Monday, 24 December 2012

Choosing your Battles: My Christmas Pearl of 2012

This blog post isn't about EBM or getting my hate on about antiquated dogma; it is about a useful pearl that I think can benefit all of my like-minded, avant-garde, #FOAMed friends out there.  In particular, this is a piece of advice that the "young whippersnapper" types like myself should pay attention to.  

Last week while at Tintinalli Rounds with one of my preceptors, we covered tons of material and talked EBM galore.  It was a nerd alert to the extreme.  While we were ranting about how "ridiculous" it is to give gravol to pediatric patients with gastro, and that ondansetron is the evidence based pediatric panacea, we paused for a serious discussion.  As residents soon to enter practice, he gave us this advice.

"Choose your battles"

Having only graduated from residency a few years ago, this preceptor moved from a highly respected pediatric EM fellowship program to a pediatric EM department in its relative infancy.  Upon arrival, he did what most of us would do in the same situation.  He wanted change.  And he didn't want a bit of change, he wanted a revolution.  There was room for improvement everywhere, with everything.  

However, he quickly realized that enthusiasm only goes so far, and knowledge translation can be a bitch.

Rather than revolutionize a new department and effectively ostracize himself in the process, he chose the battles that he wanted to fight.  Every time he saw something in need of change, he asked himself, "is this a battle I want to fight?"  

Ondansetron for pediatric gastroenteritis was a battle he wanted to fight, and there were a couple of others as well.  By limiting himself to a few battles, he could effectively stimulate change, while keeping his new colleagues from beating him senseless.
(Oh fine, I keep mentioning the peds gastro thing so head over to theNNT for a summary of this if you're interested.) 

He also made the point that while some of us are up to date and evidence based, that knowledge will never supplant the 20 years of experience that our older colleagues have.  Rules and scores allow junior physicians to "catch up faster", effectively giving us some of the gestalt that thousands of hours of ER medicine have traditionally provided.  So despite all of your book knowledge, respect your seniors/colleagues.
Another form of choosing your battles is what to do as learners desiring to challenge the status quo.

Here's a twitter conversation I saw today

The context here is that PPIs are not the miracle UGIB treatment that we once thought, and that Lauren, a FOAM loving medical student, tried unsuccessfully to convince someone (I'm guessing an attending) of this.  

This is another form of choosing our battles.  As junior learners/staff, we need to diplomatically approach these topics, and be selective as to how often we question the methods of our seniors.  Nobody likes the learner (or colleague for that matter) who contradicts everything.  I know I have probably been that annoying resident in the past, and thus ask myself "is this really worth it" before choosing a battle.  Furthermore, if circumstances (eg. busy shift, non receptive preceptor) indicate I am about to run into a stone wall, sometimes it's better to just "abort mission" and try again at a better time/place.

For what it's worth, I think Lauren picked a great battle here, and her follow-up tweet to this is impressively mature. This is an excellent example of the attitude FOAM advocates should have, so take note.

To summarize, being young and enthusiastic about medical education, EBM and FOAM is awesome.  But regardless of your medical profession (EMT, nurse, resident, etc.), if you are keen and on the FOAM bandwagon, you will be saying some crazy sounding things.  If you are in a position to effect change, fantastic, but this is another situation where less may be more, and choosing your battles wisely is a lesson for us all.

It's been Christmas Day for 30 minutes now, so put in the Die Hard (or whatever your favorite Christmas movie is), and do not stand on the corner minding your own business. Bruce Willis was just minding his own business at Nakatomi Plaza and look what happened.

With that, I wish you all Happy Holidays (whatever you may celebrate) and a great 2013. 


Saturday, 8 December 2012

Evidence Based Laceration Repair

First, a huge thanks to everyone who has been visiting the site, tweeting and spreading the #FOAMed love.  FOAM is all about word of mouth, and having others spread the word drives me to put up more posts.  Second, if you have comments or suggestions to improve the blog, questions for me, or myths you'd like to see busted, please tweet or email.  I'm always looking for new ideas.

Also, a shout out to a new podcast I've found recently.  The SGEM (Skeptics Guide to Emergency Medicine) podcast is based out of Ontario, Canada, and takes a similar approach to topics as I do.  Episode 9 covers some of the wound management myths I'm about to deal with, and a few others I've left out.  It can be found on iTunes or on their website

Onto the blog.

