Latest Revision 04 September 2018
This knowledge base article is intended to help users with the configuration process for ambulatory studies using the Noxturnal App
1 Noxturnal Mobile App – Ambulatory Study Configuration
The Noxturnal Mobile App can be used to configure Nox A1 recorders. The key steps for configuring an ambulatory recording with the Noxturnal Mobile App are the same as in Noxturnal with additional two steps which enable you to review electrode impedance values (EEG and EMG channels) and perform bio calibration. To use the Noxturnal App to configure your Nox A1 recorder, perform Impedance Check and bio calibration please follow the steps below:
1. There are two user scenarios when using the Noxturnal Mobile App for setting up an ambulatory recording depending on the workflow of the user.
- Fully hook-up the patient and then configure the recorder and perform Impedance Check.
- Use the Noxturnal Mobile App to support the hook-up of the EEG electrodes.
Steps 2-6 and 8-10 below apply for both user scenarios.
2. Launch the Noxturnal Mobile App and turn on your Nox A1 recorder. Wait until you see your recorder listed as available device. If the top right circle icon stops spinning tap it again to restart device discovery. Once your recorder appears in the list, tap it to initiate a connection to it.
3. On the “PATIENT” screen enter the patient information.
4. On the “CONFIG” screen you can configure which signals are to be recorded.
The following image shows the configuration window in the Noxturnal Mobile App. In this window you are able to configure your recorder by selecting a recording template, enable use of additional sensors (GP1 channels), enable recording of signals from auxiliary devices and schedule a recording or indicate that a recording should be started manually.
When configuring a Nox A1 recorder for a study with the Nox W7 Link in the Noxturnal Mobile App select these in the “Auxiliary device” fields. Select the auxiliary device to be used and enter the applicable link’s Bluetooth address (BDA). The Bluetooth address (BDA) of the Nox W7 has 12 digits. The BDA can be found on the Nox W7 label.
Transfer your custom recording templates and biocal templates by connecting the Nox A1 Recorder once to Noxturnal using these templates and reconnecting with the App
Note: You can create new recording types in Noxturnal. After a single recording has been configured on the A1 recorder via Noxturnal the recording types, bio calibration templates and sensor definitions will be available in the Noxturnal Mobile App for this particular recorder. If you modify the recording templates in Noxturnal you will need to configure a recording via Noxturnal again for the template changes to be reflected by the Noxturnal App.
5. On the “SENSORS” screen you can review the sensor connections as well as impedance values for the EEG and EMG electrodes if the patient is hooked-up. To switch between views for the EEG and the rest of the channels select the circle/body icon located in the lower left corner.
NOTE: The “Head EEG” label in the figure above is reporting the poorest impedance value of all the EEG channels. If the patient is not hooked up when the A1 recorder is turned on you will need to run an Impedance Check in order to get a reliable value for the “Head EEG” field (see step 6).
6. The next step is to switch to the head screen (circle icon in the lower left corner) and start the Impedance Check by pressing “Start impedance check” button in the figure below.
The following dialog will pop up and you get asked if you want to start the Impedance Check.
Note: As stated in the dialog the EXG signals are corrupted during the Impedance Check.
7. This step applies if the mobile app is used to support the hook-up of the EEG electrodes. The Impedance Check is now running and you can start hooking up the patient with the EEG electrodes and see real time impedance values/color indication on your screen. For the patient hook up it is critical to follow the steps below:
- Hookup the patient with the oximeter and other Bluetooth devices turned on – If oximeter or other Bluetooth devices are out of range it can cause delays in real time impedance values.
- Always start the patient hookup by attaching the electrode on the patient’s forehead (ground electrode) as shown below:
- You can now continue hooking up the EEG electrodes. The sensors will be reported as “Acquiring…” until at least two electrodes and the ground (forehead) connector have been connected. From that time on the impedance values will continuously display the status of the electrode connections and allow immediate feedback on changes.
- When you are satisfied with the impedance values and the hookup is completed you can perform the bio calibration on the “BIOCAL” screen. The impedance test stops automatically when moving from the impedance check window.
8. The next step is to start the recording using the Noxturnal Mobile App and do the bio calibration.
9. Finally you can review all signals being recorded from the “TRACES” screen.
10. When you have completed the configuration of the recorder and the patient is ready to go to bed it is critical you disconnect the Noxturnal Mobile App from the Nox A1 recorder by pressing the icon located in the upper right corner.
Always Disconnect the App from the Nox A1 Recorder
5 Noxturnal Mobile App when Using Auxiliary Devices
With recording profiles including auxiliary devices (Nonin 3150, Radiometer, Sentec, Resmed S9) the auxiliary devices must be in range when performing the Impedance Check and review of traces. If not, the Nox A1 recorder will do repeated scans for wireless peripherals inducing a significant transmission delay to all data being transmitted to the Noxturnal Mobile App, including impedance values. If auxiliary devices are out of range it is recommended to disable all auxiliary devices in the “Config” window before performing the Impedance Check. The devices can be enabled again when the Impedance Check has been completed.
6 Performing an Impedance Check in the Noxturnal Mobile App During a Running Study
Users may like to double check signal quality / traces during a running ambulatory recording. The Impedance Check can be initialized as described above but needs to be turned off after its use. There are three ways to turn of the impedance check:
- Tap the “Ohm”-icon in the top bar of the Noxturnal App
- Turn off the screen by pressing the power button of the tablet (the screen will automatically turn off in 10 minutes, stopping the Impedance Check)
- Switch to a different screen
While the Impedance Check is running there will be an “Ohm”-icon blinking in the Noxturnal App top bar. The “Ohm”-icon disappears once the Impedance Check is not running anymore.
Note: While the Impedance Check is running the EEG signal traces are corrupted and the period should to be scored manually as invalid data.