Can PCO2 be 0 on sleep study?

No, PCO2 (partial pressure of carbon dioxide) cannot be 0 during a sleep study. A PCO2 of 0 would indicate a complete lack of carbon dioxide in the blood, which is not physiologically possible under normal circumstances. During sleep, PCO2 levels may decrease or fluctuate due to changes in breathing patterns, but they will always remain above 0. Normal arterial PCO2 levels typically range from 35 to 45 mmHg.