ICU vs. OR: The Same Drugs, Different World!

ICU and OR environments use the same drugs, but their application differs significantly, especially in how CRNAs manage and administer these medications directly in the OR setting.

If you’re an ICU nurse eyeing the OR (hello future CRNA!), you’ve probably already seen some of the most common drugs we give on a daily basis. ICU and OR environments use the same drugs, but their application differs significantly. Vasopressors, sedatives, antibiotics, even good ol’ rocuronium for your crumping ICU patient who needs an airway STAT. But here’s the twist: the same drugs act completely differently when you’re the one holding the syringe instead of titrating a drip order.

If you're interested in the full process of making the leap, check out our guide on How to Become a CRNA. Let’s break it down.

How Do Push-Dose Pressors Differ From ICU Drips?

In the ICU, you hang your norepi drip, chart your MAP goals, and call pharmacy if the bag looks like it’s getting empty, right? Well, in the OR, you are pharmacy. You’ll be giving your own push-dose pressors (phenylephrine, ephedrine, sometimes even epi), calculating concentrations to mix your own drip bags, and drawing them up before the patient even rolls in. For more details on the specific requirements you’ll need to master, check out our CRNA School Requirements page.

• Push-dose: Short bursts for quick BP correction during induction or blood loss.
• Infusions: Same vasopressors, but usually patient-specific and temporary. You might start a norepi or phenyl gtt, but these are often bridged, not titrated for hours/days like in the ICU.

There’s a time and place for when to give ‘what’: This all depends on the patient presentation, co-morbidities, and other hemodynamics. If you want to dive even deeper, our Learning Library has a full lesson on Emotional Intelligence that can help you navigate these clinical judgment calls

Here’s a few quick intros to the drugs we often push in times of need (aka HOTN).

• Ephedrine
  Push 5–10 mg at a time
  Not used in the ICU, but it’s an OR favorite
  Watch out for refractory tachycardia!
• Phenylephrine:
  Push 50–200 mcg at a time
  Quicker onset than ephedrine
  Watch out for refractory bradycardia!
• Vasopressin
  0.5–2 units bolus at a time
  Works great when phenylephrine and ephedrine just aren’t cutting it, usually when a patient is on some kind of ACE-I or ARB at home to treat their pre-existing HTN.
  Doesn’t rely on adrenergic receptors, the perfect backup plan.

More rarely, push dose epi and norepi can be given, but they’re not typically the first “go-to’s.” Know your concentrations. There’s no “pharmacy verified” here, it’s all you. If you’re prepping for interviews and want to discuss these scenarios, don’t miss our podcast episode Ep 14: "Interviewing? Avoid these mistakes!" on Apple Podcasts.

How Do Sedative Uses Differ Between the ICU and OR?

Yes, propofol, midazolam, and dexmedetomidine still exist, but the context changes drastically. In the ICU, your sedation goal might be RASS -2 to -3. In the OR? It’s lights out, baby.

Propofol gtts run way higher during anesthesia than what you’d ever see in the ICU. You’ll also use propofol for non-intubated patients (crazy, right?) Think MAC cases, endoscopy, or cardioversion. You can use propofol without an ETT, because you’re continuously monitoring the airway and can intervene if needed (with devices other than just an ET tube).

Versed and Precedex may still make an appearance, but usually as a pre-induction relaxer, not a long-term sedative. Precedex can also be given for things like helping prevent post-op delirium and even shivering in PACU.

A lot of our drugs have multiple uses, and you’ll learn alllll about the pharmacology in school. If you want to get a head start on interview prep for these kinds of questions, check out our Interview Tips w/ Professor Temmermand Part I lesson in the Learning Library

What Are the Important Considerations When Choosing Induction Agents?

As an ICU nurse, you probably see induction meds during codes or intubations, but in the OR, induction is something we do every day. You might know the saying “you have to (se)date, before you can sux” which is a helpful reminder of which medications come first on induction.

Sedate: Etomidate, propofol, or ketamine, each has its moment:

• Etomidate: stable for the hemodynamically fragile.
• Propofol: smooth as silk but can tank your pressure.
• Ketamine: dissociative magic, especially for hypotensive or asthmatic patients.

Every choice depends on your patient’s comorbidities, ex: heart failure, sepsis, trauma, etc. School goes deep into the mechanism behind each of these drugs, as well as which populations they are best suited for, and which to avoid them in at all costs. If you want to practice answering these types of questions, our CRNA Interview Questions Guide is a great resource.

How Do Neuromuscular Blockers Differ Between ICU and OR Settings?

Sux (aka paralyze!)
Rocuronium (roc) and succinylcholine (sux) are the usual neuromuscular blocker (NMB) suspects. Which one have you seen more commonly?

Without getting too into the weeds of pharmacology, just know that rocuronium wins most days in the OR for routine, elective surgeries. Succinylcholine has its chance to shine in rapid sequence intubations with patients with full stomachs, as well as some trauma cases.

Some other NMBs you might not have seen in the ICU are vecuronium, pancuronium, atracurium, cisatracurium (Nimbex – most commonly hung as a gtt), and mivacurium.

See a pattern? The drugs ending in -ronium are steroidal neuromuscular blockers, and those ending in -curium are benzylisoquinolinium neuromuscular blockers. Both of these classes are non-depolarizing neuromuscular blockers, and succinylcholine is the odd man out as the only depolarizing NMB. (Google the difference if you’re so inclined! But don’t say I didn’t warn ya!) If you want some tangible interview tips for discussing these drugs, tune into Ep 34: "Tangible Interviewing Tips from Communications Coach Michelle Miller" on Apple Podcasts.

How Is Paralysis Reversed in the OR vs ICU?

Unlike the ICU, where you might paralyze, intubate, and move on, in the OR you reverse what you give. Before extubation after the surgery is done, you’ll check the train-of-four (TOF) on your handy dandy neuromonitoring device and give sugammadex (for roc – if you’re so lucky to have it available at your institution) or neostigmine/glycopyrrolate combos to bring those muscles back online before you drop the patient off in PACU.

Note: sux does not require reversal! For more on what to expect during clinical shadowing, check out our podcast episode Ep 51: "Questions to Ask During Your Shadow Day" on Apple Podcasts.

How Do ICU and OR Antibiotic Administration Differ?

In the ICU, pharmacy handles timing and compatibility. In the OR, you’re timing the antibiotics yourself, typically within 30–60 minutes of incision, and making sure it’s in before the surgeon says “scalpel.” Sometimes you’ll give them as a push dose (ex: 2g Ancef in 10mL NS), sometimes as a free gtt.

For more information, check these trusted resources: AANA, COA. If you want more support with interview prep, our Interview Tips w/ Professor Temmermand Part II lesson in the Learning Library is a great place to start

What Should ICU Nurses Take Away from This?

Transitioning from ICU nurse to CRNA means adapting your drug administration skills to a new, fast-paced environment where timing, dosing, and direct management are key. The CRNA Club is here to support you in mastering these differences and thriving in the OR setting.