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1. Introduction
Estimation of haemodynamic variables such as left ventricular stroke volume and cardiac index in high-risk patients is a prerequisite for performing individual goal-directed therapy. Perioperative haemodynamic optimization and individual tailored therapy have been shown to improve patients’ outcome by reducing morbidity and the length of stay on the intensive care unit [1–3]. In clinical practice, determination of cardiac index in the past was mostly related to invasive procedures such as right heart catheterization or femoral access, baring method-related complications and limitations [4–6]. In this context, less-invasive techniques based on arterial waveform analysis have gained increasing interest [7–9]. An example for a semi-invasive device for estimation of CI by pulse contour analysis is the FloTrac/Vigileo-system (Edwards Lifesciences LLC, Irvine, CA, USA), which was introduced in 2005 and since then underwent several software upgrades. The underlying method is described in detail elsewhere [10, 11]. This system requires only an arterial line connected to a special transducer (FloTrac) and has been investigated in several studies under various clinical conditions, but its precision to reflect CI is still under debate [12–14].
The aim of the present study was to investigate the precision of CI determination based on arterial waveform analysis by a third-generation device (CIWave) with transpulmonary thermodilution (CITPTD) before and after cardiopulmonary bypass (CPB). Furthermore, we studied the ability of the semi-invasive technique for tracking haemodynamic changes and trends.
2. Materials and Methods
After approval from our institutional ethics committee (Christian Albrecht University Kiel, Schwanenweg 20, D-24105 Kiel), written informed consent for participation in the study was obtained from all patients.
Fifty patients undergoing elective coronary artery bypass grafting (CABG) were studied after induction of general anaesthesia until discharge to the intensive care unit. Exclusion criteria were patients <18 years of age, a left ventricular ejection fraction ≤0.5, emergency procedures, and patients with haemodynamic instability requiring continuous pharmacologic support. Patients with intracardiac shunts, severe aortic, tricuspid or mitral stenosis or insufficiency and mechanical circulatory support were also excluded.
2.1. Instrumentation and Protocol
All patients were premedicated with midazolam 0.1 mg/kg orally 30 min before induction of anaesthesia. Routine monitoring was established including peripheral oxygen saturation (SpO2) and heart rate (HR) (S/5 monitor, GE Healthcare, Helsinki, Finland). Subsequently patients received a peripheral venous...