The Elective Rotation: A Critical Care Hospital Pharmacy Podcast

Show notes at pharmacyjoe.com/episode14. In this episode I’ll discuss the debate on whether it is better to use succinylcholine (Sux) or rocuronium (Roc) for rapid sequence intubation (RSI) in emergency settings.

The debate

For over a decade there has been a debate on whether it is better to use succinylcholine (Sux) or rocuronium (Roc) for rapid sequence intubation (RSI) in emergency settings.

I'm surprised when reading these debates by the lack of attention given to the time it takes for the patient to receive sedation after RSI.

In this episode, I'll first review how Sux and Roc stack up in terms of onset, duration, efficacy, and safety.  Then, I'll explain the reason why Roc only rocks when you, Pharmacy Nation, are around.  This discussion will be framed around the urgent need to establish an airway in a critical care setting. Elective and preoperative airway concerns are not a relevant part of this discussion.  I've also included some links to other people debating the use of these 2 drugs for RSI at the end of this post.

Onset

As long as the right dose is used, Sux and Roc have essentially the same onset of action.

Sux is dosed at 1 to 1.5 mg/kg and works within 45 seconds.

Roc works within 45 seconds too but only if you give 1.2 mg/kg. Published dosing ranges from 0.6 mg/kg to 1.2 mg/kg but the lower doses have an onset that becomes progressively unmanageable for RSI the lower you get. Go big or go home.

Duration

Paralysis from Sux should be over in 10 minutes.

Paralysis from Roc may last up to 90 minutes.

The shorter duration of Sux is often touted as a safety benefit. The claim is that if the airway can’t be placed, the patient can be bagged and ventilated until the Sux wears off.  This sounds reasonable and I used to believe it.  But hearing others debate the 2 drugs made me look closer at whether the shorter duration of Sux was in fact a safety benefit:

Even with perfect pre-oxygenation conditions, a healthy patient will go at most 8 minutes before hypoxia sets in from the apnea caused by a paralytic.  Your patient isn’t healthy though - they are critically ill and need an airway.  And chances are high that because of this illness pre-oxygenation conditions are far from perfect.  There is no such thing as “bagging them until the paralytic wears off” because after the paralytic wears off, they are still critically ill and still need an airway.  So in this context there is no difference between Sux and Roc - once you paralyze the patient you are committed to establishing an airway within the next few minutes.

Neurologic exams are very limited until the paralytic wears off, so Sux does have an advantage over Roc here, but that is a very rare concern.

I’ll talk more about the duration in regards to time to sedation later but first let's compare efficacy & safety.

Efficacy

Show notes at pharmacyjoe.com/episode13. In this episode I will discuss three topics regarding antibiotic dosing in CRRT (continuous renal replacement therapy). 1. Review CRRT antibiotic dosing rules 2. Review CRRT antibiotic dosing exceptions 3. Discuss the prevelance of antibiotic underdosing in CRRT

In this episode I will discuss three topics regarding antibiotic dosing in CRRT (continuous renal replacement therapy).

1. Review CRRT antibiotic dosing rules
2. Review CRRT antibiotic dosing exceptions
3. Discuss the prevelance of antibiotic underdosing in CRRT

The CRRT variant this episode will refer to is CVVHDF, or continuous veno-venous hemodiafiltration as this is the only type of CRRT performed at my hospital.   CVVHDF uses both convection and diffusion methods of drug and solute removal, resulting in greater drug removal than by the convection or diffusion method alone.

Much of the data for this episode comes from a paper published in Pharmacotherapy 2009 by Heintz, Matzke and Dager. Although this paper is 7 years old, it remains the reference paper for antibiotic dosing in CRRT by every tertiary drug reference I have seen. Thanks to Collin my current P4 student for confirming via literature search that this paper is still up to date!

CRRT antibiotic dosing rules

* The loading dose (if indicated) stays the same for all antibiotics in CRRT.

* If it doesn’t require renal dose adjustment, it doesn’t require adjustment for CRRT (linezolid, doxycycline, tigecycline, clindamycin, caspofungin, azithromycin, voriconazole).

* Anything with a beta lactam ring, fluroquinolones, sulfamethoxazole/trimethoprim, amphotericin B are all dosed as per normal renal function.

CRRT antibiotic dosing exceptions

* Vancomycin dose gets cut in half.

* Daptomycin either goes to q48 hour dosing or stays at q24 hour depending on how sick the patient is.  If I stay on q24 hour dosing I check the CK several times per week.

* Fluconazole gets a dosing increase to 800 mg q24 hour.  This always raises an eyebrow with the provider but there is even a paper that suggests 600 mg q12 hour may be needed, and after hearing this the doc usually thinks 800 mg / day is a bargain!

* The antivirals acyclovir and gangcyclovir get reduced from q8 to q12 dsoing.

* Aminoglycosides receive a traditional loading dose, then check level in 24 hours.

Since the 2009 Pharmacotherapy article was published there have been a few new antibiotics but they fit nicely within the rules I've described above.

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Show notes at pharmacyjoe.com/episode12. In this episode I will explain how, as a hospital-based pharmacist, I evaluate drug interactions that carry the risk of QT prolongation.

