Thanks to Dr. Joanna Middleton for leading the discussions this month

Edited by Dr David Lewis 

 

 

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Top tips from this month’s rounds:

 

Pediatric Head Injury

Clonazepam Toxicity

Pediatric(< 3 months)Fever

Wide Complex Tachycardia

 

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Pediatric Head Injury

• What are the criteria for CT Head?

In a recent Lancet article (2017),  PECARN, CATCH and CHALICE were compared.

The highest point validation sensitivities were shown for PECARN in children younger than 2 years (100·0%, 95% CI 90·7–100·0; 38 patients identified of 38 with outcome [38/38]) and PECARN in children 2 years and older (99·0%, 94·4–100·0; 97/98)

• How do I use PECARN?

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A useful review by EM Cases can be accessed here. In an update to this review they have noted recent new evidence that isolated vomiting without any other positive rule predictors may warrant observation only:

Update 2018:  A secondary analysis of the Australasian Paediatric Head Injury Rule Study demonstrated head injury with isolated vomiting (i.e. vomiting without any of clinical decision rule predictors) was uncommonly associated with TBI on CT, or the presence of clinically important TBI.  This study suggests a strategy of observation without head CT may be appropriate management.  Abstract

Vomiting alone should not instigate CT.  Risk goes up with any other Head Injury symptoms (Headache etc). These children should be observed until they are able to tolerate oral intake and the treating clinician feels comfortable that the patient is stable without additional symptoms of head injury.

This article discusses linear skull fractures. It reminds us to always consider Non-Accidental Injury in all cases of pediatric head injury, especially in the pre-mobile age group.

PoCUS may have a role to play in fine tuning risk stratification and a recent study (2018) has further evaluated diagnostic accuracy:

We enrolled a convenience sample of 115 of 151 (76.1%) eligible patients. Of the 115 enrolled, 88 (76.5%) had skull fractures. POCUS had a sensitivity of 80 of 88 (90.9%; 95% CI 82.9-96.0) and a specificity of 23 of 27 (85.2%; 95% CI 66.3-95.8) for identifying skull fractures.

• If I don’t perform a CT, then how long should a child with a head injury be observed?

There is no definite evidence-based answer to this question. However this study suggest that 6 hrs is probably safe.

Key Points

1. Always use a clinical decision rule to determine whether a child with head injury requires CT, Observation or can be safely discharged
2. When using a decision rule utilize a ‘shared decision-making’ philosophy – i.e involve the parents/carers
3. A period of observation can reduce the number of CTs performed.
4. If observation is recommended, then allow 6hrs.
5. Always consider non-accidental injury during your assessment of pediatric head injury.

 

 

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Clonazepam Toxicity

• Overdosage of clonazepam may produce somnolence, confusion, ataxia, diminished reflexes, or coma
• Clonazepam is extensively metabolized in the liver to several metabolites
• Clonazepam is rapidly and well absorbed from the GI tract
• Peak blood concentrations are reached in 2 -4 hours
• Elimination half-life … 18.7 to 39 hr

Full ToxNet entry

Treatment

Treatment is entirely supportive with IV access and fluids and maintenance of the airway and ventilation if required

Oral activated charcoal is of little value in pure benzodiazepine poisoning. It may be given to patients who have recently ingested benzodiazepines with other drugs that may benefit from decontamination

Flumazenil is rarely indicated except for iatrogenic oversedation or respiratory depression. In addition, flumazenil may cause withdrawal states and result in seizures, adrenergic stimulation, or autonomic instability in patients chronically taking benzodiazepine, or in those with ventricular dysrhythmias and seizures who are concomitantly using cocaine or tricyclic antidepressants.

Dispostion

All patients with intentional ingestion or significant ataxia, drowsiness, or respiratory depression should be observed.

Patients with severe symptoms (ie, coma, respiratory failure, or hypotension unresponsive to IV fluids) should be consulted to ICU.

Given the prolonged half-life patients strongly consider admitting patients who present with significant drowsiness or are known to have taken a large overdose.

Patients with a significant sedative drug overdose should be advised not to drive until potential interference with psychomotor performance has resolved. For significant benzodiazepine overdose, this is at least 24 hours after discharge.

Key Points

1. Clonazepam overdose is treated with supportive measures.
2. Clonazepam has a very long half-life. For significant drowsiness, admission should be considered to avoid potentially very long ED observation periods.

 

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Pediatric (< 3 months) Fever

The management of fever in infants less than 1 month is relatively straightforward. Guidelines are generally consistent (Merck,

• Full blood lab work-up (CBC, CRP, Cultures)
• Urine culture
• CXR
• RSV, Flu nasal swabs
• LP
• Empiric IV Antibiotics (e.g Ampicillin 50mg/kg and Cefotaxime 50mg/kg)
• Consult Pediatrics and Admit

Emergency Medicine Cases article can be viewed here – Episode 48 – Pediatric Fever Without A Source

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For infants older than 30 days and younger than 3 months the guidelines are variable:

ALiEM: Paucis Verbis: Fever without a source (29 days-3 months old)

NICE Guidelines (UK):  Fever in under 5s: assessment and initial management

MD Calc – Step-by-Step Approach Calculator 

Suggested Emergency Department Approach

• If Sick-Appearing treat as <3 months (see above)
• If Well- Appearing (age normal vitals):
  • Full blood lab work-up (CBC, CRP, Cultures)
  • Urine culture
  • Consider CXR
  • Consult Pediatrics (Depending on results of above will either need admission +/- antibiotics or 24hr follow-up)

Yukon Guidelines

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Wide Complex Tachycardia

Differential Diagnosis (note: repetition is deliberate!)

• Ventricular Tachycardia
• Ventricular Tachycardia
• Ventricular Tachycardia
• SVT with aberrant conduction – lots of causes
  • Pre-existing/rate-related BBB
  • Ventricular pre-excitation (AVNRT/AVRT)
  • Dysfunction of IV conduction system (toxic, metabolic, infectious, drug related etc) – hyper K, sodium channel blockers

No ‘rule’ is specific enough to correctly identify, so treat like VT

Treatment 

• Unstable?
  • ANY sign of end-organ dysfunction – hypotension, altered LOC, CHF/SOB, CP, diaphoretic etc
  • SHOCK
• Stable?
  • Shock or medical management
  • Amiodarone vs procainamide, ?adenosine (see below)

Adenosine/vagal – consider in patients where uncertain of diagnosis, unlikely to be VT, no hx of CAD, young, hx of SVT

Adenosine with WPW – ContraIndicated – may induce AV block and accelerate conduction of atrial fibrillatory impulses through the bypass tract, which can lead to very rapid ventricular arrhythmias that degenerate to VF.

“Avoidance of IV beta blockers, calcium channel blockers and digoxin due to the potential for hemodynamic deterioration in patients with stable WCT, potentially resulting in hypotension, VF and cardiac arrest”. (Uptodate)

Verapamil and diltiazem are calcium channel blockers (CCBs) that should be avoided in WCTs, as cardiac arrests from hemodynamic collapse have been reported following their administration.  Not only do these agents cause negative inotropy and at times profound vasodilation, but they may also allow WCTs to degenerate into VFIB

Caveat – RRWCT (Regular Really Wide Complex Tachy)

• One situation where you may not want to assume VT….
• What question should you ask?
  • What is the K,
  • what is the OD?
• Really, really wide complex tachycardia – >200 mseconds – consider tox or metabolic – try bicarb or calcium – if it narrows – not VTach.
• Avoid procainamide and amiodarone in these patients.