Acute asthma exacerbation (peds)

For adult patients see Asthma

Background

  • An estimated 6 million children in the US have asthma
  • In 2007, asthma lead to >700,000 ED visits
  • Asthma is part of the atopy triad (asthma, allergies, eczema)
  • A history of eczema or allergies maybe helpful in making a new diagnosis of asthma
  • Wheezing in an infant is more often bronchiolitis than asthma
  • Viral URI associated with copious rhinorrea, allergen exposure, and respiratory irritants (i.e. smoke) are common precipitants for pediatric asthma exacerbations

Clinical Features

  • Wheezing
  • Cough
  • Accessory muscle use
  • Dyspnea
  • Prolonged expiration
  • Severity of retractions occurs in caudal to cephalad direction
    • Scalene muscle contractions more severe than subcostal and intercostal retractions
  • Sign of impending ventilatory failure
    • Paradoxical respiration
      • Chest deflation and abdominal protrusion during inspiration
    • Altered mental status
    • "Silent chest"

Differential Diagnosis

Pediatric Wheezing

Evaluation

  • Clinical diagnosis
  • Can consider a blood gas if there are fears that the patient is getting tired (sleepy baby vs elevated CO2?)
    • A CO2 >45 is abnormal in a patient hyperventilating and warrants close monitoring

Consider CXR

  • 1st wheezing episode
  • Asymmetric lung auscultation findings, after treatment with albuterol
  • Poor response to medications/treatment, if history and exam are not consistent with bronchiolitis
  • Worsening symptoms
  • Fever not explained by apparent viral illness

Clinical Scores

  • 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)

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
    • Intermittent: 2.5-5mg q20min, three doses are traditionally given back to back, then repeat as needed.
    • Continuous: 0.5mg/kg/hr (max 15mg/hr)[2]
  • MDI
    • 4-8 puffs q20min given in first hour, then q1-4hr as needed

Ipratropium

  • 0.25-0.5mg q20min, given with the first three doses of albuterol, it is shown to reduce admission.

Steroids

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

  • Dexamethasone
    • 0.6mg/kg PO or IV (max 16mg); consider 2nd dose 24-36hrs later.
      • PO and IV have equal efficacy. Giving the IV form by mouth is typically better tolerated by young children (same dosing)
    • Both 1 and 2 dose regimens as effective as prednisone or prednisolone in children [4][5]
  • Prednisone
    • 1-2mg/kg/day (60mg max) in one or two divided doses for 3-5 days
  • Methylprednisolone
    • 1mg/kg IV q 4–6hr
    • Only use IV if cannot tolerate PO since equal effectiveness between dosing routes[6]

Magnesium

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

Beta-agonist

  • Epinephrine
    • 1:1000 0.01mg/kg (max 0.3mg) IM, repeat as needed
  • Terbutaline
    • Given SQ, usual dose 0.01mg/kg up to 0.3mg.
    • Longer-acting beta2-agonist promoting bronchodilation

Assisted Ventilation

  • Non-invasive ventilation
    • Consider as alternative to intubation
    • Alleviates muscle fatigue which leads to larger tidal volumes
    • Maximize inspiratory support
      • Delta pressure 10
      • PEEP >4
    • May benefit from ketamine or dexmedetomidine to mildly sedate and allow the interface

Intubation

  • Push pull (bolus) fluids prior to intubation to maximize the patient's preload and ideally decrease the chance of the patient arresting
  • 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 1-2 mg/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
    • Plateau pressure ideally <30
    • May require "permissive hypoventilation" and permissive hypercarbia and acidosis
      • Low peak pressure/avoidance of breath stacking more important than correcting CO2 [7]
    • Tidal volume 6-8cc/kg ideal wt
    • PEEP >4
    • Flow rate 80-100L/min
    • Keep FiO2 minimum to achieve SpO2 > 90%
  • Use bronchodilators even when intubated
  • Many patients require a continuous paralytic infusion for the first 24+ hrs of intubation

Outpatient Treatment

Severity Day Sx Night Sx Treatment (WHO 2008 Formulary)[8]
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 AND

Beclometasone 100-250 mcg BID

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

Beclometasone 100-500 mcg BID AND

Salmeterol inhaled 50 mcg BID

Severe persistent, < 60% peak flow Continuous daily Frequent Albuterol MDI 100-200 mcg PRN QID AND

Beclometasone 1mg BID (high dose) AND

Salmeterol inhaled 50 mcg BID AND

theophylline, leukotriene antagonist, or PO prednisolone with taper

Disposition

  • Discharge
    • Often, patients will still have mild wheezing, but should have complete resolution of tachypnea, hypoxia, and improved work of breathing
    • A short course of glucocorticoids decreases chance of relapse [9])
    • Patient should generally continue albuterol at home q6hrs for at least the first 24hrs after discharge
    • A spacer should be prescribed to be used with the MDI to improve medication delivery to the lungs
  • Admit
    • If symptoms do not significantly improve or for severe exacerbations
  • Peak flow measurements maybe helpful when deciding disposition
    • 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. Cronin et al. "A Randomized Trial of Single-Dose Oral Dexamethasone Versus Multidose Prednisolone for Acute Exacerbations of Asthma in Children Who Attend the Emergency Department." Annals of EM. May 2016. 67(5):593-601
  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. Darioli, et al. Mechanical Controlled hypoventilation in status asthmaticus. Am Rev Respir Dis. 1984; 129 (3) 385-7
  8. Stuart MC et al. WHO Model Formulary 2008. http://www.who.int/selection_medicines/list/WMF2008.pdf.
  9. 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