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I have completed bits of my EM training from India. Currently I am boarded with credentials from Christian Medical College, Vellore and also from the prestigious Royal College of Emergency Medicine, UK.  I am currently working in London as an A&E doctor, trying to appreciate the differences in the practise and culture of Emergency Medicine across different healthcare systems. I have always been an avid FOAMed supporter because FOAMed played an indispensable role during the days of my initial training. Through this blog, I aspire to disseminate knowledge and stay up to date with the EM literature. 

Monday, January 15, 2018

The "qRBBB" pattern

Presence of qRBBB in the setting of acute coronary syndrome signifies proximal occlusion of left descending coronary artery with compromise of circulation in the septal arteries supplying the bundle branches. Anterior STEMi with RBBB is associated with a higher risk of death when compared with that of patients with normal conduction. 

qRBBB with LAFBInstead of the rSR pattern (seen in RBBB), there is qRBBB pattern in V1 because the initial r wave has been knocked off by anterior wall myocardial infarction. 


Due to anterior location of the right ventricle than that of the left ventricle, activation of the right ventricular free wall can neutralize the abnormal septal forces associated with an anteroseptal MI. Therefore, in most patients with an anteroseptal infarction, abnormal Q waves in right precordial leads is mostly manifest during RBBB showing the classical qRBBB pattern, due to delayed activation of the right ventricle. 






Understanding RBBB

RBBB causes delayed depolarisation of right Ventricle as depolarisation spreads across the septum (instead of the Right Bundle) taking longer than usual. This produces characteristic ECG changes described below in the diagnostic criteria. Left Ventricle depolarisation remains normal i.e normal early part of QRS complex. 




Diagnostic Criteria 

  • Broad QRS > 120 ms
  • RSR’ pattern in V1-3 (‘M-shaped’ QRS complex) or a broad monophonic r wave or a qR complex
  • Wide, slurred S wave in the lateral leads (I, aVL, V5-6
  • Delayed intrinsicoid deflection time 


RBBB (Image from LIFTL)
RBBB often shows STD and TWI in V1-3 due to secondary depolarisation abnormalities 

Causes
  • Ischemic Heat Disease
  • Acute Pulmonary HTN (PE)
  • Chronic Pulmonary HTN (Cor Pulmonale)
  • Valvular Heart Disease
  • Myocarditis
  • Degenerative Diseases of conduction system
  • Congenital Heart Disease
  • Overdose of Na Channel Blockers
  • Idiopathic
  • Transient and Rate Related 

RBBB should NOT have any ST Elevation. Look for the qRBBB pattern and RBBB with LAFB (Leftward Axis, qR in lead I, aVL, rS in lead III) pattern. 

qRBBB in V1-4 with STE (Image from TheECGinAcuteMI)
Take Home:
  • Remember the qRBBB pattern morphology
  • RBBB should never have any ST elevation 
  • When in doubt, do serial ECGs and screening bedside ECHO to look for RWMA

References and Further Reading:
  1. Mishra, V., Sinha, S. K., & Razi, M. (2016). Right Bundle Branch Block: A Masquerader in Acute Coronary Syndrome. North American Journal of Medical Sciences8(2), 121–122. http://doi.org/10.4103/1947-2714.177347
  2. 2. Widimsky P, Rohác F, Stásek J, Kala P, Rokyta R, Kuzmanov B, et al. Primary angioplasty in acute myocardial infarction with right bundle branch block: Should new onset right bundle branch block be added to future guidelines as an indication for reperfusion therapy? Eur Heart J. 2012;33:86–95.
  3. Ganesan S, Kannan K, Victor A, Selvan KT, Arun R, Majella JC, Kumar RS, Aravind A, Viswanathan N, District V. QRBBB in acute coronary syndrome: Does it matter in modern era? Angiographic correlation. Indian Heart Journal. 2015 Dec 1;67:S38.
  4. Wong CK, Stewart RA, Gao W, French JK, Raffel C, White HD. Prognostic differences between different types of bundle branch block during the early phase of acute myocardial infarction: Insights from the Hirulog and Early Reperfusion or Occlusion (HERO)-2 trial. Eur Heart J. 2006;27:21–8. 
  5. http://hqmeded-ecg.blogspot.co.uk/2010/01/right-bundle-branch-block-with-subtle.html
  6. http://hqmeded-ecg.blogspot.co.uk/2017/04/rbbb-with-transient-st-elevation.html
  7. http://hqmeded-ecg.blogspot.co.uk/2010/11/wide-complex-tachycardia-its-really.html
  8. http://hqmeded-ecg.blogspot.co.uk/2014/03/elderly-woman-in-shock-ekg-from.html
  9. https://emcrit.org/wp-content/uploads/2015/03/Who-to-PCI-by-Smith-and-Weingart.pdf
  10. https://lifeinthefastlane.com/ecg-library/basics/right-bundle-branch-block/

Posted by:

              
     Lakshay Chanana
     
     Speciality Doctor
     Northwick Park Hospital
     Department of Emergency Medicine
     England

     @EMDidactic

Monday, January 8, 2018

Croup - Laryngotracheobronchitis

Viral Laryngotracheobronchitis (Croup) is the most common cause of stridor commonly affecting children between 6 months to 6 years old, with a peak in the fall and early winter months. Croup is acquired through inhalation of the virus. 

