Comparison of two versions of the Vigileo-FloTrac™ system (1.03 and 1.07) for stroke volume estimation: a multicentre, blinded comparison with oesophageal Doppler measurements

Our aim was to evaluate the validity of stroke volume measurements obtained using the Vigileo-FloTrac (TM) system in comparison with those obtained using oesophageal Doppler considered as a reference. Prospective, multicentre study (four university hospitals), in which investigators were blinded to stroke volume values acquired simultaneously with the other technique. Two different versions of the Vigileo software (1.03 and 1.07) were studied and compared over two consecutive periods of time. Forty critically ill patients (three ICUs) and 20 high-risk surgical patients (one operating theatre) were studied over a 6-month period. Two hundred and forty paired stroke volume values obtained using the second version of the Vigileo (1.07) yielded better correlation and agreement (R=0.48, P < 0.001; bias=4 ml, limits of agreement: +/- 41 ml) than the 207 paired values obtained using version 1.03 (R=0.12, P=0.1; bias=1 ml, limits of agreement: +/- 75 ml). However, even with the second version, the percentage error in stroke volume measurement was 58%, a value still above the range considered clinically acceptable (30%). The precision of stroke volume estimation using Vigileo-FloTrac (TM) has improved with the second version of the software (1.07), but remains insufficient to allow the replacement of the reference technique in the population studied.