RESUMO
BACKGROUND: A modelflow method provides beat-to-beat analysis of cardiovascular variables based on arterial pulse pressure analysis. In this study, we assessed the mechanism of arterial blood pressure (ABP) change during sevoflurane induction by the analysis of beat-to-beat hemodynamic changes using a modelflow method. METHODS: Beat-to-beat ABP was measured during a stable conscious state (baseline) and vital capacity induction with sevoflurane 6 vol% and oxygen 8 L/min in 18 healthy living liver transplant donors. Alterations of beat-to-beat systolic ABP, mean ABP, diastolic ABP, heart rate (HR), stroke volume (SV), cardiac output (CO), and total peripheral resistance (TPR) by sevoflurane induction were estimated noninvasively using a modelflow method simulating aortic input impedance from an ABP waveform. RESULTS: After sevoflurane induction, ABP, SV, CO, and TPR decreased significantly (all P < 0.05), but HR did not change significantly. After tracheal intubation, ABP, CO, and TPR did not change significantly compared with baseline, but HR increased and SV decreased significantly (both P < 0.05). CONCLUSIONS: Using a modelflow beat-to-beat analysis of cardiovascular variables, we found that ABP did not change significantly compared to baseline after tracheal intubation during sevoflurane induction, indicating the counteraction of increased HR and decreased SV, and that the reduction of SV by tracheal intubation suggests the suppression by increased HR and TPR compared with that after sevoflurane induction.