Case: A 25 year old female presents to the ED with a 3 cm laceration to the dorsum of her forearm.  It is superficial, entering only the hypodermis.  It is easily approximated, not over a joint, and under no tension.  Before reading on, mentally go through the steps of how you would manage this wound. (eg. cleaning, prepping, suture material, dressing) Got it?  Read on.

No procedure in medicine contains as many ancient, dogmatic teachings as laceration repair.  Considering this is something we do and teach every day, it's critical that we have an evidence based approach.

In this post, I will present the thinking that goes through my head as I prepare to close a wound.

NB. Throughout this post, we are talking about uncomplicated lacerations/wounds ie: no fracture, foreign body, tendon injury, bone injury, joint injury, immunosuppression, anti-coagulation, etc.

The reason behind all of the laceration repair dogma can be summarized in one word, infection.  

We've all seen someone prepare a simple cut as if it were an open abdomen in the OR.  Why?  Not so long ago, surgeons began using sterile technique in the OR; this was critical for reducing post-op infection rates.  Naturally, that meticulous preparation was then passed down to ED physicians as lore.  

But lets think about this for a minute.  There are millions of lacerations every year, and we see a miniscule number of them in the ED.  The rest are managed at home with water, some paper towel and maybe a band-aid.  That's certainly not sterile technique.  So why aren't our departments overrun with wound infections from people who cut themselves and didn't waste 4 green huck towels, a bottle of chlorhexidine, a sterile kidney basin, and countless other tools?  Because clean wounds rarely get infected. 

Preparing wounds with sterile technique and meticulous detail is not only unnecessary from an infectious standpoint, it's time consuming.  As a medical student and resident, laceration repair is great.  It's fun, you get to work with your hands, sit down, take a mental break.  Overall, as a presenting complaint, laceration is about as good as it gets.  As I get closer to the realm of being a staff physician, I view lacerations differently, in much the same way as I look at insertion of lines and tubes (see previous blogs).  Properly repairing a laceration remains the most important element, but efficiency and managing department flow are also critical.  Furthermore, I don't want to waste my patient's time by having them unnecessarily return to the ED for follow-up, suture removal, or complications of the procedure.

Onto the pseudoaxioms.

1)Wounds must be cleaned with fancy solutions.      NO!


We usually clean lacerations with tap water at home, so why do we need sterile water/saline or chlorhexidine in the ED? 

Thankfully, this has been studied.

First, forget antiseptics.  There is little, if any evidence that chlorhexidine or other antiseptics reduce rates of infection.  Conversely, chlorhexidine and povidone-iodine solutions are more likely damage normal cells and slow healing.  These are skin cleansers, for external use only.

So the real choice is between tap water and sterile saline/water.

This Cochrane Review last updated in 2010 included 11 quasi-randomized studies, 3 of which were RCTs.  In adults, tap water is at least as good, if not better, than sterile saline for preventing infectious complications.  In children, there was similarly no difference between tap water and sterile saline. 

I think my favorite part of this review is the authors conclusion that there is no evidence that cleansing a wound is better than not cleansing it.  Now that would be a kick ass RCT!  Even if it passed ethics, I think you'd need a used car salesman to consent the patients for the no cleansing group.

This prospective RCT done in 2007 also compared sterile saline with tap water.  Though the study had several problems, one thing it made clear was the cost savings of using tap water in place of sterile saline, a syringe and splash guard would be ~$65.6 million annually in the U.S.  That's huge!

Disclaimer: If you don't have a clean tap water source, this likely doesn't apply, but you could still be using boiled and cooled distilled water in place of the more expensive alternatives.  

When I clean a wound in the ED, especially if it's an upper extremitiy, I will anesthetize, walk the patient over to the sink, and wash their hand under running water for a few minutes. The volume difference is huge, and it takes virtually no time at all.

Bottom line: Tap water is just as good, if not better than sterile saline for irrigating simple wounds in the ED.

2)Glove selection

After I've cleaned my patient's hand in tap water, should I grab some sterile gloves to sew them up?  Maybe the patients love to see me snap on those fancy gloves that come from their own, individually sealed bag.

Bottom Line: Clean gloves are just fine.  
The best data on this comes from a 2004 study by Perelman et al. in Annals of EM.  This Canadian study was a prospective RCT, and looked at 816 patients over the age of 1 year with simple lacerations.  They found the infection rate for sterile vs non-sterile gloves was 6.1% and 4.4%, respectively with no significant statistical difference.  

Again, the cost difference between using sterile and non-sterile gloves is massive when we consider how often they are used on a daily basis.  

