The level of carbon dioxide is the determinant of successful non-invasive ventilation pressure titration in patients with non-hypercapnic primary central sleep apnea: a case report

Primary central sleep apnea (CSA) is classified as non-hypercapnic CSA. High loop gain, lower carbon dioxide (CO2) reserves, and other reasons can lead to hypocapnia in patients who develop intermittent hyperventilation during sleep. Therefore, it is necessary to monitor nocturnal CO2 level for these patients. We report a female patient diagnosed with non-hypercapnic primary CSA who complained of snoring, apnea, and excessive daytime sleepiness. With the monitoring of transcutaneous partial pressure of CO2 (PtcCO2), manual non-invasive ventilation (NIV) pressure titration was performed with continuous positive airway pressure (CPAP), bilevel positive airway pressure in a spontaneous-timed mode (BPAP-ST), and adaptive servo-ventilation (ASV) mode for three nights, respectively. Only ASV mode could stabilize the PtcCO2 above the apneic threshold (AT, approximately 40 mmHg) with successfully eliminating central apnea events. It is concluded that the level of CO2 is the determinant of successful NIV pressure titration in patients with non-hypercapnic CSA.