SpO2 monitoring in the highly dependent or critically ill infant or child

PROCEDURE

RATIONALE

Gather all necessary equipment & ensure the correct lead used with the correct module.

E.g Blue lead with Nellcor module

      Grey lead with portable MMS  module

See Fig. 4 & 5 above

The Blue lead/cable (M1943NL) must be used with the Nellcor SpO2 module &  Philips Intellivue system for sensor accuracy⁴

The Grey lead/cable should be used in the Philips MMS  module⁴ (i.e. for patient transfer)

Using the wrong lead/cable in the wrong module will give inaccurate or false SpO2 readings⁴

Make sure the probe and monitoring equipment/module is clean and in good working order

In order to minimise the risk of cross infection and ensure that the equipment is suitable for use.

Set-up for new patient to PICU:

Switch on Phillips monitoring system and ensure Nellcor SpO2 module is correctly slotted in to the system.

Plug in SpO2 lead/cable (Blue) into the Nellcor module (Fig. 4) and connect  disposable probe to lead

To ensure monitor performs self calibration and checks prior to patient connection.

To ensure the nurse can see which side the probe is emitting infrared light and thus help determine correct positioning of probe.⁴

The nurse should wash their hands and don apron and gloves

In order to minimise the risk of cross infection.⁵

Check correct type and size of probe is selected for the infant or child                    

Using the wrong size probe may lead to the 'penumbra' effect and thus give inaccurate readings.⁶

Sensor placement & site: (Fig. 1, 2, 3)

Select a suitable area for the probe to be sited ensuring probe is correct type for area and age of child.

The sensor should be positioned to ensure that the LED & photodetector are aligned directly across from one another with 5-10mm of tissue between them. ⁸

Ensure site selected is clean, dry and free from discolouration.

Using wrong site and/or type of probe may result in inability of the sensor to track the pulse thus giving inaccurate readings.^6,7

The site chosen should have a pulsatile vascular bed. For example, a finger, toe, earlobe, palm or foot.^2,7,8

The sensor should be placed on the extremity opposite arterial lines and non-invasive blood pressure devices so that pulsatile blood flow is not impeded.^7,8

In neonates and infants, the preferred site is the foot or hand (tissue is thinner allowing light to transmit through & probe to pick up reading).

In older children/adults preferred site is the index finger. Ensure light source on sensor is placed on nail side of digit ^2,8

This ensures light is transmitted between the emittor/detector, through the digit/area applied and across the arteriolar bed.

If sensor-site (skin) is too thick or thin, pigmented, dirty or coloured - e.g. dark nail polish - appropriate light transmission may be affected and errors in measurement may occur.^9,10,11,12

Attach sensor probe as per manufacturers’ instructions.

After a few seconds ensure adequate waveform displayed and that pulse corresponds to that of the infant/child. 

Where possible avoid using tape to secure to secure sensor to skin.

To ensure that the probe is detecting the pulse and calculating the saturation accurately.⁴

Pulse strength is equal to the fullness of the waveform. This waveform is vital in determining if the saturation recording is reliable.^7,8,13

Sensors attached too tightly may cause erroneously low readings. ¹⁴

Using additional tape can restrict blood flow to site and cause inaccurate readings.^14,15

Additional tape can also cause damage to the sensor and to the patient’s skin.¹⁶

Ensure audible pulse and alarm limits are set

To ensure that nursing staff are given early warning of potential problems.

Most saturation monitors have default alarm settings so individual patient adjustment is always required.

Check the sensor probe, placement and skin site regularly (maximum 8 hourly & at least 2 hourly if patient has poor peripheral perfusion).

To ensure probe is still attached correctly and not damaged. 

To ensure that prolonged use does not cause discomfort or pressure damage.

Ensure any change in observations is documented and reported to nurse-incharge

To help ensure that any potential deterioration or problem is quickly identified and managed appropriately.

Ensure all nursing staff in PICU have access to teaching materials on the principles and uses of pulse oximetry.

To ensure that nursing staff are aware of the safe and unsafe limitations of pulse oximetry monitoring.^8,12

The SpO2 will be displayed continuously via the monitor and will automatically be recorded on the hour. Each hour the nurse should check and validate (if accurate) the child’s saturation.

The PICU Clinical Information System will record whatever saturation is being monitored/displayed.¹⁷

It will not take account of other factors which may lead to an inaccurate recording. For example, if the probe has slipped off or is incorrectly attached, or if the lead/cable is not correct for module.

It is therefore vital that the nurse checks the saturation reading ‘recorded’ and adds comments or events where applicable.

Pulse oximetry is a non-invasive technology used to estimate arterial haemoglobin oxygen saturation (SaO2), by measuring the absorption of light in human tissue beds. The pulse oximeter detects and calculates the absorption of light by functional haemoglobins to produce a measurement, the SpO₂.^{2,4,7,8,13,14,18,19,20,21}

Pulse oximetry can be an extremely valuable non-invasive means of monitoring. However, it has limitations in its use and the nurse must be aware of these. Limitations include motion artefact, poor perfusion, irregular heart rhythms, children with cynaotic congenital heart disease, electromagnetic interference, probe positioning, ambient light interference and abnormal haemoglobin states, such as carboxyhaemoglobin or methaemoglobinaemia.^{8,12,13,18,19,20,21}