I will admit that in cases that require a significant amount of suturing or I want an optimal cosmetic result, (eg. facial lacs) I will use sterile gloves because they provide a much better feel than the non-sterile ones.  Go ahead and call me a hypocrite.  

3)All lacerations must be sutured using non-absorbable suture.

First, there is evidence that not all lacerations < 2 cm even require suturing in the first place.  But let's say that we do decide to close this laceration, how will we do it?

Who asks for prolene, ethilon or another non-absorbable suture when they repair lacerations?  What about vicryl rapide, fast chromic gut or another absorbable suture?  Does anyone ask for glue?

Has anyone heard this: Don't use absorbable sutures or glue, they'll get a nasty scar! 

Let's look at the evidence.

First let's take the scenario of the 3 year old child with a non-gaping facial laceration after running into a coffee table.  I'm sure many of us have gone through the joy of anesthetizing this child and suturing them while a nurse holds them in a death grip.  All the while, the parents are looking on horrified and never wanting to return to the hospital.  


While rotating through the Alberta Children's Hospital (AKA Lego-land with an ICU), I was exposed to all the awesome ways of repairing lacs in kids.  The children would have topical maxilene or lidocaine applied at triage and we would sometimes give intranasal midazolam as well.  Suffice it to say, this place is pretty much heaven as far as peds EM is concerned, and laceration repair was all happiness and roses.  Unfortunately, most of our EDs do not have these luxuries, but we do have one awesome thing.  Glue!

Again we have some Canadians to thank for this Cochrane Review looking at tissue adhesives vs. standard wound closure for laceration repair.  Eleven studies compared a tissue adhesive with standard wound closure. No significant difference was found for cosmesis at any time point examined. As would be expected, pain scores and procedure time significantly favoured tissue adhesives.  However, there was a statistically significant increased rate of wound dehiscence favouring standard wound care, with a NNH of 40.   

But what about gaping lacerations where glue won't work?

Traditionally we are taught to always use non-absorbable sutures, as they are stronger, less prone to infection, etc.  Having been sutured up several times as a child, I recall fearing the return visit for suture removal even more than the initial visit to get sewn up.  When a child is bleeding everywhere, the pain is bearable, but pulling out the scissors and forceps in front of a completely well child creates unnecessary fear.

Can we avoid this return visit without compromising cosmesis?  Yes.

This 2004 paper by Karounis et al. looked at pediatric patients (0 to 18 years) with traumatic lacerations.  It showed no differences in early or late cosmesis, wound dehiscence or need for scar revision when comparing absorbable and non-absorbable suture.  In fact, all of the outcomes showed a trend toward benefit in the absorbable suture group.  (I know, trends don't mean squat in EBM)
The main weakness of this study was the extremely high loss to follow-up of 34%.  However, this is a very common weakness of laceration repair studies, and getting good follow-up in these types of studies seems impossible.

Another study from 2008 looked at fast absorbing catgut suture vs. nylon in 88 pediatric patients.  Again there were no differences in cosmesis, infection rate, dehiscence, keloid formation or parental satisfaction.  This paper also suffered from a lack of follow-up (though it was equal in both groups).

Bottom Line: For non-gaping lacerations, glue is where it's at.  For gaping lacerations in children, absorbable suture is at least as good as non-absorbable. 
The savings on patient/parental trauma and time are huge. 

Note: Although I didn't cover staples, they are likely as good as sutures for repairing scalp lacerations.  There are small studies comparing them, but no large RCTs.

4)After closing the wound you should apply a topical antibiotic such as polysporin/neosporin.

This one may be my biggest peeve of all, as somehow the marketing of topical antibiotics that are primarily effective against Gram -ve bacteria has resulted in physicians regularly recommending these to patients.  For this, we have to go to the Dermatology literature.  This peeve comes from doing 6 weeks of dermatology electives, several of which were spent with someone who only did patch testing for contact dermatitis.

It is true that a clean, moist, covered wound will heal faster than an uncovered, dirty wound.  However, all of the dermatology literature points toward non-antibiotic containing petroleum based lubricants being equally efficacious to neomycin (Neosporin), bacitracin and polymixin B (both in Polysporin) containing ones.  Furthermore, neomycin is the number one contact allergen in patch testing at a whopping 11% of the U.S. population.  Bacitracin is not far behind at 8% of the population.
Fortunately Neosporin is no longer sold in Canada, but it is the bane of American dermatologists.

Bottom Line: Use Vaseline, Aquaphor or other petrolatum based gel for wounds, and stop creating allergies.


