A 28-year-old man is brought to the trauma centre with a tension pneumothorax following blunt chest trauma. He is hypotensive (BP 90/60 mmHg), tachycardic (HR 128/min), with absent breath sounds on the left and tracheal deviation. After immediate needle decompression, a chest tube is placed. Which agent is the drug of choice for analgesia and sedation during chest tube insertion in this haemodynamically unstable patient?