Acute Severe Asthma

Dr. Bernard Fiifi Brakatu

Outline

Pathogenesis

Pathophysiology

Trigger Factors

ER Management

PathogenesisGenetic Predisposition

Chronic Inflammation

Smooth muscle and nerve cell dysfunction

Pathophysiology

Trigger factors cause bronchial hyperactivity leading to bronchoconstriction, mucosal edema and increased mucus secretion.

Results in airway obstruction, decrease in lung compliance, alveolar hypoventilation, pulmonary vasoconstriction and decreased production of surfactant.

Hypercapnea, acidosis, respiratory failure may occur if it persists

Trigger Factors in Asthma

Viral Infections

Dusts and pollutants incl. cigarette smoke

Allergens – house dust mite, pollens, moulds, spores, animal dander and feathers, certain foods, etc

Exercise

Changes in weather patterns and cold air

Psychological factors eg. Stress and emotion

Classification –based on risk factors and

prognosis Transient Infant Wheezers- wheeze early in

life but no subseq. increased risk of developing persistent asthma. Risk factor is low lung function in early life that persists until adolescence

Atopic Asthma – Sx appear early in life but persist into childhood and adolescence. More likely to have +ve skin test to allergens, bronchial hyper-responsiveness to trigger factors and increased daily peak flow variability. Sxx are severe and deficits in lung function, tho absent immediately after birth, are present by the age of 6yrs

Non-atopic asthma – May have early or late onset of Sxx but are usually not skin test +ve to allergens by age 6.

Other atopic dxx are common eg. Eczema, vernal conjunctivitis and allergic rhinitis(Samter’s triad). Strong ass. with total serum IgE and Increased daily peak flow variability.

Clinical Classification

Mild, Infrecquent Asthma(75% of pts) –attacks occurring less than once a month

Frequent episodic asthma(20%) – more than one episode every week with symptom free intervals

Chronic Asthma(4%) – low grade wheeze present most days; wheeze with exertion, nocturnal cough and some limitation of physical activity

Severe Chronic Asthma(1%) – Sxx present everyday with stunting of growth and barrel chest deformity, and marked limitation of activity

ER Management Brief Hx:

time of onset of current exacerbationcurrent medications and allergiesrecent frequent use of beta2-agonistsrisk factors for severe, uncontrolled disease (e.g. ER visits, admissions to the hospital and ICU, and prior intubations)

Age of onset – poorer prognosis with earlier onset

Frequency of attacks

Prev or current atopic dermatitis/allergic rhinitis

Persistent nocturnal cough(cough-variant asthma)

Exposure to asthma triggers

Use of peak flow with home management respiratory score

PE Level of Consciousness, Ability to speak in full

sentences, color, pulse, blood pressure, shape of chest, FAN, Use of accessory muscles of resp, RR, AE, PN, BS, Rhonchi, Creps, etc

PEFR

Pulse oximetry

STOP THE PE AND PROCEED TO RESUSCITATE IF THERE IS: SILENT CHEST(imminent resp failure) or CEREBRAL HYPOXEMIA(Mental agitation, drowsiness and confusion)

Classification of Asthma Severity

Clinical Features

Mild Moderate Severe Life-threatening asthma

Mental Status Normal Might look agitated

Usually Agitated Drowsy of Confused

Activity Normal Activity, Exertional dyspnea

Decreased Activity or feeding(infant)

Decreased activity, infant stops feeding

Unable to eat

Speech Normal Speaks in phrases Speaks in words Unable to speak

Work of breathing Minimal intercostal retractions

Intercostal and substernal retractions

Signif. resp distress. FAN+, ICR+, SCR+ and paradoxical thoraco-abdominal movement

Marked resp distress at rest. FAN+, ICR+, SCR+ and paradoxical thoraco-abdominal movement

Chest Auscultation

Moderate wheeze Loud pan-expiratory and inspiratory wheeze

Wheezes might be audible without stethoscope

The chest is silent (absence of wheeze)

SpO2 on room Air >94% 91–94% 91–94% <90%

Peak flow vs Personal Best

>80% 60–80% best <60% Unable to perform the task or <33%

Life-threatening Asthma –

Silent chest, Cyanosis, Poor respiratory effort, Hypotension, bradycardia, Exhaustion, Confusion or drowsiness

•Acute Severe Asthma –

Unable to complete sentences in one breath; too breathless to talk or feed, Agitation, Accessory muscle use

• Pulse rate >140/min in children 2-5 years old; >125/min in children >5 years old

• Respiration >40 breaths/min in children 2-5 years old; >30 breaths/min in children >5 years old

Differentials

Severe Pneumonia

Cardiac Asthma(Acute LVF)

Acute Chest Syndrome

CCF

Loefler’s Syndrome

Principles of Treatment

Treat hypoxemia,

Give short-acting ß2-agonists,

Prescribe corticosteroids,

Assess treatment response, and

Consider other modalities of treatment.

Immediate Treatment

High flow O2 via face mask at 6-8L/min

Nebulize with 5mg Salbutamol(2.5mg in very young children) in 4mls of saline for 5-10min

Prednisolone 1-2mg/kg PO(max. 40mg)

If life-threatening – IV Aminophylline 1mg/kg/hr, IV Hydrocortisone 100mg(4mg/kg/dose) 6hrly, Add Ipratropium bromide 0.25mg(0.125 in younger children) to Neb Salbutamol

Rehydration – o/a excessive sweating, fluid loss and poor/lack of intake during acute episode. 3000mls/m2

Subsequent mngt

IF THE PT IS IMPROVING, CONTINUE:

High flow O2,

Prednisolone 1-2mg/kg dly(max. 40mg)

Nebulised Salbutamol 4hrly

IF PT IS NOT IMPROVING AFTER 30MIN:Continue O2 and steroids

Give Nebulised Salbutamol more frequently up to 30min

Add ipratropium to nebulizer and repeat 6hrly until improvement starts

IF PT STILL NOT IMPROVING, GIVE:

Aminophylline infusion(1mg/kg/hr)

Monitoring Treatment

Oxymetry : Maintain SpO2 >92%

Check PEF

Discharge Before discharging from hospital the pt:

Shd have been on discharge medications for 24hrs and have had inhaler technique checked recorded

If recorded PEF>75% predicted or best and PEF variability <25%

Treatment with soluble steroid tablets and inhaled steroid(Seretide/Symbicort) in addition to bronchodilators(Ventolin). MDIs are difficult to use in young children so include a spacer.

Nedocromil Sodium or Zafirlukast(Accolate) as prophylaxis

Educate mother on trigger factors and first aid before getting to hospital

Review within 4wks, and then every 3 to 6mnths

THANKS