Top 5 tips for understanding hemodynamics:

• Tip # 1: Understand what caused the shock and what will reverse it. The golden rule of critical care is treating the underlying cause while providing supportive care. Knowing what you’re treating, whether it is sepsis or heart failure, will help you plan out which therapies the patient should start on, like antibiotics or diuretics. In the meantime, you can then focus on supporting the patient’s blood pressure and organ function until the underlying cause is treated.
• Tip #2: Determine what kind of shock the patient. Sometimes shock is caused by blood vessels being too dilated, sometimes it’s caused by active bleeding, and sometimes it’s because the heart isn’t working correctly to pump blood. No matter the cause, it’s important to categorize the shock to know what the correct supportive therapies, whether they be fluids, vasopressor, or inotropes, should be used.
• Tip #3: We often think of shock as low blood pressure, but really it’s low blood pressure + organ failure. The ICU can be information overload, but all the numbers are just telling you about how different organs are performing or not performing. For example, if someone’s serum creatinine doubles and their urine output becomes zero, you know they’re going into renal failure. If someone suddenly develops altered mental status, that could be because not enough oxygen is getting to his or her brain. Learn how to interpret the “information overload,” and you can use that to determine how “sick” from shock a patient is.
• Tip #4: After determining what kind of medications should be used temporarily to manage the shock (e.g., fluids, vasopressors, inotropes), the next step is to monitor the efficacy of these medications. For example: if someone has septic shock with renal failure, we know that it is most often caused by leaky blood vessels or distributive shock. Based on that information, we would want to start a vasopressor which is the first-line treatment to manage this type of shock. Once we start a vasopressor like norepinephrine, we can monitor the patient’s urine output and creatinine to determine if the medication is working!
• Tip #5: Learn the mechanism of action of all the vasopressors and inotropes. I know you hear this all the time in school but understanding what drugs work at which receptors and what those receptors do will help you UNDERSTAND how to pick between the different agents, not just MEMORIZE which one to use. Remember- critical care is not black and white; you must know how drugs work in order to select the right drug for the right patient.

Written by: Ellen Huang, PharmD, BCCCP. Critical Care Clinical Pharmacist