Acute asthma exacerbation: Difference between revisions

No edit summary
No edit summary
Line 3: Line 3:
*Quickly establish severity of current presentation and history of severe exacerbations (e.g. need for ICU, intubation, etc)
*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)
*Identify any treatable precipitant (e.g. PNA, URI, GERD, esposure to irritants)
*Status asthmaticus is a life-threatening form of asthma in which progressively
*Status asthmaticus is a life-threatening form of asthma in which progressively worsening reactive airways are unresponsive to usual appropriate therapy that leads to pulmonary insufficiency.  
worsening reactive airways are unresponsive to usual appropriate therapy that leads
to pulmonary insufficiency.  


==Clinical Features==
==Clinical Features==

Revision as of 19:45, 3 June 2016

Background

  • Need to establish history of asthma or reactive airway disease (most wheezing in pts <3 y/o is not asthma)
  • 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)
  • Status asthmaticus is a life-threatening form of asthma in which progressively worsening reactive airways are unresponsive to usual appropriate therapy that leads to pulmonary insufficiency.

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

Consider CXR if:

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

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 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]
    • Single dose dexamethasone may be equally effective to 5 days of prednisone in adults[5]
    • 0.6mg/kg IV or PO (max 16mg); 2nd dose 24hr later
  • 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

  • 1-2gm IV over 30min
  • 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 0.5mg) subQ or IM Q20min x 3

Terbutaline

  • Longer-acting beta2-agonist promoting bronchodilation
  • 0.25mg subQ/IM q20min x 3
  • Caution in elderly/CHF

Non-invasive ventilation

  • Consider as alternative to intubation
  • Alleviates muscle fatigue which leads to larger tidal volumes
  • May drive nebulized treatments deeper into airways
  • Maximize inspiratory support
    • Inspiratory pressure 8
    • PEEP 0-3, only enough to match patient's auto-PEEP

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 pts requires deep sedation
  • Ventilation settings
    • Assist-control ventilation
    • Resp rate
      • Start slow to avoid air-trapping
      • RR ~ 8-10 in adults
    • Make sure plateau pressure <30
    • If >30 must lower resp rate
    • May require "permissive hypoventilation"
      • Low peak pressure/avoidance of breath stacking more important than correcting CO2 [8]
    • Tidal volume 6-8cc/kg ideal wt
    • PEEP 0
    • Flow rate 80-100L/min
    • Keep FiO2 minimum to achieve SpO2 > 90%
  • Use bronchodilators even when intubated

Asthma Arrest

  • Disconnect ventilator
  • Decompress chest
  • Consider bilateral chest tubes
  • Fluid bolus

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
    • Often, pts 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. ↑ Rehrer MW et al. A randomized controlled noninferiority trial of single dose of oral dexamethasone versus 5 days of oral prednisone in acute adult asthma. Ann Emerg Med 2016 Apr 22.
  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
Retrieved from "https://www.wikem.org/w/index.php?title=Acute_asthma_exacerbation&oldid=73545"