Acute asthma exacerbation: Difference between revisions
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==Treatment==
==Treatment==
#Albuterol
===Albuterol===
##Nebulizer
''Favor continuous nebulization to decrease the chance of admission when compared to intermittent dosing''<ref>Camargo CA et al. Continuous versus intermittent beta- agonists for acute asthma. Cochrane Database Syst Rev. 2003;(4):CD001115. PMID: 14583926.</ref>
###2.5-5mg q20min x3, then 2.5-10mg q1-4hr as needed OR
#Nebulizer
###Continuous = 0.15mg/kg/hr (max 25mg/hr)
##2.5-5mg q20min x3, then 2.5-10mg q1-4hr as needed OR
##MDI
##Continuous = 0.15mg/kg/hr (max 25mg/hr)
###4-8 puffs q20min up to 4h, then q1-4hr as needed
#MDI
#Ipratropium
##4-8 puffs q20min up to 4h, then q1-4hr as needed
##0.5mg q20min x3
===Ipratropium===
#Steroids
#0.5mg q20min x3
##Dexamethasone
===Steroids===
###As effective as prednisone especially in children <ref>Keeney, et al. Dexamethasone for Acute Asthma Exacerbations in Children: A Meta-analysis. Pediatrics. 2013-2273</ref>
Should be given in the first hour with effects to reduce admission<ref name="Rowe">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.</ref>
###0.6mg/kg IV or PO (max 16mg); 2nd dose 24hr later
#Dexamethasone
##Prednisone
##As effective as prednisone especially in children <ref>Keeney, et al. Dexamethasone for Acute Asthma Exacerbations in Children: A Meta-analysis. Pediatrics. 2013-2273</ref>
###40-60mg/day in one or two divided doses x5d
##0.6mg/kg IV or PO (max 16mg); 2nd dose 24hr later
##Methylprednisolone
#Prednisone
##40-60mg/day in one or two divided doses x5d
#Methylprednisolone
##1mg/kg IV q 4–6hr
##1mg/kg IV q 4–6hr
##Only use IV if cannot tolerate PO since equal effectiveness between dosing routes<ref>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</ref>
##Only use IV if cannot tolerate PO since equal effectiveness between dosing routes<ref>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</ref>
#Magnesium
===Magnesium===
##1-2gm IV over 30min
#1-2gm IV over 30min
##Duration of action approx 20min
#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<ref name="Rowe"></ref>
#Epinephrine
#Epinephrine
##1:1000 0.01mg/kg (max 0.5mg) subQ Q20min x 3 OR
##1:1000 0.01mg/kg (max 0.5mg) subQ or IM Q20min x 3
#Terbutaline
===Terbutaline===
*Longer-acting beta2-agonist promoting bronchodilation
##0.25mg subQ q20min x 3
##0.25mg subQ q20min x 3
##*Caution in elderly/CHF
##*Caution in elderly/CHF
#Heliox
===Heliox===
#Ketamine
*60 to 80% helium is blended with 20 to 40% oxygen
#Non-invasive Ventilation
*Heliox improves non laminar flow and may increases the diffusion of carbon dioxide by improving ventilation<ref>Kass JE: Heliox redux. Chest 2003; 123:673.</ref>
##Consider as alternative to intubation
===Ketamine===
##Alleviates muscle fatigue which leads to larger tidal volumes
*Provides bronchodilation and sedation however it does promote secretions
##Maximize inspiratory support
*Ketamine is the preferred induction agent for intubation in an asthmatic.
###Inspiratory pressure 8
*Dosing 1-2mg/kg
###PEEP 0-3
===Non-invasive Ventilation===
#Intubation
#Consider as alternative to intubation
##Consider induction w/ ketamine
#Alleviates muscle fatigue which leads to larger tidal volumes
##Ventilation of asthmatic pts requires deep sedation
#Maximize inspiratory support
###Benzos, propfol, or ketamine (1mg/kg/hr)
##Inspiratory pressure 8
##Settings
##PEEP 0-3
###Assist-control ventilation
===Intubation===
###Resp rate
#Consider induction w/ ketamine
####Start slow to avoid air-trapping
#Ventilation of asthmatic pts requires deep sedation
####RR ~ 10
##Benzos, propfol, or ketamine (1mg/kg/hr)
####Make sure plateau pressure <30
#Settings
#####If >30 must lower resp rate
##Assist-control ventilation
####May require "permissive hypoventilation"
##Resp rate
#####Low peak pressure/avoidance of breath stacking more important than correcting CO2
##Start slow to avoid air-trapping
###Tidal volume 8cc/kg ideal wt
##RR ~ 10
###PEEP 0
##Make sure plateau pressure <30
###Flow rate 80
##If >30 must lower resp rate
##Use bronchodilators even when intubated
##May require "permissive hypoventilation"
###Low peak pressure/avoidance of breath stacking more important than correcting CO2
##Tidal volume 8cc/kg ideal wt
##PEEP 0
##Flow rate 80
#Use bronchodilators even when intubated


