ASTHMA EXACERBATION

ASTHMA EXACERBATION 

Recommendations below are aligned primarily with the 2026 GINA Strategy Report, the current GINA reference available in 2026. 

ADULT ASTHMA EXACERBATION — QUICK DOSE TABLE

1. WHAT IS AN ASTHMA EXACERBATION?

An asthma exacerbation is an acute or subacute worsening of asthma symptoms and lung function compared with the patient’s usual state.Typical manifestations:

• Increasing dyspnea
• Wheezing
• Chest tightness
• Cough
• Increasing respiratory rate
• Increasing use of accessory muscles
• Falling PEF/FEV1
• Increasing requirement for reliever medication
• Hypoxemia in severe disease

Importantly, an exacerbation may occur in a patient with previously diagnosed asthma or may be the first presentation of asthma. 

The terms “asthma attack,” “acute severe asthma,” “status asthmaticus,” and “severe exacerbation” are often used interchangeably clinically, but they are not perfectly synonymous.”Status asthmaticus” generally refers to: Severe asthma exacerbation that is persistent and refractory to conventional initial therapy.

2. PATHOPHYSIOLOGY

Trigger

↓

Airway inflammatory response

↓

Release of mediators:

• Histamine
• Leukotrienes
• Prostaglandins
• Cytokines
• Chemokines

↓

3 major airway abnormalities

1. Bronchial smooth-muscle contraction→ rapid airway narrowing

2. Airway mucosal edema→ further reduction in airway caliber

3. Excess mucus + mucus plugging→ partial/complete airway obstruction

↓

Increased airway resistance

↓

Expiratory flow limitation

↓

Air trapping

↓

Dynamic hyperinflation

↓

Increased work of breathing

↓

Respiratory muscle fatigue

↓

Ventilatory failure

Why EXPIRATORY FLOW IS MORE AFFECTED THAN INSPIRATORY FLOW

During expiration:

• Intrathoracic pressure rises
• Airways naturally become narrower
• Diseased small airways collapse more easily
• Expiratory flow becomes limited

The patient therefore has particular difficulty getting air out.

This creates:

Incomplete expiration → air trapping → End-expiratory lung volume progressively increases.This is:Dynamic hyperinflation or Auto-PEEP / intrinsic PEEP

WHY DYNAMIC HYPERINFLATION IS DANGEROUS

The diaphragm becomes flattened.Instead of being a dome:

Therefore respiratory muscles must generate much greater effort.

This creates:

More effort → more fatigue → worse ventilation → more CO₂ retention

It also produces important cardiovascular effects.

3. EFFECT OF HYPERINFLATION ON CARDIOVASCULAR SYSTEM

Severe hyperinflation:

Increases intrathoracic pressure

↓

Reduces venous return

↓

Reduces RV preload

↓

Reduces LV filling

↓

Potential reduction in cardiac output

Therefore a patient with severe asthma can become:

• Tachycardic
• Hypotensive
• Pulsus paradoxus positive
• Eventually peri-arrest

PULSUS PARADOXUS

Pulsus paradoxus = exaggerated inspiratory fall in systolic BP, classically:>10 mmHg

Mechanism

During inspiration:

↑ negative intrathoracic pressure—>↑ venous return to RV—>RV expands—>Interventricular septum shifts toward LV—>LV filling decreases—>LV stroke volume decreases—Inspiratory fall in systolic BP

4. WHY A NORMAL PaCO₂ CAN BE A WARNING SIGN

Early in an asthma attack:Respiratory rate increases

Therefore:PaCO₂ usually decreases.

But in a severely tachypneic asthmatic patient, a normal PaCO₂ can actually indicate worsening ventilatory failure.

Because that means

The patient is no longer able to increase alveolar ventilation due ton Increasing muscle fatigue

Therefore:In severe asthma:

Rising PaCO₂ = red flag

especially when associated with:

• Increasing fatigue
• Reduced air entry
• Altered mental status
• Increasing respiratory effort
• Falling pH

MIXED RESPIRATORY + METABOLIC ACIDOSIS

A very sick asthmatic patient may develop:

Respiratory acidosis + metabolic acidosis

Possible causes of metabolic acidosis:

• Lactic acidosis
• Hypoperfusion
• Respiratory muscle fatigue
• β₂-agonist-associated lactate elevation
• Sepsis
• Renal dysfunction
• Ketoacidosis

Thus:

pH may fall dramatically despite only moderate CO₂ elevation.

HOW SALBUTAMOL CAN INCREASE LACTATE

High-dose β₂-agonists can increase:

• Glycolysis
• Glycogenolysis
• Lipolysis

This increases pyruvate production and can increase lactate.

