Guidelines to Asthma Management in the Emergency Department

Sujit Iyer, M.D.

Goals• To understand the burden of pediatric asthma in

the emergency department setting• To understand how time sensitive management

of asthma can improve symptoms faster, and at times change disposition

• To understand the basics of the asthma management pathway in our emergency department

• NOTE: Dosing and recommendations are based on current pediatric literature– regimens may vary by institution and clinical expertise

Asthma – Burden of Disease

• 8.9% of all children have asthma (6.5 million)• 3.8 million children had an asthma attack in

the last year• 12.8 million school days missed in one year

(2002-03 data)• 755,000 ED visits ANNUALLY (#3 of all causes)– 198,000 Hospitalizations (#1 of all causes)

• Estimated cost to treat annually: $3.2 billion

Risk factors – severe asthma

• ICU admissions, history of mechanical ventilation or rapid deterioration

• Seizures or syncope with exacerbations• Use of more than 2 MDI canisters a month• Poor adherence to controller therapy• Failure to perceive disease as severe

How do you assess severity in asthma?

• Combination of physical exam and historical findings

• You should be able to “report” your physical and historical findings to the attending and label your patient as : – Mild, Moderate, Severe

• Following is an example of ways to categorize. Please see asthma pathway sheet in ED also

Critical Asthmatic

• Severe wheezing (inspiratory and expiratory) OR • Absent breath sounds• Agonal respirations• Severe tachypnea (>50% of normal RR) OR

bradypnea/apnea (poor sign)• Severe retractions / Paradoxical breathings

(seesaw)• Lethargy, decreased muscle tone• Pulse OX < 92% on Room Air

Quick guide to normal RR and HR• An easy way to remember grossly normal RR

and HR:Age Respiratory Rate

< 2 months < 60 breaths/minute

2 – 12 months < 50 breaths/minute

1 -5 years < 40 breaths/minute

6 – 8 years < 30 breaths/minute

Age Heart Rate

2 – 12 months < 160 beats/minute

1 -2 years < 120 beats/minute

2 – 8 years < 110 beats/minute

What do I do?

• Inhaled beta agonists– Small Volume Nebulizers (SVN) vs. Continuous

therapy• SVN: 90% of drug lost in machine, more RT labor intensive• Continuous therapy: less RT labor intensive, child needs to

tolerate mask – preferred method for those needing repeat treatments for an extended period

– Nebulized vs. MDIs• MDIs at least AS effective if not superior• Not feasible in severe asthmatic with depressed mental

status or “too tired to breathe” Holding chambers (spacers) versus nebulisers for beta-agonist treatment of acute asthma,

Cochrane Review, 2006

What do I do?

• How much albuterol (general guide, will vary by institution)

• See pathway –moderate/severe exacerbation, start with continuous

Weight Unit dose (0.5%) Continuous

< 5 kg 1.25 mg (0.25 ml) 5 mg/hr (1ml/hr)

5-10 kg 2.5 mg (0.5 ml)_ 10 mg/hr (2ml/hr)

10-20 kg 3.75 mg (0.75 ml) 15 mg/hr (3 ml/hr)

>20 kg 5 mg (1ml) 20 mg/hr (4 ml/hr)

Bad signs

• Respiratory arrest imminent:– Drowsy, confused, altered mental status– Paradoxical breathing– Absence of wheeze

The sick asthmatic – impending respiratory arrest

• 1st: ABCS – we ALWAYS try to avoid intubation, see later difficult to manage, higher complications– May need to consider in those with apnea, asystole

• Consider subcutaneous beta-2 agonists– Terbutaline SC:

• 0.01 mg/kg per dose (0.01 mL/kg of a 1 mg/mL solution) with a maximum dose of 0.4 mg (0.4 mL)

– Epinephrine SC:• 0.01 mg/kg (0.01 mL/kg of 1:1000 solution [1 mg/mL]), with a maximum dose of 0.4 mL

(0.4 mg)• Solumedrol 2mg/kg IV (max 125 mg)• Albuterol x 3 doses (vs. continuous) plus Ipatropium • IV Magnesium Sulfate (50mg/kg, max 2 grams)• IV Terbutaline

– Bolus: 2-10 mcg/kg – Infusion: 0.08 - 0.4 mcg/kg/min (maximum 6 mcg/kg/min)

Steroids• Systemic glucocorticoids are indicated for most

children who present to the ED with acute asthma exacerbation.

• Exceptions: – children who respond promptly to a single

albuterol treatment– children with mild exacerbations– children who have not received beta 2-agonist therapy

within a few hours of presenting for medical care (who may respond to the initial dose of albuterol administered in the ED)

• The effects of systemic glucocorticoids may be noted within two to four hours of administration

Steroids• Benefits of early administration of steroids (WITHIN

ONE HOUR) shown in meta-analyses of 12 trials:– Early administration of systemic glucocorticoids reduced

admission rates (pooled odds ratio 0.40, 95% CI 0.21-0.78)– 8 patients (95% CI 5-21) would need to be treated to

prevent one admission.– Oral versus IV/IM — The NAEPP guidelines suggest that

oral administration of glucocorticoids is preferred to intravenous administration because oral administration is less invasive and the effects are equivalent

– Intramuscular/Intravenous administration of glucocorticoids may be warranted in patients who vomit orally administered glucocorticoids

Early emergency department treatment of acute asthma with systemic corticosteroids, Cochrane Review, 2001