==Disposition==
==Disposition==

Revision as of 03:09, 17 January 2015

Background

  • 3 questions
    • 1. Does this pt have asthma?
      • Most wheezing in pt <3yr is not asthma
    • 2. What is the severity?
    • 3. Is there a treatable preciptant?

Diagnosis

  • 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

Work-Up

Consider CXR if:

  1. Fever > 102.2
  2. Worsening sx
  3. Poor response to Rx
  4. 1st wheeze

Treatment

Albuterol

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

  1. Nebulizer
    1. 2.5-5mg q20min x3, then 2.5-10mg q1-4hr as needed OR
    2. Continuous = 0.15mg/kg/hr (max 25mg/hr)
  2. MDI
    1. 4-8 puffs q20min up to 4h, then q1-4hr as needed

Ipratropium

  1. 0.5mg q20min x3

Steroids

Should be given in the first hour with effects to reduce admission[2]

  1. Dexamethasone
    1. As effective as prednisone especially in children [3]
    2. 0.6mg/kg IV or PO (max 16mg); 2nd dose 24hr later
  2. Prednisone
    1. 40-60mg/day in one or two divided doses x5d
  3. Methylprednisolone
    1. 1mg/kg IV q 4–6hr
    2. Only use IV if cannot tolerate PO since equal effectiveness between dosing routes[4]

Magnesium

  1. 1-2gm IV over 30min
  2. Duration of action approx 20 min
  3. In patients with moderate to severe asthma there is a decreased rate of admission with an NNT of 2[2]
  4. Epinephrine
    1. 1:1000 0.01mg/kg (max 0.5mg) subQ or IM Q20min x 3

Terbutaline

  • Longer-acting beta2-agonist promoting bronchodilation
    1. 0.25mg subQ q20min x 3
      • Caution in elderly/CHF

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[5]

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

Non-invasive Ventilation

  1. Consider as alternative to intubation
  2. Alleviates muscle fatigue which leads to larger tidal volumes
  3. Maximize inspiratory support
    1. Inspiratory pressure 8
    2. PEEP 0-3

Intubation

  1. Consider induction w/ ketamine
  2. Ventilation of asthmatic pts requires deep sedation
    1. Benzos, propfol, or ketamine (1mg/kg/hr)
  3. Settings
    1. Assist-control ventilation
    2. Resp rate
    3. Start slow to avoid air-trapping
    4. RR ~ 10
    5. Make sure plateau pressure <30
    6. If >30 must lower resp rate
    7. May require "permissive hypoventilation"
      1. Low peak pressure/avoidance of breath stacking more important than correcting CO2
    8. Tidal volume 8cc/kg ideal wt
    9. PEEP 0
    10. Flow rate 80
  4. Use bronchodilators even when intubated

Disposition

  • A short course of glucocorticoids (prednisone in adults or dexamethasone in children (0.6mg/kg) decreases change of relapse [6]
  • Although classically disposition is based on peak flow measurements such results are often not available in the ED
    • Predicted = (30 x age (yrs)) + 30
    • Discharge if symptoms resolved and PEF >70% predicted
    • Admit if symptoms persist and PEF <40% predicted
    • Discharge versus admit based on physician judgment if some symptoms persist and adequate home support

See Also

Ventilator Desaturation

Source

  1. ↑ Camargo CA et al. Continuous versus intermittent beta- agonists for acute asthma. Cochrane Database Syst Rev. 2003;(4):CD001115. PMID: 14583926.
  2. ↑ 2.0 2.1 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.
  3. ↑ Keeney, et al. Dexamethasone for Acute Asthma Exacerbations in Children: A Meta-analysis. Pediatrics. 2013-2273
  4. ↑ 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
  5. ↑ Kass JE: Heliox redux. Chest 2003; 123:673.
  6. ↑ 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
  • Rosen's - Asthma
  • EMcrit Podcast 15
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