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Acute Hypoxaemic Respiratory Failure: Initial Management (Adult)

Acute Hypoxaemic Respiratory Failure: Initial Management (Adult): Acute Hypoxaemic Respiratory Failure (Adult) → Start Oxygen and Call for Senior Help →...

Pathway Overview

21 steps

Algorithm Steps

21 total

  1. 01Start

    Acute Hypoxaemic Respiratory Failure (Adult)

    SpO2 below 92% or PaO2 below 60 mmHg (8 kPa) on room air. Adults only; not for children.

  2. 02Action

    Start Oxygen and Call for Senior Help

    Target SpO2 92-96%. Target 88-92% if COPD or other risk of hypercapnia.

    • No hypercapnia risk, SpO2 85-91%: nasal prongs 2-4 L/min
    • No hypercapnia risk, SpO2 below 85%: face mask 5-10 L/min, or reservoir mask 15 L/min, or high-flow nasal oxygen
    • Target 88-92% if COPD, obesity hypoventilation, bronchiectasis, cystic fibrosis, neuromuscular or chest wall disease; start 1-2 L/min nasal prongs or 24-28% Venturi mask
    • Blood gas: check pH and PaCO2; repeat if oxygen need rises or drowsy
    • CO poisoning: high-concentration oxygen (reservoir mask 15 L/min) whatever the SpO2. Paraquat or past bleomycin: target SpO2 about 85%. Poisons 13 11 26
    • Prescribe oxygen with the target SpO2 range
  3. 03Decision

    Needs Immediate Intubation?

    Yes if arrest or peri-arrest, cannot protect the airway, exhausted with falling consciousness, or shock not responding to resuscitation. Do not trial HFNC or NIV first. Follow any documented limit on treatment.

    • Respiratory or cardiac arrest, or peri-arrest
    • Cannot protect the airway (for example GCS 8 or less, pooling secretions, vomiting)
    • Exhaustion with falling consciousness
    • Shock that does not respond to initial resuscitation
    • Drowsy from hypercapnia (COPD) with a protected airway: senior decision; NIV in HDU or ICU is an option
  4. If Yes
    1. 04Warning

      ⚠️ High Risk of Collapse at Intubation

      Hypoxaemia, shock or right ventricular failure: resuscitate before induction.

      • Most experienced operator; team brief; plan for failed intubation
      • Pre-oxygenate with NIV (or HFNC); correct hypotension first; have a vasopressor ready
      • RV failure, high-risk PE or pulmonary hypertension: very high arrest risk; avoid induction drugs that cause hypotension; use PEEP with caution; consider reperfusion
    2. 05Action

      Intubate and Ventilate

      Modified rapid sequence induction by an experienced operator, then lung-protective ventilation.

      • Early use of a videolaryngoscope
      • Pre-oxygenation with NIV halved severe hypoxaemia versus face mask (PREOXI 2024)
      • After intubation: tidal volume 4-8 mL/kg predicted body weight; plateau pressure below 30 cmH2O
      • Keep treating the cause
    3. 06Outcome

      Intubated: Mechanical Ventilation in ICU

      Treat the cause. Use the ARDS pathway if ARDS criteria are met.

    If No
    1. 07Action

      Not for Immediate Intubation: Find and Treat the Cause

      Do this at the same time as oxygen and respiratory support. Anaphylaxis: IM adrenaline first.

      • Anaphylaxis (wheeze or stridor with rash, swelling or hypotension): IM adrenaline first, not bronchodilators alone; anaphylaxis pathway
      • Chest X-ray, ECG, blood gas; bedside ultrasound if skilled
      • Pneumothorax: decompress if tension; drain before NIV
      • Pneumonia or sepsis: antibiotics and sepsis pathway
      • Cardiogenic pulmonary oedema: CPAP or NIV; heart failure pathway
      • Suspected PE: anticoagulate unless contraindicated; high-risk PE: reperfusion (PE pathway)
      • Asthma or COPD: bronchodilators. Acute asthma with rising PaCO2: ICU review now; NIV is not recommended
      • Opioid toxicity: naloxone; bag-mask ventilate if breathing is inadequate
    2. 08Decision

      On Target With Low-Flow Oxygen?

