20 years old male patient came to ER with severe dyspnoea. On examination, there is severe tachycardia, hypotension with distended neck veins. Chest x-ray is given below. Diagnosis is?

Tension pneumothoraces occur when intrapleural air accumulates progressively in such a way as to exe positive pressure on mediastinal and intrathoracic structures. It is a life-threatening occurrence requiring both rapid recognition and prompt treatment to avoid a cardiorespiratory arrest. A non-tension pneumothorax is properly called a simple pneumothorax.