Modelflow method versus continuous thermodilution technique for cardiac output measurement in liver transplant patients / 대한마취과학회지

BACKGROUND: In critically ill patients, cardiac output (CO) is used as a parameter for assessing hemodynamic status and efficacy of treatment. Continuous CO (CCO) could facilitate this assessment during general anesthesia. A new method of arterial pulse wave analysis has been introduced, which estimates beat to beat CO from arterial pressure via Modelflow. It remains uncertain how well this method performs in high output states. We analyzed the relationship between CCO and Modelflow computed from radial and femoral pressures (MFCO(RA), MFCO(FA)) during liver transplantation (LT). METHODS: Measurements were performed in 100 liver transplant patients. Groups A had 36 patients, and group C had 64 patients with both groups composed of Child-Turcotte A, B and C patients Eighty patients had CCO 10 L/min (group E) during anhepatic phase. RESULTS: CCO ranged from 5.0 to 15.4 L/min (MFCO(RA) 3.2 to 10.7 L/min, MFCO(FA) 4.3 to 11.8 L/min). Bland-Altman analyses showed the limit of agreement of MFCO(RA) (-1.5 to 5.2, bias = 1.9 L/min) and of MFCO(FA) (-2.6 to 4.4, bias = 0.9 L/min). CO measured by the two methods was significantly different in groups, except for MFCO(FA) in group C. In group D, bias was 1.5 L/min (SD 1.3 L/min) for MFCO(RA) and 0.9 L/min for MFCO(FA) (SD 1.4 L/min). In group E, biases of 3.5 L/min and 2.4 L/min were obtained for MFCO(RA) and MFCO(FA), respectively. CONCLUSIONS: These results suggest that the group-average value of MFCO is not an accurate parameter for estimating CO during LT, with the exception of MFCO(FA) in groups C and D.

Assessment of the Mechanism of Arterial Blood Pressure Change during Sevoflurane Induction: Beat-to-Beat Analysis of Hemodynamic Variables Using a Modelflow Method / 대한마취과학회지

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.