1)Tap water is as good as sterile saline

2)Clean gloves are fine

3)Glue and absorbable sutures provide the same cosmetic results as non-absorbable ones, particularly for facial lacerations.

4)Use non-antibiotic, petrolatum based gels to cover wounds, not poly/neosporin.

You now have all the evidence you need to manage simple lacerations in 5-10 minutes, without putting your patients at increased risk of infection, giving them an ugly scar, or causing a contact dermatitis.

Until next time, I'll be getting up in people's faces, not minding my own business.  I'm way less likely to get stabbed that way.  

Happy sewing.



Cleaning Wounds:

Fernandez R, Griffiths R. Water for wound cleansing. Cochrane Database of Systematic Reviews 2008, Issue 1. Art. No.: CD003861. DOI: 10.1002/14651858.CD003861.pub2. 

Moscati RM et al. Acad Emerg Med 2007; 14:404–410


Perelman VS et al. Ann Emerg Med. 2004 Mar;43(3):362-70.
Suture and glue:
Farion KJ, Russell KF, Osmond MH, Hartling L, Klassen TP, Durec T, Vandermeer B. Tissue adhesives for traumatic lacerations in children and adults. Cochrane Database of Systematic Reviews 2002, Issue 3. Art. No.: CD003326. DOI: 10.1002/14651858.CD003326. 
Karounis H et al. A Randomized, Controlled Trial Comparing Long-term Cosmetic Outcomes of Traumatic Pediatric Lacerations Repaired with Absorbable Plain Gut Versus Nonabsorbable Nylon Sutures Acad Emerg Med July 2004; 730-735

Luck RP et al. Pediatr Emerg Care. 2008 Mar;24(3):137-42.


Friday, 23 November 2012

The Gaco Cycle (No educational content)

Two weeks ago, some of the EM residents and I were in Las Vegas for the Essentials of EM conference.  It was a great time, with many highlights, one of which was the first night of drinking with Damjan, AKA the Serbian teddy bear.  Damjan's (pronounced Dam-yin) mission was to get blind drunk ASAP after getting off the plane, so he proceeded to get 4 double tremclad-cokes (actually bourbon, but they tasted like paint thinner) in our first half hour at the Cosmopolitan.

At this point he decided it was time to play some poker, so we headed over to Planet Hollywood.

What happened next is best shown in diagram form.

Two hands and 10 minutes later, we were done.
In this variation of the Krebs cycle, 8 bourbon in leads to 2 cry as the product. 

Next trip maybe we'll get to Gacolysis or Oxidative Damjanalation. 

Thursday, 15 November 2012

All about chest tubes

Of all the interventions we perform, chest tube insertion is one of the most dangerous, complicated and misunderstood.  Today I'll discuss not only the myths, but also some unfortunate realities that we must understand when we undertake this procedure.

Myth # 1

Bigger is better

I'm pretty sure we've all been told, partially thanks to ATLS, that we better put a 36 or 40 French chest tube in during trauma, otherwise the blood will clog up the tube and drainage will cease.  Wrong, wrong, wrong!

This prospective, non randomized trial of trauma patients over a 3 year period from 2007-2010 compared small (28-32 French) with large (36-40 French) chest tubes.  The operator chose tube size, and sicker patients got bigger tubes (More ISS >25, GCS <8, sBP <90, (all p<0.01) for large chest tube group)  However, there was no difference in thoracic trauma pathology between the two groups (eg. flail chest, pulmonary contusions, PTX, pneumomediastinum, etc.)

Overall, there was no difference in the rate of complications between the two groups.  This includes pneumonia, empyema and retained hemothorax.  Further, there was no difference in interventions required for retained hemothorax (Additional chest tube insertion, intrapleural throombolysis, IR guided catheter insertion, VATS and thoracotomy)
When adjusted for ISS, GCS and sBP, there was still no difference between the two groups, with respect to complication rates or interventions for retained hemothorax. 

When pneumothoraces were analyzed separately, there was no difference in rate of complications or requirement for further intervention in this group either.

The second hypothesis of this study was that bigger tubes are more painful, and a visual analogue scale was used to rate patient pain.  There was no difference in VAS scores between the small and large chest tube groups.

Bottom Line: Any tube that is at least 28 French is suitable for draining a chest.  

Although it might not hurt less than a larger tube, it may still pass through the intercostal space a little more easily, so go ahead with those smaller tubes.  The logical next question is: Are tubes smaller than 28 French adequate?  That remains to be studied.

