The symptoms of<unk>  can be vague and inconclusive, especially in those with a small PSP; confirmation with medical imaging is usually required. In contrast, tension<unk>  is a medical emergency and may be treated before imaging – especially if there is severe hypoxia, very low blood pressure, or an impaired level of consciousness. In tension<unk> , X-rays are sometimes required if there is doubt about the anatomical location of the<unk> . Chest X-ray A plain chest radiograph, ideally with the X-ray beams being projected from the back (posteroanterior, or "PA"), and during maximal inspiration (holding one's breath), is the most appropriate first investigation. It is not believed that routinely taking images during expiration would confer any benefit. Still, they may be useful in the detection of a<unk>  when clinical suspicion is high but yet an inspiratory radiograph appears normal. Also, if the PA X-ray does not show a<unk>  but there is a strong suspicion of one, lateral X-rays (with beams projecting from the side) may be performed, but this is not routine practice. File:X-ray subtle<unk>  in inspiration - annotated.Anteroposterior inspired X-ray, showing subtle left-sided<unk>  caused by port insertion File:Lateral X-ray of<unk>  in inspiration - annotated.Lateral inspired X-ray at the same time, more clearly showing the<unk>  posteriorly in this case File:Expired X-ray of<unk> .Anteroposterior expired X-ray at the same time, more clearly showing the<unk>  in this case File:Rt_sided_pneumoD.Chest X-ray showing a<unk>  on the right (left in the image), where the absence of lung markings indicates that there is free air inside the chest File:x-ray of<unk>  signs.Chest X-ray showing the features of<unk>  on the left side of the person (right in image) It is not unusual for the mediastinum (the structure between the lungs that contains the heart, great blood vessels, and large airways) to be shifted away from the affected lung due to the pressure differences. This is not equivalent to a tension<unk> , which is determined mainly by the constellation of symptoms, hypoxia, and shock. The size of the<unk>  (i.e. the volume of air in the pleural space) can be determined with a reasonable degree of accuracy by measuring the distance between the chest wall and the lung. This is relevant to treatment, as smaller<unk> es may be managed differently. An air rim of 2 cm means that the<unk>  occupies about 50% of the hemithorax. British professional guidelines have traditionally stated that the measurement should be performed at the level of the hilum (where blood vessels and airways enter the lung) with 2 cm as the cutoff, while American guidelines state that the measurement should be done at the apex (top) of the lung with 3 cm differentiating between a "small" and a "large"<unk> . The latter method may overestimate the size of a<unk>  if it is located mainly at the apex, which is a common occurrence. The various methods correlate poorly but are the best easily available ways of estimating<unk>  size. CT scanning (see below) can provide a more accurate determination of the size of the<unk> , but its routine use in this setting is not recommended. Not all<unk> es are uniform; some only form a pocket of air in a particular place in the chest. Small amounts of fluid may be noted on the chest X-ray (hydropneumothorax); this may be blood (hemopneumothorax). In some cases, the only significant abnormality may be the "deep sulcus sign", in which the normally small space between the chest wall and the diaphragm appears enlarged due to the abnormal presence of fluid. Computed tomography CT with the identification of underlying lung lesion: an apical bulla on the right side A CT scan is not necessary for the diagnosis of<unk> , but it can be useful in particular situations. In some lung diseases, especially emphysema, it is possible for abnormal lung areas such as bullae (large air-filled sacs) to have the same appearance as a<unk>  on chest X-ray, and it may not be safe to apply any treatment before the distinction is made and before the exact location and size of the<unk>  is determined. In trauma, where it may not be possible to perform an upright film, chest radiography may miss up to a third of<unk> es, while CT remains very sensitive. A further use of CT is in the identification of underlying lung lesions. In presumed primary<unk> , it may help to identify blebs or cystic lesions (in anticipation of treatment, see below), and in secondary<unk> , it can help to identify most of the causes listed above. Ultrasound Ultrasound is commonly used in the evaluation of people who have sustained physical trauma, for example with the FAST protocol. Ultrasound may be more sensitive than chest X-rays in the identification of<unk>  after blunt trauma to the chest. Ultrasound may also provide a rapid diagnosis in other emergency situations, and allow the quantification of the size of the<unk> . Several particular features on ultrasonography of the chest can be used to confirm or exclude the diagnosis. File:UOTW 6 - Ultrasound of the Week 1.Ultrasound showing a<unk>  File:UOTW 62 - Ultrasound of the Week 1.Ultrasound showing a false lung point and not a<unk>
Pneumothorax
Hemothorax
Pneumatosis
Chylothorax
Costochondritis
Urinothorax
Traumatic cardiac arrest
Hydropneumothorax