Comparison of ventilator-integrated end-tidal CO2 and transcutaneous CO2 monitoring in home-ventilated neuromuscular patients.

BACKGROUND Non-invasive transcutaneous capnometry (TcCO2) is used to assess the home ventilation's efficiency. Recently, end-tidal CO2 (ETCO2) sensors have been integrated in life-support home ventilators. The purpose of this study was to compare the ventilator-integrated ETCO2 with TcCO2, in home-ventilated neuromuscular disease patients. METHODS ETCO2 and TcCO2 were simultaneously measured during one night in 28 patients. Daytime blood gases were drawn on the following morning to measure arterial PCO2 (PaCO2). RESULTS Compared to PaCO2 values, both ETCO2 and TcCO2 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 ETCO2 and TcCO2, both considering the mean nocturnal PCO2 (r = 0.897, p < 0.001; bias -1.1 [- 9.0; 6.9] mmHg) and the maximal PCO2 value over the night (r = 0.905, p < 0.001; bias 3.1 [-4.5; 10.8] mmHg). The concordance of the two techniques in detecting overnight PCO2 fluctuations was high, with r = 0.919 (p < 0.001) for the time spent with PCO2 >45 mmHg and r = 0.943 (p < 0.001) for the time with PCO2 >50 mmHg. CONCLUSIONS The ventilator-integrated end-tidal CO2 monitoring is as reliable as the currently used transcutaneous measurement, resulting to be a valuable proxy of the overnight PCO2 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. ClinicalTrials.gov registration:NCT02068911.