kidneys are failing, dopamine will ignite the opening up of the renal arteries, causing more perfusion by shunting blood down to the kidneys so the client won’t go into chronic renal failure, and potentially losing the kidneys.

How does one determine that there is low perfusion in the kidneys?

The mean arterial pressure (MAP) determines how much blood flow is getting around the body. Normally the MAP is from 85 – 100. However, if there are problems with the kidneys, the MAP will go below 65. If this happens, the perfusion becomes compromised. To prevent this, dopamine is given.

For our next lecture, we’ll be focusing on the second vasopressor we’ve mentioned – norepinephrine (Levophed). Check it out in Simple Nursing’s website and YouTube channel.

Psychiatric Pharmacology Made Easy – Part 1

One of the biggest topics in nursing school is psychiatric pharmacology. Here at SimpleNursing.com, we breakdown every single vital information and present it to you in the simplest possible way.

Before going into the drugs that are primarily used for psychiatric clients, we will first tackle the pathophysiology. You have to keep in mind that before you know the mechanism of each type of drug, you must first know what it affects.

So, let’s get into it.

Psychiatric medications affect three major neurotransmitters in the body, namely:

  1. Dopamine
  2. Serotonin
  3. Norepinephrine

Reminder: Dopamine and serotonin are your reward and happiness hormones.

Dopamine

According to nursing books, dopamine inside the brain is for reward, pleasure, motor function, and compulsion. To easily remember all these, remember DOP. It basically stands for:

D – Determination (motivation)

O – Obsession (addiction to drugs like cocaine, methamphetamine, stimulants)

P – Pleasure (reward)

Frontal cortex of the brain is mostly affected by dopamine as a neurotransmitter.

Reminder: Dopamine for the rest of the body is different from dopamine inside the brain.

Basic concept to remember

The brain has a filter, like that of brewing a coffee, which is technically called as the blood-brain barrier (BBB). This BBB filter prevents chemicals and toxic elements to enter the brain to avoid unwanted consequences like the brain shutting down. Think of the BBB as a border patrol or security that doesn’t allow anything and everything to enter the brain.

Serotonin

This is your happy hormone. Serotonin can be best remembered by thinking of Siri, the iPhone application who basically makes you happy because she can answer any kind of question. In the nursing book, serotonin is referred to as your mood, sleep, cognition, and memory. Forget the book and just remember SER:

S – Sleep

E – Emotion

R – Remember

Basic concept to remember

Inside the brain, serotonin first affects the hippocampus and then it goes all the way around the brain, sort of like a racetrack. To remember that serotonin acts on the hippocampus, you can just think of a huge hippo with a bunch of knowledge, walking around campus.

Norepinephrine (Levophed)

Norepinephrine is primarily seen in MAOI drugs and atypical antidepressants. It is the same category as epinephrine (adrenaline) which is also called as noradrenaline or your stress hormone. Stress hormones trigger the body’s sympathetic nervous system (SNS) that then activates the increase in heart rate and blood pressure and the fight and flight mechanisms. If your SNS is activated, your parasympathetic nervous system (PNS), also known as your rest and digest, is automatically deactivated which means that you will be unable to produce gastric juice that is used for digestion and your bowel movement.

So, to remember ALL that, you can associate norepinephrine with NOR:

N – No hesitation

O – On alert

R – Recall memory

Basic concept to remember

Hypertension is a huge qualifier for norepinephrine, especially with MAOI. Also, one must take into consideration the cognitive alertness of a person. Example, a person is going into septic shock or any kind of shock for that matter, norepinephrine is immediately given.

As what Mike’s instructor said, “You use Levophed or you leave him dead.” This is because norepinephrine (Levophed) is the last line of drugs to get increase blood pressure, squeeze in and vaso-press (vasopressor) all the blood back into the vital organs or your SNS (heart, brain, lungs), urgently supplying them with oxygen.

Mike’s study tip

Get three note cards. Separately write down DOP, SER, and NOR on each note card. Copy the acronyms provided by Mike or what he likes to call “memory tricks.” Put in all information for the specific acronym. For example, for the DOP card, put in its equivalent meanings and what it mainly affects in the body.

What do you put at the back? It’s going to be further explained on the next video. So stay tuned!

For the meantime, SimpleNursing.com has created its first psychiatric course called Psychiatric 101. Here, Mike focuses on the struggle points which are the areas where students usually fail. What are these struggle points?

  1. NCLEX®-style questions
  2. Pharmacology

Psychiatric 101 is mainly created to help students pass and clear their understanding of the topics then retaining it fully. Mike will help you breakdown the biggest issues on psychiatric nursing and pharmacology. Just visit our website and be a member of our diamond and annual plans to request videos or have live webcam streaming for lectures.

Check it out!