South California EMS Medical Block Practice Test

Air bubbles entering the arterial bloodstream from lung over-expansion during rapid ascent describe an arterial gas embolism. When ascent is rapid, the lungs can over-expand and the alveoli may rupture, allowing air to enter the pulmonary veins. That air travels to the left heart and into the arterial circulation, where it can lodge in small arteries of the brain or heart and cause sudden neurologic or cardiovascular problems. This differs from decompression sickness, where gas bubbles form in tissues and venous blood due to dissolved nitrogen coming out of solution during decompression, leading to joint pain, skin symptoms, and neuro signs over hours. Nitrogen narcosis is a CNS depressant effect from high nitrogen pressure underwater, not an arterial air embolism, and dementia is unrelated to this diving physiology.