The syndrome known as Carotid Sinus Reflex during scuba diving is usually a result of dilation or widening of the internal carotid artery in the neck. Swelling can happen due to any form of stimulation to the carotid sinus artery which is generally caused by an excessively tight fitting exposure suit neck seal.

Causes of Carotid Sinus Syndrome:
Tight-fitting wetsuit top or drysuit neck seal exerting excess pressure on the neck. This may follow a rapid ascent in a dry suit, especially after a blowup with a large bubble of air collecting under the neck seal, which fails to give. This syndrome may be combined with pulmonary barotrauma.

Signs & Symptoms of Carotid Sinus Syndrome:
• Slow weak pulse
• Confusion, disorientation
• Fainting
• Nausea

First Aid Treatment for Carotid Sinus Syndrome:
• Loosen or remove the wet suit top or dry suit neck seal
• Lay the diver down
• Contact the DAN emergency hotline for advice