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682        seCtioN iii    RespiRatoRy  ` RESPIRATORY—PAThOlOgY                                                                                                          RespiRatoRy  ` RESPIRATORY—PAThOlOgY





               Pneumothorax          Accumulation of air in pleural space  A . Dyspnea, uneven chest expansion. Chest pain,  tactile
                                      fremitus, hyperresonance, and diminished breath sounds, all on the affected side.
                Primary spontaneous   Due to rupture of apical subpleural bleb or cysts. Occurs most frequently in tall, thin, young males
                 pneumothorax         and smokers.
                Secondary            Due to diseased lung (eg, bullae in emphysema, infections), mechanical ventilation with use of
                 spontaneous          high pressures Ž barotrauma.
                 pneumothorax
                Traumatic            Caused by blunt (eg, rib fracture), penetrating (eg, gunshot), or iatrogenic (eg, central line
                 pneumothorax         placement, lung biopsy, barotrauma due to mechanical ventilation) trauma.
                Tension              Can be from any of the above. Air enters pleural space but cannot exit. Increasing trapped air
                 pneumothorax         Ž tension pneumothorax. Trachea deviates away from affected lung  B . May lead to increased
                                       intrathoracic pressure Ž mediastinal displacement Ž kinking of IVC Ž  venous return
                                       Ž  cardiac output. Needs immediate needle decompression and chest tube placement.
                                               A                                B

                                                   Air in pleural
                                                   space
                                                                                                Tracheal
                                                                                                deviation


                                                     Partially                                 Collapsed
                                                     collapsed lung                            lung
























































          FAS1_2019_16-Respiratory.indd   682                                                                           11/8/19   7:34 AM
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