Patients at risk of harm from ‘inappropriate placement’ of sats probes

Inappropriate placement can produce a reading up to 50% lower or 30% higher than the real value. 

Matt Bodell
18 December 2018
person in hospital bed

‘Inappropriate placement’ of pulse oximeter probes can lead to staff being falsely reassured about a patient’s condition.

An NHS Improvement Patient Safety Alert has warned that patients may be at risk of harm through inappropriate placement of pulse oximeter probes.


Measurement of oxygen saturation, using a pulse oximeter probe, is routinely undertaken as part of patients’ vital signs during diagnosis and ongoing monitoring.

Oximeter probes can be single or multiple use and are designed to attach to specific parts of the body. Adult oximeter probes can be attached to either a finger or an ear, but are not interchangeable between these sites, whilst probes for babies and children need to be selected according to the patient’s weight.

The alert wants that if an oximeter probe intended for the finger is attached to the ear (or vice versa), or a probe intended for an adult is attached to a baby or a child (or vice versa), it can produce a reading up to 50% lower or 30% higher than the real value.

‘Falsely reassured’.

Warning that that staff may be falsely reassured about a patient’s condition, when in reality the patient is deteriorating, or may make an inappropriate intervention when in fact a patient is stable or improving.


The safety alert asks NHS organisations to ensure staff have access to appropriate equipment and the information they need to use these devices safely.

Research completed by NHS Improvement suggested that a substantial proportion of staff do not know that finger probes can give misleading results if attached to ears and that a quarter of staff do not have routine access to probes specifically for the ear – even though in almost all clinical settings some patients will need these.

The alert calls on NHS organisations to ensure staff have access to the equipment they need and education them on the risks of misplacement.

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