الفهرس 
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Abstract
Failure of weaning from mechanical ventilation is independently associated with poor outcome in critically ill patients [1]. Identifying the cause of weaning failure helps to determine the appropriate treatment, which may prompt weaning.
During weaning from mechanical ventilation, usually during a spontaneous breathing trial (SBT), heart–lung interactions impair the cardiac loading conditions, which may lead to pulmonary oedema which subsequently will lead to weaning failure. Detecting WIPO is potentially important and useful, because it can be easily treated.
Measuring the pulmonary artery occlusion pressure during an SBT directly evidences the increase in hydrostatic pulmonary pressure [3]. However, less invasive alternative methods have been developed, like the assessment of blood volume contraction, increase in B-type natriuretic peptide (BNP), in the left ventricular filling pressure at echocardiography [9] or in extravascular lung water.
For many years, the reference criterion for diagnosing WIPO was an SBT-induced increase in the pulmonary artery occlusion pressure, measured through a pulmonary artery catheter. Some alternatives have been developed. A significant increase in the B-type natriuretic peptide or the N-terminal B-type natriuretic peptide during the SBT has been shown to be reliable. Another biological method is based on the haemoconcentration that is induced during pulmonary oedema by the filtration of a significant volume of plasma throughout the pulmonary alveolo-capillary barrier. A significant haemoconcentration, as assessed by an increase in the haemoglobin and/or of the plasma protein concentration provides a reliable diagnosis of WIPO.
Echocardiography could be useful, since it estimates the left ventricular filling pressure and diastolic dysfunction during weaning failure [12]. Transpulmonary thermodilution enables one to directly show the increase in extravascular lung water during WIPO, but this requires a specific and invasive device.
Lung ultrasound in critically ill patients may be an alternative. By detecting multiple B-lines that allows the diagnosis of interstitial syndrome, lung ultrasound accurately detects pulmonary oedema. B-lines have been correlated with NT-pro-BNP in breathless patients and with extravascular lung water accumulation. Nevertheless; Lung ultrasound has never been tested as a diagnostic tool to detect WIPO.
In our study, our hypothesis is that it is possible to determine an increase in the number of B-lines that allows the diagnosis of WIPO. Our goal is to determine this threshold of B-line increase (Delta-B lines) that reliably detects WIPO, first in patients failing an SBT, because the question of WIPO mainly arises in such patients, and second in the general population of patients performing an SBT.
The aim of this study was to test the ideal profile (increase in the number of B-lines) for diagnosing WIPO using lung ultrasound to avoid the poor outcome of weaning failure.
The type of Study was prospective study. This study was performed in intensive care units of Ain Shams University Hospitals between October 2020 and March 2021.
The studied patients groups was divided into 3 groups regarding the final outcome, group I including the successful group including 28 patients, the second group was failed without WIPO including 10 cases, and finally the third group failed with WIPO including 13 cases.
The results showed that the vital signs including heart rate and respiratory rate showed a significant improvement in successful group more than the failed group at the end of SBT, on the other hand the blood pressure and temperature show insignificant difference at the end of SBT between the studied groups.
Regarding the ABG results in our study, it was found that there was a significant difference between the studied groups at the end of SBT in SaO2, pH, PO2, PCO2, HCO3.
In our results it was found that the B-lines (lung U/S) before SBT and at the end of SBT showed a highly significant difference between successful and failed group either with or without WIPO, in successful group the B-lines before SBT was 2.0±1.25 while in failed without WIPO was 5.40±1.17 and in failed with WIPO was 6.62±1.04. At the end of SBT the successful was 1.50±1.83 while in failed patients without WIPO was 6.40±1.35 and in failed patients with WIPO was 7.31, there was a highly significantly difference between the three studied groups (p <0.05).
The sensitivity of B-line in predict the successful weaning was 95.0, while the specificity was 90.0% and the accuracy was 92.0% at cut off value 5.0.
The sensitivity of B-line in predict the WIPO was 90.0, while the specificity was 84.0% and the accuracy was 87.0% at cut off value 5.5.
Conclusion
from the results of this study it was concluded that an increase in the number of B-lines ≥ 5 on four anterior points during SBT provided the best accuracy for diagnosing WIPO with lung ultrasound. We suggest calling this sign the WIPO profile. These encouraging results must be confirmed by larger series, so that LUCI may empower the non-invasive monitoring tools, including biochemical indices, for the diagnosis of this common problem.