Nocturnal Hypoxemia And The Serum Levels Of S100B In COPD Patients With Normal Oxygen Saturation At Daytime

Objective:The aim of this study was to evaluate the incidence of nocturnal hypoxemia in chronic obstructive pulmonary disease(COPD)patients with a normal oxygen saturation when awake and its effect on the serum levels of S100B.Methods:64 COPD patients with normal oxygen saturation when awake at daytime were collected and analyzed retrospectively from January 2014 to January 2016,including 36 men and 25 females,with a mean age of 65.9�9.0 years.According to having hypoxemia or not at night,the patients were divided into normal group(23 patients)and hypoxia group(41 patients),whereas according to the sleep phase of the hypoxemia,the hypoxia group was subdivided into rapid eye movement(REM)hypoxia group(20 patients had hypoxemia only in the REM phase),non-rapid eye movement(NREM)hypoxia group(13 patients had hypoxemia only in the NREM phase),and mixed hypoxia group(8 patients had hypoxemia both in REM phase and NREM phase).The incidence of the hypoxemia,general data,sleep time,blood gas test,sleep monitoring indicators,serum S100B levels and its relationship to hypoxemia were recorded and analyzed.Furthermore,the effect of nocturnal oxygen therapy(from the second day in the hospital)on the changes of serum S100B levels was also analyzed.Results:In the 64 patients,the rate of the nocturnal hypoxemia rate was 64.06%(41/64).Among the 41 COPD patients with nocturnal hypoxemia,48.78%(20/41)was occurred in REM phase,31.70%(13/41)in NREM phase and 19.51%(8/41)both in the REM phase and NREM phase.The patient's total sleep time in the hypoxia group was significantly shorter than in the normal group(p<0.001).The Pa02 in the second day in the hypoxia group was significantly lower than that in the second day in the normal group and also significantly lower than that in the first day in the hypoxia group(p<0.001).While the percentage of Sp02<90%in the total sleep time in the hypoxia group was significantly higher than that in the normal group(p<0.001).Between the two groups,there were no significant differences in PaC02 in the first two days,apnea hypopnea index(AHI),and arousal index(Arl)(p>0.05).The serum S100B in the hypoxia group,which was significantly higher than the normal group in the first two days,was significantly higher in the second day than the first day,but significantly lower in the seventh day than the first two days(p<0.001),with no significant differences compared to normal group in the seventh day(p>0.05).Furthermore,the levels of serum S100B was negatively related to Pa02(r=-0.626,p<0.001),but positively correlated with the percentage of nocturnal Sp02<90%in the total sleep time(r = 0.708,p<0.001).Conclusions:More than 50%of COPD patients with a normal oxygen saturation when awake at daytime suffer nocturnal hypoxia,also in the non-rapid eye movement phase.The serum levels of S100B was increased or decreased by nocturnal hypoxemia or after oxygen therapy,which indicates a valuable marker of hypoxia-induced brain injury in COPD patients with normal oxygen saturation when awake at daytime and hypoxemia at nighttime.