What is the treatment for respiratory failure?

Treatment of Respiratory Failure

The treatment of respiratory failure depends critically on whether it is Type 1 (hypoxemic) or Type 2 (hypercapnic), with non-invasive ventilation being first-line for Type 2 failure with pH <7.35, while high-flow nasal oxygen is preferred over conventional oxygen for Type 1 failure. 1, 2

Initial Assessment and Oxygen Delivery

Type 1 (Hypoxemic) Respiratory Failure

• Immediately administer supplemental oxygen targeting SpO₂ 94-98% using nasal cannula (1-6 L/min) or simple face mask (5-10 L/min) depending on hypoxemia severity 2
• Position the patient semi-recumbent (30-45° head elevation) if hemodynamically stable to optimize ventilation-perfusion matching 2
• Obtain arterial blood gas analysis to confirm Type 1 failure (PaO₂ <60 mmHg with normal or low PaCO₂) and establish monitoring baseline 2, 3

Type 2 (Hypercapnic) Respiratory Failure

• Administer controlled oxygen therapy with target saturation of 88-92% to avoid worsening hypercapnia—this is critical as excessive oxygen can precipitate CO₂ narcosis and respiratory arrest 4
• Obtain ABG immediately showing PaCO₂ >50 mmHg with pH <7.35 to confirm Type 2 failure 3
• Avoid targeting SpO₂ >92% in COPD patients as this worsens V/Q mismatch and hypercapnia 3

Escalation Strategy Based on Response

For Type 1 Respiratory Failure

• If SpO₂ remains <90% despite high-flow oxygen (>6 L/min), escalate to high-flow nasal oxygen (HFNO) at 40-60 L/min, which reduces intubation rates and mortality (absolute risk reduction 15.8%) compared to conventional oxygen 1, 2, 4
• HFNO provides physiologic advantages including improved oxygenation, reduced anatomical dead space, modest positive end-expiratory pressure, and reduced work of breathing 2
• If HFNO fails to maintain adequate oxygenation (SpO₂ <90% or PaO₂ <60 mmHg), consider CPAP or BiPAP, though HFNO is generally better tolerated in pure hypoxemic failure 2

For Type 2 Respiratory Failure

• Non-invasive ventilation (NIV) should be initiated when pH <7.35 and PaCO₂ >6 kPa (45 mmHg) persists despite maximum medical treatment on controlled oxygen therapy 1, 4
• Use BiPAP mode with initial IPAP 10-12 cmH₂O and EPAP 5 cmH₂O 4
• NIV reduces mortality and intubation rates in COPD exacerbations, particularly when pH is 7.25-7.35 1, 4
• Repeat arterial blood gas after 1-2 hours of NIV and again after 4-6 hours if earlier sample showed little improvement 1, 3

Specific Clinical Scenarios

Cardiogenic Pulmonary Edema

• CPAP is first-line therapy for patients with cardiogenic pulmonary edema who remain hypoxic despite maximal medical treatment, as it improves oxygenation, decreases symptoms, and reduces need for intubation 1
• NIV should be reserved for patients in whom CPAP is unsuccessful 1
• Both CPAP and NIPPV reduce the need for tracheal intubation, though insufficient data exist to demonstrate mortality reduction 1

Immunocompromised Patients

• Early NIV is recommended for immunocompromised patients with acute respiratory failure, as it decreases mortality (RR 0.68), need for intubation (RR 0.71), and nosocomial pneumonia rates (RR 0.39) 1
• The recommendation includes both bilevel NIV and early CPAP 1

Neuromuscular Disease and Chest Wall Deformity

• NIV is indicated in acute or acute-on-chronic hypercapnic respiratory failure due to chest wall deformity or neuromuscular disease 1
• NIV is the initial treatment of choice during respiratory infections in neuromuscular disease 4

De Novo Hypoxemic Respiratory Failure/ARDS

• For de novo acute hypoxemic respiratory failure, HFNO may reduce the need for intubation and improve patient comfort compared to conventional NIV 4
• Classify ARDS severity by PaO₂/FiO₂ ratio: mild (200-300 mmHg), moderate (100-200 mmHg), or severe (≤100 mmHg), which guides ventilation strategy 2, 4
• In severe cases with refractory hypoxemia, prepare for invasive mechanical ventilation with lung-protective strategies 4

Acute Asthma

• NIV should not be used routinely in acute asthma 1

Invasive Mechanical Ventilation

Indications for Intubation

• If non-invasive support fails (no improvement in PaCO₂ and pH after 4-6 hours), prepare for invasive mechanical ventilation 3
• Invasive ventilation should be used if acute respiratory failure does not respond to vasodilators, oxygen therapy, and/or CPAP or NIV 1
• Deteriorating conscious level, drowsiness, or confusion indicates impending respiratory failure requiring immediate escalation 2, 3

Ventilator Settings

• Use lung-protective ventilation with tidal volume 6 mL/kg ideal body weight and plateau pressure <30 cmH₂O 2, 4
• For mild ARDS (PaO₂/FiO₂ 200-300 mmHg), use low PEEP strategy (<10 cmH₂O) to avoid hemodynamic compromise 4
• Ventilator settings must accommodate underlying pathophysiology (e.g., longer expiratory time in COPD to minimize intrinsic PEEP) 4

Critical Monitoring Parameters

Work of Breathing Assessment

• Assess respiratory rate (concerning if >30 breaths/min), use of accessory muscles, and ability to speak in full sentences 2, 3
• Monitor for paradoxical chest wall motion or abdominal breathing 3

Serial Blood Gas Monitoring

• Perform serial ABG measurements every 1-2 hours initially, then every 4-6 hours once stable 2, 3
• Recheck ABG within 30-60 minutes after any change in FiO₂ or ventilator settings 3

Mental Status

• Monitor mental status closely as drowsiness or confusion indicates impending respiratory failure requiring immediate escalation 2, 3

Critical Pitfalls to Avoid

• Delaying NIV initiation when pH <7.35 and PaCO₂ >6.0 kPa misses the therapeutic window 4
• Administering high-flow oxygen without monitoring CO₂ can precipitate CO₂ narcosis and respiratory arrest in Type 2 failure 4
• Do not rely on SpO₂ alone to diagnose respiratory failure, as patients with chronic CO₂ retention may have acceptable oxygen saturations despite severe hypercapnia 3
• Failure to improve PaCO₂ and pH after 4-6 hours of NIV indicates treatment failure and need for intubation 3

Documentation Requirements

• Document an individualized treatment plan at initiation, including specific thresholds for escalation and intubation criteria 2
• A decision about tracheal intubation should be made before commencing NIV in every patient and documented in case notes 1