Acute asthma exacerbation (peds)

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Background

  • One of the most common complaints that brings patients to pediatric ER
  • Need to establish history of asthma or reactive airway disease
  • Quickly establish severity of current presentation and history of severe exacerbations (e.g. need for ICU, intubation, etc)
  • Identify any treatable precipitant (e.g. PNA, URI, GERD, esposure to irritants)

Clinical Features

  • Dyspnea, wheezing, and cough
  • Prolonged expiration
  • Accessory muscle use
  • Sign of impending ventilatory failure
    • Paradoxical respiration
      • Chest deflation and abdominal protrusion during inspriation
    • Altered mental status
    • "Silent chest"

Differential Diagnosis

Acute dyspnea

Emergent

Non-Emergent

Diagnosis

  • Clinical diagnosis
  • Diagnosis and treatment can be guided by clinical scores
    • Modified Pulmonary Index Score (MPIS - Utilized at CCMC)
    • Pediatric Asthma Score (PAS)
    • Pulmonary Score (PS)
    • Pediatric Respiratory Assessment Measure (PRAM)

Consider CXR if

  • Fever > 102.2
  • Worsening symptoms
  • Poor response to medications/treatment
  • 1st wheeze
  • Chest pain

Modified Pulmonary Index Score (MPIS)

Age <3 Years
Points SpO2 Acces Musc Use I:E Wheeze HR RR
0 >95% None 2:1 None; Good Aeration ≤120 ≤30
1 93-95% Mild 1:1 End Exp 121-140 31-45
2 90-92% Moderate 1:2 Insp/Exp; Good Aeration 141-160 46-60
3 <90% Severe 1:3 Insp/Exp; Poor Aeration >160 >60
Age 3-6 Years
Points SpO2 Acces Musc Use I:E Wheeze HR RR
0 >95% None 2:1 None; Good Aeration ≤100 ≤30
1 93-95% Mild 1:1 End Exp 101-120 31-45
2 90-92% Moderate 1:2 Insp/Exp; Good Aeration 121-140 46-60
3 <90% Severe 1:3 Insp/Exp; Poor Aeration >140 >60
Age ≥6 Years
Points SpO2 Acces Musc Use I:E Wheeze HR RR
0 >95% None 2:1 None; Good Aeration ≤100 ≤20
1 93-95% Mild 1:1 End Exp 101-120 21-35
2 90-92% Moderate 1:2 Insp/Exp; Good Aeration 121-140 36-50
3 <90% Severe 1:3 Insp/Exp; Poor Aeration >140 >50
  • MPIS <7 - Mild exacerbation
  • MPIS 7-10 - Moderate exacerbation
  • MPIS ≥10 - Severe exacerbation

Management

Albuterol

Favor continuous nebulization to decrease the chance of admission when compared to intermittent dosing[1]

  • Nebulizer
    • Intermitent: 2.5-5mg q20min x3, then 2.5-10mg q1-4hr as needed OR
    • Continuous: 0.5 mg/kg/hr (max 15mg/hr)[2]
    • If child using intermitent nebs at home PTA, start on continuous
  • MDI
    • 4-8 puffs q20min up to 4h, then q1-4hr as needed

Ipratropium

  • 0.5mg q20min x3

Steroids

Should be given in the first hour with effects to reduce admission[3]

  • Dexamethasone
    • As effective as prednisone especially in children [4]
    • Study found only applicable in mild/moderate exacerbations[5]
    • 0.6mg/kg IV or PO (max 16mg); 2nd dose 24hr later. PO and IV have equal efficacy
  • Prednisone
    • 40-60mg/day in one or two divided doses x5d
  • Methylprednisolone
    • 1mg/kg IV q 4–6hr
    • Only use IV if cannot tolerate PO since equal effectiveness between dosing routes[6]

Magnesium

  • Smooth muscle relaxant
  • Dose: 50 mg/kg IV, max 2-4 g
  • Duration of action approx 20 min
  • In patients with moderate to severe asthma there is a decreased rate of admission with an NNT of 2[3]

Parenteral beta-agnonist

Epinephrine

  • 1:1000 0.01mg/kg (max 0.3mg) IM Q20min x 3

Terbutaline

  • Longer-acting beta2-agonist promoting bronchodilation
  • Given SQ, usual dose 0.01 mg/kg up to 0.3 mg.

