management of acute asthma

MANAGEMENT OF ACUTE ASTHMA

Speaker :GNANDAS BARMANGuide : Dr. A. K. BALA

DEFINITION OF ASTHMA

• Asthma is a heterogeneous disease usually characterised by chronic airway inflammation.

• It is defined by history of respiratory symptoms such as wheeze, shortness of breath , chest tightness and cough that may vary over the time and in intensity together with variable expiratory airflow limitation.{GINA2015}

Definition

• Non Communicable chronic lung disease characterised by the following:

1. Airway inflammation2. Airway obstruction mainly due to Muscle Spasm

associated with mucosal edema and stagnation of Mucus

3. Airway hyper reactivity to Aerobiologicals and irritants

4. Narrowing of the airways is usually reversible, but in some patients with chronic asthma, there may

be an element of irreversible airflow obstruction.

Pathogenesis of asthma attacks

PATHOPHYSIOLOGY

Approximately 80% of all asthmatic patients report disease onset prior to 6 yr of age.

However, of all young children who experience recurrent wheezing , only a minority go on to have persistent asthma in later childhood.

Allergy in young children is the major risk factor for childhood asthma.

Types of childhood asthma

• Two main types of childhood asthma:1.Recurrent wheezing in early childhood;

primarily triggered by common viral infections of respiratory tract.

2.Chronic asthma associated with allergy that persists into later childhood and adulthood.

Types of Asthma

1. Transient Early Wheezing2. Persistent Atopy-Associated Asthma3. Non atopic Wheezing4. Asthma with Declining Lung Function5. Late onset Asthma in Females associated

with Obesity and Early Onset Puberty.6. Occupational type Asthma in Children.

WHAT IS AN EXACERBATION

• Exacerbation represents an acute or sub acute worsening in symptoms and lung function from patients usual status;

• Or in some cases initial presentation of asthma.

• FLURE UP is a better terminology.

• A flare up or exacerbation of asthma in children less than 5 yr is defined as an acute or sub acute deterioration of symptoms control that sufficient to cause distress or risk to health;

• Need to visit health care provider or required systemic steroids.

Severe airflow obstruction

Incomplete exhalation

Increased lung volume

Increased elastic recoil pressure

Increased expiratory flow

Expanded small airways

Decreased expiratory resistance

Compensated:Hyperinflation, normocapnia

Decreased expiratory resistance

Decompensated: Severe hyperinflation, hypercapnia

Worsening airflow

obstruction

Pathophysiology

Cardiopulmonary interactions

Negative intrapleuralpressure

Pulmonary edema Pulsus paradoxus

Hyperinflation

Hypotension

Altered hemodynamics

: Pathophysiology

Metabolism

V/Q mismatch

Hypoxia

Dehydration

Lactate Ketones

Metabolic acidosis

Increased workof breathing

: Pathophysiology

RISK ASSESSMENT ON ADMISSIONFOCUSED HISTORY• Onset of current exacerbation • Frequency and severity of daytime and night

time symptoms and activity limitation• Frequency of rescue bronchodilator use• Current medications and allergies• Potential triggers • History of systemic steroid courses, emergency

department visits, hospitalization, intubation, or life-threatening episodes

CLINICAL ASSESSMENT

• Physical examination findings: • Vital signs, • Breathlessness, • Air movement,• Use of accessory muscles, Retractions, • Anxiety level, alteration in mental status• Pulse oximetry • Lung function (defer in patients with moderate

to severe distress or history of labile disease)

Patients at high risk of asthma-related death

• Previous severe exacerbation (e.g., intubation or ICU admission for asthma)

