A 7-year-old boy is brought to the emergency department after being pulled out of a swimming pool. He had been submerged for approximately 4 minutes. On arrival, he is unconscious, cyanosed, and not breathing. His body temperature is 34°C. After resuscitation, he regains consciousness but remains confused. Over the next 6 hours, his respiratory distress worsens despite supplemental oxygen, and bilateral crackles are heard on auscultation. Chest X-ray shows bilateral pulmonary edema. What is the most likely pathophysiological mechanism responsible for his deteriorating respiratory status?