Vasoactives and Low Blood Pressure Part II

by Andria RN · 0 comments

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Dopamine/Inotropin

Dopamine is a dose dependent medication, meaning it activates different receptors depending upon the dose given.  Low dose activates dopaminergic receptors which causes vasodilation.  At 2-10 mcg/kg/min, beta 1 is stimulated and you get increased cardiac contractility making this a positive inotrope.  This should be easy to remember since the name of the drug is Inotropin!  At 5-10mcg/kg/min, cardiac output is increased secondary to an increase in stroke volume (SV).  Remember that Cardiac Output (CO)= SV + Heart Rate (HR).  Lastly, a dose 10 mcg/kg/min activates alpha receptors and causes vasoconstriction.

Dopamine is used with septic shock and cardiogenic shock.

Dobutamine/Dobutrex

Dobutamine is a positive inotrope (increases cardiac contractility), a positive chronotrope (increases heart rate) and it causes vasodilation.  The vasodilation decreases systemic vascular resistance (SVR) and increases cardiac output.

Dobutamine is used for severe heart failure that is refractory to other medical treatments.  It is also used in cardiogenic shock (e.g. a patient who has had a severe myocardial infarction).

Vasopressin

Vasopressin is synthetic ADH (anti-diuretic hormone).  In our body, natural ADH helps our bodies conserve water by acting on the kidneys.  In high drip concentrations, Vasopressin causes increased peripheral vascular resistance through arterial vasoconstriction- which hopefully aids in the increase of blood pressure.  This is easy to remember because Vasopressin sounds just like vasopressor.

Normally, Vasopressin is ordered at a set rate and is not titrated.  Vasopressin is used in hypovolemic shock and can be ordered alongside other vasoactive medications for hypotension with the goal of reducing pressor demands.  Basically, the goal with hanging Vasopressin is to help wean down other vasoactive drips.

Complications

There are many complications to using vasoactive medications, which is why they are only used in shock.

Hypoperfusion

Hypoperfusion can be seen in the extremeties, mesenteric organs, and kidneys.  Check your patient’s fingers and toes for color.  Hypoperfused digits will appear dusky and then necrotic.  They may be cool and will have poor capillary refill.  Assess bowel sounds and monitor strict intake and output.

Dysrhythmias

Dysrhthmias are often from stimulation of beta 1.  Sinus Tachycardia is the most common, but patients can also convert into Atrial Fibrillation and ventricular tachyarrythmias.  Ensuring that your patient has been adequately fluid resuscitated can help minimize the frequency of dysrhythmias as well as limit the severity of injury from a dysrhythmia.  If you have a patient on a vasoactive medication and you notice that the heart rate is trending higher as you titrate the medication, notify the healthcare provider immediately.  You should also notify the health care provider of any change to heart rhythm and of increased ectopy (PVC’s, PAC’s, etc.)

Myocardial Ischemia

Vasoactive medications can make the patient’s heart work harder which in turn increases myocardial oxygen consumption.  Luckily, many of the drugs cause dilation of the coronary arteries but sometimes this is not enough.  Look for any ST elevation or ST depression on the cardiac monitor and notify the MD.

Extravasation/Necrosis

Local vasoconstriction at the IV site is a risk with most vasoactive medications.  If you have to use a peripheral IV, use a large vein, like the antecubital vein.  Check your facility policy, as some medications need to be moved to a new peripheral IV site every 12 hours or so.  Ensure your patient has two good IV sites in case one becomes extravasated.  Better yet, obtain a central line for access from the health care provider.

Miscellaneous

  • Drips can be standard concentrated or double concentrated
  • There is no set way to titrate medications, be aware of your minimum and maximum and titrate up or down slowly unless your patient is not responding to small increases- then it may be beneficial to titrate up faster
  • Most of the vasoactive drugs are compatible and can be hung in the same line
  • Label your drips and date your drugs!  Drugs can expire in 12-24 hours
  • Document vital signs every 15 min or 30 min depending on your policy
  • Know how much drug you have left in the drip bag and order a new bag from pharmacy when you hang your last bag
  • Request an arterial line from the healthcare provider to ensure more effective drug titration

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