• Two or more hospitalizations or >3 ED visits in the past year• Use of >2 canisters of SABA per month• Current or recently stoppage of oral corticosteroids.• Difficulty perceiving airway obstruction or the severity of

worsening asthma.• Low socioeconomic status or inner-city residence• Illicit drug use• Major psychosocial problems or psychiatric disease• Co morbidities, such as cardiovascular disease or other chronic

lung disease• Known food allergy in a asthma patient

TREATMENT GOALS• Correction of significant hypoxemia • Rapid reversal of airflow obstruction. This is best

achieved by: Repetitive or continuous administration of a SABA or Early administration of systemic corticosteroids to patients who have moderate or severe exacerbations or to patients who fail to respond promptly and completely to SABA treatment

• Reduction of the likelihood of relapse of the exacerbation or future recurrence of severe airflow obstruction by intensifying therapy

Evaluation of asthma exacerbation severity in emergency setting

SYMPTOMS

MILD MODERATE SEVERE IMMINENT RESP ARREST

Breathlessness While walking

Can lie down

While at rest[infant-softer, shorter cry, difficult feeding]

Prefers sitting

While at rest[infant-stop feeding]

Sits upright

Talks in Sentences Phrases Words

Alertness May be agitated

Agitated Agitated Drowsy or confused

SIGNS MILD MODERATE SEVERE RESP . ARREST

IMMINENT

RESP RATE INCREASED INCREASED OFTEN >30 /min

Use of accessory muscles

Usually not common usually Paradoxical TA movement

Wheeze Moderate ,often end exp

Loud, throughout exp

Loud , both isp and exp

Absence

Pulse rate <100[normal for age]

100-120 >120 bradycardia

Pulsus paradoxus

Absent<10

May present10-25

Often present>25[adult]20-40[children]

Absence suggest resp. Muscle fatigue

FUNCTIONAL ASSESSMENTMILD MODERATE SEVERE IMMINENT

ARREST

PEAK EXPIRATORY FLOW[value predicted/personal best]

>70% 40-69 % <40% <25%

PaO2[Breathing air]

Normal[test usually not necessary]

>60 <60,possible cyanosis

Pco2 <42[test usually not necessary]

<42 >42,possible respiratory failure

Sao2[breathing air]

>95%[test usually not necessary]

90-95% <90%

Management of mild to moderate exacerbations [home based/Primary care]• Early treatment by the patient and family

member at home is the best strategy for managing asthma exacerbations .

• Provide to all patients a written asthma action plan that includes daily management and recognizing and handling worsening asthma, including self-adjustment of medications in response to acute symptoms or changes in PEF measures in the event of an exacerbation.

INITIAL TREATMENT: Inhaled SABA: up to thrice 20 minutes apart of 2–6 puffs by metered-dose inhaler (MDI) or nebulizer treatments.

If possible Controlled O2 therapy [94-98%],O2 Should not be withheld if oxymetry not availableNote: parents should seek medical attention if child is lethargic,acutely distressed,especially

children <1yr

GOOD RESPONSE

• No wheezing or dyspnea(assess tachypnea in young Children).

• PEF ≥80% predicted or personal best.

• Contact clinician for followup instructions and further management.

• May continue inhaled SABA every 3–4 hours for 24–48 hours.

• Consider short course of OCS[5-7d]

• Doubling the dose of an ICS in those patients already receiving ICS therapy has not been effective at reducing the severity or preventing progression of exacerbations

INCOMPLETE RESPONSE

• Persistent wheezing and dyspnea (tachypnea).

• PEF 50–79% predicted or personal best

• Add oral systemic corticosteroid.

• Continue inhaled SABA.

• Contact clinician urgently(this day) for further instruction.

POOR RESPONSE• Marked wheezing and dyspnea.• PEF <50% predicted or personal

best.• If distress is severe and

nonresponsive to initial treatment.

• Need SABA MORE OFTEN• Add oral systemic corticosteroid.• Repeat inhaled SABA

immediately.

• Urgent medical attention or emergency

SPECIAL NOTE • NOT RECOMMENDED:• Drinking large volumes of liquids or breathing

warm, moist air (e.g., the mist from a hot shower).• Using over-the-counter products such as

antihistamines or cold remedies.