WHICH CAUSES  tachypnea which may be mistaken for worsening bronchospasm.

5. COMMON PRECIPITANTS

6. CLINICAL PRESENTATION

Typical:

Symptoms

• Dyspnea
• Wheeze(A very severe asthmatic may actually have less wheeze because airflow is becoming extremely poor.)
• Chest tightness
• Cough
• Difficulty speaking
• Nocturnal symptoms
• Increased reliever requirement

Signs

• Tachypnea
• Tachycardia
• Wheezing
• Prolonged expiration
• Accessory muscle use
• Hyperinflation
• Reduced air entry
• Hypoxemia

SILENT CHEST

Silent chest = extremely dangerous.

It means:Airflow is so severely reduced that wheezing becomes minimal or absent.

GINA identifies drowsiness, confusion, or a silent chest as life-threatening features. 

7. SEVERITY CLASSIFICATION

GINA emphasizes using the worst clinical feature rather than relying on a single parameter. 

DO NOT WAIT FOR PEF IN A VERY SICK PATIENT

PEF is useful when the patient can perform the maneuver.

But:

A severely distressed patient may not be able to generate a reliable PEF.

And ACEP notes that PEF monitoring has not been shown to improve outcomes or reliably predict admission when universally applied; its use should be individualized. 

Therefore:Clinical assessment comes first.

Never delay lifesaving treatment just to obtain PEF.

8. Investigations 

9. MANAGEMENT 

OXYGEN

For adults/adolescents, GINA targets approximately:SpO₂ 93–95%

with adjustment for altitude where appropriate.If >50% FiO2 is required, strongly consider an alternative or additional diagnosis (e.g., pneumothorax, mucus plugging).

SALBUTAMOL

MDI + spacer

A common GINA regimen:4–10 puffs repeat:every 20 minutes for 1 hour then reassess. 

Each standard salbutamol MDI puff is commonly:100 micrograms

Thus:

4 puffs = 400 micrograms

10 puffs = 1 mg nominal dose

Delivery with a spacer is important.

NEBULIZED SALBUTAMOL

Useful when:

• Patient cannot coordinate MDI
• Severe distress
• Unable to use spacer effectively
• Continuous/repeated nebulization is required

-Dose:2.5–5 mg nebulized Q20 minutes.

-In severe asthma continuous nebulized therapy(10-15 mg/hour initially)may be used under monitoring.

IV salbutamol

IV salbutamol may be considered as an exceptional rescue therapy in refractory, life-threatening asthma when adequate inhaled β₂-agonist delivery cannot be achieved or is ineffective, under ICU-level monitoring. It is not recommended routinely because evidence has not demonstrated benefit over intensive inhaled therapy and systemic toxicity is greater.

IPATROPIUM BROMIDE(SAMA)

• Add to SABA in:moderate-to-severe exacerbations, especially severe presentations or poor response to initial SABA.
• Typical adult nebulized dose:0.5 mg every 20 minutes for the first hour followed by 0.5 mg may be nebulized Q4 hours. 

SYSTEMIC CORTICOSTEROIDS

Prednisolone 40–50 mg orally once daily usually for:

5–7 days for adults.

GINA recommends early systemic corticosteroids in moderate/severe exacerbations. 

Steroids:

• Reduce airway inflammation
• Reduce mucosal edema
• Reduce inflammatory mediator activity
• Improve β₂-receptor responsiveness
• Reduce relapse
• Reduce hospitalization

IV VS ORAL STEROIDS

If the patient can swallow and absorb medication:

Oral corticosteroids are generally adequate.

IV therapy is reasonable when:

• Cannot swallow
• Severe vomiting
• Altered consciousness
• Need for parenteral therapy

Examples:

• Methylprednisolone IV
• Hydrocortisone 100 mg IV initially followed 50 mg IV every 6 hours
• DEXAMETHASONE 12–16 mg PO/IV once daily

Advantages:

• Long half-life
• Convenient dosing
• Potentially shorter course

But prednisolone remains a standard approach.

Hydrocortisone 20 mg ≈ prednisone 5 mg ≈ methylprednisolone 4 mg ≈  Dexamethasone 0.75 mg

MAGNESIUM SULFATE

Severe exacerbation with inadequate response to initial treatment.(use is controversial)

Dose:Magnesium sulfate 2 g IV given over 20 minutes. 

Magnesium produces bronchodilation through several mechanisms, including:

• Calcium-channel effects
• Reduction in smooth-muscle contraction
• Modulation of acetylcholine release

Evidence for nebulized magnesium is less convincing than for selected IV use.

ADRENALINE / EPINEPHRINE

Not routine therapy for ordinary asthma exacerbation.

