April 29, 2012

Just Like Spiderman

A recent twitter conversation went very quickly from placement of IOs to appropriate critical usage of evidence based medicine. Below, see a nice series of 4 (short) essays on EBM -- a debate between Gordon Guyatt, described as the "founding father of EBM" and Marty Tobin, the great intensivist (whose son may or may not have been in my anatomy group as an M1), "all taking place in the pages of the journal Chest." The 2 quoted phrases as well as this debate and the articles were referred to me by the great Canadian EM/CC/US Dr. Rob Arntfield.

My impression of the debate: EBM is wonderful, but of course has its limitations. It's not as simple as RCT=great, no RCT=terrible; but some questions we can better answer with better evidence. And like Spiderman (and everything) we have to be responsible and critically apply evidence. Some questions aren't amenable to RCTs* so do the best with what you can. That is why most PEM docs still fluid resuscitate sepsis kiddies, and I still place LMAs in cardiac arrests even though it might lower measured carotid flow in 9 pigs.

The debate (all articles are free):
Point: evidence-based medicine has a sound scientific base.
Karanicolas PJ, Kunz R, Guyatt GH.
Chest. 2008 May;133(5):1067-71

Counterpoint: evidence-based medicine lacks a sound scientific base.Tobin MJ.
Chest. 2008 May;133(5):1071-4

Rebuttal From Dr. Guyatt et al
Gordon H. Guyatt, MD, MSc, FCCP, Paul J. Karanicolas, MD, and Regina Kunz, MD, PhD
Chest. 2008 May; 133 (5):1074-1075

Rebuttal From Dr. Tobin
Martin J. Tobin
Chest. 2008 May;133 (5):1076-1077

*for these, you can randomize poor dying African children to standard therapy vs placebo

April 26, 2012

Roc vs Sux

Special thanks to Reuben Strayer

As a followup to some recent online discussion about the time of onset of paralysis of rocuronium, I checked with the most devoted rocuronium supporter I know who sent me the references below. Reuben's  excellent and concise (8 minutes) lecture on roc vs sux is much more comprehensive, but I specifically want to review the small amount of data on time of onset of paralysis. Of course there is are certainly more data out there; I just used the 4 references he sent me.

Caveat: these are OR patients, but I just want the time of onset data so it should be close if not equivalent

Study 1:
outcome: measured paralysis (no response in T1 in TOF monitoring)
Roc 1.2 mg/kg
n=10 adults
mean 55 s
SD 14 s
range 36-84 s
Sux 1 mg/kg
n=10 adults
mean 50 s
SD 17 s
range 24-84 s
Study 2:

children (mean age 6.4 and 6.8 years)
outcome: apnea (not clear how they decided exactly on apnea times)
Roc 1.2 mg/kg
n=13 children (1 did not get as the roc precipitated in the IV line)
mean 15.6s
SD 7.4s
range 5-30s
Sux 1.5 mg/kg
n=13 children
mean 22.3 s
SD 12.8 s
range 12-62 s
These are only 46 patients, including 25 children, and by no means definitive. But the time of onset of paralysis is certainly comparable if not equivalent in properly dosed roc (1.2 mg/kg)

These 2 papers, as well as the 2 other citations below, also demonstrate equivalent intubating conditions between roc & sux, which is what really matters.

1: Magorian T, Flannery KB, Miller RD. Comparison of rocuronium, succinylcholine, and vecuronium for rapid-sequence induction of anesthesia in adult patients. Anesthesiology. 1993 Nov;79(5):913-8.
2:Mazurek AJ, Rae B, Hann S, Kim JI, Castro B, Coté CJ. Rocuronium versus succinylcholine: are they equally effective during rapid-sequence induction of anesthesia? Anesth Analg. 1998 Dec;87(6):1259-62.

additional studies on equivalent intubating conditions:

Patanwala AE, Stahle SA, Sakles JC, Erstad BL. Comparison of succinylcholine and rocuronium for first-attempt intubation success in the emergency department. Acad Emerg Med. 2011 Jan;18(1):10-4.
Heier T, Caldwell JE. Rapid tracheal intubation with large-dose rocuronium: a probability-based approach. Anesth Analg. 2000 Jan;90(1):175-9.

April 21, 2012

How to Give Residents Credit for Listening to Podcasts

My co-chiefs and I have article in Annals of EM (epub before print) on asynchronous learning / individualized interactive instruction, aka how to give residents conference credit for listening to podcasts.

April 1, 2012

Neutrophil gelatinase-associated lipocalin

NGAL has beta pleated sheets?
We just had a ground rounds from Dr. Alan Maisel of UCSD on the fascinating topic of biomarkers. He was the lead author of the Breathing Not Properly trial, which helped launch BNP into the world.

Two great points from his lecture:

1. Some patients with sky-high BNPs who look clinically eu- to hypovolemic are just super sick and will be diuretic intolerant. I think many of us see a really high BNP in people with a hx of heart failure and nearly-automatically order diuretics; this is probably not the right strategy.

2. There is a novel biomarker for pts who are at risk to develop kidney injury: NGAL has been studied in pediatric cardiopulm bypass, toxicology, heart failure, kidney transplantation, and in other cases.

It seems to be very sensitive and specific for development of AKI. Serum creatinine pretty much sucks, and may often give you a false sense of security. Think of toxic alcohols, when the Cr starts to rise you're already in big trouble. This molecule seems ready for prime-time, ED decision-making. Dr. Maisel's lecture presaged a time (probably not far off) when we will be getting biomarkers for renal risk in the ED.
If you think of renal function as a forest and AKI as a forest fire, creatinine tells you which trees are dead. NGAL tells you which trees are on fire.
Dr. Maisel (paraphrased)