COPD Exacerbations

Question 1

Epidemiology

Answer 1

->In-hospital mortality: 6–8% (higher in men).
->ICU admissions: AECOPD with RF = mortality ~11%.

Question 2

Pathophysiology of Respiratory Failure

Answer 2

->Not fully understood; any ↑ work of breathing may precipitate RF.
->RF may be Type 1 (hypoxic) or Type 2 (hypercapnic).

->Hypercapnia mechanisms: → due to V/Q mismatch, airflow limitation, respiratory muscle fatigue.

->Respiratory failure occurs due to
-Progressive airflow obstruction
-Hhyperinflation
-↑ WOB,
-Respiratory muscle fatigue.

->Poor prognostic features:
* Hypercapnia & Need for NIV

Question 3

Precipitants of Acute Respiratory Failure in COPD

Answer 3

->Viral + bacterial infections = 50–70% of exacerbations.
* Viral: rhinovirus, RSV.
* Bacterial: H. influenzae, S. pneumoniae,
— severe cases: Pseudomonas, Stenotrophomonas.

->Environmental triggers: smoke, fumes, air pollution.

->GORD strongly associated; mechanism unclear.

->Comorbidities misdiagnosed as AECOPD: PE, pneumonia, pneumonitis, heart failure.

• PE: found in 16% of COPD patients with exacerbation.

Question 4

Indications for ICU Admission

Answer 4

• Dyspnoea not responding to ED therapy.
• Altered mental status: confusion, drowsiness, coma.
• Persistent / worsening hypoxaemia.
• Severe / worsening hypercapnia or acidosis.
• Haemodynamic instability.

Question 5

Prognostic Indicators (on ICU Admission)

Answer 5

DECAF Score (Validated Mortality Predictor)
* Dyspnoea
* Eosinophilia
* Consolidation
* Acidaemia
* Atrial fibrillation

→ Outperforms CURB-65 for COPD + pneumonia.

Question 6

Prognostic Indicators (on ICU Admission) cont..

Answer 6

Other Predictors
* Age
* Low FEV₁
* Degree of hypoxaemia / hypercapnia
* Frequent past exacerbations
* Comorbid cardiovascular disease
* Prior hospitalisations

=>“Late failure” >48 hrs after presentation → very poor prognosis

Question 7

Prognostic Indicators (on ICU Admission) cont..

Answer 7

->Chronic Hypercapnic Respiratory Failure
at particularly high risk.
* Base excess (marker of chronic hypercapnia) = strong prognosticator.

=>Domiciliary NIV after AECOPD:
* 5-year survival 25%
* NIV after discharge → prolongs time to next admission if persistent hypercapnia at 4 weeks.

Question 8

MANAGEMENT OF ACUTE EXACERBATION OF COPD (AECOPD)

Answer 8

=>General Principles
** * Similar to other respiratory failure, but much greater focus on gas exchange.**
* Address poor respiratory mechanics: dynamic hyperinflation, loss of alveolar volume, impaired ventilation.

->Chronic compensated hypercapnia can rapidly decompensate with increased WOB from:
* poor chest wall mechanics
* malnutrition
* obesity
* myopathy( chronic steroid use)

Question 9

MANAGEMENT OF ACUTE EXACERBATION OF COPD (AECOPD) cont..

Answer 9

=>Corticosteroids
* RCTs show systemic steroids up to 2 weeks helpful
* Improve lung function + dyspnoea over first 72h.
* Reduce hospital stay.

• IV = oral if tolerated.
• No benefit to prolonged >2 weeks.
• Common adverse effect: hyperglycaemia (~15%).
• Nebulised steroids ≈ placebo; inferior to systemic.

Question 10

MANAGEMENT OF ACUTE EXACERBATION OF COPD (AECOPD) cont..
** Bronchodilators**

Answer 10

=>Short-acting β-agonists
* Mainstay therapy
* Rapid bronchodilation.
* Nebuliser vs MDI (with spacer): no superiority, but nebulisers easier in acute setting.
* Parenteral β-agonists not recommended (arrhythmias, ischaemia).

