What is the management of respiratory failure?

Management of Respiratory Failure

The management of respiratory failure requires prompt identification of the underlying cause and implementation of appropriate respiratory support, with non-invasive ventilation (NIV) being the first-line intervention for many patients with hypercapnic respiratory failure, while invasive mechanical ventilation should be considered early for those with severe hypoxemic failure or when NIV is contraindicated. 1

Types of Respiratory Failure and Initial Assessment

Classification:

• Type 1 (Hypoxemic): PaO₂ < 60 mmHg with normal or low PaCO₂
• Type 2 (Hypercapnic): PaCO₂ > 45 mmHg with or without hypoxemia

Common Causes:

• Type 1: Pneumonia, ARDS, pulmonary edema, pulmonary embolism
• Type 2: COPD exacerbation, neuromuscular disorders, chest wall deformities, central respiratory depression

Initial Management Steps:

1. Oxygen therapy:

   • Target saturation 94-98% for most patients
   • Target saturation 88-92% for patients at risk of hypercapnic respiratory failure (e.g., COPD) 2
   • Select appropriate delivery device based on severity:
     • Nasal cannula (1-6 L/min) for mild hypoxemia
     • Simple face mask (5-10 L/min) for moderate hypoxemia
     • Reservoir mask (15 L/min) for severe hypoxemia

2. Positioning:

   • Position patient upright if tolerated to improve respiratory mechanics
   • Consider prone positioning for severe hypoxemia

3. Treat underlying cause:

   • Bronchodilators for bronchoconstriction
   • Antibiotics for infection
   • Diuretics for pulmonary edema (if peripheral edema and raised JVP) 1

Non-Invasive Ventilation (NIV)

Indications for NIV:

• COPD exacerbation with respiratory acidosis (pH < 7.35, PaCO₂ > 45 mmHg)
• Chest wall deformity, neuromuscular disorders
• Cardiogenic pulmonary edema unresponsive to CPAP 1

Patient Selection for NIV:

• Respiratory acidosis (PaCO₂ > 45 mmHg) despite maximal medical treatment
• Able to protect airway and clear secretions
• Cooperative and able to tolerate mask
• Hemodynamically stable

NIV Protocol 1:

1. Decide on management plan if NIV fails
2. Determine appropriate setting (ICU, HDU, or respiratory ward)
3. Explain procedure to patient
4. Select appropriate mask and fit to patient
5. Initial settings for bi-level pressure support:
   • IPAP: 10-12 cmH₂O (increase as tolerated)
   • EPAP: 4-5 cmH₂O
   • Backup rate: 12-15 breaths/min
6. Monitor oxygen saturation continuously
7. Add supplemental oxygen if SpO₂ < 85%
8. Check arterial blood gases after 1-2 hours
9. Adjust settings as needed

Monitoring During NIV:

• Continuous pulse oximetry
• Respiratory rate and work of breathing
• Level of consciousness
• Arterial blood gases at 1-2 hours and as needed
• Patient comfort and mask fit

Invasive Mechanical Ventilation

Indications for Intubation and Mechanical Ventilation:

• Failure of NIV (deteriorating pH and PaCO₂ after 1-2 hours on optimal settings)
• Severe hypoxemia despite high-flow oxygen
• Inability to protect airway or clear secretions
• Altered mental status
• Hemodynamic instability
• Respiratory arrest 1

Factors to Consider When Deciding on Invasive Ventilation 1:

• First episode of respiratory failure
• Potentially reversible cause (e.g., pneumonia)
• Acceptable quality of life or activity level
• Patient's wishes and advance directives

Ventilation Strategy:

• Lung-protective ventilation:
  • Low tidal volumes (6 mL/kg ideal body weight)
  • Plateau pressure ≤30 cmH₂O
  • Appropriate PEEP to prevent alveolar collapse
• Consider permissive hypercapnia if needed

Special Considerations

COPD Exacerbation Management 1:

1. Bronchodilators:

   • β-agonist (salbutamol 2.5-5 mg or terbutaline 5-10 mg) or
   • Anticholinergic (ipratropium bromide 0.25-0.5 mg)
   • For severe exacerbations, both may be administered
   • Continue for 24-48 hours or until clinical improvement

2. Corticosteroids:

   • Prednisolone 30 mg/day or hydrocortisone 100 mg IV if oral route not possible
   • 7-14 day course

3. Consider IV methylxanthines:

   • Aminophylline 0.5 mg/kg/hour by continuous infusion
   • Monitor blood levels daily

4. Antibiotics if indicated

Neuromuscular Disease Management 1:

1. Consider mouthpiece ventilation (MPV) as an alternative to NIV
2. Early consideration of tracheostomy for progressive disease
3. Optimize secretion management

SARS/Severe Respiratory Infections 1:

1. Avoid aerosol-generating procedures when possible
2. Early intubation rather than CPAP/NIV to reduce infection risk
3. Use negative pressure rooms for intubation and ventilation
4. Consider moderate doses of steroids (prednisolone 30-40 mg/day) for severely ill patients with PaO₂ < 10 kPa or O₂ saturation < 90% on air

Advanced Therapies for Refractory Respiratory Failure

High-Flow Nasal Oxygen (HFNO):

• Consider as alternative to NIV in hypoxemic respiratory failure without hypercapnia 2

Extracorporeal Membrane Oxygenation (ECMO):

• Consider for patients with severe respiratory failure unresponsive to conventional therapy 3
• Allows for ultra-protective ventilation strategies

Common Pitfalls to Avoid

1. Delayed recognition of respiratory failure - Monitor high-risk patients closely
2. Inappropriate oxygen therapy - Excessive oxygen in COPD can worsen hypercapnia
3. Delayed escalation of care - Have clear criteria for NIV failure and intubation
4. Inadequate monitoring - Continue monitoring even if initial assessment is reassuring
5. Missing cardiac causes - Consider cardiac etiology, especially in elderly or diabetic patients 2

Remember that respiratory failure is a medical emergency requiring prompt intervention. Early consultation with critical care providers is recommended for patients likely to require intubation 1.