Artifact mistaken for electrical interference recorded from a pulmonary artery catheter

Artifactual signals superimposed on the electrocardiogram have been well documented [1-5]. These signals can originate from infusion pumps [1, 2], occlusion heads from cardiopulmonary bypass machines [3,4], and dialysis apparatus [5]. Artifacts on a pulmonary artery tracing, such as those produced by "catheter whip," are well described [6], and rarely if ever confuse the clinician. Extraneous electrical signals are of major concern because they pose a hazard to susceptible patients. We report a case in which the blood pressure tracing from the pulmonary artery revealed an artifact that looked at first glance like 60 cycle alternating current (AC) electrical interference. The investigation as to its origin revealed important lessons in the analysis of human error.