Step 1: Read the clues:
Blunt chest trauma, severe breathlessness, low blood pressure, no breath sounds on the right, and a hyperresonant note. Every clue points to tension pneumothorax on the right side.
Step 2: Approach by priority of care:
In trauma we follow the ABCDE order. A tension pneumothorax is a breathing problem (B) that is also threatening circulation (C).
The rule is simple: treat what kills first. Life-threatening chest injuries, including tension pneumothorax, are managed during the primary survey without waiting for tests.
Step 3: Think about the mechanism of the fix:
The trouble is trapped air under pressure. Any step that does not let the air out cannot help.
A cannula placed in the pleural space turns the tension pneumothorax into a simple, open pneumothorax within seconds. A chest drain then makes the relief lasting.
Step 4: Eliminate the other options:
Intravenous fluid and observation does nothing for the cause and loses precious time. This is not suitable.
A CT scan needs transport of an unstable patient and takes time. The diagnosis is clinical, so scanning is not needed.
Drain insertion after radiological confirmation also waits for an X-ray. When needle decompression is the quickest tool at hand, it must come first.
Step 5: Look at the signs again:
Other signs of tension pneumothorax are distended neck veins, tracheal shift away from the affected side, and a fast, weak pulse. Not all of these may be present, and a patient who is bleeding may not show neck vein distension.
None of these signs needs a scan to confirm. If the clinical picture is clear, act first.
Step 6: Pick the answer:
Only immediate needle decompression meets the need for a fast, life-saving step. This is option (4).
Final Answer:
Immediate needle decompression of the right pleural space is the correct action. This is option (4).
\[ \boxed{\text{Option (4)}} \]