What is the treatment for respiratory acidosis?

Treatment of Respiratory Acidosis

For acute-on-chronic respiratory acidosis (pH <7.35 despite optimal medical therapy), initiate bilevel non-invasive ventilation (NIV) immediately while targeting oxygen saturation of 88-92%—this approach reduces mortality, intubation rates, ICU length of stay, and infectious complications. 1, 2

Immediate First-Line Management: Controlled Oxygen Therapy

Target oxygen saturation of 88-92% using controlled delivery methods (24-28% Venturi mask or 1-2 L/min nasal cannula), as uncontrolled high-flow oxygen increases mortality by 58% in COPD patients and worsens hypercapnia. 1, 2

• Recheck arterial blood gases within 30-60 minutes after initiating oxygen therapy to assess response and avoid CO2 retention. 2, 3
• Never abruptly discontinue oxygen if excessive oxygen has already been given—step down gradually while maintaining 88-92% saturation. 4
• 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. 2

Medical Therapy (Must Be Optimized Before or Concurrent with NIV)

Bronchodilators

• Administer nebulized salbutamol 2.5-5 mg or ipratropium bromide 0.25-0.5 mg every 4-6 hours immediately. 2

Corticosteroids

• Give prednisolone 30 mg daily orally or hydrocortisone 100 mg IV for 7-14 days as standard therapy for acute exacerbations. 2

Antibiotics

• Prescribe antibiotics (first-line: amoxicillin or tetracycline) if signs of infection are present (increased sputum purulence, volume, or dyspnea). 2

Non-Invasive Ventilation: The Cornerstone of Treatment

When to Initiate NIV

Start bilevel NIV when pH remains <7.35 (particularly if pH <7.26) with PaCO2 >6.5 kPa and respiratory rate >23 breaths/min after 1 hour of optimal medical therapy and controlled oxygen. 1, 2

• The strongest evidence base supports NIV for patients with pH 7.25-7.35, where it reduces dyspnea, immediate intubation need, ICU/hospital length of stay, and improves survival. 1
• For more severe acidosis (pH <7.25), initiate NIV in a higher dependency area (HDU or ICU) without waiting for chest X-ray. 1
• Response to NIV is almost universally seen within 1-4 hours if the patient will respond—improvement in pH or respiratory rate (or both) predicts successful outcome. 1

NIV Implementation Details

• Use bilevel positive pressure ventilation (BiPAP) as the preferred modality. 2
• Ventilate for as much time as possible during the first 24 hours in patients showing benefit. 1
• Recheck arterial blood gases after 1-2 hours of NIV, then again at 4-6 hours if initial improvement is minimal. 1, 2
• If no improvement in PaCO2 and pH after 4-6 hours despite optimal ventilator settings, discontinue NIV and proceed to invasive mechanical ventilation. 1, 2

Critical Pitfall to Avoid

Do NOT use NIV in patients with hypercapnia who are not acidotic (pH >7.35)—pooled analysis shows no mortality benefit and potential for harm in this population. 1

Invasive Mechanical Ventilation

Consider intubation when pH remains <7.26 with rising PaCO2 despite NIV and optimal medical therapy, particularly if there is a demonstrable reversible cause, first episode of respiratory failure, or acceptable baseline quality of life. 2

• Two studies comparing NIV directly with invasive ventilation in patients with mean pH 7.20 showed similar survival, but successful NIV resulted in shorter ICU/hospital stay, fewer complications, and reduced need for supplemental oxygen. 1
• Important exclusions for NIV (requiring immediate intubation): respiratory arrest, apneic episodes, psychomotor agitation requiring sedation, heart rate <60 beats/min, systolic blood pressure <80 mmHg. 1

Alternative Pharmacologic Support: Doxapram

Consider IV doxapram as a temporizing measure for 24-36 hours in patients with pH <7.26 who are not candidates for immediate NIV or intubation. 2

• Arterial blood gases must be drawn at least every 30 minutes during doxapram infusion to prevent development of CO2 retention and worsening acidosis. 3
• Doxapram should be stopped if arterial blood gases deteriorate, and mechanical ventilation should be initiated. 3
• Anticonvulsants (IV short-acting barbiturates), oxygen, and resuscitative equipment should be readily available due to risk of CNS stimulation and seizures. 3

Sodium Bicarbonate: Not Recommended

Do not administer sodium bicarbonate for respiratory acidosis—there are no randomized controlled trials supporting its use, and it carries potential risks without proven benefit. 5

• Hypercapnic acidosis is well tolerated as long as tissue perfusion and oxygenation are maintained. 5
• Low tidal volume ventilation with permissive hypercapnia has beneficial effects in ARDS/ALI that may be negated by alkali administration. 5

Monitoring During Treatment and Recovery

• Monitor oxygen saturation continuously for at least 24 hours after commencing NIV. 1
• Review patients regularly to assess response and optimize ventilator settings. 1
• Measure arterial blood gases on room air before discharge to guide need for long-term oxygen therapy assessment. 2
• All patients treated with NIV for acute hypercapnic respiratory failure should undergo spirometric testing and arterial blood gas analysis while breathing air before discharge. 1