May 2011 – Page 3 – Emergency Medicine Literature of Note

Comparison of Adult Head CT Rules in Pediatrics

Interesting – if limited in prospective use – retrospective comparison of the New Orleans, Canadian, and NEXUS II instruments for risk stratifying adults suffering minor head trauma. Busy, urban children’s ED went through 8 years of data to find over 6000 patients with minor head trauma.

Unfortunately, they only looked at the 2,101 that received a head CT, so we lose a huge chunk of our population to “clinical judgement” that could have profoundly affected the specificity of the rules and perhaps had small effects on their sensitivity.

Full of interesting tidbits – 25% of their study population was under 2 years old, but 41% of their injuries were detected in the under 2 population. Sensitivity and specificity essentially rose and fell with the percentage of the cohort scanned – the New Orleans rule would have scanned 89% of their cohort…that had an incidence of 4.4% of intracranial injury. That made the sensitivity 96%, but the specificity 11% – and I hate to think what the specificity would have been if the other 4000 patients had been included. The Canadian Rule scanned the least, missed the most at 65% sensitivity, but achieved a 36% specificity.

But the real question is – what’s the point? The PECARN criteria get you up to ~96% sensitivity with a specificity of 53-58%. Kids aren’t small adults – especially infants, and especially in trauma. Don’t apply adult criteria in kids.

http://www.ncbi.nlm.nih.gov/pubmed/21465153

“Suspended Animation”

This is, actually, an important avenue of contemporary research, highly funded by DARPA at Texas A&M – although this research is from Germany – and this article is about one of the methods tested that got into the lay press a year two back.

The driving principle is that, the best way to keep someone newly dead from starting to go down all those cellular pathways that make cells go “pop”, is to shut down cellular metabolism and starve those pathways of cellular energy. This seems like a sound idea – although, a lot of other cellular pathways that maintain cellular integrity and electrochemical gradient stability are also funded by those same pathways. But, the theory is that if you have a tissue hypoxic event, slow everything down to buy you more time, fix the overriding problem, and then resuscitate the patient.

Didn’t work for these folks. 61 Wistar rats given hydrogen sulfide as their agent to paralyze cellular metabolism. Significantly better pH and less base excess initially during acute resuscitation from cellular hypoxia, so it is doing something to prevent tissue oxygen debt – but their primary outcome of neurologic preservation, they showed temporary neurologic preservation at an interim test, but no differences at the 7 day point, and no histochemical differences after sacrifice.

This sort of research is still clearly poking about in the dark right now, but it is absolutely the future of resuscitation – to give us a reason for hope in the trauma bay that return of circulation is neurologically intact and not simply just for organ donation.

http://dx.doi.org/10.1016/j.resuscitation.2011.03.038

Vital Sign “Triggers”

So, this was an interesting article about a system of vital sign “triggers” an ED implemented to get nurses to flag specific patients for more urgent attention. Not unexpectedly, the study finds that, when nurses get physician’s attention, everything happens more rapidly to those patients, orders, antibiotics, and disposition. The problem is, the article doesn’t address the appropriateness or any unintended consequences of this sort of intervention. The theory would be that these abnormal vital signs represent patients that need more urgent evaluation, but vital signs are always just one piece of the puzzle. In any event, this study spotlights something that can be reasonably construed as important – nurses should be educated to recognize potentially ill patients and notify physicians.

Of course, in the back of my mind, I was envisioning our ED (and likely many around it) which rooms patients first, and then triages them – and it then becomes the responsibility of the nurse whose zone they have entered to take and record vital signs. This results in patients being roomed much faster – which many studies have shown is likely a good thing. Unfortunately, when a patient is roomed to the high-acuity side based on chief complaint, the nurse to which they are assigned may be quite busy with their other high-acuity patients…and that patient may just sit in the room for some time without an assessment or vital signs.

Everything has potential unintended consequences.

http://www.ncbi.nlm.nih.gov/pubmed/21521399

…and Here is Why the Elderly Are Falling

Orthostatic intolerance.

Not much more to say.

An entire quarter of their convenience sample of elderly (mostly female) volunteers had a 60 point drop in their blood pressure upon standing, with only a modicum of recovery within 2 minutes.

Antihypertensive polypharmacy was weakly associated with orthostatic intolerance, and the presence of orthostatic intolerance was weakly associated with an increased number of falls.

So, if the disease (hypertension) doesn’t harm you, the treatment will.

http://www.ncbi.nlm.nih.gov/pubmed/21438868

2005 AHA CPR Guideline Changes Had No Effect

Most recently, the new “hands-only” CPR guidelines have received a lot of press and attention, and there’s a lot of excellent research showing that any intervention that stops CPR decreases survival. Well, the last time they revised the CPR guidelines, they were also intended to decrease CPR pauses, including changing the manner in which defibrillation was performed, making longer CPR intervals, and eliminating pulse checks after shocks.