• Although pursed-lip and other forms of controlled breathing may help to maintain calm during respiratory distress, these methods do not bring about improvement in lung function.

MANAGEMENT OF ACUTE SEVERE ASTHMA ATTACKS

• In emergency or PICU, secure AIRWAY BREATHING CIRCULATIONBrief history and clinical examinations.

Status Asthamaticus• Its a acute severe exacerbation of asthma that

does not respond to conventional therapy

Score Respiratory Rate

Wheezing I/E Ratio Accessory Muscle Use

0 <30 None 1 : 1.5 None

1 30 - 40 Terminal Expiration

1 : 2 1 Site

2 41 - 50 Entire Expiration

1 : 3 2 Sites

3 >50 Inspiration and Entire Expiration

> 1 : 3 3 Sites or Neck Strap Muscle Uses

Beckers Score < 4 : Mild4-7 : Moderate

> 7 : Severe

GENERAL MANAGEMENT

• OXYGEN: • Administer supplemental oxygen (by nasal cannulae or

mask, whichever is best tolerated) to maintain an SaO2[94-98%].

• Monitor SaO2 until a clear response to bronchodilator therapy has occurred.

• Titrated by pulse oxymetry.• NOTE-maintain saturation@94-98% associated with

better physiological outcome than 100% high flow O2

I.V. FLUIDS• Aggressive hydration is not recommended for older

children and adults but may be indicated for some infants and young children.

• Infants and young children may become dehydrated as a result of increased respiratory rate[insensible loss] and decreased oral intake or vomiting.

• Fluid replacement by isotonic fluids then maintenance • NOTE- over hydration should be avoided. • Serum electrolytes; specially potassium level should

be checked

CHILD WITH ACUTE ASTHMA EXACERBATION

Management

Supportive care

Admit in PICU if PIS>7

Chest X ray and ABG if indicated

Clinical assessment[PIS],Pulse Oxymetry

Comportable env.IV access

Maintain euvolemiaCARDIO RESP MONITORING

ANTIBIOTIC ,If indicated

AVOID SEDATION MONITOR K

IF VENTILATED ARTERIAL N CV ACCESS

INVESTIGATIONS • Most of the patients who have an asthma exacerbation do not

require any initial laboratory studies. If laboratory studies are ordered, they must not delay initiation of asthma treatment.

• CXR: is not recommended for routine assessment but should be obtained for patients suspected of a complicating cardiopulmonary process, as congestive heart failure, or any pneumothorax, pneumomediastinum, pneumonia, or lobar atelectasis;or cause of wheeze in doubt.

• ABG: measurement for evaluating (PCO2) in patients who have suspected hypoventilation, severe distress, or FEV1 or PEF ≤25 percent of predicted after initial treatment.

• (Note:Respiratory drive is typically increased in asthma exacerbations, so a “normal” PCO2 of 40 mmHg indicates severe airflow obstruction and a heightened risk of respiratory failure.)

• CBC,ELECTROLYTES

MEDICATIONS

B2 AGONIST:Sulbutamol continuous

nebulisation[0.15-0.5mg/kg/hr ]

MDI[100]4-8 puffs SC

terbutaline-0.01mg/kg/dose may repeat

IV -loading 10mcg/kg then 0.1-10mcg/kg/min

0

ANTICHOLINERGIC DRUGS

Ipratropium

bromide-125-500 mcg if

nebulisedOr 4-8 puffs

Every 20 mins for 3 doses

CORTICOSTEROIDS Hydrocortisone :

10mg/kg statThen 5mg/kg IV 6 hrly

Switch to per oral when stable

[1-2mg/kg/day]

BETA 2 AGONIST

• B2 agonist remain the mainstay of treatment.• Salbutamol and terbutaline is preferred due to there B2

selectivity.• They can be administered via inhaled, IV, SC or orally.• Rapid action{<5 min} and duration 4-6 hrs.• No added benefit of using levo than racemic

salbutamol.• Continuous nebulisation is superior than intermittent

doses. • The use of nebulized magnesium sulfate in combination

with SABAs may result in further improvements in pulmonary function

I.V. B2 AGONIST

• NOT ROUTINELY USED• Considered in patients unresponsive to nebulisation

or • Whom nebulisation is not feasible.• Terbutaline is the agent of choice for IV and SC route.• Adverse reactions: mostly CVS, including tachycardia,

increase QTc interval, hypertension, diastolic hypotension

• CNS- hyperactivity, tremors.• Hyperglycemia and hypokalemia are common.