Possible agents could be parainfluenza virus (most common), rhinovirus. enterovirus, respiratory syncytial virus, influenza virus and human metapneumovirus.


Clinical Presentation 
Typically, symptoms begin after 1 to 3 days of URTI symptoms (nasal congestion, rhinorrhea, cough, and low-grade fever). Classic symptoms include a harsh barking cough, hoarse voice, and stridor. Symptoms often tend to be worse at night and the severity of symptoms is related to the amount of edema and inflammation of the airway. 


Diagnosis and Assessment of Severity 
Look for tachypnea, stridor at rest, nasal flaring, retractions, lethargy or agitation, and oxygen desaturation. Symptoms are most severe on 3rd or 4th day of illness. Agitation and crying increase oxygen demand and may worsen airway compromise. Bloods and imaging are only required in children who fail to respond to conventional therapy. X Rays may demonstrate “steeple sign” (subglottic narrowing)


Steeple Sign
Croup is a clinical diagnosis
Steeple sign may be present in normal children and can be absent in up to half of those with croup






















Management 
Treatment is directed at decreasing airway obstruction and keeping the child comfortable 
  • CorticosteroidsAll patients with croup get steroids as a one- time dose (PO/IM/IV). Steroids reduce the severity and duration of symptoms and result in a decrease in return visits and hospital length of stay. The long half-life of dexamethasone (36-54 h) often allows for a single injection. Studies have shown that dexamethasone dosed at 0.15 mg/kg is as effective as 0.3 mg/kg or 0.6 mg/kg (with a maximum daily dose of 10 mg). Effects can be seen within 1 hour of oral administration. Nebulized budesonide 2 mg as a single dose and IM dexamethasone (0.6mg/kg) are alternatives to PO dexamethasone in children who are vomiting.
Treatment of croup: Nebulized epinephrine for moderate to severe croup and corticosteroids for all



  • EpinephrineEpinephrine comes as two different forms: racemic, which is composed of equal parts of L- and D-isomers, and L-epinephrine, which is the drug routinely used in acute situations in concentrations of 1:1000 and 1:10,000. 
  • L-Epinephrine (1:1000): 0.5 ml/kg neb or 5ml maximum  
  • Racemic Epinephrine (2.25%): 0.05ml/kg neb or max 0.5ml
Mild croup generally does not require epinephrine. For those with moderate or severe croup who receive nebulized epinephrine, observe in the ED for at least 3 hours before considering discharge. Epinephrine decreases airway edema through vasoconstrictive alpha effects and acts wishing 10-min lasting up to 2 hours. The use of Adrenaline decreases the number of children with croup requiring intubation, ITU admissions, and admission to the hospital. 

Observation for about 3 hours is recommended because an increase in croup scores can occur between doses of epinephrine nebulisation

  • Intubation is reserved for cases of severe croup not responding to medical treatment. When intubation is necessary, use endotracheal tubes smaller than recommended for patient size and age to avoid traumatizing the inflamed mucosa. 

Treatment options with limited evidence: 
  • Cool Mist: Humidified air was used to treat croup, but they are no longer recommended as studies have consistently failed to show clinical improvement with these interventions.
  • Heliox (70% helium/30% oxygen): Despite its theoretical benefits, studies show no definitive advantage of heliox over conventional treatment.24-28
  • Beta 2 Agonists: Insufficient data. Concerns about risk of worsening upper airway obstruction as β-receptors on the vasculature cause vasodilation (as compared to the vasoconstrictive α effects of epinephrine), which might worsen upper airway edema in croup, and there is no smooth muscle in the upper airway. Therefore, β-agonists are not recommended for treatment of croup.
  • Antibiotics have no role in uncomplicated croup 
  • Antitussives have no proven effect on the course or severity of croup and may increase sedation


Differential Diagnosis (Consider if no relief with Rx)
  • Bacterial tracheitis
  • Laryngomalacia
  • Tracheomalacia
  • Vascular rings
  • Epiglottitis (unlikely if vaccinated)
  • Foreign body aspiration
  • Peritonsillar abscess
  • Retropharyngeal abscess
  • Tracheo-esophageal fistula

Admit 
  • Moderate to Severe Croup
  • Looking toxic and not tolerating oral fluids
  • Comorbidities 
  • Social Issues
  • Persistent stridor at rest, tachypnea, retractions, and hypoxia

Discharge Advice 

  • Advise the parents/carers to use either paracetamol or ibuprofen to treat a child who is distressed due to fever. 
  • Encourage the child to take fluids regularly.
  • To check on the child regularly, including through the night.

References and Further Reading :
  1. https://cks.nice.org.uk/croup#!scenario
  2. http://www.ebmedicine.net/topics.php?paction=showTopic&topic_id=334
  3. Russell KF, Liang Y, O’Gorman K, Johnson DW, Klassen TP. Glucocorticoids for croup. Cochrane Database of Systematic Reviews 2011, Issue 1. Art. No.: CD001955.
  4. Johnson DW. Croup. BMJ Clin Evid. 2009; 2009: 0321.
  5. Bjornson, C.L. and and Johnson, D.W. (2013)  Croup in children. CMAJ. 185(15), 1317-1323

    Posted by:

                  
         Lakshay Chanana
         
         Speciality Doctor
         Northwick Park Hospital
         Department of Emergency Medicine
         England

         @EMDidactic