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Perioperative Hemodynamic Beat-To-Beat Monitoring of Cardiac Output: The New PulseCO System™
Andreas Mappes, M.D.; Marcus Gruendel, M.D.; Hermann Kuppe, M.D.
Dept. of Anesthesiology, German Heart Institute, Berlin, Germany
Introduction: For the anesthesiologist, hemodynamic online monitoring during surgery has become more important in the last decade. Due to limitations of existing technology means it has not been possible to routinely measure parameters other than heart rate and various invasive pressure values online and beat-to-beat. We report about first clinical results obtained during open heart surgery from a new technology (PulseCO system, LiDCO Ltd., UK) that measures beat-to-beat cardiac output (CO).

Methods: After ethical approval and informed consent were obtained, 16 patients for open heart surgery were monitored by PulseCO. Data (weight, height, age) and user preferences could be entered using a touch screen. The system displays CO, stroke volume, systemic vascular resistance, heart rate, mean arterial pressure (MAP) and systolic pressure variation. The procedure merely requires an analogue pressure waveform recorded from any peripheral artery. The CO is then computed according to a proprietary algorithm that uses autocorrelation to derive both the power / stroke volume and rate from the pressure wave form. For calibration we performed lithium indicator dilution measurements (LiDCO, LiDCO Ltd., UK)[1]. The potential impact of the PulseCO system on perioperative hemodynamic management of cardiovascular patients undergoing CABG, OPCAB, MIDCAB and total endoscopic interventions was evaluated. Hemodynamically relevant manoeuvres were recorded and stored e.g. intraoperatively during induction and weaning from both cardiopulmonary bypass and assist device systems. The recorded beat-to-beat data were compared qualitatively and quantitatively with a currently available continuous method of obtaining CO (CCO, Baxter Edwards, Irvine CA)[Fig.]. Statistical analysis was performed by linear regression.

Results: Hemodynamic relevant manoeuvers (stabilizer, twisting, CO2 inflation, etc.) led to changes in CO of 5% to nearly 100%. With the (semi)continuous CCO measurement a delay up to 5.2 ± 2.4 minutes was observed. Short-time changes of CO (<30 s) could not - or only considerably delayed - be registered by CCO, due to the underlying algorithm. During phases without significant changes in CO, PulseCO and CCO correlated well (r2 up to 0.69). Significant CO trends were not detected by measuring MAP alone.

Conclusions: These preliminary experiences with the PulseCO system during various cardiac surgical interventions show that the online analysis of the arterial pressure waveform allows a minimally invasive and sensitive beat-to-beat monitoring of the CO. This procedure does not necessarily require a central venous access. This may facilitate considerably the cardio-anesthesiological management during perioperative hemodynamic monitoring in the future. Further clinical studies should investigate the impact on the clinical outcome of the patients.

References: [1] Br J Anaesth 1993; 71: 262-6

Anesthesiology 2001; 95:A541
Figure 1