Parameters | Definition | Reported performance | Advantages (A)/Disadvantages (D) | References |
---|---|---|---|---|
EtCO2 | Partial pressure of CO2 in the gas mixture at the end of exhaled breath. Under constant ventilator settings, its main determinant is transpulmonary flow from the native heart | Higher values at 24 h in weaned patients; Rapid rise in EtCO2 preceded changes in hemodynamic monitoring and cardiac index; Increase of ≥ 5 mmHg above previous mean values during two consecutive 12-h periods associated with weaning and preceded native cardiac output recovery. | (A) Noninvasive alternative to thermodilution cardiac catheter; (D) Elimination of CO2 may depend on pulmonary dead-space, which is increased after CPR, thus reducing ETCO2 level; (D) May vary with change in ventilator settings. | |
LVEF | Relation between the amount of blood expelled during each cardiac cycle relative to the size of the ventricle | Greater increase (> 5%) in the first 48 h and significant improvement from cannulation to weaning associated with weaning; LVEF > 20–25% reported before attempting weaning trial. | (A) Direct marker of systolic function; (D) Load-dependent; (D) Absolute value at weaning inconsistently predicted weaning success. | Aissaoui 2011 [15], Aissaoui 2012 [52], Aissaoui 2017 [55], Akin [45], Asaumi [29], Colombo [22], Gambaro [57], Mazet [24], Ouazani [54], Pappalardo [9], Sawamura [43], Sugiura [32], Vuthoori [51],Yi [41] |
LVOT VTI | Velocity time integral (VTI) of a pulsed wave Doppler in the left ventricular outflow tract (LVOT) is directly proportional to the stroke volume of the native heart | Improvement from cannulation to weaning, values above 8.5 cm at weaning associated with success; Threshold of 10 cm reported before attempting weaning trials. | (A) Direct marker of systolic function; (D) Load-dependent. | Aissaoui 2011 [15], Aissaoui 2012 [52], Aissaoui 2017 [55], Colombo [22], Frederiksen [56], Gambaro [57], Gonzalez Martin [27], Lim [48], Mongkolpun [36], Ouazani [54], Sawada [40], Sawamura [43], Yi [41] |
TDI | Tissue Doppler velocity imaging (TDI) is a signal which correlates with myocardial motion. TDI is placed on mitral/tricuspid annulus to evaluate longitudinal systolic function | Mitral systolic velocities (Sa) higher in weaned patients both at maximal and minimal (> 6 cm/s) VA-ECMO flow; Any improvement in lateral mitral e' velocity and/or > 10% improvement in tricuspid annular S′ velocity during flow reduction trial is an independent predictor of weaning success. | (A) Load-independent, making it useful to guide the weaning process; (A) Better predictive performance than conventional parameters for weaning success; (D) Angle-dependent for valid measurement, interobserver variability. | Aissaoui 2011 [15], Aissaoui 2012 [52], Frederiksen [56], Mork [25], Ouazani [54], Yi [41] |
TAPSE | Tricuspid Annular Plane Systolic Excursion (TAPSE) is a M-mode derived marker of longitudinal right ventricular function | Higher at full flow (15 mm) in succesfully weaned patients. | (D) Limited data; (D) Angle dependency. | |
RVEF | Relation between the amount of blood expelled during each cardiac cycle relative to the size of the ventricle | 3D derived RVEF > 24.6% at first intent of decannulation associated with weaning; Higher RVEF in patients without ventricular interdependence during weaning trial. | (A) Direct marker of systolic function; (D) Load-dependent; (D) 3D Echo is time consuming and requires offline analysis without immediate assessment; (D) Two-dimensional measurement less reliable | |
Ventricular interdependence (VI) | Phenomenon whereby the function of one ventricle is altered by changes in the filling of the other ventricle | Absence of VI (Dep-) on the last day before weaning predicted successful weaning. | (A) Highlight ventricular response to load variation. | Aissaoui 2017 [55] |