Anticholinergic drugs

• Anticholinergics are now a standard of care in treatment of acute asthma in children in combination with SABA.

• Most commonly used is Ipratropium bromide by inhaled route, every 20 mins for 3 doses. Subsequently every 4-6 hrs.

• Fewer side effect due to poor systemic absorption.• Dry mouth, bitter taste, flushing , tachycardia are

common.

CORTICOSTEROIDS • These are included as first line therapy in management

of acute asthma.• Oral corticosteroids have same efficacy as parenteral

but not feasible in critically ill childrens.• Commonly used [IV] hydrocortisone ,

methylprednisolone and dexamethasone.• Because of cost hydrocortisone is preferred.• Started to work within 1-3h,maximum effect in 4-8h.• With short term high dose steroids side effects are less

as hyperglycaemia, hyper tension or acute psychosis.• Aerosolized steroids have limited role in acute asthma.

SPECIAL MEDICATIONS

•50mg/kg/dose Over 30 mins or infusion @10-20mg/kg/h,

•Can repeat once or twice after 4-6 hr

MAGNESIUM

•Loading 5-7mg/kg/min over 20 min

•Then 0.5-0.9 mg/kg/h

THEOPHYLLINE

•KETAMINE-1mg/kg/h

•Vecuronium-0.1mg/kg/h

SEDATIONS

Adrenaline

• Intramuscular adrenaline is indicated in addition to standard therapy in asthma associated with anaphylaxis or angioedema.

• Not recommended in other form of exacerbations.

MAGNESIUM SULFATE

• Not recommended as a routine for exacerbations.

• Commonly used when fail to respond with initial treatment or having persistent hypoxemia.

• Serum magnesium should be monitored if facility available.

• Common side effects include hypotension, CNS depression, muscle weakness or flushing

• Severe CARDIORESPIRATORY complication in high serum levels[>10-12 mg/dl]

METHYLXANTHINES• Infrequently use due to less effectiveness than

B2 agonist and severe side effects.• May be helpful in critically ill children who are

not responsive to standard treatment.• Serum theophylline level should preferably be

measured after 1-2h of bolus if facility avaialble.

• Toxicity includes nausea, vomiting, tachycardia, agitation.

• Severe life threatening complications are-CARDIAC ARRYTHMIAS,SEIZURES AND DEATH

ANTIBIOTICS

• Antibiotics are not generally recommended for the treatment of acute asthma exacerbations except as needed for co morbid conditions.

• Viral infections frequently contribute to exacerbations of asthma.

• The use of antibiotics is generally reserved for patients who have fever, purulent sputum or evidence of pneumonia.

• In exacerbations STEROIDS should be aggressively used than antibiotics.

SEDATION

• Sedation is not generally recommended.• Anxiolytic and hypnotic drugs are contraindicated in

severely ill asthma patients because of their respiratory depressant effect.

• INDICATED in children who are excessively anxious[not hypoxemic or hypercarbic] or intubated patients.

• Mechanically ventilated children require sedation and sometimes , muscle relaxant to prevent Tachypnea , Asynchrony and sudden cough induced Barotraumas.

• KETAMINE- is sedation of choice • It provide sedation and bronchodilation with

minimum respiratory depression.• It can lead excessive bronchial secretions• Continuous or intermittent dose of

benzodiazepine can be used• FENTANYL is the opiates of choice as less

histamine release and bronchospasm• VECURONIUM –commonly used muscle relaxant.

