Summary of asthma treatments

November 25th, 2009
by reuben in asthma

Excerpted from MSSM M&M teaching points:

* The mainstay of treatment for severe asthma is nebulized albuterol; the initial dose is 5 mg (note this is two bullet packs) x 3 for moderate to severe asthma and continuous nebulized albuterol for life-threatening asthma. Dosing for pediatrics varies, but an easy and reasonable approach is to give half dose for small children (2.5 mg) and full dose for larger children. The important thing is to make lots of smoke.

* For severe asthma, anticholinergic therapy should be added to ?2 agonists, the conventional dose is 500 mcg ipratropium bromide (Atrovent), given with the first three albuterol treatments in both adults and children.

* Corticosteroids should also be administered to all patients suffering a significant asthma exacerbation. Accepted dosing is 100-200 mg IV methylprednisolone per day or 40-60 oral prednisone per day. Pediatric dosing varies, but a dose of 1 mg/kg for both preparations is often used.

* In cases of severe asthma, it is not necessary to push oxygen saturation above 90-92%.

* In cases of severe asthma, data supports the use of intravenous magnesium. The dose is 2 g in adults and 50 mg/kg in children, infused over 20 minutes. Magnesium does not benefit patients with mild or moderate asthma.

* In cases of life-threatening asthma, consider subcutaneous or intramuscular epinephrine, especially in younger patients with good hearts. The dose is .3-.5 mg of the 1:1000 preparation (1 mg/mL). Pediatrics dose is .01 mg/kg.

* Non-invasive ventilation is of proven benefit in severe asthma, in a patient who can cooperate. Initial settings should an EPAP/CPAP/PEEP of 5 cm water; if BiPAP is used, initial IPAP should be 8 cm water. Improved results are noted if the patient is allowed to hold the unstrapped mask to her face at first, before strapping down the mask. Note that nebulized albuterol therapy must continue.

* In cases of life-threatening asthma, consider delivering a helium-oxygen mixture, which may improve air and medication delivery in very severe asthma exacerbations. Heliox is available at both MSSM and EHC through respiratory therapy. The preferred mixture is 80% helium, 20% oxygen.

* Data is conflicting, but case reports suggest that high dose ketamine may prevent intubation in severe asthma. The dose used in one pair of successful cases was 2 mg/kg bolus followed by an infusion of 2 mg/kg/hour, titrated as needed.

* Intubation of the asthmatic is a last resort. If necessary, maximize expiratory time by using small tidal volumes (6 ml/kg), rate of 8-10 per minute, with a high flow rate of 80-100L/min in a square waveform, which corresponds to a I:E time of 1:4 to 1:6. Ketamine (2 mg/kg) should be used for induction of the asthmatic for intubation.

* If an intubated asthmatic suddenly deteriorates, disconnect the ventilator and consider manually decompressing the chest (pushing down to assist with expiration). Consider tube displacement and obstruction (e.g. with mucus), and consider tube or needle thoracostomy for pneumothorax.

* Aminophylline does not appear to confer additional benefit over appropriately-dosed albuterol therapy in the emergency department.

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