      Yes if SpO2 is on target with FiO2 below 0.40 (below 6 L/min by face mask) and work of breathing is not increased.

      • Senior review if FiO2 0.40 or more, or 6 L/min or more by face mask
      • ICU review if FiO2 0.50 or more, or 8 L/min or more by face mask
      • Rising RR or rising oxygen need means deterioration
    3. If Yes
      1. 09Action

        Low-Flow Oxygen Enough: Continue and Reassess

        Titrate to the target SpO2 and treat the cause.

        • Nasal prongs preferred; mask flow at least 5 L/min
        • Early warning score with SpO2, FiO2 and RR
        • Rising oxygen need or RR: senior review and escalate support
        • Wean oxygen when SpO2 stays at the top of the target range
      2. 10Outcome

        Stable on Low-Flow Oxygen

        Continue treatment of the cause; wean oxygen to room air.

      If No
      1. 11Decision

        Needs More Support: No Hypercapnic Acidosis and No Cardiogenic Oedema?

        Yes (de novo hypoxaemic failure, including metabolic acidosis alone): high-flow nasal oxygen. No (pH below 7.35 with PaCO2 above 45 mmHg, or cardiogenic pulmonary oedema): NIV or CPAP, but not in acute asthma. Get ICU review.

        • Yes: no hypercapnic acidosis and no cardiogenic pulmonary oedema, go to HFNC
        • No: acute hypercapnic acidosis or cardiogenic pulmonary oedema, go to NIV or CPAP
        • Acute asthma: not for NIV; ICU review
      2. If Yes
        1. 12Action

          No Hypercapnic Acidosis: High-Flow Nasal Oxygen (HFNC)

          First choice for de novo hypoxaemic failure. Target SpO2 92-96%, or 88-92% if COPD or other hypercapnia risk.

          • Heated and humidified; flow up to 60 L/min as tolerated
          • Titrate FiO2 to SpO2 92-96%; 88-92% if COPD or other hypercapnia risk (repeat blood gas)
          • Monitor where intubation can happen without delay
          • NIV has no proven benefit in de novo hypoxaemic failure; do not use NIV to delay intubation
        2. 13Action

          Reassess at 1-2 Hours, Then Often

          Look for improvement or failure of HFNC or NIV.

          • Improving: RR falls, less work of breathing, FiO2 need falls
          • HFNC: ROX = (SpO2 % / FiO2) / RR; 4.88 or more at 2, 6 or 12 h means lower intubation risk
          • ROX below 2.85 at 2 h, 3.47 at 6 h or 3.85 at 12 h predicts HFNC failure
          • NIV: pH or PaCO2 not improving means failure
          • Failure: rising RR or FiO2, accessory muscles, fatigue, confusion, shock
        3. 14Decision

          Improving?

          After 1-2 hours of HFNC or NIV, and at each review.

        4. If Yes
          1. 15Action

            Improving: Continue Support and Wean

            Continue HFNC or NIV and treat the cause.

            • Wean FiO2 first, then flow or pressure
            • Keep checking ROX or blood gas: late failure can occur
            • Go back to intubation assessment if the patient worsens
            • Plan step-down to low-flow oxygen
          2. 16Outcome

            Stabilised on HFNC or NIV

            Continue treatment of the cause and wean to low-flow oxygen.

          If No
          1. 17Warning

            ⚠️ Not Improving: Assess for Intubation Now

            Failing HFNC or NIV. Do not delay intubation if it is within the goals of care.

            • Hypoxaemia or rising FiO2 despite maximal HFNC or NIV
            • Rising RR, work of breathing, fatigue or falling consciousness
            • Worsening acidosis on NIV, or shock
          2. 18Decision

            Is Intubation Within the Goals of Care?

            Yes: go to the intubation steps above. No: continue non-invasive care within the agreed ceiling of care.

