Assessment of stroke volumeindex with three different bioimpedance algorithms: lack of agreement compared to thermodilution

Objective: The accuracy of bioimpedance stroke volume index (SVI) is questionable as studies report inconsistent results. It remains unclear whether the algorithms alone are responsible for these findings. We analyzed the raw impedance data with three algorithms and compared bioimpedance SVI to transpulmonary thermodilution (SVITD). Design and setting: Prospective observational clinical study in a university hospital. Patients: Twenty adult patients scheduled for coronary artery bypass grafting (CABG). Interventions: SVITD and bioimpedance parameters were simultaneously obtained before surgery (t1), after bypass (t2), after sternal closure (t3), at the intensive care unit (t4), at normothermia (t5), after extubation (t6) and before discharge (t7). Bioimpedance data were analyzed off-line using cylinder (Kubicek: SVIK; Wang: SVIW) and truncated cone based algorithms (Sramek-Bernstein: SVISB). Measurements and results: Bias and precision between the SVITD and SVIK, SVISB, and SVIW was 1.0± 10.8, 9.8± 11.4, and -15.7± 8.2ml/m2 respectively, while the mean error was abundantly above 30%. Analysis of data per time moment resulted in a mean error above 30%, except for SVIW at t2 (28%). Conclusions: Estimation of SVI by cylinder or truncated cone based algorithms is not reliable for clinical decision making in patients undergoing CABG surgery. A more robust approach for estimating bioimpedance based SVI may exclude inconsistencies in the underlying algorithms in existing thoracic bioimpedance cardiography devices

Carotid Baroreflex Activation: Past, Present, and Future

Electrical activation of the carotid baroreceptor system is an attractive therapy for the treatment of resistant hypertension. In the past, several attempts were made to directly activate the baroreceptor system in humans, but the method had to be restricted to a few selected patients. Adverse effects, the need for better electrical devices and better surgical techniques, and the lack of knowledge about long-term effects has greatly hampered developments in this area for many years. Recently, a new and promising device was evaluated in a multicenter feasibility trial, which showed a clinically and statistically significant reduction in office systolic blood pressure (>20 mm Hg). This reduction could be sustained for at least 2 years with an acceptable safety profile. In the future, this new device may stimulate further application of electrical activation of the carotid baroreflex in treatment-resistant hypertension

Less invasive methods of advanced hemodynamic monitoring: principles, devices, and their role in the perioperative hemodynamic optimization.

The monitoring of the cardiac output (CO) and other hemodynamic parameters, traditionally performed with the thermodilution method via a pulmonary artery catheter (PAC), is now increasingly done with the aid of less invasive and much easier to use devices. When used within the context of a hemodynamic optimization protocol, they can positively influence the outcome in both surgical and non-surgical patient populations. While these monitoring tools have simplified the hemodynamic calculations, they are subject to limitations and can lead to erroneous results if not used properly. In this article we will review the commercially available minimally invasive CO monitoring devices, explore their technical characteristics and describe the limitations that should be taken into consideration when clinical decisions are made