Artifact mistaken for electrical interference recorded from a pulmonary artery catheter

Artifactual signals superimposed on the electrocardiogram have been well do cumented [1-5]. These signals can originate from infusion pumps [1,2], occl usion heads from cardiopulmonary bypass machines [3, 4], and dialysis appar atus [5]. Artifacts on a pulmonary artery tracing, such as those produced by "cathete r whip," are well described [6], and rarely if ever confuse the clinician. Extrancous electrical signals are of major concern because they pose a haza rd to susceptible patients. We report a case in which the blood pressure tracing from the pulmonary art ery revealed an artifact that looked at first glance like 60 cycle alternat ing current (AC) electrical interference. The investigation as to it, origi n revealed important lessons in the analysis of human error.