Stress echocardiography in patients who experienced mechanical ventilation weaning failure.

INTRODUCTION: Critically ill patients may suffer varying degrees of temporary myocardial dysfunction during respiratory weaning that could play an important role in weaning failure.

OBJECTIVES: In this study, we tried to assess the existence of temporary diastolic dysfunction during respiratory weaning.

METHODS: Inclusion period is from 2006 to 2015. In this study, we included 181 ventilated patients with cardiogenic shock that were being weaned from mechanical ventilation. Twenty of those patients were successfully weaned from mechanical ventilation, and the rest (161) experienced complications in their weaning process. All patients had a left ventricular ejection fraction >0.45 and E/E' ratio≤8, did not require vasoactive drugs at that time, and did not have remaining significant ischemic disease. We divided our patients into 3 groups, as follows: A, patients who could not tolerate a T-tube and required pressure-support ventilation (82); B, patients who successfully tolerated a T-tube period (20); and C, patients who could not tolerate spontaneous breathing modes of mechanical ventilation and remained on assisted mechanical ventilation. We performed stress echocardiography for the last two groups; using dobutamine to assess diastolic function and using ephedrine to evaluate functional mitral regurgitation (MR). We estimated pulmonary capillary wedge pressure through the E/E' ratio and the flow in the pulmonary veins.

RESULTS: In group A (ie, those patients who could not tolerate a T-tube trial), we observed an increase in the E/E' ratio (6.32±0.77 vs 15.2±6.65; P=.0001) and a worsening of strain (S) and strain rate (SR) (-13.6±1.80 vs -11.88±5.6, P=.0001; and -1.3±1.28 vs -0.95±0.38, P=.0001; respectively). We did not observe a change in the E/E' ratio during stress echocardiogram on those patients with successful weaning from mechanical ventilation (7.41±0.43 vs 8.38±4.57, P=.001). However, we did see in this group an increased peak velocity of the S wave and of SR (-16.11±08.72 vs -19.89±5.62 and -1.48±0.23 vs -1.59±0.21, P=.001; respectively). In 42 weaning failure patients, the dobutamine echocardiography showed an increased E/E' ratio (7.41±0.43 vs 15.98±7.98; P=.0001) and deterioration of S (-15.41±09.56 vs -12.72±6.55; P=.0001) and SR (-1.41±0.78 vs -1.22±0.65; P=.0001). In 37 patients without systolic or diastolic impairment and functional MR grade >2, ephedrine echocardiography showed an increase of effective regurgitant volume (29.56±11.32 mL vs 46.56±0.13 mL, P=.0001) and effective regurgitant orifice area (0.19±0.09 cm2 vs 0.31±0.09 cm2 , P=.0001).

CONCLUSIONS: Stress echocardiography may be helpful in detecting silent diastolic and systolic dysfunction or severe MR that could have a major impact on respiratory weaning.