Abstract: The pleural pressure indicator is a diagnostic device for use in the field where more sophisticated electronics are not permissible, though early detection of pneumothoraces relative to penetrating chest trauma is paramount to survival. When the device is used with the placement of a needle thoracentesis, it serves the user by indicating flow to and from the chest cavity. This indication is supportive of the user's diagnosis of the patients' respiratory condition. When a patient is suffering from a tension pneumothorax, positive air flow will be indicated by the device. The user can switch the check valve in the device flow path to manage intrathoracic pressure relief, therapeutically reducing the tension pneumothorax, increasing survivability. The pleural pressure indicator is a compact, portable, handheld device that is simple to operate, compatible with needles, catheters, and syringes and simple to read for a quick indication of a patient's condition.