Amplitude-integrated electroencephalography in the NICU: frequent artifacts in premature infants may limit its utility as a monitoring device.

ABSTRACT

BACKGROUND: Amplitude-integrated electroencephalography has become an important tool for assessing cortical status noninvasively. Newer units have the additional feature of visualizing the raw electroencephalogram, which has resulted in the identification of frequent artifacts. OBJECTIVE: To highlight the problem of artifacts and to introduce caution when using the amplitude-integrated electroencephalography technique to assess cortical function in the premature population. METHODS: Ten premature infants were evaluated. Compressed amplitude-integrated electroencephalography recordings were made by using a pair of standard electroencephalogram electrodes attached to the scalp frontotemporal areas. Impedance was maintained at <10 kOmega. Continuous amplitude-integrated electroencephalography recordings were performed for at least 60 minutes on several occasions in the first month. Artifacts were identified as follows large amplitude difference between the wave peaks and troughs, a jagged appearance to wave peaks and troughs, and large deflections of the overall tracing in either a positive or negative direction from baseline. RESULTS: Forty-eight amplitude-integrated electroencephalography recordings were reviewed. Of 1683 total segments analyzed, 529 (31.4%) were categorized as normal brain waves, 1013 (60.2%) as artifacts, and 142 (8.4%) as indeterminate. Generally, when the amplitude-integrated electroencephalography tracing is of modest amplitude, normal brain waves predominated, whereas with upward spikes in amplitude the accompanying raw electroencephalogram was classified as artifact. CONCLUSIONS: Artifacts contribute substantially to the amplitude-integrated electroencephalography tracing, rendering it problematic as an assessment tool in premature infants. Artifacts may be influenced by muscle activity, electrode positioning, and application techniques. Caution is recommended when using amplitude-integrated electroencephalography as an assessment tool in this population.