Abstract: [Abstract]  Objective   To observe erythropoietin (EPO) changes in severe obstructive sleep apnea hypopnea syndrome (OSAHS) patients after the noninvasive positive pressure ventilation (NPPV) treatment ;then learn more about the effects of sleep disorders on the human body. Methods   32 cases were diagnosed as moderate to severe obstructive sleep apnea hypopnea syndrome with noninvasive positive pressure ventilation, 1 and 3 months later sleep monitoring and serum erythropoietin detection were executed, sleep apnea hypopnea index (AHI), sleep mean minimum oxygen saturation (LSaO2) and serum erythropoietin (EPO) levels , and its clinical significance were analysised. Results   ① After the treatment of 3 months in patients with OSAHS whole blood viscosity , plasma viscosity, whole blood reduced viscosity, erythrocyte accumulation index , RBC, Hgb, HCT, MCH, MCV, the serum EPO, LSaO2 compared with the prior treatment ，the difference was statistically significant ( P <0.05), while compared with the control group showed no significant difference (P> 0.05), all of the above indicators in the prior treatment and control group were significantly different (P <0.05). ②after treatment for 1 month ，whole blood viscosity , plasma viscosity, whole blood reduced viscosity, erythrocyte accumulation index compared with the prior treatment had no significant difference (P> 0.05); while patients’ RBC, Hgb, HCT, MCH, MCV, LSaO2 and serum EPO compared with the prior treatment ,the difference was statistically significant (P <0.05), treatment for 3 months and the control group had no significant difference (P> 0.05). ③ Correlation analysis showed that OSAHS patients(before and after treatment)serum EPO levels and Hgb concentration , RBC were positively correlated ( all P <0. 01). AHI and serum EPO levels were positively correlated ( all P <0. 01), serum EPO levels and night LSaO2 with negatively correlated (P <0.05). Conclusion   OSAHS patients with hypoxia could induce erythropoietin increased，noninvasive positive pressure ventilation therapy can significantly improve AHI, LSaO2 , reduce the level of erythropoietin then further to reduce blood viscosity, so the early application of noninvasive positive pressure ventilation could relieve airway obstruction and its complications，for the prevention and treatment of OSAHS.

Key words: Non-invasive positive pressure ventilation, OSAHS, EPO, hemorheology, oxygen saturation