Pneumothorax is defined as the presence of air or gas in the pleural cavity (ie, the potential space between the visceral and parietal pleura of the lung), which can impair oxygenation and/or ventilation. The clinical results are dependent on the degree of collapse of the lung on the affected side. If the pneumothorax is significant, it can cause a shift of the mediastinum and compromise hemodynamic stability. ir can enter the intrapleural space through a communication from the chest wall (ie, trauma) or through the lung parenchyma across the visceral pleura.Signs and symptomsThe presentation of patients with pneumothorax varies depending on the following types of pneumothorax and ranges from completely asymptomatic to life!threatening respiratory distress" #pontaneous pneumothorax" $o clinical signs or symptoms in primary spontaneous pneumothorax until a bleb ruptures and causes pneumothorax% typically, the result is acute onset of chest pain and shortness of breath, particularly with secondary spontaneous pneumothoraces Iatrogenic pneumothorax" #ymptoms similar to those of spontaneous pneumothorax, depending on patient&s age, presence of underlying lung disease, and extent of pneumothorax Tension pneumothorax" 'ypotension, hypoxia, chest pain, dyspnea (atamenial pneumothorax" )omen aged *+!,+ years with onset of symptoms within ,- hours of menstruation, right!sided pneumothorax, and recurrence Pneumomediastinum" .ust be differentiated from spontaneous pneumothorax% patients may or may not have symptoms of chest pain, persistent cough, sore throat, dysphagia, shortness of breath, or nausea/vomiting #ee (linical Presentation for more detail.Diagnosis'istory and physical examination remain the /eys to ma/ing the diagnosis of pneumothorax. 0xamination of patients with this condition may reveal diaphoresis and cyanosis (in the case of tension pneumothorax). ffected patients may also reveal altered mental status changes, including decreased alertness and/or consciousness (a rare finding). 1indings on lung auscultation vary depending on the extent of the pneumothorax. 2espiratoryfindings may include the following" 2espiratory distress (considered a universal finding) or respiratory arrest Tachypnea (or bradypnea as a preterminal event) symmetric lung expansion" .ediastinal and tracheal shift to contralateral side (large tension pneumothorax) 3istant or absent breath sounds" 4nilaterally decreased/absent lung sounds common, but decreased air entry may be absent even in advanced state of pneumothorax .inimal lung sounds transmitted from unaffected hemithorax with auscultation at midaxillary line 'yperresonance on percussion" 2are finding% may be absent even in an advanced state 3ecreased tactile fremitus dventitious lung sounds" Ipsilateral crac/les, whee5es(ardiovascular findings may include the following" Tachycardia" .ost common finding% if heart rate is faster than 6*7 beats/min, tension pneumothorax li/ely Pulsus paradoxus 'ypotension" Inconsistently present finding% although typically considered a /ey sign of tension pneumothorax, hypotension can be delayed until its appearance immediately precedes cardiovascular collapse 8ugular venous distention" 9enerally seen in tension pneumothorax% may be absent if hypotension is severe (ardiac apical displacement" 2are finding(ommon findings among the types of pneumothoraces include the following" #pontaneous and iatrogenic pneumothorax" Tachycardia most common finding% tachypnea and hypoxia may be present Tension pneumothorax" :ariable findings% respiratory distress and chest pain% tachycardia% ipsilateral air entry on auscultation% breath sounds absent on affected hemithorax% trachea may deviate from affected side% thorax may be hyperresonant% ;ugular venous distention and/or abdominal distention may be present Pneumomediastinum" :ariable or absent findings% subcutaneous emphysema is the most consistent sign% 'amman sign