Obstructive form of Acute Respiratory Failure is connected with sharp violation of passableness of respiratory airways. It is one of most often frequent and at the same time one of the most dangerous kind of Acute Respiratory Failure.

Various causes can lead to obstruction of the upper or lower airways:

• tongue root retraction, throat blockage by stomach contents, presence of a foreign body in the throat (trachea) or in the main bronchi, hematoma, tumour and etc.
• traumatic obstruction of the top respiratory airways
• inflammatory hypostasis of vocal chords, an intraligamentary laryngitis, a sputum accumulation
• acute bronchospasm and bronchorrhea, hypostasis of large bronchi mucosa at bronchial asthma or chronic obstructive pulmonary disease exacerbation
• early expiratory closure of small respiratory paths

No matter what's the cause of obstructive pathology, the resistance of respiratory airways increases dramatically (according to Poiseuille's law). Increasing bronchial resistance leads to intensifying of regional non-uniformity of lung ventilation and dumping non-oxygenated blood into the left atrium. Besides, high resistivity of respiratory airways increases breath work, its power and oxygen price that leads to the depletion of compensatory mechanism. Hence a dangerous hypoxemia arises, followed by hypercapnia.