Ipatropium Bromide (Atrovent®)

• Inhaled anticholinergic – bronchodilation through smooth muscle relaxation

• Multiple reviews, studies have shown multiple doses in combo with inhaled beta 2 agonists to:– Reduce hospital admissions– Improve lung function– And DID NOT:

• Change length of stay when hospitalized • Prevent ICU admission

Doctor, the pulse OX is low. I think the patient is getting sicker

• Why does the pulse ox in moderate asthma exacerbations PREDICTABLY go down after inhaled beta agonist treatment (transiently)?– V/Q mismatch (V = ventilation, Q = pulmonary

perfusion)– In severe asthma – lung will respond by decreasing

perfusion to poorly ventilated areas (shunt)– Beta agonists may initially worsen this mismatch by

shunting more blood flow to areas that are poorly ventilated (improving Q to areas still with poor V)

V/Q mismatch• V/Q ratio determines the adequacy of gas exchange• In normal lung (gravity affects V/Q ratio when standing),

overall V/Q of normal lung is 1 :– V/Q > 1 at apex of lung– V/Q < 1 at the base of lung

• When V/Q is < 1 THROUGHOUT the lung: hypoxemia• Perfusion of POORLY ventilated areas leads to

intrapulmonary shunting – and decreased O2 sat (hypoxemia)

• Perfusion will change faster than ventilation – so when start inhaled beta agonists will initially get more perfusion to areas not well ventilated and thus INCREASE V/Q mismatch and decrease sats!

V/Q mismatch• Diagram showing effects of decreased ventilation-perfusion

ratios on arterial oxygenation in the lungs.• Three alveolar-capillary units are illustrated. • Unit A has normal ventilation and an alveolar PO2 of 100 mm

mL/min Hg (shown by the number in the middle of the space). The blood that circulates through this unit goes from 75% (the saturation of mixed venous blood) to 99%.

• Unit B has a lower ventilation-perfusion ratio and a lower alveolar PO2 of 60 mm Hg. The blood that goes through this unit reaches a saturation of only 90%.

• Unit C is not ventilated at all. Its alveolar PO2 is equivalent to that of the venous blood, which travels through the unit unaltered.

• The oxygen saturation of the arterial blood reflects the weighted contributions of these 3 units.

• If it is assumed that each unit has the same blood flow, the arterial blood would have a saturation of only 88%. Ventilation-perfusion mismatch is the most common mechanism of arterial hypoxemia in lung disease. Supplemental oxygen increases the arterial PO2 by raising the alveolar PO2 in lung units that, like B, have a ventilation-perfusion ratio greater than zero.

• When initially given inhaled beta agonists may get increased perfusion to units that look like C and transiently have a decrease in saturation, until the ventilation in these areas improves

Adapted from Kliegman: Nelson’s Textbook of Pediatrics, 18 th Edition

Magnesium Sulfate

• Consider in those who continue to deteriorate despite beta agonists, steroid, Ipatropium– May improve clinical exam and clinical asthma

scores– Mechanism of action: smooth muscle relaxation– Side effects: hypotension – make sure adequately

hydrated.– Dose: 50-75 mg/kg IV, max 2.0 – 2.5 grams

Parental beta-2 agonists• See prior info on sc dosing in immediate therapy of severe

asthmatic• Intravenous

– For those that are poorly responsive to conventional therapy (no evidence to use at beginning of therapy)

– Mixed data on efficacy vs. inhaled alone– Side effects: dysrhythmias, hypertension, and myocardial

ischemia– Terbutaline:

• 10 microgram/kg bolus over 10 minutes• followed by 0.3 to 0.5 microgram/kg per minute• every 30 minutes the infusion may be increased by 0.5 microgram/kg

per minute to a maximum of 5 microgram/kg per minute

Nonstandard therapies

• Heliox– Mixture of helium and oxygen - ? May improve

beta agonist delivery by decreasing turbulence from lower gas density

– Can consider in those not responding to conventional therapy.

Nonconventional therapy• Intubation

– Associated with significant morbidity (barotrauma, hypotension) and DEATH

– Asthma is a disease where you can not BREATHE OUT – intubation merely pushes AIR IN (exhalation is a passive process during mechanical ventilation)

– Consider only in severe cases failing conventional therapy– Manipulation of airway can precipitate worsening bronchospasm -

>50% of all complications occur during or immediately after intubation DO NOT take this decision lightly!

– Relative indications after failure of conventional therapy:• Hypoxemia despite high concentrations of O2• Severe/Deteriorating work of breathing• Altered mental status • Respiratory or cardiac arrest

– Hypercarbia alone IS NOT AN INDICATION FOR INTUBATION. But rising CO2 despite max therapy may help guide management

Disposition

• Complex decision, based on clinical status and social factors

• Likely automatic admit: – Needs albuterol every 2-3 hours– Needing supplemental oxygen

• Things to consider– Time since last treatment (sustained improvement > 1

hour from last treatment good sign)– Should discharge on oral steroids and inhaled beta

agonists

Key Points

• Identify key risk factors and signs of severe exam findings quickly

• Inhaled beta agonists, Ipatropium, and oral/iv steroids should be considered in EVERY patient with at least a moderate exacerbation

• RE-Evaluation and escalation of therapy in the initial hours are keys to improving disposition and preventing deterioration

YOU’RE NOT DONE!

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