Type 1 Respiratory Failure

T1RF = PaO2 <8 with normal/low CO2 — an oxygenation problem (V/Q mismatch/shunt): atelectasis, pneumonia, PE, oedema, aspiration, ARDS. Target SpO2 94–98%, prescribe oxygen, treat the cause (post-op: analgesia IS respiratory treatment). Refractory…

Hypoxaemia Pathway

The pathway

1 · ABG types it

PaO2 <8, CO2 normal/low = T1RF
Low CO2 = working hard
CO2 >6 → different (T2RF) pathway

2 · Differential

Atelectasis (post-op day 1–2)
Pneumonia/aspiration
PE — any time
Oedema (fluids/cardiac), ARDS

3 · Oxygen to target

94–98%, prescribe it
Cannulae → mask → 15L NRB
88–92% ONLY for CO2 retainers

4 · Treat the cause

Post-op: analgesia, sit up, physio, incentive spirometry
Antibiotics if pneumonia
CTPA if PE suspicion; diurese oedema

5 · Track trajectory

Rising O2 requirement = escalation trigger
NEWS + repeat ABG
RR >30 + tiring = pre-arrest

6 · Escalate refractory

SpO2 <92% on 15L → critical care: CPAP/HFNO
Consider ARDS (bilateral infiltrates + precipitant)
NIV only in monitored areas

Drugs

Drug	Dose	Route	Notes
Oxygen	Titrate to SpO2 94–98%	INH	Prescribe with target. Escalate device to achieve it.
Analgesia (post-op)	Multimodal ± PCA review	PO/IV	A splinted abdomen cannot ventilate — analgesia treats hypoxia.
Antibiotics	Per CURB-65/local policy	IV/PO	For genuine pneumonia — not for atelectasis fever alone.

When to escalate

SpO2 <92% on 15L NRB — critical care now,RR >30, tiring, or falling GCS — peri-arrest call,Bilateral infiltrates + shock — ARDS pathway,Unexplained refractory hypoxia — CTPA for PE

Reference: BTS Emergency Oxygen Guideline / BTS pleural + pneumonia guidance

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