The carotid body: a review of its anatomy, physiology and clinical importance.

The carotid body is a peripheral chemoreceptor that monitors arterial blood gas tensions and pH. Its main function is to contribute to the regulation of breathing although there is evidence for a reflex influence on the pulmonary circulation and the kidney. The carotid body's acute response to hypoxia is a rapid increase in breathing. The chronic response to hypoxia such as would occur at high altitude or as a consequence of COPD, includes growth of the organ, both hyperplasia and hypertrophy, modification of amine content and an attenuation of its hypoxic sensitivity. It is the latter aspect that may cause severe problems of management of COPD for the clinician. It is postulated that the attenuated hypoxic sensitivity may play a role in the deterioration of the COPD patient.