الفهرس 
Strategies of Airway AssessmentOnly 14 pages are availabe for public view
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Abstract
For ultrasonic analysis of the upper airway, the most suitable probes are those with higher frequency (>7.5 MHz) and high resolution. Structures of the upper airway are nearly completely filled with air. Due to the very high acoustic impedance of air, ultrasonograpy cannot directly depict the inside of air-filled organs. Fortunately, due to their superficial position, the frontal and lateral walls of nearly all upper airway segments are visible by ultrasonic examination either partially or completely.
By ultrasonography, one can visualize the airway from the tip of the chin to the mid-trachea plus the pleural aspect of the most peripheral alveoli as well as the diaphragm. Additional parts of the airway can be seen with special techniques. Trachea can be differentiated from the esophagus when performing transesophageal US and the tissues surrounding the more distal airways from the mid-trachea to the bronchi can be visualized with endoscopic US via a bronchoscope.
Ultrasonography has many clinical applications. It can be used for direct observation of whether the tube enters the trachea or the esophagus without the need for ventilation or circulation. Localisation of the cricothyroid membrane, prediction of difficult laryngoscopy in surgical patients, evaluation of pathology that may influence the choice of airway management technique and assessment of obstructive sleep apnea are other uses of ultrasonography. Ultrasonography can be also beneficial in evaluating prandial status, prediction of the appropriate diameter of endotracheal, endobronchial or tracheostomy tube. In additions, it must be used routinely in airway-related nerve blocks. Further more, it is helpful in confirmation of laryngeal mask placement and during surgical and percutaneous dilatational tracheostomy (PDT). US is accurate in evaluation of lung pathology and diagnosis of pneumothorax.