Academic Day Seminars

ADS – Acute Asthma


Some of my notes about acute asthma management (aka status asthmaticus):

PRAM score is composed of: O2 saturation on room air, air entry, wheezing, suprasternal indrawing, scalene contractions/retractions (seen on the neck).


  • MDI are at least as effective as nebulizers
    • No difference in hospital admissions, PEF, or FEV1 at 30 minutes
    • Shorter length of stay in ED with MDIs, less tachycardia, tremors with MDIs (33 mins less)
  • Number of puffs of salbutamol is controversial/not well established in the literature
    • At BCCH: <20 kg = 5 puffs ; >20 kg = 10 puffs (salbutamol 100 mcg/puff)

Salbutamol + Ipratropium

  • Only to be used in moderate-severe exacerbations:
    • Reduces hospital admissions (not shown in mild asthma exacerbations)
  • PK: ipratropium takes a bit longer to work and may have a slightly longer duration.
  • Admin multiple fixed-doses within 60-90 mins of presentation (for mod-severe); no benefit beyond this time frame


  • Reduces acute and chronic relapse rates, hospitalizations
  • NSS change in the use of beta-2 agonists, PFTs or adverse outcomes
  • PO and IM bioavailability of dexamethasone is similar – so no real reason to use IM unless patient is NPO.
  • Dex vs Pred:
    • No diff between pred vs dex in terms of relapse and hospital admissions
      • Less vomiting with dex (both in ED & at home)
      • Only need 1-3 days (depending on length of stay, etc.) of dex vs. 5 days of pred (= ease of administration)
        • Dex t1/2 = 36-54 hrs vs. pred t1/2 = 12-36 hrs
    • Give IV formulation orally (is 4 mg/mL vs. susp which is 1 mg/mL = ease of administration)
    • Max = 16 mg/dose

Magnesium Sulfate IV:

  • Dec. hospital admissions (benefit greatest in those w/ severe acute asthma), dec overall hospital LOS, +/- improved parameters of lung function
    • Studies used MgSO4 at 1 hour of ED visit (after 3 rounds of inhaled bronchodilator)
  • 25-75 mg/kg IV over 20 mins (BCCH uses 25-50 mg/kg IV over 20 mins)
  • 100 mg (for everyone) IV over 35 mins
  • Nebulized MgSO4 has found no significant outcomes to date. On-going MagNUM study at BCCH ED


  • BCCH still uses this drug – even though its off of most of the guidelines
  • Improved lung function at 6 and 24 hrs and early symptom scores
  • No diff in PICU LOS
  • Inc emesis (RR ~2-6)
  • Monitoring:
    • 30 minutes post LD, 6 hours post start of an infusion
    • Target: 55-110 umol/L (5-15 mcg/mL)
    • Toxicity associated with emesis, diuresis, tachy, arrhythmias, seizures, sudden death

Ketamine (“special K”)

  • Stimulation CNS sympathetic outflow dec catecholamine reuptake)
  • Inc CBF
  • Hallucination, dreams
HEENT Inc IOP, nystagmus, corneal reflexes preserved
CV Myocardial depressant however CNS sympathetic outflow inc HR (20%) Inc SBP (25%)
RESP Dec RR (2-3 min), bronchodilation (direct relaxant)
GI Inc salivation
MSK Inc muscle tone
  • NSS for pulmonary index scores in rate of improvement at any time interval (0-2 hrs)
  • NSS between groups in improvement of hypoxia, tachypnea, tachycardia or BP
  • Not powered to detect diff between groups for LOS (either in ward, home or PICU)
  • No discontinuation because of ADRs
  • Children studies: no differences compared to placebo
    • Critique dosage –was it too low?
  • May be an appropriate agent to use in PICU pt who requires sedation for mech ventilation.

Salbutamol IV

  • 1 trial: Salb 15mcg/kg infusion x 10 minutes
  • Improvement of sx is questionable and challenging to generalize to our practice (since the study’s comparator was continuous neb salbutamol which is not used at BCCH ED)
  • Invasive and can cause tachycardia!

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