Check out this red hot podcast on Heat Illness

The heat is on! With warm weather comes a plethora of heat-related problems in the ED. That’s why I’m sharing this edition of PEM Currents, the Pediatric Emergency Medicine Podcast. The focus is on heat illness in its many forms. Learn about everything from the benign prickly heat, to life threatening heat stroke. Stay cool and learn something all right?

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PEM Currents podcast on swallowed foreign bodies

Kids eat stuff they’re not supposed to. Most of the time foreign bodies pass harmlessly through the GI tract. Occasionally they will get stuck. It is your job to figure out who has an impacted foreign body, and how to diagnose and manage it.

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Why we do what we do: Antibiotics for dog bites

For a long time when encountering a patient who had suffered a dog bite I reflexively placed the patient on antibiotics. Generally, either amoxicillin/clavulanate or clindamycin. Along the way I began to question whether or not there is evidence to support this practice, since I also haven’t seen many infected dog bites. As you may already be aware, most dog bites are from an animal known to the victim. One study from Australia noted that >4/5 were known. In children under 5 the bites are more likely to be in the head/neck (60-70%). See Patronek at al. for more. In older children and adults the extremities – more commonly the dominant hand – are involved.

The exact rate of infections is hard to estimate since many patients with dog bites likely do not seek care. But, in those that do seek care >24 hours after the bite the rate of infections seems to be higher. Overall though, infections from dog bites are more infrequent than almost any other animal – see Capellan from Emerg Med Clin North Amer for more. If a wound needs to be closed copious irrigation is a must. Debriding dead/compromised tissue is key, as is avoiding deep sutures and any tissue adhesive. It is OK to allow the wound to drain. Ultimately, despite these practices I still wonder whether or not antibiotics truly make a difference. This is, unfortunately, where the literature is a bit thin.

Dog-bite lacerations: a controlled trial of primary wound closure
C Maimaris and D N Quinton
Arch Emerg Med. 1988 Sep; 5(3): 156–161

This was randomized trial of 96 patients of all ages (though most were <30 years). Together they had 169 dog bites. 92/169 were closed and 77/169 were not. No patient got antibiotics. Overall 13/169 wounds developed infection – with no difference between sutured or not (7.6 versus 7.8 percent).

Antibiotics to prevent infection in patients with dog bite wounds: a meta-analysis of randomized trials
Cummings, P
Ann Emerg Med. 1994 Mar;23(3):535-40.

Eight randomized trials were reviewed with the cumulative incidence of infection in controls 16%. The relative risk for infection in antibiotics vs not was RR=0.56 (95% CI, 0.38 to 0.82). The number needed to treat was approximately 14.

Relative risk estimates and 95% CI for individual studies and the summary relative risk estimate for all studies. A relative risk estimate less than 1.0 indicates that antibiotic treatment reduces the risk of infection. The reference number is given for individual studies. *Study has a relative risk estimate of infinity.

Relative risk estimates and 95% CI for individual studies and the summary relative risk estimate for all studies. A relative risk estimate less than 1.0 indicates that antibiotic treatment reduces the risk of infection. The reference number is given for individual studies. *Study has a relative risk estimate of infinity.

Primary closure of mammalian bites
Chen et al.
Acad Emerg Med. 2000 Feb;7(2):157-61.

This observational study evaluated 145 bites that underwent primary closure. Dogs made up more than half 88/145, but cat and human bites weer also included muddying the waters a bit with regard to the question at hand. majority of the wounds (57 percent) were on the head and neck. Only 8 patients (5.5%) developed infection despite having received antibiotics. The study was purely descriptive.

Antibiotic prophylaxis for mammalian bites
Medeiros et al.
Cochrane Database Syst Rev. 2001

This Cochrane review of 8 RCTs trials saw no statistically significant reduction of local wound infection in antibiotic prophylaxis (4%, 10 of 225 patients) versus controls (5.5%, 13 of 238 patients). The odd ratio was 0.74 (95% CI 0.30 to 1.85). Subanalysis did show that antiobiotic prophylaxis lowered the rate of infection in dog bites of the hand – 28% to 2%, with an OR = 0.10 (95% CI 0.01 to 0.86). The number needed to treat for hand infections was 4.