Myth #2

Directing the chest tube.  ie: Up for air, down for blood.

Every medical student/resident is asked this question repeatedly throughout their training.  "Where would you put the tube for a hemothorax?  What about a pneumothorax?"  The answers is always posterobasal for fluid and apical for air, right? 

2 things about this myth.  First, once the tube gets inside the chest, our ability to direct it is poor.  Second, as long as you are in the pleural space, you'll be fine.  It is a closed system and you have suction.  The fluid will drain regardless.  You may still have complications, but it's not because you put the tube in the apex of a hemothorax.

More important than directing the chest tube is ensuring it's in the pleural space, not advancing when you meet resistance and not causing any other complications.

There is a BestBets on this topic which can be found here.  There really isn't great data on this, so it is more of a physics myth than anything else.

Truth #1

Complications of chest tubes - This is not a myth, this is for real.

This is one critical point for all of us, but especially for residents inserting chest tubes.

The morbidity associated with chest tube insertions is astronomical!  About 25-30% of chest tube insertions have a complication, regardless of who inserts them.  A 2012 AAST study looking at post-traumatic empyema rates in major trauma centers is 27%.  That is crazy.
However, as an EM resident, I was disappointed to read this article that suggests EM residents may be the worst of all.  Really it's only a trend toward significance, and a retrospective study, but I'm still a bit sad to read it.  

We have to do something to get these rates of complications down.  

Use of antibiotic prophylaxis when inserting chest tubes is a topic of controversy.  EAST (The Eastern Association for the Surgery of Trauma) published a guideline in 2000 suggesting antibiotic prophylaxis for chest tube insertion.  More recently, this meta-analysis reviewing antibiotic prophylaxis was published in 2012.

For penetrating trauma, I would say that at least a single dose of antibiotic (1st gen cephalosporin) should be given at the time of insertion, if time and resources allow. This results in reduced rates of empyema and pneumonia, which in turn affects hospital and ICU LOS. 

For blunt trauma, which is the majority of what we see in Canada, no statistically significant reduction in infectious complications was found, and you may choose to withhold antibiotics in this group.

In all cases, duration of therapy is controversial.  It appears that short term (single dose or 24 hours) is equally effective as prolonged antibiotics (until time of chest tube removal).

Bottom line: Our rates of post-chest tube complications (empyema and pneumonia) are ridiculously high, even in major trauma centers.  A single dose of cefazolin at the time of chest tube insertion is a pretty benign intervention, and in my opinion warranted, particularly in penetrating trauma.

I'm curious who is giving antibiotics and if so, is it single dose, 24 hours, or longer?


1)Any chest tube at least 28 French is suitable for traumatic hemo/pneumothorax.

2)Get the tube in the pleural space but direction doesn't matter.

3)Complications of chest tubes are exceedingly high.  Give a single dose of peri-procedure antibiotics (particularly in penetrating trauma) and use sterile technique.

Until next time, I'll be standing on the corner, mindin' my own business. 



References and some chest tube links from people much more intelligent than me:

Own the chest tube with Chris Nickson at Life in the Fast Lane

Michael McGonigal's Trauma Professionals Blog has some great videos and posts about chest tubes as well.

Eastern Association of Surgeons for Trauma (EAST) Guidelines for Hemothorax and Occult PTX can be found here.

EAST Guideline on antibiotic prophylaxis for tube thoracostomy can be found for free here.
This is the reference. J Trauma. 48(4): 758-759, April 2000.

2012 Meta-analysis for antibiotic prophylaxis
Bosman A, de Jong MB, Debeij J, van den Broek PJ, Schipper IB.  Br J Surg. 2012 Apr;99(4):506-13

Chest tubes: Does Size Matter
Inaba, K et al. J Trauma 72(2):422-427, 2012.

Post-traumatic chest tube empyema rates
J Trauma 73(3):752-757, 2012.

Sunday, 21 October 2012

Why should we insert CVCs?

CVCs/CVLs are found in many, if not all critically ill ICU patients.  Why? 

To monitor central venous pressure and fluid responsiveness?  To measure markers of perfusion?  To provide fluid resuscitation?

Let's discuss some common myths surrounding the uses of CVCs.

A good place to start is a list of indications for insertion of central lines.  Take UpToDate as an example.  They list 5 indications for CVC insertion:

1)Hemodynamic monitoring including central venous pressure (CVP), central venous oxygen saturation (SCvO2) or for insertion of a pulmonary arterial catheter.

