What is the management of hypoxic hypercapnic respiratory failure?

Management of Hypoxic Hypercapnic Respiratory Failure

The management of hypoxic hypercapnic respiratory failure should begin with controlled oxygen therapy targeting saturations of 88-92%, followed by non-invasive ventilation (NIV) when pH <7.35 and pCO2 >6.5 kPa persist despite optimal medical therapy.

Initial Assessment and Management

Oxygen Therapy

• Initiate controlled oxygen therapy with target saturation of 88-92% for all patients with hypoxic hypercapnic respiratory failure 1
• Use Venturi masks or nasal cannulae to deliver precise oxygen concentrations
• Avoid excessive oxygen use in patients with COPD as this increases risk of worsening respiratory acidosis 1
• If patient is on long-term oxygen therapy (LTOT), consider patient-specific target ranges 1

Medical Therapy

• Administer appropriate medications based on underlying cause:
  • For COPD: Bronchodilators, systemic corticosteroids, antibiotics if indicated
  • For neuromuscular disorders: Address specific underlying conditions
  • For obesity hypoventilation syndrome: Optimize medical management

Blood Gas Monitoring

• Obtain arterial blood gas (ABG) measurement prior to initiating NIV 1
• Recheck ABGs after 30-60 minutes of oxygen therapy to assess response 1
• Monitor for worsening PCO2 or falling pH even if initial PCO2 was normal 1

Non-Invasive Ventilation (NIV)

Indications for NIV

• Start NIV when pH <7.35 and pCO2 >6.5 kPa persist despite optimal medical therapy 1
• Severe acidosis alone does not preclude a trial of NIV if appropriate monitoring and expertise are available 1

NIV Setup

1. Decide on management plan if NIV fails and document in notes 1
2. Select appropriate location (ICU, HDU, or respiratory ward)
3. Explain NIV to the patient
4. Select appropriate mask and ventilator
5. Initial ventilator settings for hypercapnic respiratory failure 1:
   • Mode: Pressure support or pressure control
   • IPAP: Start at 12-15 cmH2O, titrate as needed
   • EPAP: Start at 4-5 cmH2O
   • Backup rate: 12-15 breaths/min
6. Attach pulse oximeter for continuous monitoring
7. Hold mask in place initially to familiarize patient before securing
8. Add supplemental oxygen if SpO2 <85% 1

Monitoring During NIV

• Clinical assessment and repeat ABG at 1-2 hours 1
• Adjust settings if necessary based on patient comfort and ABG results
• Monitor for signs of NIV failure:
  • Worsening physiological parameters (particularly pH and respiratory rate)
  • Deteriorating level of consciousness
  • Inability to clear secretions
  • Patient intolerance

Duration of NIV

• Maximize time on NIV in first 24 hours based on patient tolerance 1
• Gradually taper NIV use over 2-3 days as patient improves 1
• NIV can be discontinued when pH and pCO2 normalize and patient's condition improves 1

Escalation of Care

Indications for Intubation and Invasive Mechanical Ventilation (IMV)

• Failure to improve or worsening despite optimal NIV
• Severe acidosis not responding to NIV
• Decreased level of consciousness (GCS <8)
• Inability to protect airway or clear secretions
• Hemodynamic instability

Important Caveat

• The use of NIV should not delay escalation to IMV when appropriate 1
• Continued use of NIV when the patient is deteriorating increases mortality 1

Special Considerations

Sleep-Disordered Breathing

• If sleep-disordered breathing pre-dates or complicates AHRF, use a controlled mode of NIV overnight 1

Sedation

• Use sedation with caution and only with close monitoring 1
• For agitated/distressed patients, intravenous morphine 2.5-5 mg may improve NIV tolerance 1

Advanced Technologies

• Extracorporeal CO2 removal (ECCO2R) may be considered in specialized centers for patients failing conventional therapy, though evidence is limited 1, 2

Discharge Planning and Follow-up

• Review reasons for admission and identify preventable factors
• Discuss future care planning with patient and family
• Arrange early specialist review and pulmonary rehabilitation if appropriate
• Provide warning card/inform ambulance services about need for controlled oxygen therapy
• Consider referral to home NIV service for appropriate patients (neuromuscular disease, suspected sleep-disordered breathing) 1

Common Pitfalls to Avoid

1. Administering excessive oxygen leading to worsening hypercapnia
2. Delaying initiation of NIV when indicated
3. Using inadequate ventilatory pressures during NIV
4. Failing to recognize NIV failure and delaying intubation when needed
5. Not considering underlying causes that may require specific treatment
6. Sudden cessation of oxygen therapy, which can cause life-threatening rebound hypoxemia 1

Remember that the management approach should be guided by regular reassessment of the patient's clinical status and blood gas parameters, with appropriate escalation of care when needed.