[Daytime hypercapnia in patients with obstructive sleep apnea hypopnea syndrome in Han and Uygur nationality]

Abstract

Objective: To evaluate the incidence and factors related to daytime hypercapnia in Han and Uygur patients with obstructive sleep apnea hypopnea syndrome (OSAHS). Methods: There were 221 patients with OSAHS (include 179 Han patients and 42 Uygur patients) in Sleep Center of Department of Respiratory and Critical Care Medicine of Karamay Central Hospital from 2015, Jan to Dec. All the patients underwent polysomnography (PSG), nocturnal oximetry, daytime blood gas analysis, pulmonary function test and Mouth occlusion pressure (P_0.1) results were recorded. The features of hypercapnia was analyzed for patients with OSAHS, and linear regression analysis was used to evaluate the arterial carbon dioxide partial pressure (PaCO₂) levels and related factors. Results: Daytime hypercapnia occurred in 16.7% (37/221) of the 221 patients with OSAHS. Compare with no hypercapnia groups, the body mass [(31.6±5.6) vs (27.9±1.7) kg/m²], sleep apnea index (AHI) [(40.9±26.3) vs (32.2±20.1) times/h], the percentage of time spent at oxygen saturation below 90 (SIT₉₀) [(38.6±31.9)% vs (23.9±23.6)%], P_0.1 [(3.08±2.86) vs (2.03±1.20) mmHg, 1 mmHg=0.133 kPa] were higher in hypercapnia groups, but the mean nocturnal arterial oxygen saturation (MSaO₂) [(86.0±15.5)% vs (92.0±3.0)%], the nadir arterial oxygen saturation (LSaO₂) [(68.9±13.0)% vs (75.3±9.9)%] and arterial partial pressure of oxygen (PaO₂) [(74.5±23.0) vs (86.1±14.8) were lower in hypercapnia groups (all P<0.05). Compare with Han patients with OSAHS, MSaO₂ and LSaO₂ was lower, PaCO₂ and P_0.1 was higher in Uygur patients (all P<0.05). Conclusions: Uygur OSAHS patients with hypercapnia have a higher daytime PaCO₂ than the Han counterparts. BMI, AHI, MSaO₂, P_0.1 level are all related with daytime hypercapnia in OSAHS.