VENTILATORY SUPPORT

VENTILATION

NON-INVASIVE : NIPPV can be tried

prior to conventional ventilation

INVASIVE VENTILATION:VC mode with-

Vt<6ml/kgRR-HALF OF

NORMALI:E-1:3/1:4

MINIMUM PEEPIN INFANTS –

PRESSURE CONTROLLED

MECHANICAL VENTILATION

• Indications are- Altered sensorium or coma. Increasing or decreasing pulsus paradoxus. Rapid deterioration of mental status. Cardiopulmonary arrest Severe lactic acidosis[sp in infants] Refractory hypoxemia.

• Intubation and mechanical ventilation should be considered in a child who responds poorly to initial therapy or rise of PCO2

• Rapid sequence intubation is preferred along with premedication with atropine, sedatives and muscle relaxant .

• Cuffed tube with largest diameter of appropriate age should be used.

• Typically slow ventilator rate with prolonged expiration, low PEEP.

• Extubation should be attempted as soon as possible.

• “Permissive hypercapnia” or “controlled hypoventilation” is the recommended ventilator strategy .

• Permissive hypercapnia provides adequate oxygenation and ventilation while minimizing high airway pressures and barotrauma

• It involves administration of as high a fraction of inspired oxygen as is necessary to maintain adequate arterial oxygenation, acceptance of hypercapnia [upto 90 mmHg],with acceptable pH ≥7.2

COMPLICATIONS OF INVASIVE VENTILATION

• Most frequent complications in these children are-

• HYPOTENSION[should be anticipated during intubation]

• Pneumothorax /subcutaneous emphysema• Cardiac arrest.• If hypotension or hypoxemia not corrected by

fluids and alteration of setting,then tension pneumothorax must be considered.

NON INVASIVE VENTILATION

• NIV can be tried before invasive ventilation.

• No strong recommendation regarding use of NIV in severe asthma.

• Should not be tried in agitated patient and not be sedated in order to receive NIV

NOT RECOMMENDED• Chest physical therapy is not recommended :• For most exacerbations, chest physiotherapy is

not beneficial and is unnecessarily stressful for the breathless asthma patient. Because mucus plugging is a major contributing cause of fatal asthma.

• Avoid mucolytic agents (e.g., acetylcysteine, potassium iodide) because they may worsen cough or airflow obstruction.

OTHERS HELIOX Heliox is a breathing gas composed of a mixture

of helium (He) and oxygen(O2). Heliox has been used medically since the 1930s . It was

the mainstay of treatment in acute asthma before the advent of bronchodilators.

Mixture of 21% O2 (the same as air) and 79% He, although other combinations are available (70/30 and 60/40).

INDICATIONS-children who not responding to conventional therapy or who receiving high pressure MV ,HELIOX may be good adjunct therapy

Bronchoscopy, bronchial lavage

• Marked mucus plugging may render bronchodilating and anti-inflammatory therapy ineffective

• “Plastic bronchitis” has been described in asthmatic children

• Combined bronchoscopy/lavage can be used in desperately ill asthmatic children

DISCHARGE AND FOLLOW UP AFTER EXACERBATION

ORAL MEDICATIONS:OCS- Prednisolone [1-2mg/kg/day] or equivalent steroid for 3-5 days. INHALED MEDICATIONS: SABA- 2-6 puffs 4-6 hrly as needed. ICS- start inhaled corticosteroids if not started

previously at lowest possible dosing for one month.Patients who started it previously should steps up

for 2-4 weeks.

• PEAK FLOW METER- in selected patients[>5yrs] To monitor the A.M-P.M variations• FOLLOW UPS-• To primary clinician or asthma clinic within 7

days of discharge.• Follow up should be for at least 1-2 months

after the attack.

ACTION PLAN[before or at discharge]

• REFERENCES –• Nelson’s textbook of pediatrics.• AIIMS PICU guideline• GINA updates 2015• EPR 3; 2007• INTERNET.

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