%0 Journal Article %A Sigurd Aarrestad %A Elin Tollefsen %A Jean-Paul Janssens %A Anne Louise Kleiven %A Magnus Qvarfort %A Ole Henning Skjønsberg %T Validity and contribution of transcutaneous CO2 (TcCO2) in monitoring chronic hypoventilation treated with non-invasive ventilation (NIV) %D 2014 %J European Respiratory Journal %P P4707 %V 44 %N Suppl 58 %X Introduction:Residual hypercapnia can be present in daytime or during sleep in patients with chronic hypoventilation treated with NIV; thus CO2 should be monitored both during daytime and sleep.Aims:1) to compare arterial CO2 (PaCO2) measured by radial puncture with TcCO2,2) to measure overnight drift of the TcCO2 sensor and3) to evaluate the contribution of overnight TcCO2 vs. solely using pulse oximetry (SpO2) for detecting nocturnal hypoventilation (NH).Methods:42 patients with: neuromuscular diseases (23), central hypoventilation syndrome (3), obesity hypoventilation syndrome (12) and restrictive thoracic disorders (4) were studied.PaCO2 (room air) was compared with simultaneously measured TcCO2 values. Overnight drift was estimated by measuring a defined gas concentration in the evening, after calibration of the sensor, and repeating this measurement in the morning. Overnight TcCO2 and SpO2 were measured during NIV.Definition of:NH: TcCO2 >7,3 kpa or ≥1,33 kpa increase to above 6,7 kpa ≥10 minutes.Normal SpO2: SpO2 < 90% in <10% of the recording time.Results:TcCO2 correlated significantly with PaCO2 (r = 0.966 p<0.0001). The Bland-Altman plot showed a mean bias of 0.25 kpa (Limits of agreement; -0.26 – 0.76). Mean technical drift was 0.01 kpa/hr(± 0.08).NH was found in 15 patients, 8(53%) had normal and 7(47%) had an abnormal overnight SpO2.Conclusions:TcCO2 accurately reflects PaCO2 in patients with chronic hypoventilation and can be used to monitor CO2 overnight during NIV without any clinically significant drift.TcCO2 can detect NH in patients with normal nocturnal SpO2, and can differentiate NH from other causes of nocturnal hypoxemia. %U