الفهرس 
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Abstract
Patients admitted to the intensive care unit (ICU) or respiratory intensive care unit (RICU) because of severe episodes of acute exacerbations of chronic obstructive pulmonary disease (AECOPD) have considerably high in- hospital (24%) and 1-year (59%) mortality rates (GOLD 2017). The utility of NIV in acute hypercapnic respiratory failure in COPD is well-established. Since the mid-1990’s, studies have demonstrated superior outcomes in patients with hypercapnic respiratory failure during COPD exacerbation when treated with NIV compared to management without NIV. It is now a standard component of the management of these patients and is included in the most recent international guidelines (Wedzicha, et al.2017).
In particular, risk of death is much higher in those patients receiving invasive mechanical ventilation (MV) once an NIV strategy has proven to be ineffective (Demoule, et al. 2006).
Researchers in previous studies have observed that patients with chronic obstructive pulmonary disease (COPD) might have a higher rate of diaphragmatic dysfunction (DD) than to age- and sex-matched healthy control individuals. During AECOPD, biological factors related to systemic inflammation, prolonged use of steroids, and lung mechanical abnormalities due to hyperinflation may act as synergic mechanisms leading to DD (Gayan and Decramer, 2013).
Therefore, in the current present study, we wanted to investigate the clinical outcomes of patients with AECOPD requiring NIV and presenting with DD detectable by US.
Our study was conducted on 41 patients with acute exacerbation of COPD requiring NIV, diaphragmatic ultrasound was done for all of them, DTF was then calculated for all patients before application of NIV.
In the current study we did comparative statistical analysis between failure and succeeded groups of NIV, regarding age , sex , risk factors (smoking, previous hospital admission , previous use of steroids or theophylline , previous NIV or MV , comorbidities) , pneumonia , FEV1 ,pulmonary hypertension, blood gases at admission and just before weaning from NIV , electrolyte disturbance , diaphragmatic parameters measured by US.
There was statistically significant difference between the studied groups regarding smoking (P-value = 0.029), previous hospital admission (P-value = 0.033) and comorbidity (P-value= 0.031) and regarding pneumonia (P-value=0.036), regarding ICU stay length (P-value=0.000).
There was statistical significant difference between the studied groups regarding DTF (P-value=0.003).
Variables which were significantly different between failure patients and success patients were employed to carry out multivariate regression analysis, so as to screen out the independent risk factors for NIV failure. Results showed that DTF, smoking and pneumonia were independent risk factors for NIV failure in AECOPD patients
ROC curve was calculated for the use of DTF as an index for predicting failure of NIV. The area under curve [AUC] 0.762(95% confidence interval 0.615 to 0.910).
The optimal cut-off point of DTF for being an index for weaning from mechanical ventilation was ≥ 0.306 with a sensitivity of 70.5 % and a specificity of 79.1% and with a PPV value of 70.59 and a NPV 79.17.
The prevalence of diaphragmatic dysfunction in all studied patients was 18 patients (435%) out of 41 patients. As the cut off level of DTF was below 0.306
Prevalence of diaphragmatic dysfunction among failure group was 12 (70.5%) out of 17 patients.
Within the failure group (17 patients) there were 12 patients had diaphragmatic dysfunction (DD+), while 5 patients didn’t had (DD-), with P value 0.002.