Category: Respiratory Monitoring | PediaDevices Practical Guide

Respiratory Function Monitors in Child Care: A Complete Guide to Types, Use, and Safety

Last updated: 2025 | Reading time: ~8 min

What Is a Respiratory Function Monitor?

A respiratory function monitor is a medical device that measures one or more aspects of breathing and lung function. The term covers several types of devices, each measuring a different parameter such as oxygen levels in the blood, airflow speed, lung volume, or carbon dioxide levels in exhaled air.

These monitors are used across many settings including hospitals, clinics, emergency units, and at home. In children, monitoring respiratory function is especially important because breathing problems can develop and worsen quickly, and young children often cannot describe their symptoms clearly.

Purpose and Where These Devices Are Used

Respiratory function monitors are used to:

• Check blood oxygen levels during illness, surgery, or recovery
• Monitor children with chronic conditions such as asthma, cystic fibrosis, and bronchopulmonary dysplasia
• Assess lung function before and after treatment
• Detect breathing problems during sleep
• Guide decisions about when to start or stop oxygen therapy
• Monitor the effectiveness of breathing medications
• Check ventilation in children on breathing support

Types of Respiratory Function Monitors

The four main types used in child care are described below. Each serves a distinct purpose.

How to Use: Step-by-Step Guide

Pulse Oximeter

1. Make sure the hand or foot is warm. Cold skin reduces accuracy.
2. Select the correct probe size for the child's age (infant, paediatric, or adult).
3. Place the probe on a finger or toe, ensuring the light source and detector are on opposite sides of the digit.
4. Keep the child as still and calm as possible. Movement causes inaccurate readings.
5. Wait 10 to 20 seconds for the reading to stabilise before recording.
6. Read both the SpO2 percentage and the heart rate on the display.
7. Note: Nail polish, especially dark colours, can interfere with the reading. Remove if present.

Peak Flow Meter

1. Set the marker on the scale to zero (the lowest reading).
2. Attach a clean mouthpiece.
3. Have the child stand or sit up straight.
4. Ask the child to take a full, deep breath in.
5. Place the mouthpiece in the mouth with lips sealed tightly around it.
6. Blow out as hard and as fast as possible in one short blast.
7. Record the number where the marker stopped.
8. Repeat the test 3 times. Record the highest of the three readings.
9. Compare the reading to the child's personal best value as guided by a healthcare provider.

Spirometer (Clinic Setting)

1. The child should be seated comfortably with back straight and feet flat on the floor.
2. A nose clip is placed on the nose to prevent air escaping through the nostrils.
3. The child is instructed to breathe normally for a moment, then take a maximal breath in.
4. Place lips firmly around the mouthpiece and blow out as hard and fast as possible, continuing until lungs are fully empty (usually at least 6 seconds for older children).
5. The device records the airflow and volume data automatically.
6. The test is repeated at least 3 times to get reproducible results.
7. Results are interpreted by a trained healthcare professional using reference tables.

Capnograph

1. Used only by trained medical personnel in clinical settings.
2. For sidestream capnography: attach the sampling cannula or nasal prong to the patient's airway or breathing circuit.
3. For mainstream capnography: attach the sensor directly to the breathing circuit or endotracheal tube connector.
4. Power on the device and allow it to calibrate if required.
5. Observe the waveform (capnogram) on the screen. A normal wave has a characteristic rectangular shape.
6. Monitor ETCO2 values alongside the waveform. Abnormal values or waveform changes indicate breathing problems.
7. Document readings every 5 minutes in monitored settings as per clinical guidelines.

Precautions and Important Warnings

Frequently Asked Questions

How to Keep the Device Safe and in Good Working Condition

Pulse Oximeter

• Clean the probe regularly with a soft cloth and alcohol wipe (as per manufacturer guidelines)
• Do not submerge the device in water
• Inspect the probe cable for cracks or damage before each use
• Store in a clean, dry case away from direct sunlight and heat
• Replace disposable probes after single use; do not reuse them on different patients
• Check battery levels regularly; low batteries can cause inaccurate readings

Peak Flow Meter

• Use a new disposable mouthpiece for each user or each session
• Wash reusable mouthpieces in warm soapy water and allow to air dry completely
• Do not put the main body of the device in water
• Check that the marker slides freely and the scale is readable
• Replace the device if it is dropped and the scale marker no longer moves smoothly
• Use the same brand and model consistently - readings are not directly comparable across different brands

Spirometer

• Use a new disposable mouthpiece and filter for each patient
• Calibrate the device regularly as specified by the manufacturer (usually daily in clinical use)
• Keep the device protected from dust and moisture when not in use
• Follow the manufacturer's cleaning and servicing schedule
• Have the device serviced and calibrated by a qualified technician at regular intervals

Capnograph

• Use single-use sampling lines and nasal cannulas; do not reuse
• Check that sampling lines are not kinked or blocked before use
• Clean the sensor head (mainstream) with recommended wipes only
• Store equipment away from extreme temperatures and humidity
• Perform regular calibration as per the device manual
• Service and maintain the device through authorised service providers only

Additional Information Worth Knowing

Interpreting Results in Context

Numbers from respiratory monitors must always be interpreted alongside the clinical picture. A child may have a normal SpO2 while working very hard to breathe (compensated respiratory distress). Similarly, a slightly low SpO2 in a healthy, comfortable child may reflect a probe placement issue rather than true hypoxia. Devices provide data; clinical judgement determines what the data means.

Ethnicity and Pulse Oximetry Accuracy

Studies published in recent years have identified that conventional pulse oximeters can overestimate SpO2 in individuals with darker skin pigmentation, potentially masking true hypoxia. This is a recognised limitation. Some newer-generation devices incorporate additional wavelengths and algorithms to reduce this disparity. This is an active area of ongoing research and device development.

Wearable and Remote Monitoring Devices

Several wearable infant and paediatric monitors are now available that track SpO2 and heart rate through sensors worn on the foot or wrist. Some of these have received regulatory clearance. These are intended for use under medical supervision for specific conditions such as apnoea of prematurity, congenital heart disease, and bronchiolitis. They are not a replacement for standard medical monitoring and should only be used as advised by a healthcare provider.

Home Telespirometry

Portable handheld spirometers connected to smartphone apps allow lung function measurements to be performed at home and transmitted to a clinical team. Research has shown this can be feasible and useful in managing conditions like asthma and cystic fibrosis, allowing early detection of worsening lung function. However, training and adherence to correct technique are essential for the results to be valid.

Reference Values in Spirometry

Spirometry results are compared against reference (predicted) values derived from large population studies. These values are based on age, height, sex, and ethnicity. The most widely used reference equations currently are the Global Lung Initiative (GLI) equations, which include paediatric populations. It is important that reference values appropriate for the child's background are used during interpretation.

Suggested References and Resources

Reviewed and verified by a Paediatrician | PediaDevices