Management of Respiratory Failure with Acidosis
For patients in respiratory failure with acidosis, immediately initiate controlled oxygen therapy targeting SpO2 88-92% and start non-invasive ventilation (NIV) when pH <7.35 and PaCO2 >6.5 kPa persist after optimal medical therapy. 1
Immediate Assessment and Oxygen Management
Obtain arterial blood gases immediately to confirm respiratory acidosis (pH <7.35 and PCO2 >6.0 kPa) and guide management 1, 2
Initiate controlled oxygen therapy using 24% Venturi mask at 2-3 L/min, 28% Venturi mask at 4 L/min, or nasal cannulae at 1-2 L/min to achieve target SpO2 of 88-92% 1, 3, 2
Avoid excessive oxygen administration as PaO2 above 10.0 kPa increases risk of worsening respiratory acidosis in hypercapnic patients 2, 4
Repeat ABGs after 30-60 minutes of oxygen therapy or sooner if clinical deterioration occurs 1, 3, 2
Optimal Medical Therapy
Administer nebulized bronchodilators (β-agonist and anticholinergic) which can be delivered during NIV or during brief breaks 3
Start systemic corticosteroids with prednisolone 30 mg/day orally or IV hydrocortisone 100 mg if oral route not possible 3
Consider antibiotics if signs of infection are present 3
Consider IV aminophylline (0.5 mg/kg/hour) if not responding to initial treatment 3
Non-Invasive Ventilation Initiation
Start NIV when pH <7.35, PaCO2 ≥6.5 kPa, and respiratory rate >23 breaths/min persist after one hour of optimal medical therapy. 1
For PaCO2 between 6.0-6.5 kPa, consider NIV on a case-by-case basis 1
Severe acidosis alone does not preclude NIV trial in an appropriate area with ready access to intubation capability 1
Begin with bilevel NIV using initial settings of CPAP 4-8 cmH2O and pressure support 10-15 cmH2O 3
Document an individualized escalation plan at treatment initiation specifying measures to take if NIV fails 1
Monitoring and Response Assessment
Continuously monitor oxygen saturation, respiratory rate, and level of consciousness 3
Repeat ABGs after 1-2 hours of NIV initiation to assess improvement in pH and PCO2 1, 3, 2
Improvement in pH and respiratory rate within 1-2 hours predicts successful NIV outcome 1
Worsening pH and respiratory rate indicate need to change management strategy including interface change, ventilator adjustment, or proceeding to intubation 1
Maximize NIV time in first 24 hours depending on patient tolerance 1
Criteria for Escalation to Invasive Mechanical Ventilation
Consider intubation if no improvement or worsening occurs after 1-2 hours of optimized NIV. 3
Specific indications include:
Life-threatening hypoxemia (PaO2/FiO2 <200 mmHg) despite NIV 3
Persistent tachypnea >35 breaths/min despite NIV 3
pH remains <7.25 after initial NIV treatment 3
Impaired consciousness (GCS <8), though successful NIV outcomes have been reported despite impaired consciousness 1
Discontinuation of NIV
Discontinue NIV when pH normalizes, pCO2 improves, and general clinical condition improves 1
Taper daytime NIV use over 2-3 days depending on pCO2 levels before discontinuing overnight 1
Critical Pitfalls to Avoid
Never use sodium bicarbonate for pure respiratory acidosis - there is lack of clinical evidence for net benefit and potential risks including worsening hypercapnia from CO2 generation 5
Do not delay NIV escalation to invasive ventilation when clinically appropriate, as continued NIV use during deterioration increases mortality 1
Monitor for life-threatening hypokalemia during rapid correction of respiratory acidosis, especially with concurrent hypotension and fluid resuscitation 6
Recognize mixed acid-base disorders by calculating anion gap, as metabolic acidosis may coexist with respiratory acidosis 7
Do not attempt full correction of low total CO2 content during first 24 hours as this may cause unrecognized alkalosis due to delayed ventilatory readjustment 8