Risposte agli stimoli ipossico e ipercapnico nella sindrome dell'apnea ostruttiva nel sonno

In order to study the relationship between neurochemical control of ventilation and the severity of obstructive sleep apnea syndrome (OSAS), 37 OSAS patients were subjected to hypoxic and hypercapnic rebreathing tests during wakefulness and to polysomnographic study. We found that neither the slope of the regression line between PACO2 and ventilation, nor that between oxyhemoglobin saturation (SaO2) and ventilation, were significantly correlated with the rate of apneas during sleep; conversely, both showed a significant logarytmic correlation with mean SaO2 during sleep (p<0.01). The correlation coefficient was higher for the hypoxic (r=0.79) than for the hypercapnic (0.63) response. We conclude that the responsivity to hypercapnia, and even more the responsivity to hypoxia, apparently influence the severity of apnea-related desaturation, but not apnea onset frequency.