Calibrating Your Etco2 Monitor: A Step-By-Step Guide

Calibration is an essential process for ensuring the accuracy of CO2 sensors in ETCO2 monitors. While some modules are calibrated during manufacturing, periodic calibration is necessary to maintain precision. The calibration procedure involves placing the module in a well-ventilated room, accessing the settings, selecting the room, choosing the CO2 option, and initiating a manual calibration. This process takes 6 to 8 hours, and it is important to leave the auto-calibration feature enabled. Regular calibration ensures that ETCO2 monitors provide reliable data for medical professionals.

Calibration tools and methods

The most common and accurate method for calibrating a monitor is by using a calibration tool: a calibrated tristimulus colorimeter. This tool helps adjust the monitor's output to match an absolute reference. While this method is highly accurate, it requires an investment in equipment and software, or the contracting of a professional calibrator, which can be costly.

An alternative method is to use basic test patterns to calibrate the monitor. This approach can substantially enhance the picture quality and provide a more balanced image, although it may not be suitable for critical work in professional settings.

• Backlight/Brightness: This setting changes the amount of light emitted by the monitor, making it brighter. Adjusting the backlight does not significantly alter the accuracy of the screen, so it can be set to the user's preference.
• Picture Mode: The picture mode presets alter most of the image settings. It is important to adjust these settings when calibrating without a colorimeter, as it can be challenging to enhance the monitor's colour accuracy otherwise. The 'Standard' or 'Custom' presets are generally the most accurate.
• Brightness and Contrast: These settings change how the screen displays tones at different brightness levels. They can be adjusted by displaying different gradient patterns, and most of the calibration can be done accurately without a dedicated tool.
• Sharpness: Adjusting the sharpness changes the appearance of the edges of shapes on the screen. The default setting is usually fairly accurate, and it is simple to adjust by setting it to the maximum and then lowering it until no strange pattern forms between the lines and shapes.
• Colour Temperature: This setting adjusts the overall picture temperature, with cooler temperatures giving a blue tint and warmer temperatures producing a yellow or orange tint. A 6500k colour temperature is recommended as it is equivalent to midday light and is the standard for most screen calibrations.
• White Balance: The white balance refers to the balance of colours across different shades of grey, but it is challenging to adjust these settings accurately without the necessary equipment.

It is important to note that calibrating a monitor by eye can be a trial-and-error process, and it may take a few attempts to achieve the desired results. Most monitors have a reset feature to revert any changes and return to the default settings if needed.

Calibration frequency

For critical applications in medical settings, it is recommended to calibrate ETCO2 monitors regularly to ensure optimal performance and accuracy. The calibration interval can vary depending on the manufacturer's specifications and the usage patterns. For example, for intensive care units (ICUs) or emergency departments where the monitors are used continuously and play a vital role in patient care, a more frequent calibration schedule, such as quarterly or semi-annual, may be appropriate. This helps compensate for any drift in accuracy that may occur over time due to factors such as component ageing or environmental conditions.

In less critical settings or for devices used less frequently, a less stringent calibration schedule can be implemented. For instance, biannual or annual calibrations may be sufficient to maintain acceptable performance. However, it is essential to closely monitor the performance of the ETCO2 monitors and perform calibrations more frequently if any discrepancies or issues are identified.

It is worth noting that some manufacturers may have specific recommendations or requirements for calibration intervals to ensure compliance with safety standards and regulations. Therefore, it is crucial to refer to the manufacturer's guidelines and instructions for the specific ETCO2 monitor being used. Additionally, if the device is serviced or repaired, calibration may be necessary to ensure it functions accurately after any interventions.

Furthermore, the environment in which the ETCO2 monitor is used can also influence the calibration frequency. For instance, if the device is exposed to extreme temperatures, high humidity, or significant vibration levels, more frequent calibration may be warranted. This is because environmental factors can impact the performance and accuracy of the sensors and other components over time.

