What are the immediate ventilation support recommendations for a patient experiencing respiratory distress or failure, considering options such as Continuous Positive Airway Pressure (CPAP), Bi-level Positive Airway Pressure (BiPAP), and High Flow Nasal Cannula (HFNC) Airvo?

Ventilation Support Quick Crash Review

Initial Decision Framework: Choosing the Right Support

For acute hypercapnic respiratory failure (pH <7.35), BiPAP/NIV is the first-line intervention and should be initiated immediately unless contraindications exist. 1, 2 For acute hypoxemic respiratory failure without hypercapnia, high-flow nasal cannula (HFNC) is increasingly preferred over NIV and may reduce mortality. 2

Absolute Contraindications to NIV (Any Mode)

Before considering any non-invasive support, verify the patient does NOT have: 1, 2

• Recent facial/upper airway surgery or facial trauma/burns
• Fixed upper airway obstruction
• Active vomiting or recent upper GI surgery
• Inability to protect airway
• Copious respiratory secretions
• Hemodynamic instability

Critical Pre-Treatment Decision

Document whether the patient is a candidate for intubation if non-invasive support fails BEFORE starting any therapy. 1, 2 This decision must be verified with senior staff immediately.

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BiPAP (Bi-level Positive Airway Pressure)

Primary Indications

• COPD exacerbation with respiratory acidosis (pH <7.35, H+ >45 nmol/l) despite maximal medical therapy - this is the strongest evidence-based indication 1, 2
• Acute-on-chronic hypercapnic respiratory failure from chest wall deformity or neuromuscular disease 1
• Decompensated obstructive sleep apnea with respiratory acidosis 1
• Post-extubation respiratory failure in COPD patients 1

Initial Settings

Start with IPAP 8-12 cmH₂O and EPAP 3-5 cmH₂O, titrating up based on response 3

Location of Care

• pH 7.30-7.35: Respiratory ward with appropriate monitoring 2
• pH <7.30: HDU/ICU mandatory 2

Interface Selection

• Use full-face mask initially in acute setting 1, 2
• Switch to nasal mask after 24 hours as patient improves 1

Monitoring Timeline

• Check arterial blood gases at 1-2 hours - lack of improvement in pH, PaCO₂, or PaO₂ at this timepoint predicts failure 1, 2
• Expected response: increased pH, decreased PaCO₂ within 1-4 hours 1, 4
• If no improvement by 4-6 hours, prepare for intubation 1

Success Rates

• Acute hypercapnic respiratory failure: 80% success rate (20/25 patients) 4
• Hypoxemic respiratory failure: Only 48% success rate (15/31 patients) - consider HFNC instead 4

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CPAP (Continuous Positive Airway Pressure)

Primary Indications

• Cardiogenic pulmonary edema remaining hypoxic despite maximal medical treatment - strongest indication 1
• Diffuse pneumonia with persistent hypoxemia 1
• Chest wall trauma with hypoxemia despite adequate analgesia 1

Settings

• Start at 10 cmH₂O with FiO₂ 0.6 1
• Can escalate to 12-15 cmH₂O if needed 1
• Some guidelines suggest up to 15-20 cmH₂O for severe cases 1

Target Oxygen Saturation

• Standard patients: SpO₂ 94-96% 1
• COPD/hypercapnic risk: SpO₂ 88-92% 1, 5

Key Limitation

CPAP cannot be used in patients who are not spontaneously breathing - these patients need BiPAP or intubation 1

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HFNC/Airvo (High-Flow Nasal Cannula)

Primary Indications

• De novo acute hypoxemic respiratory failure - superior to NIV with mortality benefit 2
• Post-extubation prophylaxis in low-risk patients 1
• Alternative when BiPAP/CPAP not tolerated 6
• Less severe ARDS patients as initial trial 1

Initial Settings Algorithm

Standard Setup: 5

• Flow rate: 40-50 L/min (can range 35-60 L/min)
• Temperature: 37°C
• FiO₂: Titrate to achieve SpO₂ target

