Background: Non-invasive transcutaneous capnometry (TcCO 2 ) is used to assess the home ventilation9s efficiency. Recently, end-tidal CO 2 (ETCO 2 ) sensors have been integrated in life-support home ventilators. Aims: The purpose of this study was to compare the ventilator-integrated ETCO2 with TcCO2, in home-ventilated neuromuscular disease patients. Methods: ETCO 2 and TcCO 2 were simultaneously measured during one night in 28 patients. Daytime blood gases were drawn on the following morning to measure arterial PCO 2 (PaCO 2 ). Results: Compared to PaCO 2 values, both ETCO 2 and TcCO 2 showed a small bias (-0.1 mmHg and 0.6 mmHg, respectively) and a similar critical difference (6.8 mmHg and 7.3 mmHg, respectively). We found a good correlation between ETCO 2 and TcCO 2 , both considering the mean nocturnal PCO 2 (r=0.897, p 2 value over the night (r=0.905, p 2 fluctuations was high, with r=0.919 (p 2 >45 mmHg and r=0.943 (p 2 >50 mmHg. Conclusions: The ventilator-integrated end-tidal CO 2 monitoring is as reliable as the currently used transcutaneous measurement, resulting to be a valuable proxy of the overnight PCO 2 evolution. This result opens the possibility of a simplification in the monitoring of home ventilated patients, since ETCO2 measurement can be performed directly at home, with a low additional cost. However, the accuracy of both these measurement techniques is not sufficient to replace blood gases, which remain the reference examination.
