Tissue Doppler imaging of the diaphragm and outcome of weaning from mechanical ventilation

Abstract

Purpose: This study aimed to employ tissue Doppler imaging to monitor diaphragmatic peak velocity and acceleration during contraction and relaxation in mechanically ventilated patients, with the objective of assessing the potential utility of this technique in predicting weaning outcomes.

Methods: A total of 89 adult subjects were recruited in this study. After 30 min of spontaneous breathing trial, the diaphragm motion parameters, including peak contraction velocity, peak relaxation velocity, contraction acceleration and relaxation acceleration, were measured in real time using tissue Doppler imaging. According to the results of weaning, the patients were divided into successful weaning group and failed weaning group. The differences of diaphragmatic tissue Doppler imaging monitoring indicators between the two groups were analysed, and the receiver operating characteristic curve was drawn to analyse the value of each ultrasound parameter in predicting weaning.

Results: In the successful weaning group, there were 61 subjects, while in the failed weaning group, there were 28 subjects. The peak contraction velocity, peak relaxation velocity, contraction acceleration and relaxation acceleration of the diaphragm were significantly higher in the failed weaning group compared to the successful weaning group (P < 0.05). The area under the curve of diaphragmatic peak contraction velocity, peak relaxation velocity, diaphragmatic contraction acceleration and diaphragmatic relaxation acceleration were 0.81 (0.72-0.91), 0.85 (0.77-0.93), 0.74 (0.63-0.86) and 0.86 (0.78-0.94), respectively.

Conclusions: The diaphragm ultrasonic tissue Doppler imaging variables can serve as predictive indicators for weaning mechanical ventilation in patients, thus providing an effective tool to assist critical care physicians in determining the optimal timing for weaning mechanical ventilation.

Keywords: diaphragm ultrasound; mechanical ventilation weaning prediction; tissue Doppler imaging technique.

Figure 1

Schematic representation of tissue Doppler imaging during the contraction and relaxation of the diaphragm. dTDI exhibits two waves, one during diaphragmatic contraction (above the baseline) and one during diaphragmatic relaxation (below the baseline). dTDI, tissue Doppler imaging variables of the diaphragm.

Figure 2

Schematic representation illustrating the measurement of diaphragm tissue Doppler imaging variables. Contraction peak velocity = the maximal velocity during contraction (cm/s); contraction acceleration = the slope of the steepest portion of the contraction velocity curve from baseline to contraction peak velocity (cm/s²); peak relaxation velocity = the maximum diaphragmatic velocity during relaxation (cm/s); relaxation acceleration = the slope of the steepest portion of the relaxation velocity curve from baseline to peak relaxation velocity (cm/s²).

Figure 3

Flow chart.

Figure 4

d‐TDI patterns in the two groups. (a) Patients in the successful weaning group; (b) Patients in the failure weaning group. d‐TDI, tissue Doppler imaging variables of the diaphragm.

Figure 5

Receiver operating characteristic curves for diaphragmatic displacement tissue Doppler variables and conventional diaphragm movement velocity. d‐AC, acceleration of diaphragm contraction; d‐AR, acceleration of diaphragmatic relaxation; d‐MCV, mean velocity of diaphragmatic contraction; d‐PCV, peak contraction velocity of the diaphragm; d‐PRV, peak relaxation velocity of the diaphragm.