2)For infusion of irritants (eg. vasopressors, TPN, chemotherapy)

3)Transvenous cardiac pacing

4)Plasmapheresis, apheresis, hemodialysis or CRRT

5)Poor peripheral venous access

I would say this list is consistent with the common teaching of today.  While none of these is 100% wrong, there are many problems with indications 1 and 5 on this list.  By the end of this post, hopefully you'll agree with me that CVCs are primarily for 3 things: 

Infusion of irritants, transvenous pacing, and pheresis/HD/CRRT.

Let's look at #1 first.

There is no dispute that you can measure a CVP using a CVC.  But what is the value of that number in predicting volume status or guiding fluid resuscitation?

Nothing, zero, nada!

You might as well pick a random number out of your head and assign it to your patient's CVP, as it will be just as useful in guiding your resuscitative efforts.  The best review article on this subject comes from Paul Marik's Tale of Seven Mares in an issue of Chest, 2008. (All articles cited below)  In this meta-analysis, 24 studies (803 patients) were included, with patients primarily in ICU and OR settings.  

3 questions were asked:  
1)What is the relationship between CVP and blood volume?  
Terrible.  Of the 5 studies that looked at this outcome, the pooled correlation coefficient was 0.16 (95% CI, 0.03 to 0.28)

2)What is the ability of CVP to predict fluid responsiveness?
Also terrible.  "The pooled correlation coefficient between baseline CVP and change in stroke index/cardiac index (reported in 10 studies) was 0.18 (95% CI, 0.08 to 0.28)."

3)What is the ability of a change in CVP (Delta CVP) to predict fluid responsiveness?
Still brutal.  "The pooled correlation between DeltaCVP and change in stroke index/cardiac index (reported in seven studies) was 0.11 (95% CI, 0.01 to 0.21). 
The baseline CVP (reported in 11 studies) was 8.7 +/- 2.3 mm Hg in the responders, as compared to 9.7 +/- 2.2 mm Hg in nonresponders (not significant; p = 0.3)." 

A picture is worth a thousand words: Predictive value of CVP for volume responsiveness.


A word about the stats: The correlation coefficient (r) is a measurement of the strength and direction of the relationship between two variables, and is measured between 0 and 1. A coefficient of 1 would mean the CVP is perfectly predictive of the blood volume, while a coefficient of 0 means there is no association between the two variables.  Generally, a coefficient of <0.5 means a weak association, while >0.8 is a strong association.  

Thus, the ability of CVP to predict volume status/volume responsiveness is beyond poor. As an aside, the article is called the Tale of Seven Mares because the only study that has shown CVP to be predictive of fluid responsiveness was an animal study done in seven standing horses.  So now when you are asked to go hook up that CVP tracing, you can say "I don't recall seeing a horse in that ICU bed."  If you're a staff you can say that, med students and residents might want to be a little more careful.

So what does CVP actually measure?  It measures right atrial pressure.  So you could justify hooking up the CVP probe by saying you wanted to check if the patient had elevated right sided pressures for some reason (eg. PE, RV infarction, TR).  But if you really wanted to do that, slapping on the ultrasound probe and looking at the RV is much faster and less invasive.

How about the central venous O2 saturation?  That's good isn't it?
The ScvO2 is a fine measurement, but at least in the case of septic shock, we have a non-inferior, less invasive alternative in the form of lactate clearance.  
This comes from a JAMA 2010 article, in which 300 patients with severe sepsis/septic shock (as per the 2001 Rivers Early Goal Directed Therapy (EGDT) criteria) were treated.  One group of 150 patients was resuscitated to the EGDT endpoints for CVP, MAP and ScvO2, while the other group was resuscitated using CVP, MAP and a lactate clearance of 10% in the first 6 hours.  There was no in-hospital mortality difference between groups, and it was concluded that lactate clearance was non-inferior to ScvO2. 

Let's now look at the 5th indication for CVC insertion, fluid resuscitation.

CVC insertion is not a benign procedure, nor is it a rapidly performed procedure, especially in inexperienced hands.  Over a one week period last month, I witnessed four carotid punctures when residents were attempting to insert IJs. 
There is now a much safer, faster method for fluid resuscitation.

Intraosseous access (EZ-IO) pictured above.

Intraosseous access has traditionally been used more commonly in pediatric populations, but now is making it's way into adult resuscitative algorithms as well.  It is faster and requires less operator skill than establishing a peripheral iv.  More importantly, when a pressure bag (or blood pressure cuff) is used, the flow rates are just as good as CVCs.
Emerg Med J 28:201-202
Int J Emerg Med. 2009 September; 2(3): 155–160.

