The aim of the study is to compare results of the assessment of cardiac output and intrathoracic blood volume by two methods--transpulmonary (TTD) and ultrasound (UTD) thermodilution.
Materials and methods: The prospective study included 58 patients (sepsis, septic shock, acute respiratory distress syndrome, intracranial haemorrhages), which underwent femoral artery catheterization with "Pulsiocath" 5Fr catheter (PICCO technology). For the means of ultrasound the catheter was connected to the central venous catheter by an arteriovenous loop. Sensors on arterial and venous ends of the loop registered the time and the volume of the indicator, blood properties and the ultrasound curve. Cooled (0 to 8 C) 5% glucose solution was used as an indicator for TTD, while heated (up to 37C) 0.9% NaCl solution was used as an indicator for the ultrasound. The cardiac output (CO) was measured by TTD and UTD, the global end diastolic volume (GEDV) by TTD, its analogue total end diastolic volume (TEDV) by UTD, intrathoracic blood volume (ITBV) by TTD and central blood volume (CBV) by UTD. 218 pairs of measurements were conducted. Oscillations of CO (TTD) were 2.76-16.3 l/min (8.6 +/- 2.48 l/min) and of CO (UTD)--2.92-18.1 l/min (8.72 +/- 2.65 l/min). There was a strong correlation between CO (TTD) and CO (UTD). The systematic mistake was 0.12 l/min, percentage based mistake--20.9%. ITBV correlated with CBV. There was a big systematic mistake found, which measured as much as 323 ml, the percentage based mistake was 36.5%. The correlation between GEDV and TEDV was (r = 0.70, p < 0.01). The TTD ejection fraction (23.2 +/- 5.6%) was lower (p < 0.01), than by UTD (57.8 +/- 15.2%).
Results: Both methods demonstrate close values of CO. GEDV was higher than TEDV and physiological heart volume. The absolute values of GEDV and ITBV measured by TTD are higher than the actual ones, although they reflect the changes of blood volume and can be used as dynamic preload parameters.