Transpulmonary thermodilution: advantages and limits

Abstract

Background: For complex patients in the intensive care unit or in the operating room, many questions regarding their haemodynamic management cannot be answered with simple clinical examination. In particular, arterial pressure allows only a rough estimation of cardiac output. Transpulmonary thermodilution is a technique that provides a full haemodynamic assessment through cardiac output and other indices. Main body: Through the analysis of the thermodilution curve recorded at the tip of an arterial catheter after the injection of a cold bolus in the venous circulation, transpulmonary thermodilution intermittently measures cardiac output. This measure allows the calibration of pulse contour analysis. This provides continuous and real time monitoring of cardiac output, which is not possible with the pulmonary artery catheter. Transpulmonary thermodilution provides several variables beyond cardiac output. It estimates the end-diastolic volume of the four cardiac cavities, which is a marker of cardiac preload. It provides an estimation of the systolic function of the combined ventricles. It is more direct than the pulmonary artery catheter, but does not allow the distinct estimation of right and left cardiac function. It is easier and faster to perform than echocardiography, but does not provide a full evaluation of the cardiac structure and function. Transpulmonary thermodilution has the unique advantage of being able to estimate at the bedside extravascular lung water, which quantifies the volume of pulmonary oedema, and pulmonary vascular permeability, which quantifies the degree of a pulmonary capillary leak. Both indices are helpful for guiding fluid strategy, especially in case of acute respiratory distress syndrome. Conclusions: Transpulmonary thermodilution provides a full cardiovascular evaluation that allows one to answer many questions regarding haemodynamic management. It belongs to the category of "advanced" devices that are indicated for the most critically ill and/or complex patients.

Intraoperative Troponin Elevation in Liver Transplantation Is Independently Associated With Mortality: A Prospective Observational Study

“…Furthermore, patients without ITE were able to increase contractility after graft reperfusion, indicating an appropriate physiological response to the hemodynamic challenge, whereas the ITE group failed to show this response even though they received a larger intraoperative fluid volume and required more frequent use of noradrenaline. Although the evaluation of cardiac function is dependent on preload and afterload conditions, the preload measured by GEDVI was not significantly different between patients with and without ITE until the abdominal closure, suggesting that troponin elevation during LT is predominantly related to intraoperative myocardial dysfunction.…”

Transpulmonary thermodilution detects rapid and reversible increases in lung water induced by positive end-expiratory pressure in acute respiratory distress syndrome

“…With TPTD, we also measured the pulmonary vascular permeability index (PVPI) [1,33] (also averaged from five successive thermodilution measurements) and cardiac index (CI).…”

The crashing patient: hemodynamic collapse

“…The most common calibration system uses transpulmonary thermodilution which calculates the CO from the reciprocal of the integral of the area under the curve that describes the change in temperature in blood induced by a bolus of cold saline (Stewart–Hamilton equation) [23]. Because SVV and PPV are calculated relative to mean values of SVV and PPV (Table 1), these parameters are not affected by the lack of calibration.…”

“…starting a vasopressor, an episode of vasodilatation, etc.) and ideally every hour if the CO is essential to interpret the hemodynamic profile of the patient [20,23]. Therefore, the use of PCA devices is most helpful after the initial ‘salvage’ phase of resuscitation.…”