[The thermodilution determination of right ventricular volumes and ejection fraction in the critical patient. Volumetric vs pressure measurement assessment].
The widespread use of hemodynamic investigation techniques, allowed a better understanding of the right ventricle (RV) pathophysiology and led to progressive reevaluation of its role. A modification of the classical Swan-Ganz catheter, made possible the measurement of the ejection fraction (EF) and of the end-systolic and end-diastolic volumes of RV just by the simple application of the thermodilution technique. In this paper, we first refreshed the basic theoretical principles of the technique and then presented our preliminary results of one-year experience in ICU. A non-homogeneous group of 36 critically ill patients (septic shock 17, COPD 13 and ARDS 6) was studied. Specifically we found that neither the data of central venous pressure nor those of RV end diastolic pressure, were able to estimate the real preload, i.e. RV end diastolic volume (r = 0.01 and r = 0.03 respectively with "p" not significant). We compared the data of RV EF with that of the end systolic pressure/volume (P/V) ratio in a group of patients before and during the administration of dobutamine to evaluate their sensitivity to identify changes of contractility. The results obtained support the superiority of RV end systolic P/V ratio over RV EF to detect variations of contractile status. We conclude that the use of the thermodilution technique to measure the volumes of RV, allows a real evaluation of the preload. At the same time it avoids all the problems associated with the measurement of transmural pressure and with the changes produced by shifting of intrapleural pressure. Finally the end systolic volume may be combined with the pressure data to estimate the contractile status and, in our experience, this parameter has proved more sensitive than EF in order to detect changes of contractility of the right ventricle.
De Monte
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A
Servizio di Anestesia e Rianimazione II, Ospedale Civile di Udine.
Baigorri
F
F
Bertolissi
M
M
Artigas
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A
D001794:Blood Pressure; D016638:Critical Illness; D006801:Humans; D008173:Lung Diseases, Obstructive / Q000503:physiopathology; D012128:Respiratory Distress Syndrome / Q000503:physiopathology; D012772:Shock, Septic / Q000503:physiopathology; D013318:Stroke Volume; D013815:Thermodilution / Q000379:methods*; D016278:Ventricular Function, Right