Sustained low efficiency dialysis should not be interrupted for performing transpulmonary thermodilution measurements

CRRT influences PICCO measurements in febrile critically ill patients

The aim of this study was to investigate whether continuous renal replacement therapy (CRRT) influences the global end-diastolic volume index (GEDVI), cardiac index (CI), and extravascular lung water index (EVLWI) measured by Pulse Index Continuous Cardiac Output (PICCO) in febrile patients. Fifteen fever patients were included in this study. CI, GEDVI, EVLWI, heart rate (HR), and mean arterial pressure (MAP) were measured at five time-points: before CRRT (T0), immediately after CRRT started (T1), 15 min after CRRT started (T2), immediately after CRRT stopped (T3), and 15 min after CRRT stopped (T4). Results have shown that CI and GEDVI were decreased significantly in T1 (CI: 4.09 ± 0.72 vs 2.81 ± 0.58 L/min m², P = 0.000 and GEDVI: 727.86 ± 63.47 vs 531.07 ± 66.63 mL/m², P = 0.000). However, CI and GEDVI were significantly increased in T3 (CI: 4.09 ± 0.72 vs 7.23 ± 1.32 L/min m², P = 0.000 and GEDVI 727.86 ± 63.47 vs 1339.17 ± 121.52 mL/m², P = 0.000). There were no significant differences in T2 and T4. Among the five-time points, no measurement errors were observed with regards to HR, MAP, and EVLWI. Therefore, the data herein contained suggests that PICCO measurements should begin 15 min after the start or stop of CRRT.

Lower blood return temperature than core temperature as a causal factor of decreased cardiac output assessed by transpulmonary thermodilution during blood purification

We aimed to evaluate whether cardiac output assessed by transpulmonary thermodilution during blood purification is affected by the difference between the blood return temperature and core temperature. We applied different blood return temperatures using a thermostat bath during blood purification in four pigs. After the blood return temperature stabilized and blood purification process stopped, the cardiac output assessed by transpulmonary thermodilution was measured. The thermostat bath was set at 35°C, 40°C, 45°C, and 50°C, with the order changed at random; four measurements were made at each temperature. Cardiac function was evaluated by echocardiography when ice-cold saline was administered in a pig. A decrease in the blood return temperature resulted in decreased cardiac output assessed by transpulmonary thermodilution, whereas an increase resulted in increased cardiac output assessed by transpulmonary thermodilution. Echocardiography revealed that the change in the blood return temperature did not affect the left ventricular ejection fraction.

Transpulmonary thermodilution techniques in the haemodynamically unstable patient

PURPOSE OF REVIEW

Transpulmonary thermodilution (TPTD) devices invasively measure not only cardiac output but also several other haemodynamic variables estimating cardiac preload, cardiac preload, systolic function, the lung oedema and systolic function, the lung oedema and the pulmonary permeability. In light of the recent literature, we describe how different indices are measured, emphasize their clinical interest and list potential limits and side-effects of the technique.

RECENT FINDINGS

Estimation of cardiac output measurement with TPTD is now well established, at least when compared with the pulmonary artery catheter. The advantage of calibrating the pulse contour analysis, as it is allowed by TPTD indices, is clearly established over uncalibrated devices. The greatest advantage of TPTD is to measure extravascular lung water and pulmonary permeability, which may be useful to diagnose acute respiratory distress syndrome and manage fluid therapy in various critical diseases. It also allows a rapid detection of left ventricular systolic failure. The information it provides must be considered complementary to that provided by echocardiography.

SUMMARY

TPTD provides several indices that may help in making decisions during the therapeutic management of haemodynamically unstable patients. It should be used for the most critically ill patients, whose management requires a reliable, precise and holistic view of the cardiopulmonary condition.