Sleep Transcutaneous vs. End-Tidal CO₂ Monitoring for Patients with Neuromuscular Disease

This study compared transcutaneous carbon dioxide partial pressure (PtcCO₂) and end-tidal carbon dioxide partial pressure (PetCO₂) monitoring during sleep for patients with neuromuscular disease. Design This is a retrospective study of patients whose PtcCO₂ and PetCO₂ were monitored before they began using noninvasive mechanical ventilation. The outcomes were divided into four groupings: group 1, both PtcCO₂ and PetCO₂ are greater than or equal to 49 mm Hg; group 2, PtcCO₂ is greater than or equal to 49 mm Hg but PetCO₂ is less than 49 mm Hg; group 3, PtcCO₂ is less than 49 mm Hg but PetCO₂ is greater than or equal to 49 mm Hg; and group 4, both PtcCO₂ and PetCO₂ are less than 49 mm Hg. Results A total of 39 subjects (mean [SD] age, 27.7 [19.3] yrs) were enrolled. PtcCO₂ values were significantly higher than PetCO₂ values (P < 0.001). The intraclass correlation coefficient between maximal and mean values of PtcCO₂ and PetCO₂ was 0.612 and 0.718, respectively. Bias and limits of agreement between PtcCO₂ and PetCO₂ were-7.5 mm Hg and-21.3 to 6.3 mm Hg for maximal values and-4.8 mm Hg and-14.8 to 5.3 mm Hg for mean values. Group 2 included 19 (48.7%) and group 3 included 3 (7.6%) patients who showed discrepancy of hypercapnia between two methods. Conclusions Maximum PtcCO₂ was significantly greater than maximum PetCO₂ for both groups and, therefore, tends to be higher than PetCO₂ in this population. This should be taken into consideration when assessing patients for sleep hypoventilation.