Respiratory Failure: First Assessment

Airway, Breathing & Ventilation · ICU Decoded chapter 7 · Locked — free with a referral

By Dr Javed Akhtar · Last reviewed 3 October 2026

Cited to ATS/ERS respiratory failure frameworks.

Key points

Type I (hypoxemic): weigh V/Q mismatch against shunt, hypoventilation, and diffusion; check the A-a gradient.
Type II (hypercapnic) failure: reduced respiratory drive ('won’t breathe': central causes) versus respiratory pump failure ('can’t breathe': neuromuscular weakness, obstructive disease or chest-wall restriction).
Choose support by mechanism: HFNO for de novo hypoxaemic failure; bilevel NIV for acute hypercapnic acidosis; CPAP or bilevel NIV for cardiogenic pulmonary oedema. Follow work of breathing, gases and oxygenation; intubate promptly for clinical failure.
Treat the cause and dose oxygen like a drug: target 92–96% (88–92% in COPD retainers).

Investigations

First tests: Pulse oximetry with oxygen device/FiO2, Arterial blood gas, Chest X-ray, Sodium, potassium, bicarbonate, urea and creatinine.

Only if indicated: Bedside echocardiography, Respiratory culture, CT pulmonary angiography.

Repeat monitoring: Arterial blood gas, Pulse oximetry with oxygen device/FiO2.

Management pathways in this chapter

Etiologies of Hypercapnic Respiratory Failure by Respiratory Pump Component
General Strategy for Hypoxemic Respiratory Failure
Choosing Initial Support in Acute Respiratory Failure

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Treatment orders with doses
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