Use IM epinephrine when:

anaphylaxis or angioedema is present.

GINA explicitly recommends epinephrine first when the patient presents with features of anaphylaxis as well as asthma. 

Typical adult anaphylaxis regimen:Epinephrine 0.5 mg IM

using 1 mg/mL (1:1000) solution

IV epinephrine may be considered only as an exceptional rescue therapy in refractory, life-threatening asthma when conventional inhaled therapy cannot be effectively delivered, and should be undertaken in a closely monitored critical-care setting. There is no standardized GINA-recommended IV epinephrine infusion dose for asthma exacerbation.

ANTIBIOTICS

Do NOT routinely give antibiotics.

Most exacerbations are not bacterial infections.

Consider antibiotics only when there is convincing evidence of bacterial infection, such as:

• Pneumonia
• Bacterial sinusitis in appropriate context
• Another documented bacterial infection

GINA specifically advises against routine antibiotic prescribing for asthma exacerbations. 

THEOPHYLLINE

Not routinely recommended for acute asthma exacerbation.

Why?

Limited additional efficacy + significant toxicity.

Potential adverse effects:

• Nausea/vomiting
• Tremor
• Tachyarrhythmia
• Seizures
• Toxicity due to narrow therapeutic window

HELIOX

• Helium-oxygen mixtures reduce gas density.
• Formulated as a 70:30 or 80:20 mixture, so this isn’t an option for patients requiring >30% FiO2
• Theoretically:lower gas density → reduced turbulent flow resistance
• May help selected patients with severe airflow obstruction, but evidence is insufficient for routine use.

Montelukast

Montelukast 10 mg PO/NG once daily may be continued in an intubated adult who was already taking it chronically. It may also be considered as an adjunct in patients with aspirin/NSAID-exacerbated respiratory disease (AERD), although it is not established rescue therapy for the acute exacerbation.

β-BLOCKERS

Avoid non-selective β-blockers during acute severe bronchospasm when possible.

They can antagonize β₂-mediated bronchodilation.

If a cardiovascular indication makes β-blockade essential, specialist risk-benefit assessment is required.

10. SEDATION

Dexmedetomidine can provide sedation with relatively little respiratory depression, making it attractive in some spontaneously breathing/NIV situations.

However:

Major adverse effects

• Bradycardia
• Hypotension

Morphine should be avoided because histamine release could theoretically worsen bronchospasm

11. NONINVASIVE VENTILATION(NIV)

NIV/BiPAP may sometimes be considered in carefully selected severe asthma patients.

Potential theoretical benefits:

• Reduces work of breathing
• Provides inspiratory support
• May counter intrinsic PEEP
• Can improve ventilation

But evidence is considerably less robust than in COPD.

• The ideal respiratory rate might be around ~15-25 b/m.
• A respiratory rate >25 suggests excessive tachypnea, which may promote gas trapping.
• A respiratory rate <<15 raises the possibility of oversedation (especially following opioids).

HFNC in acute severe asthma

HFNC is not established as routine first-line respiratory support for acute asthma exacerbation. It can be considered in selected patients with hypoxemia or significant respiratory distress, but evidence in asthma is much weaker than in acute hypoxemic respiratory failure from other causes.patients who are unable to tolerate NIV or patients with less severe disease, HFNC can be used

At high HFNC flow:Nebulized aerosol + high gas flow

→ increased impaction/dilution

→ less aerosol reaching the distal airways.

12. INTUBATION 

Intubation in severe asthma can precipitate:

• Hypotension
• Severe dynamic hyperinflation
• Barotrauma
• Cardiovascular collapse
• Arrest

INDICATIONS FOR INTUBATION

1. Cardiac/respiratory arrest

2. Severe altered mental status

3. Inability to protect airway

4. Severe exhaustion

5. Progressive respiratory acidosis

6. Refractory hypoxemia

7. Worsening despite maximal medical therapy

8. Severe hemodynamic instability

9. “Dying” clinical appearance

DO NOT INTUBATE BASED ON CO₂ ALONE

Procedure

KETAMINE

Ketamine is often attractive for induction in severe asthma because it:

• Provides sedation
• Provides analgesia
• Usually maintains cardiovascular tone relatively well
• Has bronchodilatory properties

Dose :1–2 mg/kg IV titrated to the clinical situation.

ETT

ETT size: In adults, use the largest practical ETT, commonly ≥8.0 mm internal diameter when anatomy permits. A larger tube reduces airway resistance and facilitates suctioning/bronchoscopy

⚠️ Avoid aggressive bag-mask ventilation

After induction/intubation, avoid delivering:

• High respiratory rates
• Excessive tidal volumes
• Excessively rapid manual ventilation

because:High minute ventilation→ inadequate expiratory time→ air trapping

13. VENTILATION STRATEGY

The biggest mistake is:Trying to normalize PaCO₂ rapidly.

