Hemopneumothorax, or haemopneumothorax, is the condition of having air in the chest cavity (pneumothorax) and blood in the chest cavity (hemothorax). A hemothorax, pneumothorax, or the combination of both can occur due to an injury to the lung or chest. Cause
The pleural space is located anatomically between the visceral membrane, which is firmly attached to the lungs, and the parietal membrane which is firmly attached to the chest wall (a.k.a. ribcage and intercostal muscles, muscles between the ribs). The pleural space contains pleural fluid. This fluid holds the two membranes together by surface tension, as much as a drop of water between two sheets of glass prevents them from separating. Because of this, when the intercostal muscles move the ribcage outward, the lungs are pulled out as well, dropping the pressure in the lungs and pulling air into the bronchi, when we breathe in. The pleural space is maintained in a constant state of negative pressure (in comparison to atmospheric pressure). If the chest wall, and thus the pleural space, is punctured, blood, air or both can enter the pleural space. Air and/or blood rushes into the space in order to equalise the pressure with that of the atmosphere. As a result, the fluid is disrupted and the two membranes no longer adhere to each other. When the rib cage moves out, it no longer pulls the lungs with it. Thus the lungs cannot expand, the pressure in the lungs never drops and no air is pulled into the bronchi. Respiration is not possible.
The timing, severity of the thrombocytopenia, the occurrence of new thrombosis, and the presence of alternative explanations, all determine the likelihood that HIT is present. A commonly used score to predict the likelihood of HIT is the "4 Ts" score introduced in 2003. A score of 0–8 points is generated; if the score is 0–3, HIT is unlikely. A score of 4–5 indicates intermediate probability, while a score of 6–8 makes it highly likely. Those with a high score may need to be treated with an alternative drug, while more sensitive and specific tests for HIT are performed, while those with a low score can safely continue receiving heparin, as the likelihood that they have HIT is extremely low. In an analysis of the reliability of the 4T score, a low score had a negative predictive value of 0.998, while an intermediate score had a positive predictive value of 0.14 and a high score a positive predictive value of 0.64; intermediate and high scores, therefore, warrant further investigation. The first screening test in someone suspected of having HIT is aimed at detecting antibodies against heparin-PF4 complexes. This may be with a laboratory test of the enzyme-linked immunosorbent assay type. This ELISA test, however, detects all circulating antibodies that bind heparin-PF4 complexes, and may also falsely identify antibodies that do not cause HIT. Therefore, those with a positive ELISA are tested further with a functional assay. This test uses platelets and serum from the patient; the platelets are washed and mixed with serum and heparin.