Non-invasive ventilation

  • Consider as alternative to intubation
  • Alleviates muscle fatigue which leads to larger tidal volumes
  • Maximize inspiratory support
    • Inspiratory pressure 10
    • PEEP 0-5

Heliox

  • 60 to 80% helium is blended with 20 to 40% oxygen
  • Heliox improves non laminar flow and may increases the diffusion of carbon dioxide by improving ventilation[7]

Intubation

  • Consider induction with Ketamine
    • Provides bronchodilation and sedation however it does promote secretions
    • Ketamine is the preferred induction agent for intubation in an asthmatic.
    • Dosing 1-2mg/kg
  • Ventilation of asthmatic patients requires deep sedation
  • Ventilation settings
    • Assist-control ventilation
    • Resp rate
      • Start slow to avoid air-trapping and allow for longer expiration time
      • Consider I:E ratio of 1:2 or 1:3
    • Make sure plateau pressure <30
    • May require "permissive hypoventilation" and permissive hypercarbia and acidosis
      • Low peak pressure/avoidance of breath stacking more important than correcting CO2 [8]
    • Tidal volume 6-8cc/kg ideal wt
    • PEEP 0-5
    • Flow rate 80-100L/min
    • Keep FiO2 minimum to achieve SpO2 > 90%
  • Use bronchodilators even when intubated

Outpatient Treatment

Severity Day Sx Night Sx Treatment (WHO 2008 Formulary)[9]
Mild intermittent, > 80% peak flow < 2/wk < 2/mo Albuterol MDI 100-200 mcg prn qid
Mild persistent, > 80% peak flow >2/wk >2/mo Albuterol MDI 100-200 mcg prn qid

PLUS Beclometasone 100-250 mcg bid

Moderate persistent, 60-80% peak flow Daily with exacerbations weekly > 1/wk Albuterol MDI 100-200 mcg prn qid

PLUS Beclometasone 100-500 mcg bid

PLUS Salmeterol inhaled 50 mcg bid

Severe persistent, < 60% peak flow Continuous daily Frequent Albuterol MDI 100-200 mcg prn qid

PLUS Beclometasone 1 mg bid (high dose)

PLUS Salmeterol inhaled 50 mcg bid

PLUS (if needed) SR theophylline, leukotriene antagonist, or PO prednisolone with taper

Disposition

  • Discharge - if symptoms resolve, remember patient will often have decreased O2 saturations after treatment due to V/Q mismatch, look for resolution of symptoms and subjective improvement.
    • Often, patients will still have mild wheezing, but should have complete resolution of tachypnea, hypoxia, and work of breathing if being discharged
      • Discharge versus admit based on physician judgment if some symptoms persist and adequate home support
    • A short course of glucocorticoids (prednisone in adults or dexamethasone in children (0.6mg/kg) decreases change of relapse [10])
  • Admit - if symptoms persist or are severe
  • Classically disposition is based on peak flow measurements, such results are often not available in the ED
    • Predicted = (30 x age (yrs)) + 30
    • PEF >70% predicted → high likelihood of successful discharge
    • PEF <40% predicted → should be admitted

See Also

External Links

References

  1. ↑ Camargo CA et al. Continuous versus intermittent beta- agonists for acute asthma. Cochrane Database Syst Rev. 2003;(4):CD001115. PMID: 14583926.
  2. ↑ National Asthma Education and Prevention Program (NAEPP), “Expert Panel Report 3 (EPR-3): Guidelines for the Diagnosis and Management of Asthma,” Clinical Practice Guidelines, National Institutes of Health, National Heart, Lung, and Blood Institute, NIH Publication No. 08-4051, prepublication 2007; available at http://www.nhlbi.nih.gov/guidelines/asthma/asthgdln.htm.
  3. ↑ 3.0 3.1 Rowe BH et al. Magnesium sulfate for treating exac- erbations of acute asthma in the emergency depart- ment. Cochrane Database Syst Rev. 2000;(2):CD001490. PMID: 10796650.
  4. ↑ Keeney, et al. Dexamethasone for Acute Asthma Exacerbations in Children: A Meta-analysis. Pediatrics. 2013-2273
  5. ↑ Keeney, et al. Dexamethasone for Acute Asthma Exacerbations in Children: A Meta-analysis. Pediatrics. 2013-227
  6. ↑ Rowe BH, Keller JL, Oxman AD. Effectiveness of steroid therapy in acute exacerbations of asthma: a meta-analysis. Am J Emerg Med. Jul 1992;10(4):301-10
  7. ↑ Kass JE: Heliox redux. Chest 2003; 123:673.
  8. ↑ Darioli, et al. Mechanical Controlled hypoventilation in status asthmaticus. Am Rev Respir Dis. 1984; 129 (3) 385-7
  9. ↑ Stuart MC et al. WHO Model Formulary 2008. http://www.who.int/selection_medicines/list/WMF2008.pdf.
  10. ↑ Chapman K. Effect of a short course of prednisone in the prevention of early relapse after the emergency room treatment of acute asthma. NEJM. 1991;324(12):788
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