The symptoms of Type 2 Decompression Sickness are due to:

• A. Air embolism in the pulmonary artery
• B. Small air emboli in the alveolar-capillary membranes
• C. Non-cardiogenic pulmonary edema from activation of the inflammatory cascade
• D. Air emboli in the CSF altering the responses of central chemoreceptors

Answer: (C)

Type II decompression sickness affecting the lungs is driven by bubbles in the bloodstream and tissues that trigger a systemic inflammatory response. This inflammatory cascade increases the permeability of the pulmonary capillaries, causing non-cardiogenic pulmonary edema. It’s not mainly about obstructive air bubbles in the pulmonary artery, nor about microemboli in the alveolar-capillary membranes as the primary mechanism, and it doesn’t implicate the CSF or central chemoreceptors. So the pulmonary symptoms are best explained by edema from inflammation-induced capillary leak, i.e., non-cardiogenic pulmonary edema.