The given X-ray features and clinical scenario point towards the diagnosis of tension pneumothorax. The next best step in the management is wide bore needle insertion in the 5th intercostal space.
The chest X-ray shows a well-demarcated area devoid of lung markings on the left side with tracheal deviation and the mediastinal shift to the right side.
Tension pneumothorax is a clinical diagnosis, and treatment should never be delayed while waiting for radiological confirmation.
Imaging modalities used are ultrasound – extended focused assessment with sonar for trauma (eFAST), chest x-ray, and spiral CT.
A tension pneumothorax develops when there is a tear either in the parietal or visceral pleura.
This tear acts as a one-way valve i.e. air enters from the lung or chest wall through it during inspiration but has no way to escape during expiration.
This ultimately leads to the collapse of the affected lung.
It usually occurs following penetrating or blunt chest trauma, iatrogenic lung injury, or mechanical positive pressure ventilation.
It is characterized by:

Chest pain
Tachypnoea, and acute dyspnea
Sudden onset hemodynamic compromise (tachycardia, hypotension, low O2 saturation, loss of consciousness)
Neck vein distention
Tracheal deviation away from the side of injury
Decreased chest movements on the affected side
Hyper-resonance on percussion on the affected side
Absence or decreased breath sounds on the affected side

Immediate management- needle decompression or needle thoracostomy i.e. insertion of a wide-bore needle in the 5th ICS anterior to the midaxillary line
Definitive management- tube thoracostomy or chest tube insertion in the 5th ICS in the triangle of safety identified as a triangle that lies anterior to the midaxillary line above the nipple, below, and lateral to the pectoralis major muscle.

Other Options:

Pericardiocentesis is done in cases of cardiac tamponade which is characterized by the presence of hypotension, distended jugular veins, and muffled heart sounds (Beck's triad).
The breath sounds are absent in tension pneumothorax while they are present in cardiac tamponade.
Surgery for pneumothorax can be performed by video-assisted thoracoscopic surgery (VATS) or as an open procedure (thoracotomy) in cases of spontaneous pneumothorax failing to settle despite chest drainage.
Pleural adhesion is achieved by chemical pleurodesis where talc is used and is insufflated into the chest cavity.

Reference: Bailey & Love's Short Practice of Surgery - 26th Edition (Page no- 367,368 919-921).

Cardiothoracic Vascular Surgery