الفهرس 
Respiratory physiology of pulmonary oedemaOnly 14 pages are availabe for public view
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Abstract
The term non-invasive mechanical ventilation (NIMV) refers to the application of artificial ventilation without any conduit access to the airways i.e., without an endotracheal or tracheostomy tube. Recently, NIMV has assumed a prominent role in the management of acute respiratory failure.
Although intubation and mechanical ventilation are life-saving measures, they carry significant risks .Noninvasive ventilation, in conjugation with standard medical therapy, has been successfully used to support gas exchange and prevent intubation in patients with acute exacerbation of COPD. The need for endotracheal intubation may be reduced by one-half.
Compared with invasive mechanical ventilation, NIMV decreases the risk of ventilator-associated pneumonia and optimizes comfort. Because of its design, success depends largely on patient cooperation and acceptance. Some factors that may limit the use of NIMV are mask- (or interface-) related problems such as air leaks, mask intolerance due to claustrophobia and anxiety, and poorly fitting mask.
Approximately 10–15% of patients fail to tolerate NIMV due to problems associated with the mask interface despite adjustments in strap tension, repositioning, and trial of different types of masks. Other mask-related problems include facial skin breakdown, aerophagia, inability to handle copious secretions, and mask placement instability.
The most commonly used interfaces in both acute and long-term settings are nasal and oro-nasal masks. The use of NIMV has increased dramatically in the last decade due to the availability of more accessible interface and the desire to avoid complications of intubation.
Several studies have proved its role in acute exacerbation of chronic obstructive pulmonary disease COPD , weaning failure and cardiogenic pulmonary edema. However, the definitive role of NIMV in hypoxemic respiratory failure is still being evaluated. Patient selection, appropriate application of interface and proper monitoring determine the success or failure of NIMV.
An interest in the methods of artificial respiration has long persisted, stimulated by attempts at resuscitation of drowning victims. Reports dating from the mid 1700s document a bellows-type device being the most commonly used form of respiratory assistance.
Negative-pressure tank-type ventilators came into use in the next century This spawned a variety of cuirass and tank negative-pressure ventilators, with the general principle of enclosing the thorax, creating negative pressure to passively expand the chest wall and lungs.
This led to the Drinker-Shaw iron lung in 1928, which was the first widely used negative-pressure ventilator. the Emerson tank ventilator became the standard for ventilatory support.
Development of positive-pressure valves delivered through tracheostomy tubes permitted the delivery of intermittent positive pressure during inspiration.
This quickly replaced the negative-pressure ventilators, further supported by the development of the cuffed endotracheal tube and bedside ventilators.
However, positive-pressure ventilation delivered through either a translaryngeal endotracheal tube or a tracheostomy tube were also associated with a host of complications, specifically injury to the larynx and trachea, as well as other issues involving the timing.