Mechanical ventilation with positive end-expiratory pressure in critically ill patients: comparison of CW-Doppler ultrasound cardiac output monitoring (USCOM) and thermodilution (PiCCO).

Background Aggressive mechanical ventilation can markedly and unpredictably aff ect cardiac function. The fall in cardiac output (CO) is due to a reduction in left ventricular stroke volume (SV). The aim of the present pilot study was to assess the eff ects of diff erent positive end-expiratory pressure (PEEP) levels on circulatory function and to compare them with continuous wave (CW)-Doppler ultrasound cardiac output monitoring (USCOM) and a thermodilution-based haemodynamic monitoring system (PiCCO).Methods Twenty mechanically ventilated (PEEP ≤10 mbar) adult patients (female n = 6, male n = 14, mean age 62 years, mean SAPS II-score 48.5), the majority with pneumonia and septic shock) were followed with USCOM and PiCCO at stepwise increased PEEP-levels from 0-10 mbar (1 mbar steps). The changes in CO/SV were recorded.Results With both methods, an increase of PEEP resulted in a decrease of SV and CO. Although the absolute decrease was consistently higher by USCOM, the changes of the parameters were qual...