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Mx of critically severe paediatric asthma

initial management

  • oxygen to maintain SaO2 > 92%
    • use high flow intranasal oxygen if needed
  • contact senior staff ASAP and move patient to a resuscitation cubicle
  • continuous salbutamol nebulisers (0.5% undiluted) until infusions are commenced
  • nebulised ipratropium 20 minutely x 3 doses, added to salbutamol:
    • <20kg: 250 mcg nebule/dose
    • >20kg: 500 mcg nebule/dose
  • iv access x 2
  • take bloods for FBE, U&E, lactate and serial venous blood gas as needed
    • arterial blood gases are usually not needed but if intubated, then consider via arterial line
  • methylprednisolone 1 mg/kg i.v. 6-hourly
    • alternatively, can use iv hydrocortisone 4mg/kg 4-6hrly
  • portable CXR to exclude complications of asthma

inadequate response or in extremis

  • if in extremis, may need to intubate then start infusions
  • if not a tertiary paediatric hospital, contact the tertiary hospital to arrange retrieval service and transfer

start infusions

  • the following are as per RCH ICU 2008
iv salbutamol
  • use 50ml obstetric salbutamol solution (1mg/ml) undiluted
  • determine base infusion rate for 1mcg/kg/min = wt x 0.06 ml/hr
  • for those over 40kg, calculate as if 40kg1)
  • load dose is 5-10mcg/kg/min for 1 hour = 5-10 x the base infusion rate calculated above
    • many give a load dose of 5mcg/kg over 10min2) but this is nonsensical if they then advise initial maintenance infusion rate of 5mcg/kg/min, titrated to 1-10mcg/kg/min
  • maintenance rate is 1-2mcg/kg/min = 1-2 x the base infusion rate calculated above
iv aminophylline
  • use in addition to iv salbutamol, if inadequate response to iv salbutamol or child is in extremis
  • must be given in separate line to iv salbutamol (hence the 2nd iv access line)
  • set up infusion by adding 25mg/kg aminophylline to 5% dextrose to make total of 50mls = 0.5mg/kg/ml
  • if patient is NOT on aminophylline or theophylline then give a LOADING DOSE:
    • 10mg/kg (max. 500mg) over 1 hour = 20ml/hr if weight < 50kg, otherwise 500mg/(0.5mg/kg x weight in kg) ml/hr
  • maintenance aminophylline infusion:
    • age 1-9 years:
      • rate = 1.1mg/kg/hr = 2.2ml/hr if using 0.5mg/kg/ml infusion as above
    • age 10 yrs and over:
      • rate = 0.7mg/kg/hr = 1.4ml/hr if using 0.5mg/kg/ml infusion as above
iv magnesium sulphate
  • may be of benefit
  • load dose infusion 50mg/kg of magnesium sulphate infused over 20min:
    • 0.1ml/kg of 50% magnesium sulphate diluted to 20ml with 0.9% saline and infuse at 1ml/min for 20min.
  • maintenance infusion:
    • 0.12mmol/kg/hr (to max. 8mmol/hr) = 0.06ml/kg/hr (max. 4ml/hr) of 50% solution (2mmol/ml)
    • aim for target serum magnesium level of 1.5-2.5mM

consider early intubation

  • especially if poor response or becoming tired and rising PCO2:
  • experienced staff - consider calling anaesthetics to assist
  • ensure equipment and medications checked and ready as per usual rapid sequence induction
    • eg. vecuronium 0.1mg/kg every 30min or so
  • maintenance sedation
  • CXR post-intubation
  • care with ventilation (see below)
  • arterial line to monitor blood gases

suggested ventilator settings for paediatric asthma

  • the prime aims are to ensure:
    • maintenance of oxygenation SaO2 > 92%
    • maintenance of near-normal pCO2 levels 35-45 mmHg
    • minimise risk of iatrogenic pneumothorax
    • minimise risk of iatrogenic air trapping and resultant impaired venous return which may result in hypotension and pulseless electrical activity (PEA)
  • aim for prolonged expiratory phase and lower respiratory rate than normal (eg 8-12/min for adolescent)


asthma_paed_severe.txt · Last modified: 2020/01/07 13:47 (external edit)