MOVEMENT OF PULMONARY-ARTERY CATHETERS

Intraluminal movements of pulmonary artery catheters are seldom consid ered, although they may have a significant impact on flow measurement and safety. The purpose of this study was to document the movements of these catheters within the heart cycle, and to establish whether any patterns existed. We analyzed two-dimensional real time echocardiograp hy cross-sectional images of the human pulmonary artery in 20 patients , plotting the position of the intra-arterial catheter frame-by-frame onto a standardized template. We found that movement of the catheter w ithin the pulmonary artery occurred in a seemingly random pattern. The re was no movement pattern to the inferior right of the vessel, an are a known to have complex velocity profiles and erroneous velocity measu rements. The catheter moved substantially throughout the heart cycle, occasionally quite close to the vessel wall. We observed significant m ovement of the pulmonary artery catheter throughout the heart cycle, w ithout any predictable pattern. Although we did not specifically inves tigate the effect of these movements on cardiac output, they imply tha t intra-arterial Doppler flow measurements from the pulmonary artery m ay be inaccurate, since a stable catheter position, and, hence, a samp le volume, cannot be ensured. Further speculation can be made on the i mplications of these movements in regard to thermodilution cardiac out put and safety.