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Impedance Checks and Views for the Nox A1 System


This Customer Service Document explains how clinicians can ensure reliable readings from the impedance values provided by the Nox A1 PSG System.

Impedance Checks & Views

By running impedance checks, clinicians can take the guesswork out of how well the system’s electrodes pick up the sensitive electro-physiological signals they are designed to measure.

The Nox A1 PSG System has built-in features for running continuous impedance views to help clinicians determining whether impedance is too high on any given electrode.

These continuous impedance views are visible in Noxturnal both through the Impedance View, visible under View -> Impedance View in the Noxturnal Toolbar and also in the left axis of the ExG signals which receive a colored “squiggly line” for signals which may have high impedance values. See the screenshots for more information.

Definition of the impedance values and how their colors are defined below

When clinicians observe too high impedance values from the Impedance Views they should always run an Impedance Check before they start manoeuvring electrodes with the intent to improve their impedance values. The Impedance Check is different from the Impedance Views as it is an active measurement of the impedance values of the electrodes.



The impedance value of ExG electrodes can differ greatly depending on what type of electrodes are being used. Some types of electrodes can show higher impedance values (solid gel electrodes) when compared to other types (e.g. wet gel electrodes). It is always recommended to use the clinical judgement of the signal characteristics if there is doubt on the quality of the signals being measured.

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*Please note that not all features or all products are available in all markets. Our products are medical devices and subject to registration/approval in each market area. For more information on product availability please contact

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