What is the treatment for respiratory acidosis?

Treatment of Respiratory Acidosis

The cornerstone of treating respiratory acidosis is controlled oxygen therapy targeting 88-92% saturation combined with optimal medical management, followed by non-invasive ventilation (NIV) if pH remains <7.35 despite initial therapy. 1

Immediate Management: Controlled Oxygen Therapy

Target oxygen saturation of 88-92% using controlled delivery devices to prevent worsening hypercapnia while avoiding dangerous hypoxia. 2, 1 This approach reduces mortality by 58% in COPD patients compared to high-concentration oxygen. 2

Oxygen Delivery Methods:

• Use 24% Venturi mask at 2-3 L/min or 28% Venturi mask at 4 L/min as first-line oxygen delivery. 1
• Nasal cannulae at 1-2 L/min are an acceptable alternative. 1
• Never use high-concentration oxygen (>35%) as this worsens respiratory acidosis and increases mortality. 1, 3
• Recheck arterial blood gases within 60 minutes after initiating oxygen therapy. 1

Critical pitfall: If excessive oxygen has already been administered, step down gradually to controlled delivery rather than abruptly discontinuing oxygen. 3

Medical Therapy (First-Line Treatment)

Bronchodilators

• Administer nebulized salbutamol 2.5-5 mg or ipratropium bromide 0.25-0.5 mg every 4-6 hours immediately. 1
• Drive nebulizers with compressed air (not oxygen) if PaCO₂ is elevated, while continuing supplemental oxygen at 1-2 L/min via nasal prongs during nebulization. 1

Corticosteroids

• Give prednisolone 30 mg daily orally or hydrocortisone 100 mg IV for 7-14 days. 1
• Systemic corticosteroids are standard therapy regardless of acidosis severity. 1

Antibiotics

• Prescribe antibiotics if signs of infection are present (increased sputum purulence, volume, or dyspnea). 1
• First-line: amoxicillin or tetracycline unless previously ineffective. 1

Non-Invasive Ventilation (NIV): The Critical Intervention

Initiate bilevel NIV when pH <7.35 persists after initial medical therapy and controlled oxygen, particularly if pH <7.26 or respiratory distress continues. 2, 1 This is where the strongest evidence base exists for NIV benefit. 2

Specific Indications for NIV:

• pH <7.35 with PaCO₂ >6.5 kPa (49 mmHg) and respiratory rate >23 breaths/min despite optimal treatment. 2, 1
• pH 7.25-7.35 represents the sweet spot where NIV has the strongest evidence for reducing mortality, intubation rates, ICU length of stay, and infectious complications. 2

NIV Implementation:

• Use bilevel positive pressure ventilation (BiPAP) as the preferred modality. 1
• Start NIV promptly—delays worsen outcomes. 1
• Response should be seen within 1-4 hours (improvement in pH, respiratory rate, or both). 2
• Recheck arterial blood gases after 1-2 hours of NIV, then again at 4-6 hours if initial improvement is minimal. 2, 1

NIV Failure Criteria:

If no improvement in PaCO₂ and pH after 4-6 hours despite optimal NIV settings, discontinue NIV and consider invasive mechanical ventilation. 2, 1

Stratification by Acidosis Severity

Mild Hypercapnia Without Acidosis (pH >7.35):

• NIV is NOT recommended in patients with hypercapnia who are not acidotic. 2
• Focus on medical therapy and controlled oxygen (88-92% saturation). 2

Moderate Acidosis (pH 7.25-7.35):

• This is the primary indication for NIV with the strongest evidence base. 2
• Patients should be managed in a designated area with staff experienced in NIV. 2

Severe Acidosis (pH <7.25):

• Manage in higher dependency area (HDU or ICU) with immediate NIV availability. 2
• Consider NIV as alternative to first-line intubation if no contraindications exist. 2
• Have a clear plan for escalation to invasive ventilation if NIV fails. 2

Invasive Mechanical Ventilation

Consider intubation and invasive ventilation if pH remains <7.26 with rising PaCO₂ despite NIV and optimal medical therapy. 1

Factors Favoring Intubation:

• Demonstrable reversible cause (pneumonia, drug overdose). 1
• First episode of respiratory failure. 1
• Acceptable baseline quality of life and functional status. 1
• Respiratory arrest or apneic episodes. 2
• Psychomotor agitation requiring sedation. 2
• Hemodynamic instability (heart rate <60 beats/min, systolic BP <80 mmHg). 2

Monitoring During Treatment

• Continuous oxygen saturation monitoring for at least 24 hours after commencing NIV. 2
• Arterial blood gases should be measured if clinical deterioration occurs at any time. 1
• Patients receiving NIV should be reviewed regularly to assess response and optimize ventilator settings. 2
• Breaks from NIV should be made for medications, physiotherapy, and meals, but patients showing benefit should be ventilated as much as possible during the first 24 hours. 2

Before Discharge

• Measure arterial blood gases on room air before discharge to guide need for long-term oxygen therapy assessment. 1
• Perform spirometric testing before discharge. 2
• All patients with spinal cord lesions, neuromuscular disease, chest wall deformity, or morbid obesity who develop acute hypercapnic respiratory failure should be referred to a center providing long-term ventilation at home. 2