الفهرس 
Introduction
Predictors of weaning and extubationOnly 14 pages are availabe for public view
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Abstract
Mechanical ventilation is a common intervention used to support critically ill children in the Pediatric Intensive Care Unit (PICU). Premature extubation or unnecessary prolongation of mechanical ventilation are of great risk to the patients. Determining the optimal time to discontinue mechanical ventilation is an important task. The diaphragm is the major respiratory muscle, contributing to 75% of resting lung ventilation and its dysfunction predisposes to respiratory complications and can prolong the duration of mechanical ventilation. Ultrasonography is a fast, easy, safe, accurate, noninvasive and portable method for evaluating diaphragmatic function at the bedside. We conducted this prospective observational study to evaluate diaphragmatic movement as a predictor for successful extubation in mechanically ventilated infants and children in comparison with other predictors (Vtspon, RSBI and WOB). Our study included 100 mechanically ventilated patients, aged between 1 month and 16 years. The right and left diaphragmatic movements were measured by ultrasonography within 6 hours before extubation. Vtspon, RSBI and WOB were measured simultaneously before extubation. The patients were classified into successful group (66 patients) or failed group (34 patients) according to the extubation outcome (extubation failure was defined as the need for reintubation or NIPPV within 48 hours after extubation). During the study period, we collected data from four hundred healthy subjects aged between 1 month and 16 years recruited from the outpatient clinic of MUCH (control group). We assessed interobserver and intraobserver reproducibility of diaphragmatic sonographic measurements using data from another 80 healthy subjects. The sensitivity and specificity of Vtspon, RSBI, and WOB as predictors for successful extubation were calculated using the cutoff values determined by the receiver operating characteristic (ROC) curves. The right diaphragmatic movement AUC was 0.59 which was not discriminative. So, we considered values between 5th and 95th percentiles for the right diaphragmatic movement plotted against body weight in our control group as the normal reference range for right diaphragmatic movement. The major findings in our study are that the right diaphragmatic movement was significantly higher in the successful group than in the failure group. It had a high sensitivity (91%) and low specificity (53%) in predicting successful extubation. Vtspon was significantly higher in the successful group than in the failure group. Its cutoff value, as a predictor for successful extubation, was 6.6 ml/kg determined from the ROC curve (AUC = 0.78) with a sensitivity of 73% and a specificity of 76%. It is the most reliable predictor for extubation success as it has the highest AUC compared to RSBI, WOB and right diaphragmatic movement. RSBI was significantly lower in the successful group than in the failure group. Its cutoff value, as a predictor for successful extubation, was 8 breath/min/ml/kg determined from the ROC curve (AUC = 0.73) with a sensitivity of 70% and the specificity of 59%. WOB was significantly lower in the successful group than in the failure group. Surprisingly, we have found that the WOB had a comparable predictive value to Vtspon as it had a sensitivity of 82% and a specificity of 70% using a cutoff value of 0.26 J/L determined from ROC curve (AUC = 0.76). In the study group, contrary to the common perception, there was no statistically significant difference between successful and failure groups concerning the duration of mechanical ventilation before extubation. Also, there was no statistically significant difference between the successful and failure groups with reference to the patients’ age or gender. We have measured, for the first time, the normative reference values for diaphragmatic sonographic data for healthy infants and children and plotted the percentile curves for normal right diaphragmatic movement against body weight; these data are of great value for the clinician and for future researches. We assessed the reproducibility of diaphragmatic movement and thickness using Pearson correlation coefficient (revealed a strong significant correlation between measurements) and Bland-Altman plots (revealed low bias values and high degree of agreement between measurements). So, ultrasonography is proved to be a reproducible diagnostic tool for evaluation of diaphragmatic movement and thickness in our study population.