A novel EEG artifact in the intensive care unit.

The authors describe a novel EEG artifact in two patients whose records were otherwise suppressed. The saw-toothed waveform, containing 5.5- and 11-Hz rhythms, was induced as a movement artifact by a hemoperfusion machine connected to the patient. The artifact is highly characteristic, but could be easily misinterpreted as a cerebral rhythm if one is not aware of the entity. The artifact should be suspected when invariant, saw-toothed rhythms appear beyond the temporal and occipital lobes, and also contaminate the electrocardiographic channel. It can be proved by its disappearance on stopping and reemergence with starting the rotary pump action of the device.