eComment: Double-knotted Swan-Ganz catheter - potential for non-invasive ultrasonic cardiac output monitoring?

I read with great interest the recent report by Dr. Camargo [1]. Complications using an invasive Swan-Ganz catheter have been encountered since the introduction of the catheter [2]. As early as in 1976 Dr. Block reported the snaring of a Swan-Ganz catheter by a suture to control bleeding in the right atrium [3]. We encountered a double-knotted Swan-Ganz catheter in a patient following coronary artery bypass grafting with fatal outcome due to pump failure. Therefore, no attempt was performed to retrieve the doubleknotted Swan-Ganz catheter percutaneously. Given the potential fatal complications of invasive Swan-Ganz catheters, non-invasive means of cardiac output monitoring might be considerable. Ultrasonic cardiac output monitoring (USCOM, Sydney, Australia) using CWDoppler has been reported to correlate highly with invasive Swan-Ganz catheter cardiac output in postcardiac surgery patients with a mean difference of 0.2 l/min and a correlation coefficient r=0.870 [4]. A recent comparative study between USCOM and Swan-Ganz catheters in instable ICU patients found acceptable correlations [5]. Thus, in a selected patient cohort, given the potential complications of invasive Swan-Ganz cardiac output monitoring, it might be worth considering non-invasive alternatives for hemodynamic assessement.