The effect of daytime PaCO2 on subjective sleep quality and HRQOLs in patients receiving long-term NIV

Background and Aims: In patients with long-term NIV, high daytime PaCO 2 results partially from nocturnal hypercapnia. High daytime PaCO 2 might result from insufficient nocturnal NIV, and should be corrected to lower levels by modulating ventilator settings. However there are slight evidences that lower PaCO 2 could enhance subjective sleep quality and HRQOLs, so we investigated. Methods: We have started a 5-years prospective study including 355 patients receiving LTOT and/or long-term NIV. Daytime PaCO 2 , subjective sleep quality (PSQI and AIS), daytime sleepiness (ESS), HRQOLs (SRI, HAD), and exertional dyspnea (MRC) were examined and analyzed. The method of Holm was used to adjust the P values in nonparametric analyses. Results: Ninety-seven patients received long-term NIV. There were no correlations between their daytime PaCO 2 and their subjective sleep quality (PSQI; p=1.00 and AIS; p=1.00). There was also no correlation between their daytime PaCO 2 and their daytime sleepiness (ESS; p=0.87). Their daytime PaCO 2 had no correlation with their HRQOLs (SRI; p=1.00, HAD-anxiety; p=1.00 and HAD-depression; p=1.00), and exertional dyspnea (MRC; p=1.00). Conclusions: Higher daytime PaCO 2 in patients receiving long-term nocturnal NIV had neither relation with lower subjective sleep quality nor with more sleepiness. Lower daytime PaCO 2 was not correlated with better HRQOLs. These findings were unexpected for us as respiratory physicians who had introduced long-term NIV to lower both daytime and nighttime PaCO 2 leading to enhancing survival in more than 500 hypercapnic patients since 1989. Long-term NIV may be good but bitter medicine for some patients.