This may require excessive minute ventilation.That causes:

short expiratory time

↓

air trapping

↓

dynamic hyperinflation

↓

hypotension/barotrauma

Therefore:Allow prolonged expiration.

Neuromuscular blockade

• Avoid continuous paralytic infusions 
• because patients often receive high-dose systemic corticosteroids, and prolonged corticosteroid exposure combined with neuromuscular blockade has been associated with ICU-acquired myopathy/weakness.
• Paralysis should therefore be reserved for selected situations, such as severe patient–ventilator dyssynchrony that persists despite adequate sedation(PROPOFOL/FENTANYL/KETAMINE), or life-threatening respiratory acidosis, hypoxemia or hemodynamic compromise where ventilator control cannot otherwise be achieved. 
• If an NMBA is required, use the lowest effective dose for the shortest possible duration, provide adequate analgesia and deep sedation, and reassess frequently for discontinuation. 

PEEP IN INTUBATED ASTHMA

FIRST MEASURE AUTO-PEEP(intrinsic PEEP)

During controlled ventilation:Use an:End-expiratory hold

The measured pressure can estimate:intrinsic PEEP, AutoPEEP makes difficult to trigger breath.

• If Patient is triggering the ventilator use 5 cm PEEP
• If Patient not Triggering Breath  then External PEEP(PEEP that you set on  ventilator) should be ~75% of the intrinsic PEEP.(Volume-cycled ventilation: Increasing PEEP causes an increase in plateau pressure.)

IMMEDIATE RESPONSE TO SEVERE AUTO-PEEP

An intubated asthmatic suddenly becomes:

• Hypotensive
• Tachycardic
• Difficult to ventilate
• High airway pressures

Think: Dynamic hyperinflation.

If the patient is crashing:Temporarily disconnect from ventilator

allow passive exhalation

while simultaneously assessing:

• Pneumothorax
• Tube obstruction
• Circuit problems
• Severe bronchospasm

If blood pressure rapidly improves after disconnecting, severe dynamic hyperinflation is strongly suspected.

This is a temporary emergency maneuver, not definitive treatment.

BAROTRAUMA

Severe asthma + mechanical ventilation can cause:

• Pneumothorax
• Pneumomediastinum
• Subcutaneous emphysema

Risk rises with:

• High airway pressures
• Severe air trapping
• Excessive minute ventilation

14. DIFFERENTIAL DIAGNOSIS

1. COPD exacerbation
2. Pulmonary edema
3. Pulmonary embolism
4. Pneumothorax
5. Pneumonia
6. Anaphylaxis
7. Upper-airway obstruction(Wheeze loudest over throat.)
8. Foreign body
9. Vocal cord dysfunction / inducible laryngeal obstruction
10. Aspirated material
11. Metabolic acidosis with compensatory tachypnea
12. Panic/hyperventilation
13. Cardiac ischemia

15. ICU ADMISSION INDICATIONS

Consider ICU for:

• Life-threatening exacerbation
• Altered mental status
• Silent chest
• Respiratory failure
• Rising PaCO₂
• Severe acidosis
• Need for continuous nebulization
• NIV requiring close monitoring
• Mechanical ventilation
• Hemodynamic instability
• Failure of aggressive ED treatment

16. POSSIBLE DISCHARGE FEATURES

A patient is more suitable for discharge when:

• Symptoms have substantially improved
• Work of breathing is minimal
• Oxygenation is satisfactory on room air
• Reliever requirement has decreased
• PEF is improving
• PEF is generally >60–80% of personal best/predicted when feasible
• Patient can manage medications
• Home support is adequate

GINA uses these factors in its discharge assessment. 

17. FOLLOW-UP

After an exacerbation, follow-up should be arranged relatively soon.

GINA recommends follow-up within approximately:

2–7 days for adults and earlier in children. 

At follow-up assess:

• Symptoms
• Reliever use
• Lung function
• Adherence
• Inhaler technique
• Trigger exposure
• ICS therapy
• Action plan
• Need for specialist referral

18. WRITTEN ASTHMA ACTION PLAN

Every patient should ideally have an individualized written/digital action plan.

Vaccination: Patients with asthma should receive routine age- and risk-appropriate vaccinations. Particular attention should be given to annual influenza vaccination, COVID-19 vaccination, and pneumococcal vaccination when indicated, because respiratory infections are important triggers of asthma exacerbations. Vaccination should generally be deferred only during moderate/severe acute illness;