3 Common Artifacts That a Sleep Technologist Must Manage
The typical artifacts that a sleep technologist can expect to encounter
What needs to be understood in order to assure collection of superior sleep studies? Let's review some of these artifacts for those who may have missed this informative offering!
To avoid a study filled with artifacts, a tech must begin with a great electrode and sensor application. With regard to this, the old adage comes to mind that “you take out what you put in’ or “garbage in-garbage out." After sensor and electrode application, the technologist must review the system that is processing these signals and ultimately must monitor the whole setup throughout the study. Doing this properly will ensure a limited amount of artifact and a sleep recording that is of high quality!
The first artifact we should discuss is the EKG artifact. This is a common artifact seen in the EEG, EOG, or EMG channels. Sometimes it is caused by impedance imbalances between exploring and reference electrodes. Sometimes in obese patients and others it is present in spite of low impedances!
Other times the reference electrodes (M1 and M2) need to be moved to a position higher on the mastoid process- or even on the earlobes! If this doesn’t help then you also can "double reference” or “join” M1 and M2 via the software on your system to get an average reference. Current software on sleep systems makes this a simple process of one click in most cases.
This is usually apparent in all the channels as patients shift normally in sleep or in response to a disruptive breathing event. It usually resolves itself when the patient stops moving but attention must be paid to ensure once movement has stopped that no electrodes have been dislodged or upset. If there is continued artifact once the movement stops, the technologist must isolate the cause and repair -or re-reference the problematic channel(s).
Large movements may cause temporary loss of the oximetry signal. Various nail treatments also can cause improper oximetry values. It is important to explain to the patient that we need to have a proper surface to attach the oximetry probe so as to accurately diagnose sleep issues. These days we have new types of nail treatments that are not easily removed. If this presents a problem that cannot be avoided, the technologist may need to find another suitable place for the oximetry probe such as a toe or an earlobe.
An earlobe or toe also may be a better location for oximeter probe placement for pediatric patients as with these placements the probe is not as easily disrupted by an anxious child! Because children move frequently, it is important to monitor for oximetry artifact very closely!
Hopefully you will keep these tips in mind and continue to produce great studies for your employer- and more importantly – for your patient!
For more information on artifacts and troubleshooting them, refer to our Artifact and Troubleshooting Guide.
Learn about dealing with artifacts in our Case of The Month offering on the topic
This AAST Case of the Month is an excellent resource for learning to deal with artifacts. In this learning module, Dr. Rich Rosenberg discusses the various artifacts found in a patient recording, methods for reducing artifact and the impact of artifact on record scoring.