PEMBlog updates (New baby edition)

Sorry that there’s not been a new post this week – our third son was born and he requires some attention. Babies can be so selfish.

Anyway, more great content coming soon – including:

  • An in depth post on procalcitonin
  • A podcast interview with Todd Florin, one of the Pediatric Emergency Medicine faculty at Cincinnati Children’s Hospital Medical Center on therapies for bronchiolitis
  • An exploration of what it means when an ultrasound for appendicitis can’t find the appendix
  • More on ketamine for procedural sedation, including laryngospasm and its dissociative properties

Thanks for your continued support of the site, and stay tuned!

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Do vagal maneuvers actually work on SVT in children?

So you’ve gone ahead and diagnosed supra ventricular tachycardia. While getting ready to place an IV and draw up adenosine somebody (a seasoned RN perhaps) suggests that you try vagal maneuvers. Perhaps you’re feeling pessimistic that day, and wondering if they ever work. And, which one should you choose anyway? Let’s answer both questions.

How should vagal maneuvers be performed in children?

First of all, these should only be done in the child who is stable. In infants and young children (who can’t cooperate) apply a bag filled with ice and cold water to their face (the whole face) for 15-30 seconds. This will initiate the “diving reflex” whereby the child’s glottis closes, intrathoracic pressure increases and they valsalva. The EKG should be recording while this is done. You can also try inserting a rectal thermometer. In older children ask them to “bear down” like they are going to have a bowel movement, or have them blow hard on an occluded straw. Doing so for 15-20 seconds will potentially stimulate the vagus nerve. Do not perform carotid massage or orbital pressure.

Do vagal maneuvers work?

Surprisingly, at least according to a few studies the answer is yes. Garson et al. from J. Pediatrics in 1981 noted that 63% (12/19) of their SVT cases that had valsalva performed converted (at least for a short time). In a 1994 study form the American Journal of Cardiology Muller et al. saw that ice to the face terminated tachycardia in 9 of 46 episodes (20%). Note that both studies were pediatric only – which is rarer in the literature – and had very small numbers of patients. Nevertheless, in the stable patient you really have nothing to lose, even if you think that the likelihood of  aborting SVT is low.

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Briefs: Assessing and staging burn severity

It’s cold out and people are trying to warm themselves up by any means necessary. In the Emergency Department that means you may end up seeing some burns. It is important not only to assess these burns, but also determine what percentage of the body surface area is superficial versus partial AND full thickness. Wait a second… Aren’t we supposed to specify the percentage of second and third degree burns. yeah, that’s technically true as well, but the terminology has changed and thus I wanted to make sure that everyone was up to date.

Before we get in to staging, let’s look at the major tenets of burn first aid:

  • ABCs
  • Remove of clothing
  • Wash off chemicals
  • Cover the burn with a clean dry sheet – it’s OK to put a cold wet compress on small burns, but not for large burns. This can lead to hypothermia. Do not use butter.

Again, burns were formerly classified by degree, now the emphasis is placed on burn depth:

Superficial

Formerly known as First Degree Burns

Involve only the epidermis. The skin is red, dry and blanches with pressure. There is minor swelling and pain but no blisters. Resolution by 5–7 days. A good example is a sunburn.

from Wikipedia

From Wikipedia.com

Superficial Partial Thickness

Formerly known as Second Degree Burns - but to better differentiate between deeper partial thickness burns it was broken off into its own subgroup.

These involve the epidermis and dermis and thus form blisters within 24 hours. A burn initially thought to be superficial may actually be partial thickness since these blisters might not initially be there. They are painful, red, weeping and blanching. Healing can take 1-3 weeks, usually without scarring.

From Wikipedia.com

From Wikipedia.com

Deep Partial Thickness

Formerly known as Second Degree Burns

These burns extend down to the deep dermis injuring hair follicles and glands. They are painful to the touch and form easily unroofed blisters. The skin is mottled and non-blanching. These take 3 to 9 weeks to heal and generally leave hypertrophic scars

From Wikipedia.com

From Wikipedia.com

Full Thickness

Formerly known as Third Degree Burns

These result in the destruction of the entire dermis and underlying subcutaneous tissue. Sometimes painless (damaged nerves). The skin is dry, waxy and white/gray. There are no blisters and the skin is non-blanching. If the eschar that encircles a limb or digit it can lead to strangulation. Skin grafting is required.

From Wikipedia.com - One week old Deep Partial Thickness Burn

From Wikipedia.com – One week old Deep Partial Thickness Burn

Fourth Degree

These burns are deep and potentially life threatening. They extend to muscle, fascia and/or bone and the damaged tissues need to be excised because they are dead.

