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Comparison of three noninvasive cardiac output monitors in patients undergoing therapeutic hypothermia after cardiac arrest


We planned to observe the performance of the LiDCOplus (LiDCO Systems, UK), PiCCO (Pulsion Medical Systems, Germany) and NICO (Novametrix-Respironics, USA) continuous cardiac output monitors during therapeutic hypothermia and rewarming post cardiac arrest. PiCCO calibration failure during hypothermia has been reported [1, 2]. Use of the LiDCOplus and the NICO monitor during therapeutic hypothermia has not been reported. The LiDCOplus pulse power analysis is calibrated using a bolus of lithium chloride instead of transpulmonary thermodilution. Function of the NICO is based on the Fick principle and on partial rebreathing of carbon dioxide. LiDCOplus and NICO performance should not be affected by hypothermia.


Local research ethics committee approval was obtained. Patients admitted to our ICU for therapeutic hypothermia after cardiac arrest were recruited to the study following assent from the next of kin. Hypothermia was induced with 2 l crystalloid at 4°C and maintained using an Alsius Coolguard Icy Catheter (Alsius Corp., USA) inserted via the femoral vein. A 5 F PiCCO catheter was inserted in the femoral artery on the opposite side and connected to the PiCCO and LiDCOplus monitors. A NICO system was attached to the patient's tracheal tube. Systems were calibrated and recalibrated according to the manufacturer's instructions (PiCCO 8 hourly, LIDCOplus 24 hourly). The bladder temperature was recorded and maintained at 33°C for 24 hours. The temperature, heart rate, blood pressure, and cardiac output on all three monitors were recorded hourly. After 24 hours, patients were rewarmed at 0.25°C/hour to a target of 36.5°C.


Six patients were recruited over 8 months. All patients were at the target temperature of 33°C when cardiac output was first recorded. No problems were encountered calibrating the PiCCO, LiDCOplus or NICO monitors at temperatures as low as 33°C. All three monitors were observed to trend together (Figure 1). Statistical analysis of these trends will be available at the time of presentation.

Figure 1
figure 1

abstract P210


LiDCOplus, PiCCO and NICO perform comparably in the temperature range of 33 to 36.5°C.


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Haslam, G., Kelly, F., English, W. et al. Comparison of three noninvasive cardiac output monitors in patients undergoing therapeutic hypothermia after cardiac arrest. Crit Care 13 (Suppl 1), P210 (2009).

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  • Therapeutic Hypothermia
  • Transpulmonary Thermodilution
  • Continuous Cardiac Output
  • Pulsion Medical System
  • Research Ethic Committee Approval