Upper airway reflexes

It is usually assumed that upper airway pressure receptors mediate the reflexes involved in sleep apneas, but many other receptors may be involved, including those responding to chemical stimuli. The reflexes to upper airway negative pressure have been further studied, and the timing of their inputs shown to be important. Their effects on the cardiovascular system, including cerebral blood flow, have been emphasized. The central nervous pathways for the upper airway reflexes and their relationship to the neuronal circuits of the respiratory rhythm generator are being analyzed, but no clear pattern has emerged. Many neurotransmitters have been identified, usually on the motor pathways, which points to possible therapeutic approaches. The central nervous pharmacology and the neuronal pattern for the cough reflex have been described, and a similar approach to other upper airway reflexes, especially those involved in sleep apneas, would be valuable.