Context-Specific Adjustments:

• Hypoxemic respiratory failure: Start higher (50-60 L/min) for greater PEEP effect 5
• Post-extubation: 35-50 L/min typically sufficient 5
• Hypercapnic failure: Consider NIV first; if not tolerated, HFNC at 35-60 L/min 5

Titration Protocol

Flow Rate: 5

• Increase by 5-10 L/min if work of breathing increases
• Decrease by 5-10 L/min if patient discomfort
• Maximum typically 60 L/min (some patients cannot tolerate >40-50 L/min)

FiO₂: 5

• Adjust in 5-10% increments
• Target SpO₂ 94-98% (non-hypercapnic patients)
• Target SpO₂ 88-92% (hypercapnic risk patients)

Monitoring Parameters

Assess at 30-60 minutes after initiation: 5

• Respiratory rate (should decrease)
• Work of breathing (accessory muscle use)
• Oxygen saturation
• Patient comfort

Common Complication: Bloatedness

Management Strategy: 6

• Titrate flow down in 5-10 L/min increments while monitoring SpO₂
• Elevate head of bed 30-45 degrees
• Encourage mouth closure during therapy
• Consider simethicone if persistent
• If bloating significantly impacts comfort/nutrition, consider switching to conventional oxygen or NIV

Pediatric Considerations

• Weight ≤10 kg: Start ≥1 L/kg/min 5
• Weight >10 kg: Start ≥10 L/min 5

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Comparative Effectiveness

HFNC vs NIV in Hypoxemic Failure

HFNC is increasingly preferred for de novo hypoxemic respiratory failure based on mortality benefit 2. However, NIV remains superior for hypercapnic respiratory failure with 46% mortality reduction and 65% reduction in intubation rates 2.

BiPAP vs CPAP Selection

• Use BiPAP for: Type 2 respiratory failure, COPD, poor respiratory drive, need for backup rate 1
• Use CPAP for: Pure hypoxemic failure, cardiogenic pulmonary edema, spontaneously breathing patients 1

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Post-Extubation Support Strategy

Prophylactic Approach (High-Risk Patients)

Use NIV immediately after extubation for 24-48 hours in high-risk patients (age >65, heart failure, chronic lung disease), especially if hypercapnic 1. This reduces acute respiratory failure and reintubation rates.

Prophylactic Approach (Low-Risk Patients)

Use HFNC for hypoxemic patients at low risk of reintubation 1

Therapeutic Approach (Established Post-Extubation Failure)

Do NOT use NIV for established post-extubation respiratory failure except in COPD patients or obvious cardiogenic pulmonary edema - it delays necessary reintubation 1

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Critical Pitfalls to Avoid

Delayed Intubation

The most dangerous error is continuing non-invasive support when it is clearly failing 2. Delayed intubation after failed NIV is associated with respiratory deterioration, cardiac arrest, and increased mortality.

Inadequate Monitoring

Continuous monitoring must include: 2

• Pulse oximetry
• Respiratory rate
• Heart rate
• Patient comfort and conscious level
• ABG at 1-2 hours

Wrong Modality Selection

• Using NIV for pure hypoxemic failure when HFNC would be superior 2
• Using HFNC first-line for hypercapnic failure when BiPAP has proven mortality benefit 2
• Attempting NIV in patients with copious secretions or inability to protect airway 1, 2

Inadequate Oxygen Titration

Avoid excessive oxygen - target SpO₂ 88-92% in hypercapnic patients to prevent worsening CO₂ retention 1, 5. For non-hypercapnic patients, target 94-98% 5.

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ARDS-Specific Considerations

Non-invasive support with close monitoring is reasonable in less severely ill ARDS patients 1. However, if PaO₂/FiO₂ remains <150 mmHg despite non-invasive support, intubation with lung-protective ventilation, prone positioning, and neuromuscular blockade should be strongly considered 1.

For severe ARDS (PaO₂/FiO₂ ≤100 mmHg), non-invasive support frequently fails and early intubation is often necessary 1.