Dissertation committee:
Σεραφείμ Νανάς, Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Χριστίνα Ρούτση, Καθηγήτρια, Ιατρική Σχολή, ΕΚΠΑ
Γεράσιμος Φιλιππάτος, Καθηγητής Ιατρική Σχολή, ΕΚΠΑ
Ανδρέας Καραμπίνης, Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Kασσιανή Θεοδωράκη, Αναπ. Καθηγήτρια, Ιατρική Σχολή, ΕΚΠΑ
Ιγνάτιος Οικονομίδης, Αναπ. Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Ιωάννης Βασιλειάδης, Επικ. Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Summary:
The pathophysiology of weaning failure in ICU patients that are mechanically ventilated is complex. The rate of weaning failure is about 31% of mechanically ventilated patients. Cardiac dysfunction is a common cause of weaning failure. Patients with impaired cardiac function who fail to adequately increase cardiac output and O2 transport in order to meet additional O2 needs during weaning process are led to weaning failure. Left ventricle diastolic dysfunction can affect unfavourably the result of weaning process, because the asymptomatic, at rest, diastolic dysfunction can become symptomatic during the cardio-respiratory exercise of transport from mechanical ventilation in spontaneous breathing (breathing as exercice) and so, can lead to weaning failure.
The purpose of our study was to investigate of the role of cardiac diastolic dysfunction in weaning from mechanical ventilation, along with the investigation of the merit of modern cardiac biomarkers. For this purpose we studied, a total number of 42 patients, who were under MA for more than 48 hours, and they underwent a 2-hour T-tube spontaneous breathing trial. Before the disconnection from the mechanical ventilation and the start of spontaneous breathing trial was assessed the left ventricle diastolic function with transthoracic echocardiography (transmitral flow or pulsed-waved Doppler and tissue Doppler imaging). In particular, the control of left ventricular diastolic dysfunction was based on assessing the echo indexes Ε, Α, Ε/Α, e΄ (or E΄), Ε/e΄ and DTE of transmitral flow and TDI (tissue Doppler imaging). Based on these echo parameters the left ventricular diastolic dysfunction was graded as grade 0 (or physiological diastolic function), grade I, II or III. Before the disconnection of the patient from mechanical ventilation (baseline) and start of spontaneous breathing trial (SBT) and after the end of SBT we recorded respiratory, hemodynamic parameters and cardiac biomarkers (BNP, cTNI, CK-MB and myoglobin).
In conclusion, our study showed that in a general ICU population, patients undergoing a spontaneous breathing trial to wean from the mechanical ventilation, 1. LV diastolic dysfunction was an independent risk factor for weaning failure, 2. there were no significant differences in transthoracic echocardiography indexes of left ventricular diastolic function (such as E/A, E/e ', DTE), measured under mechanical ventilation, prior to the spontaneous breathing trial, between patients who succeeded and them who failed to wean from mechanical ventilation, 3. the BNP levels increased significantly more in patients who failed to wean, and 4. there was a significant correlation between grades of diastolic dysfunction and baseline BNP levels, before weaning attempts. As a conclusion, the role of cardiac diastolic dysfunction seems to be important in weaning outcome, and its assessment by transthoracic echocardiography prior to initiation of weaning attempts may detect those patients who are highly likely to fail. In addition, the combination of the TTE study with BNP levels could complement the clinical information in the complex setting of weaning failure.
