Wednesday, July 28, 2010

Hands-Only CPR

Now@NEJM just posted an article detailing the results of two new studies on Hands-Only or Compressions-Only CPR or Cardiocerebral Resuscitation (CCR). These studies[1,2] look very promising, in fact they showed no appreciable difference in overall survival-to-discharge for traditional CPR versus CCR. Moreover, when one of the studies, by Rea et al[1], compared using CCR to CPR survival-to-discharge of cardiac arrest victims of a primary cardiac etiology there was an increase from 12.3% to 15.5%, although it was not statistically significant. However, when comparing CCR to CPR to non-cardiac etiologies, there was a higher percentage of survivability in the CPR group (7.2% vs. 5.0%), although this as well was not statistically significant.

So what does this mean?

The researchers in Rea et al[1] note that while there was no statistically significant difference between the two, there was a clinically significant trend towards higher survival-to-discharge numbers using compressions alone. Additionally, 80.5% (n=981) of callers given compressions-only instructions began compressions versus 72.7% (n=960) given traditional CPR instructions. Overall 76.7% (n=1941) of callers began either CCR or CPR, which means 1 in 4 callers declined to perform some form of resuscitation.

Taking a closer look at the efficacy of the caller instructions, there is a nearly 8% increase in initiation of compressions under compressions-only instructions. Applying that increase to the CPR-instructions group would have meant nearly 75 more patients would have received compressions! Potentially another 9 people could have gone home from the hospital. Rea et al went as far as saying this was a clinically significant difference, but we all know how big of a difference it makes having just one more person walk home.

So what should we do?

I think progressive systems with tight integration between first responders, EMS, and dispatch need to get the Hands-Only word out to the public. Start using Hands-Only dispatch instructions along with an aggressive public information campaign. I feel in just a 60-90 second TV advertisement, Hands-Only CPR could be demonstrated to the public effectively. You could even throw in your favorite prime time TV cast to really capture those eyeballs.

I've not been in EMS very long, but my heart sinks every time I walk into a house and there has been no attempt at CPR. Our response times are often in the 8-9 minute range which means most of our attempts are futile. I understand the psychological barriers are high, but we need something to improve the rates of bystander CPR. If these studies have shown one thing, it is that Hands-Only CPR has a good chance of doing just that.

1. Rea TD, et al. CPR with Chest Compression Alone or With Rescue Breathing. N Engl J Med 2010; 363: 423-433. [at]
Conclusions: Dispatcher instruction consisting of chest compression alone did not increase the survival rate overall, although there was a trend toward better outcomes in key clinical subgroups. The results support a strategy for CPR performed by laypersons that emphasizes chest compression and minimizes the role of rescue breathing.

2. Svensson L, et al. Compression-Only CPR or Standard CPR in Out-of-Hospital Cardiac Arrest. N Engl J Med 2010; 363: 434-442. [at]
Conclusions: This prospective, randomized study showed no significant difference with respect to survival at 30 days between instructions given by an emergency medical dispatcher, before the arrival of EMS personnel, for compression-only CPR and instructions for standard CPR in patients with suspected, witnessed, out-of-hospital cardiac arrest.

Tuesday, July 20, 2010

Morphine Equivalents Visualized

My day job involves the creation of visualization software to help engineers evaluate complex systems. In my last post detailing Morphine Equivalents there was math, and numbers, and eyes glazing. So, as an aide to the previous post I submit to you a graph of the three narcotic dosing schedules. I pulled the half-lives from Wikipedia and assumed a bioavailability of 100% for the IV route.

The half-lives used are:
  • Morphine: 2-3 hours
  • Fentanyl: 2-4 hours
  • Dilaudid: 2-3 hours

Tuesday, July 6, 2010

Morphine Equivalents

A pretty hot topic lately has been prehospital pain control and how for the most part it is viewed as a failure. Granted, the perception of how well prehospital providers handle pain control is not what I'm looking to talk about, Rogue Medic and the bloggers at Paramedicine 101 have touched on this topic quite a number of times.

What I'd like to do is add a little math to the discussion. Over at Street Watch: Notes of a Paramedic there is an excellent post about a new study on Fentanyl versus Morphine combined with a more liberal pain control protocol. The protocol mentioned "Morphine Equivalents," something of which I was only tangentially aware.

"Morphine Equivalents" are basically a unit of measure used to compare the efficacy of opiods. After a trivial amount of Googling I came across an easy to follow guide from the University of Alberta's Multidisciplinary Pain Centre which listed conversion factors between various opiods. Using these conversion factors, we could compare how equivalent various pain control protocols are.

In North Carolina our 2009 EMS protocols allow 3 opiods for the treatment of pain: dilaudid, morphine, and fentanyl. Per the conversion guide, these drugs compare as follows:
  • 1 mg of Fentanyl is equivalent to 100 mg of Morphine
  • 1 mg of Dilaudid is equivalent to 5 mg of Morphine
So let's examine the 2009 NC Protocols for Pain Control:
  • Morphine: 4 mg IM/IV/IO bolus, may repeat with 2 mg every 3-5 minutes to a max 10 mg or clinical improvement
  • Fentanyl: 50-75 mcg IM/IV/IO bolus, may repeat with 25 mcg every 20-30 minutes to a max 200 mcg or clinical improvement
  • Dilaudid: 1-2 mg IM/IV/IO bolus, may repeat with 1 mg every 20-30 minutes to a max 5 mg or clinical improvement
Now let's do the conversion to Morphine Equivalents (MSeqv hereafter):
  • Fentanyl: 5-7.5 MSeqv bolus, may repeat with 2.5 MSeqv every 20-30 minutes to a max 20 MSeqv
  • Dilaudid: 5-10 MSeqv bolus, may repeat with 5 MSeqv every 20-30 minutes to a max 25 MSeqv
Both the Fentanyl and Dilaudid protocols allow for a higher loading dose in Morphine Equivalents. They both offer a much higher maximum dosage as well. However, if we look at the rebolus schedule they compare poorly to Morphine. Fentanyl's maintenance schedule is 5x weaker, and Dilaudid's is 2.5x weaker than the equivalent Morphine schedule.

Moreover, when you compare the amount of Morphine Equivalents per minute allowed by the protocol, assuming you had the maximum time required to deliver each medication, you find both Fentanyl and Dilaudid compare poorly to Morphine:
  • Morphine: 0.8 MSeqv/minute (max reached in 12 minutes)
  • Fentanyl: 0.2 MSeqv/minute (max reached in 120 minutes)
  • Dilaudid: 0.3 MSeqv/minute (max reached in 80 minutes)
Take this with a huge grain of salt, because this mathematical comparison does not take into account bioavailability, half-life, side effects, rate of administration, and probably a whole host of other important factors. However, what this comparison does show is that while pain control protocols have improved and prehospital providers have options, they aren't all necessarily equal!