they are not normally connected to a negative pressure circuit, as this would result in rapid re-expansion of the lung and a risk of pulmonary edema ("re-expansion pulmonary edema"). the tube is left in place until no air is seen to escape from it for a period of time, and x-rays confirm re-expansion of the lung. if after 2–4 days there is still evidence of an air leak, various options are available. negative pressure suction (at low pressures of –10 to –20 cmh2o) at a high flow rate may be attempted, particularly in psp; it is thought that this may accelerate the healing of the leak. failing this, surgery may be required, especially in ssp. chest tubes are used first-line when pneumothorax occurs in people with aids, usually due to underlying pneumocystis pneumonia (pcp), as this condition is associated with prolonged air leakage. bilateral pneumothorax (pneumothorax on both sides) is relatively common in people with pneumocystis pneumonia, and surgery is often required. it is possible for a person with a chest tube to be managed in an ambulatory care setting by using a heimlich valve, although research to demonstrate the equivalence to hospitalization has been of limited quality. pleurodesis and surgery pleurodesis is a procedure that permanently eliminates the pleural space and attaches the lung to the chest wall. no long-term study (20 years or more) has been performed on its consequences. good results in the short term are achieved with a thoracotomy (surgical opening of the chest) with identification of any source of air leakage and stapling of blebs followed by pleurectomy (stripping of the pleural lining) of the outer pleural layer and pleural abrasion (scraping of the pleura) of the inner layer. during the healing process, the lung adheres to the chest wall, effectively obliterating the pleural space. recurrence rates are approximately 1%. post-thoracotomy pain is relatively common. video-assisted thoracoscopic surgery (vats) wedge resection a less invasive approach is thoracoscopy, usually in the form of a procedure called video-assisted thoracoscopic surgery (vats). the results from vats-based pleural abrasion are slightly worse than those achieved using thoracotomy in the short term, but produce smaller scars in the skin. compared to open thoracotomy, vats offers a shorter in-hospital stays, less need for postoperative pain control, and a reduced risk of lung problems after surgery. vats may also be used to achieve chemical pleurodesis; this involves insufflation of talc, which activates an inflammatory reaction that causes the lung to adhere to the chest wall. if a chest tube is already in place, various agents may be instilled through the tube to achieve chemical pleurodesis, such as talc, tetracycline, minocycline or doxycycline. results of chemical pleurodesis tend to be worse than when using surgical approaches, but talc pleurodesis has been found to have few negative long-term consequences in younger people. aftercare if pneumothorax occurs in a smoker, this is considered an opportunity to emphasize the markedly increased risk of recurrence in those who continue to smoke, and the many benefits of smoking cessation. it may be advisable for someone to remain off work for up to a week after a spontaneous pneumothorax. if the person normally performs heavy manual labor, several weeks may be required. those who have undergone pleurodesis may need two to three weeks off work to recover. air travel is discouraged for up to seven days after complete resolution of a pneumothorax if recurrence does not occur. underwater diving is considered unsafe after an episode of pneumothorax unless a preventive procedure has been performed. professional guidelines suggest that pleurectomy be performed on both lungs and that lung function tests and ct scan normalize before diving is resumed. aircraft pilots may also require assessment for surgery. neonatal period for newborn infants with pneumothorax, different management strategies have been suggested including careful observation, thoracentesis (needle aspiration), or insertion of a chest tube. needle aspiration may reduce the need for a chest tube, however, the effectiveness and safety of both invasive procedures have not been fully studied. prevention a preventative procedure (thoracotomy or thoracoscopy with pleurodesis) may be recommended after an episode of pneumothorax, with the intention to prevent recurrence. evidence on the most effective treatment is still conflicting in some areas, and there is variation between treatments available in europe and the us. not all episodes of pneumothorax require such interventions; the decision depends largely on estimation of the risk of recurrence. these procedures are often recommended after the occurrence of a second pneumothorax. surgery may need to be considered if someone has experienced pneumothorax on both sides ("bilateral"), sequential episodes that involve both sides, or if an episode was associated with pregnancy. epidemiology the annual age-adjusted incidence rate (aair) of psp is thought to be three to six times as high in males as in females. fishman cites aair's of 7.4 and 1.2 cases per 100,000 person-years in males and females, respectively. significantly above-average height is also associated with increased risk of psp – in people who are at least 76 inches (1.93 meters) tall, the aair is about 200 cases per 100,000 person-years. slim build also seems to increase the risk of psp. the risk of contracting a first spontaneous pneumothorax is elevated among male and female smokers by factors of approximately 22 and 9, respectively, compared to matched non-smokers of the same sex. individuals who smoke at higher intensity are at higher risk, with a "greater-than-linear" effect; men who smoke 10 cigarettes per day have an approximate 20-fold increased risk over comparable non-smokers, while smokers consuming 20 cigarettes per day show an estimated 100-fold increase in risk. in secondary spontaneous pneumothorax, the estimated annual aair is 6.3 and 2.0 cases per 100,000 person-years for males and females, respectively, with the risk of recurrence depending on the presence and severity of any underlying lung disease. once a second episode has occurred, there is a high likelihood of subsequent further episodes. the incidence in children has not been well studied, but is estimated to be between 5 and 10 cases per 100,000 person-years. death from pneumothorax is very uncommon (except in tension pneumothoraces). british statistics show an annual mortality rate of 1.26 and 0.62 deaths per million person-years in men and women, respectively. a significantly increased risk of death is seen in older patients and in those with secondary pneumothoraces. history an early description of traumatic pneumothorax secondary to rib fractures appears in imperial surgery by turkish surgeon şerafeddin sabuncuoğlu (1385–1468), which also recommends a method of simple aspiration. pneumothorax was described in 1803 by jean marc gaspard itard, a student of rené laennec, who provided an extensive description of the clinical picture in 1819. while itard and laennec recognized that some cases were not due to tuberculosis (then the most common cause), the concept of spontaneous pneumothorax in the absence of tuberculosis (primary pneumothorax) was reintroduced by the danish physician hans kjærgaard in 1932. in 1941, the surgeons tyson and crandall introduced pleural abrasion for the treatment of pneumothorax. prior to the advent of anti-tuberculous medications, pneumothoraces were intentionally caused by healthcare providers in people with tuberculosis in an effort to collapse a lobe, or entire lung, around a cavitating lesion. this was known as "resting the lung". it was introduced by the italian surgeon carlo forlanini in 1888 and publicized by the american surgeon john benjamin murphy in the early 20th century (after discovering the same procedure independently). murphy used the (then) recently discovered x-ray technology to create pneumothoraces of the correct size. etymology the word pneumothorax is from the greek pneumo- meaning air and thorax meaning chest. its plural is pneumothoraces. other animals non-human animals may experience both spontaneous and traumatic pneumothorax. spontaneous pneumothorax is, as in humans, classified as primary or secondary, while traumatic pneumothorax is divided into open and closed (with or without chest wall damage). the diagnosis may be apparent to the veterinary physician because the animal exhibits difficulty breathing in, or has shallow breathing. pneumothoraces may arise from lung lesions (such as bullae) or from trauma to the chest wall. in horses, traumatic pneumothorax may involve both hemithoraces, as the mediastinum is incomplete and there is a direct connection between the two halves of the chest. tension pneumothorax – the presence of which may be suspected due to rapidly deteriorating heart function, absent lung sounds throughout the thorax, and a barrel-shaped chest – is treated with an incision in the animal's chest to relieve the pressure, followed by insertion of a chest tube. for spontaneous pneumothorax the use of ct for diagnosis has been described for dogs and kunekune pigs.