Primary repair of facial dog bite injuries in children
Wu et al.
Pediatr Emerg Care. 2011 Sep;27(9):801-3.

This descriptive report of 87 consecutive patients under age 18 with dog bite facial injuries, all of which received an antibiotic. None developed wound infection.

Why did I choose this topic for a Why We Do What We Do? Well, I do feel that this is an area where we practice reflexively. There really is limited evidence for what seems to be a routine practice. I do suspect that there is a bias towards patients who seek care in an ED/office. There are probably thousands of dog bites that happen at home and do not result in an ED visit. Do those get infected? Probably not in all honesty. Nevertheless, I am left in a bit of a quandry, as I feel that we should always be practicing evidence based medicine. So, based on the available literature it makes sense to put patients on prophylactic antibiotics for a dog bite wound if;

  • The wound has been primarily closed
  • Moderate to severe wounds (crush injury, devitalized or missing tissue, deep bites to tendons or bone)
  • Puncture wounds
  • Bites to the hands, feet, genitals or face
  • Asplenic or immunocompromised patients

If you are going to prescribe antibiotics (though not the exact focus of this post), I would use Amoxicillin/clavulanate, a broad spectrum cephalosporin if penicillin allergic, or clindamycin. If you aren’t going to prescribe prophylactic antibiotics have a good discussion with the patient and their family.

Reducing pain during incision and drainage of abscesses

Performing incision and drainage on an abscess is painful for the patient. I realize that is as obvious a statement as I could possibly make. I wanted to briefly touch on some of the many interventions that you can use to decrease pain during I&D.

Before the procedure

Consider factors that will impact tolerance of the procedure

  • Developmental level – can the child comprehend what you are doing and agree to hold still
  • Prior procedures/experiences – Has this patient had an I&D before? How was it done? Was adequate local anesthesia used – or were they just “held down” while some doctor squeezed the abscess.
  • Patient and parent anxiety level – Generally the antidote to this is good preparation and education about what the procedure entails. You know, the risks and benefits stuff that should not be glossed over when obtaining consent.
  • Expected duration of procedure – Is this a big abscess? Will it take longer than 30-40 minutes? Is it a pilonidal or hidraadenitis suppartiva? Some abscesses are better managed in the OR.
  • Developmental delay, autism and sensory disorders – It goes without saying that a toddler and a teenager can tolerate an I&D in very different ways. Relying on the parent to help you understand how a child’s developmental delay will impact tolerance of the procedure is critical obviously.
  • Location, size and number of abscesses – Children with abscesses in areas with a high density of nerve endings will experience more pain. Examples include the face, genitals and perirectal area.
  • Can the patient be safely held? – You definitely want ot make sure the child can protect their airway. If a child cannot be safely held without compromising the ABCs then the abscess may need to be drained in the OR.
  • Do you have support personnel like a Child Life Specialist available?

