Asthma Exacerbations

Gil C. Grimes, MD2008-4-17

Family Medicine

Objectives Discuss triggers Describe generalized approach to

asthma exacerbation Understand initial medical approach Understand the role of steroids Understand the role of supplemental

medications

Asthma Triggers Allergens

Dust, dander, molds, grass pollens, tree pollen

Synergy with respiratory viruses 26 % of those admitted had respiratory

virus 66% sensitized to mite or animal dander BMJ 2002:30;324:763

Asthma Triggers Air pollutants

Ozone, sulfur dioxide, cigarette smoke Cohort study asthmatic children showed

association between exacerbation and nitrogen dioxide (lancet 2003 7;36:1939)

Ozone exposure increase rescue med use in moderate pediatric asthmatics (JAMA 2003 290;14:1859)

Asthma Triggers Respiratory infections

#1 cause in young children Seasonal viral infection can increase IgE and

eosinophils (Arch Int Med 1998 158;22:2453) Rhinovirus increases LRT complications in

asthmatics (Lancet 2002 Mar9;359:831) RSV bronchiolitis in child <12 months risk

factor for later asthma 11 of 47 at 3 years with RSV 1 of 93 at 3 years without RSV Pediatrics 1995 April;95(4):500

Consider atypical bacteria (10% of admitted peds)

Asthma Triggers Miscellaneous

GERD Perfume Sulfites Exercise Emotion (laughing or crying) Foods (shellfish, chocolate, nuts)

The case 38 year old female with asthma who has

been wheezing since being at a party earlier that evening. Thought she was having an allergic reaction and gave herself Epinephrine which helped for a while. She has been treating with her MDI for the last two hours without improvement (16 or more puffs).

PMH: Asthma, allergies prior tobacco Meds: Azmacort, Singulair, Zyrtec,

Albuterol O: 134/58 P104, AF, R28 Sat 90% (RA)

Approach to the patient What do you do first? What is you first medication? How long will you do this prior to

changing? How will you monitor for change?

Initial approach Precipitating Factors

Chest pain Sputum production Fever

Just like prior attacks? Have you taken steroids? What has worked in the past? Have you ever been intubated? What are your medications?

Evaluation Physical Severe

Tachycardia Tachypnea Accessory muscle use Retractions Flaring in infants Ability feed in infants Inability to recline PEFR <50% of best

Evaluation Physical Life Threatening

Cyanosis Silent chest Fatigue Inability to speak Decreased level of consciousness PEFR <33% of best

Vitals Pulse oximetry Radiograph

Pneumothorax Pneumomediastinum Pneumonia Poor response to therapy

Laboratory Testing ABG

Not terribly predictive Stage I respiratory alkalosis decreased

PCO2 Stage II alkalosis and hypoxia Stage III fatigue CO2 rises (repeat if PCO2

>30) Stage IV respiratory failure elevated

PCO2 correlates with PEFR <200L/min

Mortality risks Higher in adults

Status most common cause of death asthmatics

Decreased FEV1, advanced age, h/o tobacco use

Eosinophilia increases mortality 7.4x Increased FEV1>50% after

bronchodilator increases mortality risk 7x

Clinical Calculators Pediatric Calculator Asthma Score (0-10 points)

Respiratory rate 40-60 (1 pts) >60 (2 pts) Wheezing via stethoscope expiratory (1pt)

inspiratory & expiratory (2pts) Retractions subcostal (1pts) subcostal &

intercostal (2pts) Observed dyspnea mild (1pts) marked (2pts) I-E ratio equal (1pts) I<E (2pts)

Higher score correlates with length of stay

Therapy Generally accepted and effective

Oxygen supplementation (titrate) Beta-2 agonists Atrovent Magnesium Sulfate (?) Hydration

Oxygen First line therapy

2-3 Liters via nasal cannula Target 92% pulse ox

NRB vs. Nasal cannula 100% increased PaCO2 100% decreased PEFR Chest 2003 Oct;124(4):1312

Aerosol Medications Metered Dose Inhalers

Meta-analysis of MDI vs. Neb in pediatrics

Nebs increased admission rate Difference greatest with severe cases Key is proper use of MDI J Pediatric 2004 Aug 145(2):172

Beta 2 Agonist Demonstrated Benefit If nebulized dose used, oxygen powered

not air powered (BMJ 2001 323:98) Continuous Nebs more effective than

once hourly Every 15 minutes or continuous No difference in side effects Reduced admissions Most improvement among severest group Cochrane review Issue 2, 2004

Beta 2 agonist IV Route? Cochrane review Issue 2 2004 15 studies indicates no evidence to

support this approach Does not address SQ epinephrine

or terbutaline Inhalation route is preferred route

Anticholinergics Moderate to severe exacerbations in

children Multiple doses of Anicholinergics effective

25% reduction in admissions NNT 12 Single dose not effective Cochrane review Issue 2 2004

No benefit to continuing once admitted Arch Pediatric Adolescent Med 2001;155:1329

Steroids Low dose steroids appear as effective as

high dose 80 mg/day of methyprednisalone 400 mg/day hydrocortisone Parenteral no better than oral Reduces readmission rates, relapse rate,

and rescue inhaler use for 21 days Best if given within one hour of arrival in ED Cochrane review Issue 2, 2004

Magnesium Intravenous route Adults

beneficial with severe exacerbation (FEV1<25% predicted)

1.2-2 gm IV over20-30 minutes NNT 8 Ann Emerg Med 2000;36:181-90 Cochrane review Issue 2, 2004

Pediatrics Small RCT (30 patients) Used 40 mg/kg IV vs. saline NNT to prevent one admission 2 Arch Pediatric Adolescent Med 2000;154:979

Magnesium Nebulized route

Small RCT 58 adults 2.5 ml mag sulfate with 2.5 mg

Albuterol via neb 3 doses q 30 minutes NNT 5 for admission Lancet 2003 Sept 27;362:1079

Unclear or Useless Tx Antibiotics

No identified role Cochrane issue 2, 2004

Heliox No identified role Cochrane issue 2, 2004

Aminophylline Results in more side effects no reduction in

patient oriented outcomes Cochrane issue 2, 2004

Decision Tree in ER Good response to therapy

Absence of symptoms Absence of signs PEFR > 300 L/min Watch for 4 hours for wearing off of beta

Admit if response is poor Continued wheezing Continued dyspnea PEFR <200 L/min Pneumothorax, pneumomediastinum

Consider Intubation/BiPAP Obtunded Sitting up/leaning forward with diaphoresis Patient exhaustion