The “Resuscitations Outcomes Consortium” did a crossover study looking at survival to hospital discharge before and after the implementation of the new guidelines…and they found no statistically significant differences. They did find a clinically significant improvement in VT/VF survival that went from 14% to 18%, but the p-value was 0.06 – and it’s hard to attribute that solely to the guidelines because there are other significant baseline differences, particularly a 28% to 34% increase in bystander CPR.

Should be interesting to see if widespread implementation of the new CPR guidelines increase overall or subgroup survival.

The paper also mentions their current studies, looking at whether automated devices improve outcomes and when AED analysis should be performed in sequence.

http://www.ncbi.nlm.nih.gov/pubmed/21497983

Early Recognition of Massive Transfusion

From trauma resuscitation, a Chinese study trying to predict who will need massive transfusion after trauma. They have a 7-item scoring system retrospectively derived…and it’s probably not terribly helpful.

It’s a nice idea, considering there’s only so much blood readily available in the bank, and a lot of massive transfusion protocols are 1:1 with FFP and sometimes platelets, so advance warning based on the initial clinical evaluation would definitely be helpful. There are some interesting pieces of information in the paper, although, I wish they had all their OR listed for massive transfusion, as opposed to just the ones that shook out from their stepwise regression. Their highest predictor for massive transfusion – a hemoglobin < 7 g/dL with an OR 45.7. SBP < 90 and positive CT or FAST were also predictors with useful OR. Their rule is a little unusual for a theoretically beneficial intervention (massive transfusion), as they focus on specificity rather than sensitivity – probably due to a need to conserve blood component products.

In the end, though, I think most folks with a hypotensive trauma patient whose FAST is positive and a Hgb < 7 could clinically predict massive transfusion as well as this rule does.

http://www.ncbi.nlm.nih.gov/pubmed/21458905

Pediatric Sedation with Propofol

Lovely descriptive statistics of 25,000 occurrences of propofol sedation in children.

Interestingly – 75% of their sedations occurred in radiology. My experience has primarily been to sedate children for uncomfortable procedures – but I am aware that our pediatric critical care intensivists staff the MRI machine specifically to run sedations for children for imaging.

2.3% had “serious adverse events” – although their “other adverse events” includes 1.3% who had “unexpected need for PPV”, which, to me, seems rather serious. 1% had airway obstruction, another 1% had desaturation and 0.5% had apnea. They also did some chart mining to see if anything showed up as associated with a serious adverse event. The highest OR was only 4.6, and that was when an “upper respiratory” diagnosis was documented in the chart. Other associations included prematurity, and then the addition of benzo, ketamine, anticholinergics, or opioids to the sedation.

I would say there are a couple emerging trends that might help further increase sedation safety – addition of end-tidal CO2 monitoring might give better warning of apnea and desaturation, and increased use of nitrous oxide may reduce the number of propofol sedations needed. Otherwise – be ready for too much excitement in one out of fifty pediatric sedations.

http://www.ncbi.nlm.nih.gov/pubmed/21513827

MRSA is Everywhere and You Can’t Stop It

No doubt your hospital has an infection control committee, signs for handwashing, sterile showers, plasma arc denudes, etc. and your e-mail box is filled with Journey to Zero or Destination: Excellence spam.

Unfortunately, it didn’t seem to work up at Mayo. They had ICUs where they put signs up trying to inspire more barrier precautions and hand hygiene, they did more surveillance and topical intranasal antibiotics – and the intervention group valiantly tried to obey. They were somewhat poor in their compliance with suggested barrier precautions, but they were used far more often than in the control clusters – and they found no differences in any of their measures of MRSA or VRE colonization or infection following their intervention.

I will certainly not argue against cleanliness and godliness, but I am impressed they published this lovely negative study to confound us and make us think about how we should go about focusing our resources effectively.

http://www.ncbi.nlm.nih.gov/pubmed/21488763

News Flash: Dilaudid Treats Pain

Albert Einstein in Montefiore is singlehandedly, repeatedly pushing literature regarding appropriate titration of pain control in the Emergency Department. They have several previously published papers describing their hydromorphone 1 + 1 protocol, describing its safety and efficacy. This paper is their prospective, randomized version demonstrating its safety and superiority to “usual practice”. You could implement their protocol tomorrow and have better narcotic pain control in your ED. It clearly works.

But the real issue this line of research uncovers is not that they’ve discovered a magic protocol. What we’re missing by taking the simple interpretation is more that our pain control in the ED is flawed. If you look at the morphine equivalents their patients received in this article, they’re preposterous. I am a huge proponent of 0.1mg/kg for morphine – even in adults – and their mean dose in the “usual care” arm was 6mg morphine equivalents, and their mean additional dose was 3mg. 0.1mg/kg is a starting dose for morphine that gives less than 50% of patients adequate pain relief – which is where the second part of their protocol comes in. Scheduled reassessment for pain and a standing order for additional medication is another area where “usual care” will obviously fall behind, simply because of the uncontrollable chaos of the ED.

So, my take home from this article is that protocolized, standing orders for narcotic analgesia in appropriately selected patients is safe and effective, and, you can use their protocol or develop your own.

http://www.ncbi.nlm.nih.gov/pubmed/21507527