In summary, the calibration frequency of ETCO2 monitors depends on various factors, including the criticality of the application, usage patterns, manufacturer recommendations, and environmental conditions. Adhering to a regular calibration schedule and closely monitoring the performance of the devices helps ensure the accuracy and reliability of ETCO2 monitors in clinical practice.

Manual calibration steps

Manual calibration of a CO2 sensor can be done by following these steps:

• Place the module in a well-ventilated room.
• Go to Settings > Manage my Home.
• Select the room where the main module of the Station is located.
• In Configurations, select CO2.
• Launch a manual calibration by clicking on the corresponding button.
• Do not disconnect the main module from its power supply or remove the batteries from the Additional Smart Indoor Modules for 8 consecutive hours once the manual calibration request has been made.
• Verify that a spinner is displayed on the recalibrate button to ensure that the calibration is in progress.
• Leave auto calibration enabled.

The manual calibration will last 6 hours and it is based on fewer measurement points than the automatic calibration, so you may observe spikes in the graphs. The accuracy of the CO2 sensor is ± 100ppm to 1000ppm and ± 10% for measurements greater than 1000ppm.

It is recommended to carry out the calibration procedure for a capnograph at least once a year. Calibration should be conducted more frequently if needed.

Automatic calibration

While automatic calibration can be highly convenient, it is important to note that it may not always be as accurate as manual calibration, which utilises a calibration tool or test patterns. Additionally, automatic calibration is not a standard feature on all ETCO2 monitors, and some higher-end models may require manual calibration to ensure optimal performance.

For those who prefer the convenience of automatic calibration, it is recommended to review the product specifications before purchasing an ETCO2 monitor to confirm that it offers this feature. This will ensure that the device can self-calibrate and adapt to its environment without requiring manual intervention.

It is worth noting that even with automatic calibration, there may be times when a manual calibration is necessary. For example, if the device is consistently providing readings that seem inaccurate or are significantly different from expected values, performing a manual calibration can help resolve any discrepancies.

In conclusion, automatic calibration is a valuable feature for ETCO2 monitors as it reduces the need for frequent manual calibration. However, it is not a substitute for proper maintenance and occasional manual calibration to ensure the device's accuracy and optimal performance.

Calibration accuracy

To achieve calibration accuracy, ETCO2 monitors need to be properly calibrated and maintained. Calibration typically involves using calibration gases with known CO2 concentrations to adjust the device's sensor. This process helps ensure that the monitor's readings are accurate and reliable. The microCapStar End-Tidal CO2 Monitor, for example, uses a single calibration gas and room air for calibration. It also has built-in diagnostics to monitor for any issues, such as plugged sample tubing, which can affect calibration accuracy.

Regular calibration is essential to maintain the accuracy of ETCO2 monitors. Some devices have automatic calibration features, while others may require manual calibration. For instance, the Netatmo CO2 sensor is calibrated automatically every week to adapt to the surrounding environment. However, it also allows for manual calibration, which can be initiated through the application settings and takes six hours to complete.

In addition to calibration, there are other factors that can influence the accuracy of ETCO2 monitors. These include the environmental conditions, such as temperature and humidity, as well as the presence of interfering gases or substances that can affect the sensor's performance. Maintaining proper environmental conditions and ensuring the sensor is free from contaminants are crucial for calibration accuracy.

Furthermore, the design and specifications of the ETCO2 monitor itself play a role in calibration accuracy. Factors such as the response time, resolution, and stability of the device can impact the accuracy of readings. For example, the microCapStar monitor has a rapid response time of 75mS, a high resolution of 0.01%, and long-term stability, contributing to its accuracy in measuring end-tidal CO2 concentrations.

Overall, achieving calibration accuracy in ETCO2 monitors requires proper calibration techniques, regular maintenance, consideration of environmental factors, and an understanding of the device's specifications and limitations. By ensuring calibration accuracy, healthcare providers can rely on the monitor's readings to make informed decisions regarding patient respiratory status and treatment.

Frequently asked questions