Evaluating QTc drug interactions

Prolonged QTc interval leading to torsades. It is the adverse medication event that keeps pharmacists awake at night. In this episode I will explain how, as a hospital-based pharmacist, I evaluate drug interactions that carry the risk of QT prolongation.

This is an area of my practice that I struggled with for quite some time. It took 4 things to get myself to a spot where I can comfortably judge the significance of these drug interactions.

1. Understanding that the QTc is a number on a piece of paper, nothing more.  
2. Make peace with the ECG and learn how to read and interpret it from a pharmacist’s point of view.
3. Read the ACC/AHA guidelines on the prevention of torsades in hospital settings.
4. Read the Top 100 Drug Interactions by Hansten and Horn.

QTc = A number on a piece of paper

Just because a drug interaction may prolong the QTc does not mean that the patient will experience torsades.  Have you ever heard the axiom treat the patient, not the number? Nothing could be more accurate when it comes to evaluating QTc interactions.

Making peace with the ECG

In episode 10 I discussed how the Pharmacist and the ECG should be friends.  If you haven’t listened to episode 10 already and are unsure of what, from a pharmacist’s perspective, you should be doing with the ECG - go ahead and listen to it now.

Most of the time, you can use the QTc number from a 12 lead ECG evaluate a QTc drug interaction. But knowing how to calculate the QTc yourself can be quite handy sometimes. Use the following picture and this link to learn how to calculate the QTc yourself.

Another trick I use and I talk about more in episode 10 is to eyeball the QT and compare it to the R-R interval on the patient’s monitor. If the QT is less than half the R-R interval, the QTc will be normal. If not, then you should investigate further by looking at the 12-lead. This allows me to save time not crunching numbers or looking at 12-leads for those patients who clearly have normal ECG.

Prevention of torsades in a hospital setting

This paper, published in Circulation 2010, is a must read for a hospital based pharmacist.  It covers what torsades looks like, ECG signs that indicate risk of torsades, how torsades originates, drugs that cause torsades, monitoring, and management of torsades should it occur.

Here are a few highlights of the article:

How torsades originates

Show notes at pharmacyjoe.com/episode11. In this episode I’ll discuss PharmacyJoe-ism #7: Making patient focused risk benefit assessments.

Why Is My Patient In the ICU and How Sick Are They?

The topic for today’s show is PharmacyJoe-ism #7: Making patient focused risk benefit assessments.

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?

As the expert in drug therapy, you need to know how different drugs exert their effects on the electrical system of the heart.

Pharmacist review of the ECG is relatively straight forward compared to other professions. We should be able to identify the rhythm, look for signs of drug toxicity, and calculate a QTc. We don’t need to worry about the different leads, or which lead is looking at which side of the heart, or any of the other complicated nuances other providers need to know.

In this episode I'll review the ECG components, propose a step-wise approach to identifying the rhythm, and give examples for the following pharmacy related ECG abnormalities:

* Hyperkalemia

* ST-segment elevation MI

* Prolonged QTc interval

* ECG signs of drug toxicity

* Beta blockers

* Digoxin

* Tricyclic antidepressants

* Antiarrythmics

* Dysrhythmias

* Torsades

* Ventricular Tachycardia / Fibrillation

* Atrial Fibrillation

* Heart block

Review of ECG components

P wave - represents atrial depolarization
QRS complex - represents ventricular depolarization
T wave - represents ventricular repolarization
PR interval - represents time for the impulse to travel from the SA node through the AV node to the ventricles
QT interval - represents the time for ventricular depolarization and repolarization to occur (called the QTc interval when corrected for heart rate)
R-R interval - represents the time between beats and is used to calculate the heart rate

 

Image courtesy of ecg.utah.edu

Stepwise process to interpreting an ECG

There are many different ways to approach ECG interpretation.  Whether you use my approach or another, be sure to use the same process each time.

1. Is there a P wave before each QRS complex? This tells you if the rhythm originates in the SA node.
2. Is the R-R interval regular?
3. Is the rate below 60 or above 100?
4. Is the PR interval normal? It should be less than 5 small boxes on the ECG.
5. Is the QRS complex normal? It should be narrow, 2-3 small boxes on the ECG.
6. Is the QT less than half the R-R interval? If not, the QTc is likely prolonged.
7. Does each QRS complex look the same? If not, this could indicate PVCs or PACs.

Hyperkalemia

Look for flat or missing P waves, peaked T waves, and wide QRS interval.

ST segment elevation MI

Look for a markedly elevated ST segment, that appears like a "tombstone".  Diagnosis of acute MI is far more complicated, but I find it valuable to know this basic identification.  The ST segment elevation indicates a complete blockage to a coronary artery.  The example below is an acute MI with proximal LAD occlusion.

Prolonged QTc interval

In the example below the QTc is about 640 msec (normal is around 450 msec or less).

Show notes at pharmacyjoe.com/episode10. In this episode I’ll review the ECG components, propose a step-wise approach to identifying the rhythm, and give examples for the following pharmacy related ECG abnormalities: Hyperkalemia ST-segment elevation MI Prolonged QTc interval ECG signs of drug toxicity Beta blockers Digoxin Tricyclic antidepressants Antiarrythmics Dysrhythmias Torsades Ventricular Tachycardia / Fibrillation Atrial [...]