Fizjologia i patofizjologia zastawki żyły szyjnej wewnętrznej w warunkach krążenia pozaustrojowego

Wojciech Dąbrowski, Andrzej Nestorowicz

Summary
Internal jugular valves are the only venous valves between the right ventricle and the cerebral vessels. Their major role is to prevent sudden changes in cerebral venous pressure during increased intrathoracic pressure, e.g. coughing, sneezing or defecation. Retrograde cerebral venous flow may occur because of the presence of internal jugular valve incompetence, and brief transmission of high venous pressure may occur during positive pressure ventilation, resulting in the disturbance of brain function. The competence of the internal jugular venous valve may be also compromised in the elderly and when the vein is cannulated for insertion of a central venous catheter, as this is common during cardiac surgical procedures. It has been suggested that neuropsychological disturbances, sometimes observed after these operations may be partly caused by cerebral flow disturbances due to internal jugular valve incompetence. Cardiac bypass and mechanical ventilation may also play an important role. Doppler ultrasonography of internal jugular valve function should be performed in high-risk patients before surgery and mechanical ventilation, and in cases where any incompetence is observed, an alternative route for venous access should be considered.

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