Final answer:
The patient should be referred for 4)an emergency upper endoscopy due to the signs of a significant upper gastrointestinal bleed.
Step-by-step explanation:
The 45-year-old man with a history of hematemesis and melena should be referred for an emergency upper endoscopy. His presentation is suggestive of a significant upper gastrointestinal bleed, which could be due to ulcers, gastritis, or other gastrointestinal pathology.
The use of ibuprofen, particularly at high doses, and his alcohol and tobacco consumption are likely contributing factors to his condition. Discontinuation of ibuprofen and advising cessation of alcohol and tobacco are also essential steps in the management of his condition.
Given the acuity of his presentation and the finding of bright red blood in the nasogastric tube that failed to clear with saline irrigation, alongside orthostatic changes indicating hypovolemia, an urgent endoscopic evaluation is warranted to identify the source of bleeding and to initiate appropriate therapeutic interventions.