Final answer:
For a patient with signs of peritoneal irritation and free air under the diaphragm, indicating a possible perforated abdominal viscus, emergent surgical evaluation and intervention are necessary, alongside supportive measures like IV fluids and antibiotics.
Step-by-step explanation:
A patient presenting with sudden onset of severe, diffuse abdominal pain, peritoneal signs, and the presence of free air under the diaphragm on an abdominal x-ray (AXR) is highly suggestive of a perforated abdominal viscus leading to peritonitis. The appropriate management for this patient involves emergent surgical consultation and likely surgery. This condition is a medical emergency, as it can rapidly lead to sepsis and other serious complications without prompt intervention. In the interim, the patient should receive nothing by mouth (NPO status), intravenous fluids for stabilization, broad-spectrum antibiotics to combat possible infection, and analgesia for pain control.