Q. What are the clinical profiles of pediatric patients with acute myocarditis and dilated cardiomyopathy (DCM) before diagnosis?
A. Data suggest children with acute myocarditis and DCM most commonly present with difficulty breathing. Myocarditis and DCM may mimic other respiratory or viral illnesses, but hepatomegaly or the finding of cardiomegaly and an abnormal electrocardiogram result may help distinguish these diagnoses from other more common pediatric illnesses.
Methodology: A retrospective cross-sectional study was conducted to identify patients with myocarditis and DCM who presented over a 10-year span at 2 tertiary care pediatric hospitals. Patients were identified based on the International Classification of Diseases, Ninth Revision, diagnostic codes.
Findings: A total of 693 charts were reviewed. Sixty-two patients were enrolled in the study. Twenty-four (39%) patients had a final diagnosis of myocarditis, and 38 (61%) had DCM. Of the 62 patients initially evaluated, 10 were diagnosed with myocarditis or DCM immediately, leaving 52 patients who required subsequent evaluation before a diagnosis was determined. Study patients had a mean age of 3.5 years, 47% were male, and 53% were female. Common primary complaints were shortness of breath, vomiting, poor feeding, upper respiratory infection (URI), and fever. Common examination findings were tachypnea, hepatomegaly, respiratory distress, fever, and abnormal lung examination result. Sixty-three percent had cardiomegaly on chest x-ray, and all had an abnormal electrocardiogram results.
Analysis: With our recent H1N1 epidemic, there were case reports of patients with myocarditis. It is an extremely difficult diagnosis to make in the face of a busy emergency department and flu season. However, some things to remember about myocarditis include:
-The most common etiology in North America is viral -Coxsackie A and B, ECHO viruses, and Influenza viruses
-Neonates and infants may present with lethargy, poor feeding, irritability, pallor, fever, and failure to thrive. Symptoms suggestive of heart failure like diaphoresis with feeding, rapid breathing, or respiratory distress may be present.
-Older children and adolescents may complain of weakness, fatigue, chest pain, and shortness of breath
-Wheezing is often present and can be misleading!
-The Physical examination may reveal tachypnea, tachycardia, hyperthermia or hypothermia, and hypotension.
-Signs of poor perfusion and heart failure such as tachycardia, weak pulses, decreased capillary refill, cool mottled extremities, jugular venous distention, hepatomegaly, and lower extremity edema may be present.
-Heart tones may include an S3, and may be muffled if pericarditis is present.
-The most common dysrhythmia is sinus tachycardia. ECG shows tachycardia, low QRS voltages, flattened or inverted T waves with ST-T wave changes and prolongation of the QT interval
-A tachycardia faster than expected for the degree of fever (10 BPM for each degree of temperature elevation) may be indicative of myocarditis.
-A chest xray may reveal cardiomegaly, but early in the disease process, the heart size may be normal.
Also, consider myocarditis in patients who are worsening in the face of fluid administration. Often, the reflex is to administer more IV fluids in these patients. However, I encourage you to take another look at the patient, re-examine them and obtain an ECG. The way to diagnose myocarditis, is to always have it in your differential diagnosis as wheezing is often misleading and can take us down the path of Respiratory syncytial virus or pneumonia very easily.
Q. In the ED, a significant amount of radiation exposure is due to CT scans performed for the diagnosis of appendicitis. Ultrasonography eliminates radiation but has inferior sensitivity. How would an interdisciplinary initiative work that used a staged US and CT pathway to maximize diagnostic accuracy while minimizing radiation exposure?
A. Half of the patients who were treated using this pathway were managed with definitive US alone with an acceptable negative appendectomy rate (7%) and a missed appendicitis rate of less than 0.5%. Visualization of a normal appendix (negative US) was sufficient to obviate the need for a CT in the authors’ experience. EPs used an equivocal US in conjunction with clinical assessment to care for one-third of study patients without a CT and with no known cases of missed appendicitis. These data suggest that by employing US first on all children needing diagnostic imaging for diagnosis of acute appendicitis, radiation exposure may be substantially decreased without a decrease in safety or efficacy.
Citation: Ramarajan N. Krishnamoorthi R, Barth R etal. An Interdisciplinary Initiative to Reduce Radiation Exposure: Evaluation of Appendicitis in a Pediatric Emergency Department With Clinical Assessment Supported by a Staged Ultrasound and Computed Tomography Pathway. Acad Emerg Med. 2009 Nov;16(11):1258-65.