From Wikipedia.com

From Wikipedia.com


 

Measurement of burn surface areas follows the rule of nines (> 14 years old):

  • Head and neck: 9%
  • Each upper limb: 9%
  • Thorax and abdomen, front: 18%
  • Thorax and abdomen, back: 18%
  • Perineum: 1%
  • Each lower limb: 18%

Rule of palm (< 10 years of age): 

Child’s palm not including fingers = 1% body surface area. More useful in smaller burns. Children have a proportionally larger head – thus it represents 18% BSA in infants and small children.


A final point – take a good history – many burns have a great story behind them.

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Evaluation of a clinical prediction model for febrile children with SBI

It goes without saying that a clinical prediction rule, and for that matter an associated online tool (one of which in particular we’ll get to in a minute) is only as good as your initial clinical judgment and as practical as the environment in which you work. These types of rules also need to be grounded in solid methodology with prospective validation.

The aforementioned rule that I alluded to was published in BMJ and discussed at the Cincinnati Children’s Hospital Medical Center Pediatric Emergency Medicine journal club recently.

You can take a look at the article here: Article Link

And the online decision tool for SBI here: Online Tool

Here are a few thoughts shared from the engaging discussion:

  • The precise number of predictor variables were not clearly defined in the methods. In addition there were so many predictors that it ran the risk of overfitting – this limits applicability to broader populations.  This fits the study it was anchored to well, but not necessarily others. There was also some heterogeneity between the study sites, and in terms of what the individual providers did. The predictors were also not clearly specified a priori.
  • You need to have a sufficient number of outcomes for each predictor, generally 10 for each. In a study with 35 predictor variables you’d need 350 outcomes for a potentially rare disease/outcome. This is hard to accrue. The predictors with poor interrater reliability, those without high numbers of positive results, and if 2 predictors are similar (℅ linear) you can start to winnow down the list.
  • Unfortunately this study had some missing data – in this study they used computer magic (multiple imputation) to run the models multiple times to try to predict what those missing variables would be. In general, if >30% of the samples are missing this technique is limited.
  • The external validation population in this study (Coventry) had a higher prevalence of SBI. Was this due to luck? And how did it effect the results?
  • There were multiple cases of SBI – but it is important to remember that the conditions they defined as SBI (pneumonia, UTI, septicemia and meningitis) are heterogeneous clinically. There were very few cases of septicemia and meningitis – the worst of the bunch.
  • In summary, this turned out to be a decent pneumonia rule but not great for others. It turns out that if you have a patient with clinical pneumonia/suspicion for pneumonia CRP will increase sensitivity to see a pneumonia on the Xray. How many of us actually get a CRP in these scenarios though?
  • And finally, procalcitonin was not included – which is interesting given that this was Europe. See the following article from Luaces-Cubells et al. for more. I’ll be posting on procalcitonin in the near future.

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Three reasons why you should not give diphenhydramine as pretreatment in migraines

If you’re a regular reader of the blog you know that I’ve posted on migraines before. For instance, you can check out the “Why We Do What We Do” on antiemetics (prochlorperazine and metoclopramide). Other excellent Pediatric Emergency Medicine educators have posted on the topic recently as well – see Sean Fox’s recent post on PedEMMorsels.

I wanted to take this opportunity to discuss an addition to the familiar “migraine cocktail” that is variably used in EDs – that addition, is diphenhydramine. Many Emergency Departments actually have this on their headache pathway by “default.” Allow me to present 3 reasons why, at least in pediatric patients, that you shouldn’t necessarily give benadryl as a matter of habit to every patient with a migraine.

There’s no convincing proof that it helps when given before/at the same time as the antiemetic +/- toreador. There is some limited evidence in adults – see Vinson et al which showed that it reduces akathisia. But that’s all.

It may actually reduce the effectiveness of the dopaminergic properties of the antiemetics. This mechanism is poorly understood, but the histamine blockade may serve to reduce the effect. Thus, wait until that patient actually has symptoms, rather than preemptively giving it. There is also no proof that patients will have the same dyskinetic/akasthisic reaction each time – but if they’ve had it before this is probably an OK indication to pre-treat with benadryl.

Giving diphenhydramine increases the risk of a return visit to the ED. yes, the effect is small (1.5% increase), but its there and the data is based on a study of over 30,000 patients in this month’s edition of Pediatrics.

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5/2/1 – 50! Dextrose volume for hypoglycemia

There is a quick memory aid that will help you remember how much dextrose to give to patients with hypoglycemia. It is commonly known as the 5/2/1 rule, or the rule of 50.

D10  5 mL/kg

D25  2 mL/kg

D50  1 mL/kg

Note that all three, when multiplied, equal 50 (e.g. 5ml/kg x 10 = 50)

Given the hypertonicity of D50 it can be dangerous to give through a peripheral IV. It can cause phlebitis and thrombosis and in pediatric patients it is rarely indicated, especially when D10 or D25 (in bigger kids) will work just as well.

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