Should patients with type 2 respiratory (resp) failure who are not chronic carbon dioxide (CO2) retainers be placed on scale 2 respiratory support?

Management of Type 2 Respiratory Failure in Non-Chronic CO2 Retainers

Patients with type 2 respiratory failure who are not chronic CO2 retainers should be placed on scale 2 respiratory support, specifically bilevel positive airway pressure (BiPAP), as this is the most appropriate intervention for acute hypercapnic respiratory failure in these patients. 1

Understanding Type 2 Respiratory Failure

Type 2 respiratory failure is characterized by:

• PaCO₂ ≥ 45 mmHg (6 kPa)
• pH < 7.35
• Usually accompanied by hypoxemia (PaO₂ < 60 mmHg) 2

Appropriate Respiratory Support Selection

For Non-Chronic CO2 Retainers:

1. Initial Assessment:

   • Measure arterial blood gases to confirm type 2 respiratory failure
   • Assess respiratory rate and level of consciousness
   • Determine if this is a first presentation or recurrent episode

2. Oxygen Therapy:

   • Start with controlled oxygen therapy
   • Target SpO₂ of 94-98% (not the lower 88-92% range used for chronic CO₂ retainers) 1
   • Use nasal cannulae at 2-6 L/min or simple face mask at 5-10 L/min 1

3. Escalation to NIV:

   • If respiratory acidosis persists (pH < 7.35 and PaCO₂ > 45 mmHg) despite maximal medical treatment and appropriate controlled oxygen therapy, initiate BiPAP 1
   • BiPAP is specifically indicated for type 2 respiratory failure in patients who are not chronic CO₂ retainers 1

Evidence-Based Rationale

The British Thoracic Society and NHS guidelines specifically recommend BiPAP for patients with type 2 respiratory failure who are not chronic CO₂ retainers 1. While CPAP is indicated for hypoxemic respiratory failure, BiPAP is the preferred mode for patients with type 2 respiratory failure regardless of whether they have chronic respiratory disease 1.

For patients who are not chronic CO₂ retainers but develop acute hypercapnia:

• They don't require the lower oxygen saturation targets (88-92%) used for chronic CO₂ retainers 1
• They should receive standard oxygen therapy targeting 94-98% saturation 1
• If they develop respiratory acidosis, they should be escalated to BiPAP rather than continuing with oxygen therapy alone 1

Monitoring and Reassessment

• Closely monitor patients for the first 1-2 hours after initiating BiPAP
• Check arterial blood gases at 1-2 hours after starting BiPAP
• If PaCO₂ and pH have deteriorated after 1-2 hours on optimal settings, consider alternative management plan 1
• If no improvement but no deterioration, continue BiPAP and reassess with repeat arterial blood gases after 4-6 hours 1

Important Caveats

1. Location of Care:

   • Patients with type 2 respiratory failure who are not chronic retainers should be managed in an environment where immediate escalation to invasive ventilation is possible (HDU or ICU) 1
   • This is particularly important as they may deteriorate more rapidly than chronic CO₂ retainers who have developed compensatory mechanisms

2. Contraindications to NIV:

   • Inability to protect airway
   • Severe agitation
   • Hemodynamic instability
   • Recent facial or upper airway surgery

3. Failure of NIV:

   • If pH < 7.25 despite optimal BiPAP settings, consider early intubation 1
   • Non-chronic CO₂ retainers may have less tolerance for prolonged hypercapnia and acidosis

By following this approach, patients with type 2 respiratory failure who are not chronic CO₂ retainers will receive appropriate respiratory support that addresses their specific physiological needs while minimizing the risk of complications.