Background and Goal of Study: The accuracy of cardiac output (CO) measurement by FloTracTM-VigileoTM system (FV, Edwards Lifesciences, Irvine, CA, USA) has been progressively improved with several software version upgrades and its clinical use has been widespread in the perioperative setting in Japan. However, FV cannot be used in all institutions. The technology of FV is based on the physical principal : arterial pulse pressure (PP) ∝ left ventricular stroke volume (SV) ∝ standard deviation of arterial blood pressure (BP-STD), and SV = BP-STD • χ. The χ factor compensates for differences in vascular compliance and resistance. Therefore, we focused on PP, and the aim of this study was to confirm whether monitoring of PP changes is useful for hemodynamic management in intraoperative setting. 
Materials and Methods: The study was conducted on 11 patients (ASA Ⅰ~Ⅲ, age 48 to 80 yr) with sinus rhythm and without moderate or severe valve regurgitation. We prospectively monitored the patients by FV, collected 100 consecutive data acquired every minute during two hours. No bolus of cardiovascular agent was injected during the collection period. Data included PP, SV, BP-STD and χ. Correlations between PP and SV, BP-STD, χ were analyzed using the Pearson r-correlation coefficients.
Results and Discussion: Correlation between PP and SV was 0.052≤r≤0.823: a strong positive correlation (r>0.7) was observed in 3 patients and a moderate positive correlation (0.4<r≤0.7) was observed in 4 of 11 patients. Correlation between PP and BP-STD was 0.757≤r≤0.969: a strong positive correlation was observed in all 11 patients. Correlation between PP and χ was 0.057≤r≤0.943: a strong positive correlation was observed in 8 patients and a moderate positive correlation was observed in 1 of 11 patients. However, χ did not affect to the correlation between PP and SV. In several patients with no correlation between PP and SV, there were very little variations in SV.
Conclusions: PP was proportional to SV in 7 of 11 patients, however, there was no correlation between PP and SV in several patients. These results suggest that in order to consider monitoring of PP change as a useful indicator of hemodynamic management further study is needed.

Examination of the usefulness of pulse pressure in the evaluation of the perioperative cardiac output