الفهرس 
Anatomy of The Respiratory SystemOnly 14 pages are availabe for public view
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Abstract
Acute Respiratory Failure (ARF) is a syndrome in which the respiratory system fails in one or both of its gas exchange functions: oxygenation and carbon dioxide elimination. In practice, it is defined as a PaO2 value of less than 60 mmHg while breathing air or a PaCO2 of more than 50 mmHg. It develops over minutes to hours; therefore, pH is less than 7.3. It is characterized by life-threatening derangements in arterial blood gases and acid-base status.
The act of respiration engages 3 processes: transfer of oxygen across the alveolus, transport of oxygen to the tissues, and removal of carbon dioxide from blood into the alveolus and then into the environment. Respiratory failure may occur from malfunctioning of any of these processes.
Central and peripheral nervous system disorders, abnormalities of the airways and abnormalities of the alveoli are the most common pathophysiologic causes of ARF.
The mortality rate associated with ARF varies according to the etiology e.g. acute respiratory distress syndrome, the mortality rate is approximately 45% in most studies; this percentage has not changed over the years. Acute exacerbation of Chronic Obstructive Pulmonary Disease (COPD) carries a mortality rate of approximately 30%.
The diagnosis of ARF begins with clinical suspicion of its presence. Confirmation of the diagnosis is based on arterial blood gas analysis. Evaluation of an underlying cause must be initiated early, frequently in the presence of concurrent treatment for ARF.
The signs and symptoms of ARF reflect the underlying disease process and the associated hypoxemia or hypercapnia. Localized pulmonary findings reflecting the acute cause of hypoxemia, such as pneumonia, pulmonary edema, asthma, or COPD, may be readily apparent. In patients with Acute Respiratory Distress Syndrome (ARDS), the manifestations may be remote from the thorax, such as abdominal pain or long-bone fracture. Neurological manifestations include restlessness, anxiety, confusion, seizures, or coma.
Treatment of the underlying cause is required. Endotracheal intubation and mechanical ventilation may be required. Respiratory stimulants such as doxapram may be used, and if the respiratory failure resulted from an overdose of sedative drugs such as opioids or benzodiazepines, then the appropriate antidote such as naloxone or flumazenil will be given.