The topic for today’s show is PharmacyJoe-ism #7: Making patient focused risk benefit assessments.
Why Is My Patient In the ICU and How Sick Are They?
My ability to do this greatly improved when I started to explicitly and on a basic level think about why is a patient in the ICU and how sick are they?
Why is the patient in the ICU?
On the first day PGY-1 or APPE rotation with me, I make sure to give a basic explanation of why a patient might be in the ICU. From my point of view in an open medical/surgical ICU there are 3 reasons for ICU admission:
1. One or more of a patient’s vital organ systems has failed and we need to support them. This could be respiratory failure from pneumonia, or post-ROSC care of a cardiac arrest patient, or hypotension requiring vasopressors from sepsis.
2. Something happened to the patient that places them at high risk of a vital organ system failing, and we want to immediately recognize and support it if/when that happens. This could be watching a patient for 24 hours after alteplase for acute ischemic stroke, or a patient who just had a high risk surgical procedure, or a patient with delirium tremens requiring high doses of benzodiazepines.
3. Politics. The patient knows somebody, or is a “VIP”, or Dr. so-and-so wants to keep them “one more day”, or there is some bed availability issue. Why in the world you would want to subject your “VIP” to the perils of ICU care any longer than absolutely necessary is beyond me. How would that look if the Governor dies of C.Diff or a CAUTI on the tail end of an unnecessary extension in their ICU stay?
Focusing on what exactly is requiring the patient to be in the ICU helps me identify and prioritize patient problems.
How sick are they and why does it matter?
I constantly use my opinion of how sick the patient is to guide drug dosing.
Have you ever noticed how some drugs have recommended dose ranges that are so wide you can drive a bus through them?
1. Tetanus immune globulin can be 500 or 6000 units
2. Norepinephrine can run between 0.01 mcg/kg/min to 50 or 100 times that amount
3. Thiamine can be 100mg, 250mg, or 1500mg per day
Having a wide therapeutic index is great for avoiding toxicity but can be a real mystery when going for maximum efficacy.
What if the patient’s renal function is right on the cusp of a decision point for dose reduction? Should you cut the antibiotic dose in half for a septic patient because their creatinine clearance is 49 instead of 51?
To help guide you in these gray areas, you should be making some sort of assessment of how sick the patient is. I like to keep my assessment relatively simple and focused on the big picture of why the patient is in the ICU to begin with. Here is how I do it:
1. How does the patient look? Are they discolored? In distress? Unresponsive?
2. How many systems are being supported? Ventilator? Pressors/inotropes? Dialysis?
3. How intense is the support? PEEP/FIO2? Pressor dose? Number of pressors? CRRT? Number of consultants? Number of IV pumps in use?
4. How successful is the support? MAP>65? Tachycardia resolving? O2 sats acceptable? Urine output trending positive? Fever persisting? Following commands?
5. What do the labs say? Are the 2nd set of blood cultures negative? WBC trending down? Creatinine trending down? Lactate normal? Liver enzymes normal?
If your patient is sick, and you are debating on adjusting a dose for one of their primary problems, take a hard look at the risk:benefit for that patient. Are you just saving a few dollars of piperacillin-tazobactam or are you saving their kidneys from too much amikacin?
What factors do you take into account when determining drug dosing for your critically ill patients? What is your biggest challenge in trying to determine how sick a patient in ICU is? I’d love to hear from you!
If you like this post, check out my book – A Pharmacist’s Guide to Inpatient Medical Emergencies: How to respond to code blue, rapid response calls, and other medical emergencies.
I think an important thing to take into consideration in critically ill patients is how accurate you think their Scr is. We sometimes over estimate CrCl at my hospital as many pts are elderly/frail without much muscle mass and some have limited mobility (also remember to use correction factor for paraplegic/tetraplegic patients). I try to take that into consideration when I’m determining whether to round up or down on a dose if the pt’s calculated CrCl is borderline.