Utilize local anesthetics properly

  • Apply Lidocaine 4% cream before the procedure – I recorded a podcast on this one. Note that LMX works a bit faster than EMLA, but that both are appropriate. LET is only used on lacerated skin. You can expect that LMX or EMLA will provide topical anesthesia for a depth of 2-3mm max. This is NOT sufficient for the full I&D, but it will reduce the pain of local injection to a degree.
  • Use buffered Lidocaine (9:1 ratio with 8.4% Bicarbonate – e.g. 1 mL bicarb to 9 mL lidocaine) – Lidocaine is acidic. Acids hurt when they are injected into your skin. Buffering with bicarbonate solution can reduce the pain of subcutaneous injection.
  • Use a smaller needle and inject slowly – I prefer a 1 inch to 1.5 inch 27 gauge needle. The smaller gauge limits the speed at which lidocaine enters the skin and reduces discomfort.
  • Warm the lidocaine – colder lidocaine hurts more. Room temperature is fine.
  • Stimulate the skin adjacent to the injection site – Do you find yourself instinctively rubbing your elbow when you smack your “funny bone?” What you are effectively doing is stimulating adjacent nerves to “cross the signals” and confuse the pain sensing fibers. You can do this by hand, or with a device like the Buzzy.
  • Use good ring block/field block technique – Remember that an abscess is roughly a circular shaped lesion. Therefore, pain innervation comes from all angles. You should not simply inject at the incision site. Calculate your max dose of lidocaine (4-5 mg/kg for 1% lidocaine without epi, 7 mg/kg with epi) and aim just deep enough to create a subtle wheal and to hit the junction point of the local nerve fibers. Insert a 27 to 30 gauge needle at an oblique angle just under the epidermis a small distance away from the edge of the abscess (avoid injecting into the abscess which can be painful and ineffective). Inject in a ring around the abscess, going through already-numb skin when possible (this is where the topical 4% lidocaine helps). A recent survey based study indicated that only 60% of Emergency Medicine physicians used this technique.

    From AAFP “Regional Anesthesia for Office Procedures: Part I. Head and Neck Surgeries”

  • Wait at least 3 minutes for full effect – Lidocaine takes time to work on those sodium channels. Wait at least 3 minutes, but ideally 5 to 7 for the patient to be comfortably numb.

Consider adjuvant medications

It’s generally a good idea to give pain medicines before the procedure, especially if you aren’t going to use sedation. Remember that older children may need sedation as well, especially those who are anxious, have large abscesses (requiring packing), have had prior I&D’s, or have abscesses in painful locations (face, genitalia, axilla).

If you need to control pain only

  • Fentanyl – 2 mcg/kg IN or 1 mcg/kg IV Max 100 mcg/dose. Useful in children with small abscesses when local anesthesia is adequate. May not be adequate if anxiety is a significant component.

If you only need a little anxiolysis

  • Midazolam – 0.5-1 mg/kg PO (higher doses under age 6). Max 20 mg. Useful in children with small abscesses when local anesthesia is adequate. But NOT helpful if local anesthesia is not adequate to reduce anxiety (i.e. you can’t reason with them).

If you need to control pain and anxiety

  • Moderate/procedural sedation – Institutional procedures may vary, but generally this involves drugs like ketamine, propofol or combinations thereof. I use ketamine most often and find that an initial dose of 1.5 to 2 mg/kg in children under 6-8 years of age is more effective.
  • Nitrous – If you have it gas is a great option for the calm, mature child (> 4 years of age for nasal mask, > 2 years of age for face mask).

D-dimer utility in pediatric patients with suspected PE

Great read from the PEM Playbook by Tim Horezko at the Pediatric Emergency Playbook. The bottom line is that he asserts that D-dimer should have limited utility in the diagnostic workup of pulmonary emboli in children who almost always have a reason for a PE like malignancy, prior DVT etc,. In fact, 98% of kids with PE have at least one identifiable risk factor, most with two. He notes that,

“The only data we have in using d-dimer in children is to prognosticate in established cases. It is only helpful to track therapy for children who have chronic clots. This is where our adult approach can get us into trouble. Basically, think of the d-dimer in children like it doesn’t even exist. It’s not helpful in our setting for our indications.”

He goes on to state that,

“Up to a third of adults with [idiopathic] PE have no known risk factor, which makes decision tools and risk stratification important in this population.”

In short, if you think a kid has a DVT-  get an ultrasound. If you think they might have a PE and you need to rule it out don’t use the D-dimer as it has not been adequately studied. Instead, go straight to imaging like a CT angiogram or VQ scan.

Read more from Tim at the excellent Pediatric Emergency Playbook.