These two tables are from 2 different papers, but are conveniently labeled as Table 2 and Table 3. The first table shows flow rates of standard peripheral and central iv catheters, with and without pressure bags. 

The second table shows IO flow rates in sick human patients in Singapore.  You can see the flow rates with a pressure bag compare to a 20 gauge peripheral iv infusion rate, and also compare favorably with CVC infusion rates. In many of these patients, they had both a tibial and humerus IO placed for resuscitation.
springer.comThis journalToc AlertsSubmit OnlineOpen Choice
NB. The humerus IO generally allows much faster infusion rates than the tibia, despite what this small study shows.

Some pearls regarding IO access:
1)In order to achieve the most rapid infusion volumes with the least patient discomfort, after establishing IO access, give 40 mg of lidocaine (eg. 2 cc of 2%) mixed into a 10 cc NS flush syringe.  Do this before starting your infusion.  In healthy patients, the cardiac effects of this are minimal.
2)Any medication that can be given IV, can be given IO.  
3)In an urgent ED situation, IO is your friend.  Use one, use two, you could put in ten before someone established a central line.  Once you have volume resuscitated them somewhat, establish a peripheral IV.

One more CVC related myth = Infectious complication rates
I've always been taught that femoral lines are BAD! The groin is dirty, so infectious complication rates must be higher, right? Aren't DVT rates higher too?

Again we have Paul Marik to thank for this one, as he decided to undertake a meta-analysis looking at these questions.  This study included 2 RCTs and 8 cohort studies and looked at approximately 3200 femorals, 3200 subclavians and just under 11000 IJs.  The total number of catheter days was 113000.
The bottom line from this analysis is that there is no significant difference in catheter related bloodstream infections with any of the three sites.  
The analysis also suggests no difference in the rate of DVT, however, this was not an outcome declared at the start of the trial, and there was significant heterogeneity between studies.

My overall take on CVCs
1)CVCs have one MAJOR role: Infusion of irritants - ie: pressors, inotropes, TPN, chemo
They are also needed for transvenous pacers and other therapies in the ICU setting (eg. HD, CRRT)

2)It's time to take another look at EGDT.  Not only is the CVP an inaccurate measurement, it is a potentially dangerous one.  Attaching a CVP tracing may deter you from giving volume when it is needed, or may stimulate you to give volume when the tank is full and your patient needs vasopressors.
Furthermore, the ScvO2 can be effectively replaced with serial lactate measurements as markers of tissue perfusion.  Lactate going down = good.  Lactate going up = really bad.

3)If you want to put in a femoral line, go ahead.  I'm still going to stick with IJs and subclavians, except in codes/crash lines, but fems are defensible.  In all cases, strict sterile technique.

4)IOs kick ass.  They're fast, well-tolerated by patients, require limited operator skill, and can provide big volumes of fluid if you put on a pressure bag.  Plus, power tools are fun.

Disclaimer: The Rivers study was a landmark study and monumental achievement.  As with any EBM, it is only a matter of time before we start to assess the individual interventions that comprised EGDT, and see which ones (fluids and antibiotics) were more valuable than others (CVP).

Until next time, I'll just be standing on the corner, minding my own business.


Original Rivers EGDT article
CVP for fluid responsiveness
Marik PE, Baram M, Vahid B. Chest. 2008 Jul;134(1):172-8.
IO+IV papers

Friday, 12 October 2012

Welcome to SOCMOB!

"You're not going to use lidocaine with epi for that ring block, are you?"

"Whoa, that potassium is 7, go get some Kayexalate."

"Calcium in a digoxin overdose, you'll kill them!"

Do any of the above sound familiar to you?  I hope so!

I'll venture to guess that many of you have heard injecting the "fingers, toes, ears, nose or hose" with epinephrine will cause your patient's bits to start falling off.  Or that Kayexalate will "exchange that potassium" and fix hyperkalemia. And if you give an amp of calcium to a dig toxic patient, their heart will turn to stone!

What is this all about?  
David Newman of the NNT and SMART EM fame said it best in this article from Annals of EM in 2007:

"Although axioms are universally accepted principles or rules, pseudoaxioms, like pseudoscience, are false principles or rules often handed down from generation to generation of medical providers and
accepted without serious challenge or investigation."