=>Anticholinergics (e.g., ipratropium)
* Equally effective; combination therapy (β-agonist + anticholinergic) = superior bronchodilation.

=>Methylxanthines (theophylline)
* Not recommended in the acute setting (lack of additional benefit + ↑ nausea, vomiting, tremor, palpitations, arrhythmias).

Question 11

MANAGEMENT OF ACUTE EXACERBATION OF COPD (AECOPD) cont..
Antibiotics

Answer 11

=>In mechanically ventilated severe exacerbations, antibiotics
↓ mortality
↓ MV duration
↓ hospital LOS.

=>Recommended agents:
* Amoxicillin–clavulanate
* Cephalosporins
* Macrolides
-> Duration: 3–7 days[GOLD]

->Broader agents (fluoroquinolones / β-lactam–β-lactamase inhibitors) for:
* resistant gram-negatives
* recurrent severe exacerbations
* prior Pseudomonas colonisation

Question 12

Mx cont..
Oxygen Therapy

Answer 12

• Maintain adequate oxygenation; most respond to 24–28% O₂.
• CO₂ retention on FiO₂ > 30% due to V/Q mismatch + Haldane effect.
• Controlled oxygen therapy ↓ hypercapnia, acidosis, mortality.
• High-flow face mask or nasal device allows better titration

Question 13

Mx cont..
Assisted Ventilation

Answer 13

=>Non-Invasive Ventilation (NIV)
* Indicated in type 2 RF with pH < 7.32 (definite) or pH < 7.35 (probable).
* Predictors of need for NIV: pH & hypercapnia > hypoxia.

=>CI for NIV
Contraindications / failure risks:
* Respiratory arrest
* ↓ consciousness
* Cardiovascular collapse
* Excessive secretions → aspiration risk
* Vomiting
* Facial trauma
* Severe obesity
* Recent facial surgery
* Burns

Answer 14

Evidence
* RCTs: NIV ↓ intubation by up to 42%, ↓ mortality, ↓ nosocomial complications.
* NIV outside ICU is effective when delivered by trained staff– Training of staff more important than location of NIV
* Early NIV failure m/c in
late initiation, intolerance, inadequate tidal augmentation, or triggering issues.

Question 15

Monitoring Response

Answer 15

Assess ABGs, RR, work of breathing, haemodynamics.
* Response within 1–4 hours predicts success.

NIV Failure → intubation
* Consider early intubation in:
* Severe encephalopathy
* Arrest
* Progressive hypercapnia
* Haemodynamic instability

Question 16

Invasive Mechanical Ventilation

Answer 16

• Post-intubation: correct hypoxaemia with modest FiO₂.
• Respiratory acidosis corrected slowly using low RR + prolonged expiratory time.
• Limit auto-PEEP from air trapping (major haemodynamic compromise risk), Anticipate DHI-> prolonged Exp time,
• First 12–24 hours may require paralysis to minimise dyssynchrony.
• High airway pressures → complications: circulatory collapse, barotrauma, pneumothorax.

=>Pressure vs volume control
* Evidence unclear; pressure-limited ventilation safer when risk of dynamic hyperinflation is high.

Question 17

Invasive Mechanical Ventilation
cont..

Answer 17

Weaning
* Up to 20–30% of COPD pts fail traditional SBT criteria.
* Failure to wean due to expiratory flow limitation.
* Evidence supports extubation to NIV after 48h MV → ↓ reintubation, ↓ mortality.
* High-flow nasal cannula (HFNC) ≈ NIV for reintubation prevention.

Question 18

SUMMARY

Answer 18

• AECOPD carries high ICU mortality and poor 1-year outcomes.
• Steroids, bronchodilators, controlled O₂, and early NIV are foundational.
• Avoid intubation if possible; when required, anticipate dynamic hyperinflation.
• Extubation to NIV or HFNC improves outcomes.
• Identify precipitating factors (infection, PE, cardiac disease).