Methodology: This was a retrospective outcomes analysis of patients presenting after hours for suspected appendicitis at an academic children’s hospital ED over a 6-year period. The pathway established US as the initial imaging modality. CT was recommended only if US was equivocal. Clinical and pathologic outcomes from ED diagnosis and disposition, histopathology and return visits, were correlated with the US and CT. ED diagnosis and disposition, pathology, and return visits were used to determine outcome.
Findings: A total of 680 patients met the study criteria. A total of 407 patients (60%) followed the pathway. Two-hundred of these (49%) were managed definitively without CT. A total of 106 patients (26%) had a positive US for appendicitis; 94 (23%) had a negative US. A total of 207 patients had equivocal US with follow-up CT. A total of 144 patients went to the operating room (OR); 10 patients (7%) had negative appendectomies. One case of appendicitis was missed (<0.5%). The sensitivity, specificity, negative predictive value, and positive predictive values of our staged US-CT pathway were 99%, 91%, 99%, and 85%, respectively. A total of 228 of 680 patients (34%) had an equivocal US with no follow-up CT. Of these patients, 10 (4%) went to the OR with one negative appendectomy. A total of 218 patients (32%) were observed clinically without complications.
Analysis: As we become increasingly concerned about radiation exposure in children, it is important to have pre-defined algorithms for the evaluation of acute abdominal pain. Many sites have the following care plan:
-The patient has positive examination findings for appendicitis and has an elevated peripheral white blood cell count and CRP surgeon is consulted
-Equivocal physical examination findings or lab tests, with suspicion for appendicitis US
-Positive US for acute appendicitis surgeon is consulted with most patients going to the OR for appendectomy. If there is concern for an abscess, a CT may be requested as the surgeon may opt for interventional radiology drain placement as initial management
-US equivocal and ED physician still has a suspicion for appendicitis CT scan
Several issues arise with this type of algorithm, the most important being the operator comfort and radiologist comfort level with US evaluation. The second is the amount of time that the patient will be in the ED as this is a tiered algorithm requiring an US tech and a CT tech. However, since patients are screened based on a true need for CT scan, we are exchanging a prolonged ED course for reduced radiation exposure.
Q. Ketamine is one of the most commonly used sedatives to facilitate painful procedures for children in the emergency department. What are the risk factors that predict ketamine-associated airway and respiratory adverse events?
A. High intravenous doses, administration to children younger than 2 years or aged 13 years or older, and the use of coadministered anticholinergics or benzodiazepines.
Citation: Green S, Roback M, Krauss B etal. Predictors of Airway and Respiratory Adverse Events With Ketamine Sedation in the Emergency Department: An Individual-Patient Data Meta-analysis of 8,282 Children. Annals of Emergency Medicine.Ann Emerg Med. 2009 Aug;54(2):171-80.e1-4. Epub 2009 Jun 6
Methodology: We pooled individual-patient data from 32 ED studies and performed multiple logistic regressions to determine which clinical variables would predict airway and respiratory adverse events.
Findings: In 8,282 pediatric ketamine sedations, the overall incidence of airway and respiratory adverse events was 3.9%, with the following significant independent predictors: younger than 2 years (odds ratio [OR] 2.00; 95% confidence interval [CI] 1.47 to 2.72), aged 13 years or older (OR 2.72; 95% CI 1.97 to 3.75), high intravenous dosing (initial dose ≥2.5 mg/kg or total dose ≥5.0 mg/kg; OR 2.18; 95% CI 1.59 to 2.99), coadministered anticholinergic (OR 1.82; 95% CI 1.36 to 2.42), and coadministered benzodiazepine (OR 1.39; 95% CI 1.08 to 1.78). Variables without independent association included oropharyngeal procedures, underlying physical illness (American Society of Anesthesiologists class ≥3), and the choice of intravenous versus intramuscular route.
Analysis: This study shows that as with any other agent, the higher the dosing regimen, the more likely you are to encounter adverse events. It is interesting that the use of anticholinergic agents and benzodiazepines are listed in the risk factors associated with adverse events because many of us have been trained to administer atropine with ketamine especially for procedures involving the oropharynx. Anecdotally, while 2 studies have shown that the use of midazolam with ketamine did not change the risk of emergence reactions, I personally like to use this adjunct in children over 8 years of age. The prior studies gave the benzodiazepine after the ketamine and it made more sense to give the benzodiazepine prior to the dissociative agent. If any fellows are reading this article, here is a great research project for you. Just duplicate the previous ketamine-midazolam studies, using the reverse order of agents.