Air embolism and veins is greater than atmospheric pressure, an air embolus does not often happen when a blood vessel is injured. In the veins above the heart, such as in the head and neck, the venous pressure may be less than atmospheric and an injury may let air in. This is one reason why surgeons must be particularly careful when operating on the brain, and why the head of the bed is tilted down when inserting or removing a central venous catheter from the jugular or subclavian veins. When air enters the veins, it travels to the right side of the
Head and neck cancer to prevent the development of leukoplakia, the white plaques that are the precursor for carcinomas of the mucosal surfaces, in adult smokers. Another study examined a combination of Vitamin E and beta carotene in smokers with early-stage cancer of the oropharynx, and found a worse prognosis in the vitamin users. Betel nut chewing is associated with an increased risk of squamous cell cancer of the head and neck. Some head and neck cancers are caused by Human papillomavirus (HPV). In particular HPV16, is a causal factor for some head and neck squamous-cell carcinoma (HNSCC). Approximately 15 to 25% of HNSCC