          3. If Yes
            1. Path rejoins step 04Shared downstream outcome
            If No
            1. 19Outcome

              Not for Intubation: Care Within the Ceiling of Treatment

              Continue HFNC or NIV only if they help and are tolerated. Focus on comfort; involve palliative care.

        If No
        1. 20Warning

          ⚠️ Hypercapnic Acidosis or Oedema: Check NIV Is Safe

          If NIV is not safe or not possible, go to the intubation steps above.

          • Cannot protect the airway or GCS falling: intubate (drowsy from hypercapnia: NIV only in HDU/ICU with experienced staff)
          • Acute asthma: NIV not recommended; ICU review and assess for intubation
          • Vomiting; facial trauma or burns; fixed upper airway obstruction; undrained pneumothorax (drain first)
        2. 21Action

          Hypercapnic Acidosis or Cardiogenic Oedema: NIV or CPAP

          Bilevel NIV for acute hypercapnic acidosis. CPAP or bilevel NIV for cardiogenic pulmonary oedema.

          • COPD: bronchodilators and controlled oxygen first; start NIV if pH below 7.35 and raised PaCO2 persist
          • Agree and document the plan if NIV fails before you start
          • Blood gas before and after starting NIV, and after each change
          • HDU, ICU or a ward with NIV-trained staff
          • Settings: local NIV protocol, COPD or heart failure pathway
          • Hypercapnic risk: target SpO2 88-92%
        3. Path rejoins step 13Shared downstream outcome

Guideline Source

ERS Clinical Practice Guidelines: High-Flow Nasal Cannula in Acute Respiratory Failure (Oczkowski et al., Eur Respir J 2022;59:2101574)

DOI: 10.1183/13993003.01574-2021View Guideline

Clinical Safety Information

Clinical Decision Support — Not a Substitute for Clinical Judgment

Individual patient factors may require deviation from these recommendations.

Known Limitations

  • Adults only. Oxygen targets differ in CO poisoning, paraquat, past bleomycin and possibly pregnancy: get specialist advice.
  • Covers initial choice of support. Use the COPD, heart failure, PE, pneumonia or ARDS pathways for the cause and NIV or ventilator settings.
  • Intubation thresholds and ROX cut-offs support, not replace, senior clinical judgement.
  • Local resources and protocols may differ.

Contraindicated Populations

pediatricneonatal

Applicable Regions

AUUSEUGlobal

AU: Oxygen targets and escalation thresholds follow the TSANZ 2022 position statement on acute oxygen use in adults. Poisons Information Centre 13 11 26.

Global: HFNC and NIV choice follows ERS 2022 (HFNC), ESICM 2023 (ARDS/AHRF) and ERS/ATS 2017 (NIV) guidelines.

Version 2Next review: 2027-09-30

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Frequently Asked Questions

What is the Acute Hypoxaemic Respiratory Failure: Initial Management (Adult)?

The Acute Hypoxaemic Respiratory Failure: Initial Management (Adult) is a emergency clinical algorithm for Critical Care. It provides a structured decision tree to guide clinical decision-making, based on ERS Clinical Practice Guidelines: High-Flow Nasal Cannula in Acute Respiratory Failure (Oczkowski et al., Eur Respir J 2022;59:2101574).

What guideline is the Acute Hypoxaemic Respiratory Failure: Initial Management (Adult) based on?

This algorithm is based on ERS Clinical Practice Guidelines: High-Flow Nasal Cannula in Acute Respiratory Failure (Oczkowski et al., Eur Respir J 2022;59:2101574) (DOI: 10.1183/13993003.01574-2021).

What are the limitations of the Acute Hypoxaemic Respiratory Failure: Initial Management (Adult)?

Known limitations include: Adults only. Oxygen targets differ in CO poisoning, paraquat, past bleomycin and possibly pregnancy: get specialist advice.; Covers initial choice of support. Use the COPD, heart failure, PE, pneumonia or ARDS pathways for the cause and NIV or ventilator settings.; Intubation thresholds and ROX cut-offs support, not replace, senior clinical judgement.; Local resources and protocols may differ.. Individual patient factors may require deviation from these recommendations.

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