الفهرس 
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Abstract
COPD (Chronic Obstructive Pulmonary Disease) represents a significant and growing healthcare concern as a leading cause of morbidity and mortality worldwide. An exacerbation of COPD is an event in the natural course of the disease characterized by a change in the patient‘s baseline dyspnoea, cough and/or sputum beyond day-to-day variability sufficient to warrant a change in management. Mechanical ventilation for acute respiratory failure in patients with COPD is associated with high rates of intensive care unit (ICU) mortality (37 to 64 percent). (13)
A major driving force behind the increasing use of noninvasive ventilation has been the desire to avoid the complications of invasive ventilation. Although invasive mechanical ventilation is highly effective and reliable in supporting alveolar ventilation, endotracheal intubation carries well-known risks of complications like for example ventilator-associated pneumonia. Ventilator-associated pneumonia has been associated with increased morbidity and mortality.
Noninvasive ventilation (NIV) had the organization of ventilatory support without utilizing an invading synthetic airway (an endotracheal tube or a tracheostomy tube). NIV had conveyed through an interface, ordinarily a facial or a nasal mask, which links the case’s airway to the ventilator tubing. Noninvasive ventilation has been shown to augment tidal volume, reduce breathing frequency, rest the muscles of respiration and improve gas exchange.
To decrease invasive ventilation complications, researchers have studied the role of noninvasive ventilation in weaning by replacing invasive support with noninvasive support in patients who are ready to be weaned but not yet ready for mechanical ventilation to be removed. Many factors decease the incidence of complication of invasive ventilation compared to noninvasive like no artificial airway is used and the cough reflex is preserved so the risk for ventilator associated pneumonia is reduced. Additionally, noninvasive weaning may reduce the requirement for sedation, decrease psychological distress and permit speech and oral intake. However, with noninvasive weaning (NIV), clinicians must anticipate drying of secretions; accept that only partial ventilatory support can be provided and full protection of airway is not achieved.
Side effects with NIV are usually related to mask discomfort, air pressures, or gas flows. Serious complications can occur such as aspiration pneumonia, pneumothorax, and hypotension.. Mask discomfort is the most common complication of NIV. Air leaks around the mask often result in eye irritation. In addition, the strap pressure required to maintain an airtight fit often creates excessive pressure over the bridge of the nose and cheek area. Pressure sores may develop, leading to skin breakdown and ulceration of the nasal bridge. Other major complications of NIV include mucus plugging, hypoxemia, hypotension, and respiratory arrest. Mucus plugging is more likely to occur if the patient is dehydrated or has difficulty expectorating secretions or if humidification is inadequate. High oxygen flow rates (up to 40 L/min) have been associated with life threatening airway obstruction caused by inspissated secretions.
The purpose of this study was to further assess the effectiveness of non-invasive ventilation as a new modality for weaning of COPD patients from MV. Compared with the traditional gradual weaning, NIV was assessed regarding Invasive ventilation free days at day 28, MV period, and weaning duration in hours, ICU stay and 28 days survival In spite of the strong evidence that support the use of NIV to replace invasive mv to reduce complication of intubation and thus reducing mortality and improving outcome. This is more evident in certain patient population e.g. COPD with acute exacerbation and has been proven by previously conducted randomized controlled trials. However its use as an alternative for early weaning extubation remains controversial.
In our study we were not able to find out an advantage of NIV over conventional way of weaning as both groups were similar regarding 28 day mortality, ICU length of stay, duration of invasive mechanical ventilation and complications of mechanical ventilation.There was no statistically significant difference.
Patients of both groups showed statistically insignificant difference in demographic data (age, gender, and weight), APACHE II score on admission, and duration of mechanical ventilation before randomization and co morbidities. Weaning failure during spontaneous breathing trial (SBT) was 72.7% (40/55) which is higher than that reported in the literature which is ranged from 35%to 67%.
This finding could be explained by the relatively more critical general condition as expressed by high APACHE II score on admission. The duration of weaning in hours was less in NIV group compared to invasive group (51±32.6 versus 55±9.8) however that difference was statistically insignificant.
The number of complication was less in NIV group however the difference was statistically insignificant. The most common complication was nosocomial pneumonia 20% and septic shock 20%. We did not observe any reduction in mortality rate.