A 32-year-old man with acute appendicitis is brought to the OR for emergency appendectomy. He consumed a full meal 2 hours ago. During induction, you plan rapid sequence intubation (RSI). After preoxygenation and loss of consciousness with propofol and succinylcholine, you notice the patient is difficult to ventilate manually — high airway pressure, minimal chest rise. What is the most appropriate immediate next step?