The anatomical compartments and their connections as demonstrated by ectopic air

Abstract

Air/gas outside the aero-digestive tract is abnormal; depending on its location, it is usually called emphysema, referring to trapped air/gas in tissues, or ectopic air/gas. It can be associated to a wide range of disorders, and although it usually is an innocuous condition, it should prompt a search for the underlying aetiology, since some of its causes impose an urgent treatment. In rare instances, it may itself represent a life-threatening condition, depending on the site involved and how quickly it evolves. Abnormal air/gas beyond viscera and serosal spaces, reaches its location following some anatomic boundaries, such as fascia, which may help search the source; however if the air pressure exceeds the strength of the tissues, or the time between the aggression and the imaging is too long, the air/gas is almost everywhere, which may hinder its cause. Good knowledge of the anatomic spaces and how they connect between them facilitates the quick detection of the cause.Teaching points• Ectopic air can be depicted on conventional radiographs; but CT is more sensitive and accurate• Visceral and retropharyngeal spaces directly communicate with mediastinum• Renal fascia is a single multilaminated structure, which contains potential space

Tracheostomy Exchange Resulting in Rare Combination of Pneumomediastinum, Pneumothorax, Massive Pneumoperitoneum, and Subcutaneous Emphysema

“…The proposed mechanism of the spread of air from the chest to the abdomen has been the rupture of pulmonary alveoli due to extreme pressure and distention [ 2 ]. Air spreads to mediastinum by dissecting the lung hilum along the peribronchovascular sheath.…”

Spontaneous pneumomediastinum, pneumoretroperitoneum, and cervicofacial subcutaneous emphysema after repeatedly and forcefully blowing into a bottle

“…Therefore, if the air pressure surpasses the strength of the tissues, or the time between the aggression and the imaging is too long, the air can travel to other areas hindering its primary location. The mediastinum is continuous directly with the visceral and retropharyngeal spaces (14). The reason behind using 100% oxygen is to replace nitrogen in the escaped air with oxygen; nitrogen is absorbed slowly by capillaries, however, oxygen is absorbed rapidly (15).…”

Imaging of spaces of neck and mediastinum by endoscopic ultrasound

“…[ 19 ] CT images obtained after pneumomediastinography have also demonstrated several compartments of the mediastinum where spread of gas occurs from one space to another [ Figure 17 ]. [ 3 20 ] Different methods of imaging of the posterior mediastinum have been described and standard techniques of imaging of the different lymph node stations have been described by the International Association for the Study of Lung Cancer (IASLC). [ 21 22 23 24 25 ] The mediastinal spaces are described in this article as having boundaries, but in reality they are all continuous with each other directly or indirectly [Tables 2 and 3 ].…”