AIM

  • To maintain oxygen at the minimum concentration in the blood to achieve adequate tissue oxygenation and minimise the threat of oxygen or carbon dioxide toxicity

OXYGEN PRESCRIPTION

The three questions to ask

  • Critical or non-critical illness?
  • Risk of type 2 respiratory failure?
  • Is the patient hypoxic?
Guidance of prescribing tool

How to prescribe

  • Oxygen saturation target:
    • SpO2 88–92% for non-critical patients at risk of type 2 (hypercapnic) respiratory failure
    • SpO2 94–98% for all other patients
  • Oxygen flow rate
  • Delivery device (e.g. Venturi mask, nasal cannulae, reservoir mask)
  • Frequency (continuous or PRN use for pallative care only)

MONITORING

  • Monitor SpO2 continuously
  • If oxygen requirement increases, seek senior advice
  • Closely observe patients at risk of CO2 retention for signs of reduced respiratory effort, or conscious level, (GCS <14 or V on the AVPU scale)
    • if patient at risk of CO2 retention, repeat ABGs in 30–60 min after any further increase in FiO2 or if conscious level deteriorates
  • Discuss any deteriorating patient with consultant responsible for management of co-morbidity and critical care team

Signs of respiratory deterioration – seek medical advice

  • Increased respiratory rate (especially if >30/min)
  • Reduced SpO2
  • Increased oxygen dose required to maintain SpO2 in target range
  • Increased NEWS score
  • CO2 retention
    • drowsiness
    • headache
    • flushed face
    • tremor

Guidance on results of ABG

  • Seek immediate senior review
  • Consider NIV or invasive ventilation
  • Treat with lowest FiO2 to keep SpO2 88–92% via Venturi mask pending senior medical advice
  • Investigate and treat for metabolic acidosis and keep SpO2 94–98%
  • Treat with lowest dose Venturi mask that will keep SpO2 between 88–92%
  • Repeat ABGs at 30–60 min
    • if respiratory acidosis (pH <7.35 and PaCO2 >6.0), seek immediate senior review, consider NIV
    • if PaO2 ≥8.0 kPa, consider reducing FiO2 but keep between 88–92%
  • Seek immediate senior review
    • consider invasive ventilation
  • Treat urgently
  • Reconsider COPD or other undiagnosed chronic hypercapnic respiratory failure
    • if likely, aim for SpO2 of 88–92%
    • otherwise, aim for SpO2 94–98% pending senior review
  • Monitor SpO2
  • Additional oxygen not required unless saturation falls below target range

WEANING FROM OXYGEN

  • When patient stable, consider using nasal cannulae
  • When oxygen therapy is no longer indicated, step down oxygen to room air as soon as possible, monitoring SpO2
  • If unable to wean but patient stable, request home oxygen team to review

© 2022 The Bedside Clinical Guidelines Partnership.

Created by University Hospital North Midlands and Keele University School of Computing and Mathematics.

Research and development team: James Mitchell, Ed de Quincey, Charles Pantin, Naveed Mustfa