Final answer:
Capnography is the most reliable method for the immediate confirmation of ET tube placement because it measures the concentration of carbon dioxide in exhaled breath, confirming correct placement in the trachea.
Step-by-step explanation:
The question asks which method is the most reliable for confirming immediate endotracheal tube (ET) placement during intubation. The correct answer is that capnography is the most reliable method for confirming ET tube placement. Chest rise and breath sounds can be misleading as they do not necessarily confirm endotracheal intubation; the tube could be in the esophagus causing the stomach to inflate.
Visual inspection is not conclusive because it does not provide information about gas exchange. Pulse oximetry is not the gold standard because there can be a delay in showing desaturation if the tube is incorrectly placed, and the readings could reflect previously inhaled oxygen rather than current respiration. Capnography, on the other hand, measures the concentration of carbon dioxide in the exhaled breath, which immediately verifies that the tube is correctly placed in the trachea and the patient is exchanging gas effectively.