**3. Clinical presentation**

*Pneumothorax*

space

to loud music [24, 25].

2.Communication between the atmosphere (direct or indirect) and the pleural

PSP has an incidence of 7.4 to 18 cases per 100,000 population each year in males and 1.2 to 6 cases per 100,000 populations each year in females [17, 18]. Risk factors for PSP include tall thin people, male sex, and smoking. The recurrence range is 25–50%, and most recurrences occur in the first year [19]. Female gender, tall male, low body weight, and persistent smoking are associated with a high rate of recurrence [20]. In the largest epidemiologic study of PSP from Bobbio et al. with 42,595 patients, they found that the mean age was significantly greater in women than in men (41 ± 19 vs. 37 ± 19 p < 0.0001), rehospitalization was more frequent in women than in men in patients aged <50 years (p < 0.0001). In the 50–64 years age group, surgical procedures and rehospitalizations were more frequent in men than in women (p = 0.002 and p < 0.0001, respectively). The most commonly performed procedures were thoracoscopic resection of blebs (52% of cases) and talc pleurodesis (24% of cases). Surgery was associated with younger age, secondary pneumothorax, and ICU surveillance (p < 0.001) [21]. Moderate smoking (22 cigarettes/day) increases the risk of first episode of PSP up to 22 times. PSP usually occurs at rest, so the lack of physical activity should be avoided in the counseling of these patients [17]. Thoracic endometriosis may lead to catamenial pneumothorax and should be considered in women with PSP temporally related to menstruation [22]. Malnutrition in patients with anorexia nervosa may lead to the development of PSP. Birt-Hogg-Dubé syndrome (which predisposes patients to benign skin tumors and renal cancers) is an autosomal dominant condition defined as a rare cause of PSP [23]. Precipitating factors include atmospheric pressure changes and exposure

An increased frequency of PSP is seen in patients with Marfan syndrome and homocystinuria. Marfan syndrome is a common inherited connective tissue disorder with typical skeletal, ocular, and cardiovascular manifestations. Pulmonary involvement occurs less frequently, with PSP being the most frequently reported. Karpman et al.'s study in 2011 found a prevalence of pneumothorax in patients with Marfan syndrome between and 11%. The increased risk of pneumothorax has been attributed to the presence of apical blebs, bullae, and abnormal connective tissue constituents in the lung parenchyma or increased mechanical stresses in the lung apices due to the tall body habitus. Patients who have Marfanoid features such as long stature, hyperextendable joints, and dislocated lens should be studied by CT scanning to identify blebs and bullae. This may allow risk stratification for pneumothorax in patients with this syndrome and also favors identification of aortic root disease, which leads to aneurysmal dilation, aortic regurgitation, and dissection [26, 27]. A multidisciplinary approach is fundamental in these patients and their family, who must be thoroughly investigated, to confirm the disease and to initiate the treatment, thus decreasing mortality, especially due to cardiovascular causes; also a medical genetics consultation should be provided for genetic

PSP recurrence rates are typically cited as between 16 and 52%, which makes

counseling about future risk difficult and creates uncertainty regarding the optimal management. Thoracic Society guidelines advise that pneumothorax recurrence is an indication for surgery (whether second ipsilateral or first contralateral) [29]. Unfortunately, there is no consensus on which treatment offers the best reduction in risk of recurrence [6]. A systematic review demonstrates a 32% PSP recurrence rate, with almost all the risk in the first year. Recurrence rates

3.Presence of gas-producing organisms in the pleural space

**16**

counseling [28].

Symptoms in primary spontaneous pneumothorax may be minimal or absent. These clinical symptoms depend on proportion and the size of the pneumothorax. Patients may present an abrupt onset of pleuritic chest pain associated with dyspnea and shortness of breath, and some patients may experience shoulder tip pain [29]. Severe symptoms are not common, and when this happens it suggests a tension pneumothorax. Typical examination findings in primary spontaneous pneumothorax include ipsilateral decreased breath sounds on auscultation, percussion hyperresonance, and thoracic hypoexpansion. The presence of observable breathlessness has influenced subsequent management in previous guidelines [29, 31]. Hemodynamic compromise is unusual in PSP. Arterial blood gas measurements are frequently abnormal in patients with pneumothorax. Arterial oxygen tension is lower according to the extent of the pneumothorax but oxygen saturations are adequate, and pulmonary function tests are poor predictors of the presence or size of a pneumothorax [32].

The clinical features in tension pneumothorax are shortness of breath, dyspnea, tachypnea, respiratory distress, hypoxemia, hypotension, tachycardia and ipsilateral decreased air entry, and percussion hyperresonance. This condition requires an urgent thoracic decompression when the diagnosis is suspected, and the clinicians should be prepared to perform urgent thoracic decompression without chest radiographic confirmation in these patients [31].
