Changes in the arterial PCO2 during a single night's sleep in patients with obstructive sleep apnea

To investigate the relationship between hypercapnia during sleep and its influence on the PaCO2 during the morning after sleep in patients with obstructive sleep apnea syndrome (OSAS), the transcutaneous PCO2 (PtcCO(2)) was measured throughout the night, and the arterial blood gases (ABG) mere also measured while awake before and after polysomnography in 30 OSAS patients with (n=13, hypercapnic group: HC) and without (n=17, normocapnic group: NC) hypercapnia. Significant differences were observed in the body mass index (p=0.03), the difference between the highest PtcCO(2) during sleep and the PtcCO(2) during awake before sleep (D-PtcCO(2)), (HC: 11.1+/-1.7 mmHg; NC: 6.3+/-0.5 mmHg; p=0.0057) and the lowest SaO(2) during sleep (p=0.0007). In the HC, the PaCO2 on the morning after sleep (50.0+/-0.14 mmHg) was significantly increased (p=0.0029) compared with the PaCO2 on the night before sleep (47.4+/-1.1 mmHg). In the NC, this phenomenon was not observed. Severe hypercapnia (high D-PtcCO(2)) during a single night's sleep has a significant effect on the waking PaCO2 immediately following sleep in the HC.