Important Terms & An Example
You’ll soon learn that many of your critically ill patients will require vasoactive medications. I want to make sure we get on the same page here with terms. Please know that most drips can only be given in critical care environments because patients who are sick enough to justify these bad boys require pretty close monitoring.
Drips and Titration = Often abbreviated as gtt or gtts, these are medications given through an IV at a specific rate. You, as the ICU RN, then adjust the rate (or “titrate”) according to what’s going on with the patient/your nursing assessment based upon the order in the chart (more on orders later). Physicians rarely, if ever, touch an IV pump. This is 100% your domain and your responsibility.
Vasoactive = These medications elicit some sort of an effect on the blood vessels (whether that be relaxing the vessel/dilation, or that be tightening/constricting the vessel)
Vasopressor = Medications that cause vasoconstriction and therefore raise the blood pressure. You may also hear these referred to as “pressors” (although that’s not an official term).
Vasodilator = Medications that cause vasodilation of the vessels, and therefore lower the blood pressure.
Now, there are other kinds of drips that are not related to optimizing hemodynamic parameters like heart rate and blood pressure. These would still be considered drips because you’re titrating them. These drips include paralytics, sedatives, antiepileptics, and more less common ones. We’re not going to dive into all of those in this email course.
An example of how a vasopressor works
Buckle up new ICU nurse, because you’re going to give these medications all the time! Most likely, you’ll do so every shift.
Sepsis is one of the most common reasons a patient lands in intensive care. As the nurse, you’ll be responsible for maintaining their hemodynamics within specific parameters (most specifically, the blood pressure, heart rate, and oxygen saturation).
Your text book will tell you that sepsis causes profound system-wide massive vasodilation and increased capillary permeability. But, what does that really mean?
Let’s pretend you decided to be all sustainable and whatnot and plant your own vegetable garden. You can keep people alive, so that means you can keep plants alive, right?
(Spoiler alert: Just because you can keep people alive does NOT mean you can keep plants alive. I am a walking testimony of this phenomenon. I think I have brown thumb instead of a green one. Mainly because my plants all turn brown and die, but also because of the countless code browns I’ve cleaned up over the years.)
So you’re in your garden, getting ready to water this vast array of beautiful plants who hopefully all have DNRs and living wills set up, and you pick up your garden hose. You turn on the spigot (that’s the right word for it, right? Just kidding, I definitely had to Google it) to get the water flowing. You turn it on, water flows out, and life is great. The sun is reflecting off the water droplets kissing your fresh new plants with sweet, sweet hydration. Mother Earth gives you a wink, approving nod, and smirky-smile.
Now, let’s imagine that the spigot is stuck. You can’t turn the pressure up or down. Water is flowing how it should be, so you’re not too worried. You might as well be Professor Sprout, head of Herbology, planting mandrakes in the warm sun just before taking your afternoon tea…
Now, imagine that in a sort of Harry Potter magical fashion, the hose itself suddenly grows wider and wider. It’s no longer the diameter of a quarter… It's now the diameter of a coffee cup. What do you think that does to the water you want to get to your plants? Do you think it’s still flowing at the same rate as before? No, not at all. (You’re going to earn that brown thumb much faster than you thought!)
Now, let’s do another Harry Potter flick of a wand and make that hose turn into one of those hoses that has holes all over it (called a sprinkler hose, yes I also Googled that one too) that waters everything around it.
Between the coffee cup diameter and the holes all over it, our once steady stream of life-giving water is now barely at a slow trickle. So, how is this like vasopressors? That garden hose is your patient’s blood vessels. Vasopressors would be like tightening that droopy hose up so it’s no longer the diameter of a coffee cup. We’re not quite back to the diameter of a quarter, but we’re getting there. That decrease in diameter raises the pressure and enables blood water to get to your plants.
The fancy way of saying that is it causes vasoconstriction and increases systemic vascular resistance (SVR). Some vasopressors are also positive inotropes, which also increase contractility of the heart. In this example, that’d be like also turning up the pressure of the spigot.
Instead of getting water to plants, it’s getting blood to vital organs of your patient’s body like their brain, lungs, heart, and kidneys.
Septic patients often require vasopressor support to maintain a blood pressure that will perfuse these organs (often a mean arterial pressure, or MAP, greater than 65 is the goal). Arguably, as an ICU nurse you’re going to see this almost every shift. While that example is more specific to sepsis, it’s the same mechanism if your patient is experiencing vasodilation.