The Arrow "Hands-Off" thermodilution catheter (AHO) is completely shielded during balloon testing, preparation, and insertion. To assess the value of the AHO in the prevention of systemic infections associated with pulmonary artery catheterization (SIAPAC), we conducted a randomized prospective study over an 18-mo period. The patients were randomly assigned to two groups, of which one received the thermodilution catheter routinely used in our department and the other, the AHO catheter. The diagnosis of SIAPAC was based on recovery of the same organism from the thermodilution catheter (TC) and blood samples, absence of any other infectious focus, and improvement or resolution of clinical evidence of infection after removal of the TC. A total of 166 TCs were randomized in 150 patients. The two groups (mean +/- SD) were comparable in terms of age, SAPS on admission (15.6 +/- 5.2 versus 15.2 +/- 6.2), SAPS on the day of catheter insertion (17.6 +/- 4.8 versus 17.3 +/- 5.8), duration of catheter insertion (22.8 +/- 11.3 versus 25.3 +/- 19.5 min), insertion site, hemodynamic status, duration of use of the TC (3.6 +/- 1.3 versus 3.5 +/- 1.5 d), and outcome. A total of eight cases of SIAPAC were diagnosed in the standard TC group, versus none in the AHO group (p < 0.002). No cases of SIAPAC occurred in those patients who had their TC for less than four days. This study demonstrates the value of the AHO for preventing systemic infections associated with prolonged pulmonary artery catheterization.