Using ultrasound of heart, lungs and diaphragm to predict weaning success: A prospective observational study

Abstract

BACKGROUND. In ICU patients deciding the optimal timing for extuba-tion is challenging and clinical predictors are not very accurate. Ultra-sonographic assessment of the diaphragm function has been used to predict successful extubation.1 However, cardiorespiratory function also greatly impacts a patient's ability to wean from mechanical ventilation. OBJECTIVE. To assess if a combination ultrasound measurements of the diaphragm, heart and lungs could predict extubation success more accur-ately than using single-organ ultrasonography assessment. METHODS. This prospective observational study in the Intensive Care Unit of a tertiary academic hospital included adult patients who were in-vasively ventilated for > 72 hrs. Exclusion criteria included paraplegia, tracheostomy or planned non-invasive ventilation (NIV) after extubation. Ultrasound measurements of heart (left ventricular function (LVF)), lungs (number of B-lines) and diaphragm (thickening fraction (TFdi%)) were performed within 6 hours before extubation during spontaneous breathing trial. Patients not needing reintubation or NIV within 48 hrs after extu-bation were recorded as successful extubation. A logistic regression prediction model using backward selection was made. RESULTS. In this interim analysis, 39 patients were included of which 77% were male, with a mean age of 61 (+/-17) years and a median of 126 [95-207] and 96 [84-185] hours on mechanical ventilation in the successful and failed group, respectively. Of these patients, 7 (18%) required reintubation within 48 hours. Patients in need of reintuba-tion compared to patients who were extubated successfully had no significant difference in TFdi% (21.2% vs. 25.5%; p=0.36), left ventricular function (72% good vs. 71% good, p=.94) or B-lines (17 [9-24] vs. 7 [3-15] p=.072), although a trend for more B-lines was observed in the extubation failure group. Multivariable regression analysis showed that addition of B-lines and classic parameters such as PaO2 and FiO2 to the thickening fraction has added value in predicting extubation (Table 1). This was not the case for LVF. CONCLUSION. The results of this study suggest that addition of lung ultrasound to diaphragm ultrasound might have added benefit in predicting extubation success, while for LVF this does not seem to be the case. Variables included: Age, Gender, Ventilation Time (VT), FiO2, PaO2, SOFA-score, Thickening fraction, BLUE-Profile, B-lines, Whitebloodcellcount, CRP, Hemoglobin (Hb), LVF, Creat, Breathing Frequency (BF), Pressure Support (PS), Tidal Volume (TV) Variables removed: Age, Gender, VT, SOFA, BLUE-Profile, WBC, CRP, Hb, LVF, BF, PS, TV N=39 Nagelkerke R2=.651 [Table Presented].