What is the management of acute respiratory failure?

Management of Acute Respiratory Failure

Acute respiratory failure requires immediate controlled oxygen therapy targeting 88-92% saturation, followed by non-invasive ventilation (NIV) when pH <7.35 and pCO2 >6.5 kPa persist despite optimal medical therapy, with early ICU consultation for patients at risk of requiring intubation. 1, 2

Immediate Clinical Assessment

Perform rapid evaluation focusing on three critical parameters:

• Oxygenation status: Target oxygen saturation of 88-92% in all patients with acute hypercapnic respiratory failure 1, 2
• Acid-base status: Obtain arterial blood gas analysis immediately to classify respiratory failure type and severity 1, 2
• Evidence of organ dysfunction: Assess work of breathing, mental status, vital signs, and presence of comorbidities 1, 2

Recheck arterial blood gases 1-2 hours after initiating oxygen therapy to ensure adequate oxygenation without worsening hypercapnia 2, 3

Oxygen Therapy

Administer controlled oxygen via Venturi mask (24-28%) for patients at risk of hypercapnic respiratory failure, entraining oxygen as close to the patient as possible 2, 3

Monitor oxygen saturation continuously for at least 24 hours after initiating treatment 2, 3, 4

Non-Invasive Ventilation (NIV)

Initiate NIV when pH <7.35 and pCO2 >6.5 kPa persist despite optimal medical therapy, as this reduces mortality and need for intubation 2, 4

NIV Implementation Protocol:

• Start with low pressures (IPAP 10-12 cmH2O, EPAP 4-5 cmH2O) and gradually increase as tolerated 2
• Select appropriate mask interface based on patient comfort and facial anatomy, ensuring proper fit to minimize leaks 2
• Provide NIV for as many hours as possible during the first 24 hours, allowing breaks only for medications, meals, and physiotherapy 2
• Measure arterial blood gases after 1-2 hours of NIV and again after 4-6 hours if earlier sample showed little improvement 2, 4

If no improvement in PaCO2 and pH after 4-6 hours despite optimal ventilator settings, discontinue NIV and evaluate for invasive ventilation 2

Critical Organizational Requirements:

The BTS/ICS guidelines emphasize that NIV facilities must have level 2 staffing equivalence with one nurse for every 2 NIV cases, especially during the first 24 hours 1. This is a common pitfall—UK national audits show notably worse outcomes than trial data due to inadequate facilities and delayed ventilatory support 1.

10-20% of NIV-treated patients should be managed in HDU/ICU, requiring good operational links between admitting teams and critical care 1

High-Flow Nasal Oxygen (HFNO)

Consider HFNO rather than NIV for acute hypoxemic respiratory failure, as it may be better tolerated and results in modest reduction in hospital-acquired pneumonia 1, 2, 3

HFNO is recommended over conventional oxygen therapy for postextubation acute hypoxemic respiratory failure 1, 2

However, low-certainty evidence shows HFNO compared with NIV may slightly increase mortality (ARD 1.7%) and reintubations (ARD 2.0%) in postextubation patients 1

Pharmacological Management

Administer steroids, bronchodilators, and antibiotics as indicated during the immediate assessment phase 1

Deliver nebulized bronchodilators during breaks from NIV, or via nebulizer inserted into ventilator tubing if patient is NIV-dependent 2, 4

For agitated/distressed patients on NIV, consider intravenous morphine 2.5-5 mg (with or without benzodiazepine) to improve tolerance 2

Invasive Mechanical Ventilation

Consider invasive ventilation when:

• NIV fails as initial therapy after 4-6 hours 2, 4
• Patient has contraindications to NIV 2, 4
• Risk/benefit analysis favors better outcome with invasive ventilation 2, 4

When using invasive ventilation, set tidal volumes of 6 mL/kg ideal body weight with positive end-expiratory pressure, limiting peak/plateau pressures below 30 cmH2O 2

Critical Pitfall to Avoid:

Avoid prolonged ineffective NIV before intubation, as delayed intubation is associated with worse outcomes 1. The BTS/ICS guidelines identify "lack of progression from NIV to IMV" as a major deficiency in UK practice 1.

Monitoring for Treatment Failure

Assess for deterioration indicators:

• Worsening blood gases despite therapy 2
• Deteriorating mental status or work of breathing 2
• Development of complications (pneumothorax, aspiration pneumonia, mask pressure sores) 2
• Intolerance of ventilatory support 2

Patients with more severe acidosis (pH <7.30) should be managed in HDU or ICU rather than general wards 2

Recovery and Discharge Planning

Perform spirometric testing and arterial blood gas analysis while breathing air before discharge for all patients treated with NIV for acute hypercapnic respiratory failure 2, 4

Arrange early specialist review, pulmonary rehabilitation, and smoking cessation as indicated 1

Provide warning card and inform ambulance services regarding future need for controlled oxygen therapy 1

Refer patients with spinal cord lesions, neuromuscular disease, chest wall deformity, or morbid obesity who develop acute hypercapnic respiratory failure to centers providing long-term ventilation at home 2