Tense pneumothorax results when the communication between the lung and the pleura acts as a one way valve. Air can enter the pleural cavity during inspiration, but its escape is prevented during expiration, so that the pneumothorax tends to increase in size and tension. As the resulting dyspnea increases, the patient's inspiratory efforts become more vigorous, more air is pumped into the pleural cavity, and the condition is made more acute. This form of pneumothorax is not common, but it is important because of the distressing symptoms it may produce. Although it usually occurs as a complication of active pulmonary disease, there are instances in which there is little or no clinical evidence of a pathologic process in the lung and in which the etiology is not clear: cases of so-called idiopathic tense pneumothorax.
The majority of patients with valvular, or tense, pneumothorax get well under conservative management. After a