As medical trainees, whether we are nurses, paramedics, residents, or any other health care provider, we are bombarded with information at every opportunity.  Often, it is the simple question, "Why?", that befuddles us or our preceptors the most.  We often respond with correct, evidence based answers.  But just as often, we give answers like "that is how we've always done it" or "Rosen's, Tintinalli's or (insert other textbook) says so?  It is at times like these that we must go back and look at why humans, and not computers, practice medicine.  

Medicine is a field based in Science, and prides itself on the powers of observation, logic and reasoning.  Over thousands of years, observation has served us extremely well, but in the past few decades, there has truly been a paradigm shift.  Evidence based medicine.  More recently, Free Open Access Medical Education or Med-ucation (FOAM) has spread like wildfire, and we are able to share information in real time, across the globe.  Rather than wait months or years for an NEJM article to be published and disseminated across the country, we can now tweet critical appraisals of articles that came out yesterday.  

Combining EBM and FOAM, medicine is in a golden era, not because of the superior technologies and techniques we have available, but because we can instantly re-examine the evidence for a particular topic through an online search.  Just tweet it to a friend, and the discussion begins.

Let's take a look at the pseudoaxioms mentioned above.  Since it's an intro blog, I've chosen three that have been reviewed beautifully by some of the super-geniuses in the EM world.  

First, the purported dangers of injecting epinephrine into digits.  

This was still (and maybe still is) published in Toronto Notes when I began medical school in 2006. For Canadian med students/residents, Toronto Notes is kind of like a bible for our end of medical school licensing exam.  In addition to the paper linked above, David Newman gave an amazing lecture on pseudoaxioms for USC Grand Rounds in Nov. 2011.  It can be found in the itunes store if you search "USC Emergency Medicine."  

Bottom line:  Don't put your finger in hot boric acid!   A common theme that arises from papers advocating against the use of epinephrine was the surgeons sending their patients home with instructions to keep their wounds clean by immersing them in "hot boric acid".  Sometimes, the patients were still partially or fully anesthetized, and thus could not feel the temperature or severity of the burns being caused by the acid.  
In his lecture, Dr. Newman also covers some other great ED myths including; septal hematomas, treatment of strep throat and others.  Well worth a listen.

Second up is the use of Kayexalate or sodium polystyrene sulfonate for treatment of acute hyperkalemia.  There is a brilliant podcast over at the emcrit site that is a must-listen for anyone who has ever used Kayexalate.  Have a listen, then do yourself a favor and look up the two 1961 NEJM references and have a read.  Great stuff!

Bottom line: Kayexalate is no more effective than placebo in reducing potassium for treatment of acute hyperkalemia.  The drug was approved by the FDA in 1958, yet it was 3 years before a study was required to be done on it.  This study is a must read, as it contained 10 patients, 5 of whom received sorbitol+resin, 3 received sorbitol only and 2 received sorbitol+resin as an enema.  The sorbitol only group had a non-statistically greater reduction in serum potassium (6.3 to 4.6) than the sorbitol+resin group (6.6 to 5.2).  They state "sorbitol alone is as effective as a combination of resin and sorbitol in removing potassium, or more so. However, sorbitol alone necessitated a greater volume of debilitating diarrhea. In either case the predictability of the fall in serum potassium was impressive." A second study supporting the use of Kayexalate was in the same issue of NEJM, and was an uncontrolled, 32 patient trial with NO CONTROL GROUP.  Yup, times have changed.

Recently, there have been multiple case reports of intestinal ischemia/colonic necrosis with Kayexalate, one of which can be found here.  Safety and effectiveness are reviewed by Sterns et al. here.  So when I show up with my K of 8, no Kayexalate for me please.

Finally, digoxin toxicity.  As a cardiac poison that's been in use for hundreds of years, the literature on this is a lot of fun to read.  There are countless articles that start with sentences like "Over the past year I have seen four cases of poisoning with foxglove", which is how articles were written back in the day.  Along with this body of mostly observational literature comes many conclusions based on case reports, including the concept of the "stone heart".  This refers to cardiac arrest precipitated by giving calcium to hyperkalemic patients.  Amit Maini of ED Trauma Critical Care does a great job of reviewing this here.
Bottom line: Calcium is unlikely to cause any harm in acute digoxin toxicity, and even less likely in chronic toxicity.

Inspired by the great reviews above, I'll do my best to analyze other medical dogma, and separate the axioms from the pseudoaxioms.

Please send me your questions, comments and ideas for future topics using the contact page, comments or on twitter @socmobem