The Research Of Lipid Metbolism And Its Correlative Factors In Patients With Obstructive Sleep Apnea

Part I Lipid metabolism disorder in patients withobstructive sleep apneaObjective To investigate the effect of obstructive sleep apnea(OSA) on lipid metabolism, through the analysis of normal weight and obese patients with OSA.Methods 540 patients referred to PSG for evaluation of sleep apnea symptoms between June 2011 and November 2014 were included in this study. Demographic data and PSG parameters were recorded. Blood glucose and blood lipids levels were systematically measured. Based on the apnea-hypopnea index(AHI) and the body mass index(BMI), these patients were divided into four groups: normal BMI+primary snoring group(n=126), normal BMI+OSA group(n=119), overweight(obesity)+primary snoring group(n=53), weight(obesity)+OSA group(n=242).Results 1. In the group of primary snoring patients, the percent of hyperlipidemia was increased significantly in overweight(obesity) patients, compared with normal BMI patients(P=0.002). Total cholesterol(TC), low density lipoprotein(LDL), very low density lipoprotein(VLDL) levels increased significantly(P=0.044), high density lipoprotein(HDL) level decreased significantly(P = 0.003) in overweight(obesity) patients. 2. In the group of normal BMI patients, compared with primary snoring patients, the percent of high blood pressure increased(P=0.003) in OSA patients. The level of HDL decreased in OSA patients(P=0.001). 3. Compared with primary snoring patients, the composition of disease in OSA patients has an obvious difference(P=0.004). 4. In the logistic regression analysis with hyperlipidemia as the dependent variable, Age, BMI, AHI and epworth sleepiness scale(ESS) were included in the regression equation.Conclusions Obesity and OSA are risk factors of the lipid metabolism disorders. In addition to obesity, the sleep time changes and the severity of OSA is also the causes of the lipid metabolism disorders.Part II The relationship of serum lipoprotein lipse,leptin levels and dyslipidemia in patients withobstructive sleep apnea syndromeObjective To investigate the relationship of serum lipoprotein lipse(LPL), leptin levels and dyslipidemia in patients with obstructive sleep apnea(OSA).Methods Over night polysomnography(PSG) was performed to 158 patients with snoring in our Sleep Center of the Second Affiliated Hospital from June 2011 to April 2013. Based on the apnea-hypopnea index(AHI), these patients were divided into four groups: primary snoring group(AHI<5events/hour, n=26), mild group(5events/hour ≤AHI <15events/hour, n=23), moderate group(15events/hour ≤AHI <30 events/hour, n=31) and severe OSA group(AHI≥30events/hour, n=78). According to the body mass index(BMI), the primary snoring group and OSA group could be divided into normal BMI group and the overweight(obesity) group. The levels of LPL and leptin were measured by enzyme-linked immunosorbent method, and we observed the levels of lipid, LPL and leptin in different groups. Observed the correlation with OSA and blood lipid, which includes blood total cholesterol(TC), triglyceride(TG), high density lipoprotein(HDL), low density lipoprotein(LDL) and very low density lipoprotein(VLDL). And the levels of LPL and leptin were also observed after 6 months CPAP in 49 patients with OSA.Results From the comparison result of the four groups, we had procured that AHI, night blood lowest oxygen saturation(L-Sa O2), percent of total time with oxygen saturation level <90%(TS90%) had statistical significance(P<0.01). The serum LPL gradually reduced in the four groups. There was a significant increase of the serum LPL level in the severe OSA group((36.8±15.5)vs(44.7±17.2)μg/L, P=0.022), compared with the primary snoring group. There were no signifcant differences of leptin level in the four groups. Compared with primary snoring group, severe OSA group had a significant higher serum TC, TG and LDL(P=0.025,0.001,0.049). The level of HDL in OSA group were significantly lower than primary snoring group(all P<0.05). In the bivariate correlation, the lipid level was correlated with BMI, the levels of TC and LDL was negatively correlated with LPL. In logistic regression analysis, BMI and LPL were included in the regression equation. Furthermore, we found no correlation between the serum leptin level and lipid. Additionally, after adjustment for BMI and age, serum LPL levels showed significant negative correlations with AHI and oxygen decrease index(ODI)(r=-0.701,-0.628, P=0.024,0.042), and no correlation with sleep time and structure. Compared with the normal BMI patients, there was a significiant increase of VLDL((0.8±0.3) vs(0.5±0.2)mmol/L, P=0.034) and decrease of LPL((37.1±10.3) vs(54.2±22.2)μg/L, P=0.047) in the overweight(obesity) in primary snoring group. Compared with primary snoring group in normal BMI groups, there was a significiant increase of TG, VLDL and decrease of LPL, HDL in the OSA group(all P<0.05). The level of LPL increased significiantly after 6 months CPAP((60.3±9.1) vs(38.1±6.9)μg/L, P =0.001).Conclusions There are lipid disorders in OSA patients, both obesity and OSA are risks for lipid disorder. The lower level of LPL is caused by sleep apnea and intermittent hypoxia, which is correlated with lipid disorder in OSA patients, and have no relation with leptin levels. Part III The relationship of lipid metabolism disorders and serum liver enzymes in patients with obstructive sleep apnea-hypopneaObjective Our study investigated the liver enzymes level in obstructive sleep apnea-hypopnea(OSA) and primary snoring patients and the relationship of hyperlipidemia and the liver enzymes level, in order to find out whether the liver injury had effects on the dyslipidemia in OSA patients.Methods 540 patients with snoring referred to polysomnography(PSG) for evaluation of sleep apnea symptoms between June 2011 and November 2014 were included in this study. Demographic data and PSG parameters were recorded. Serum alanine aminotransferase(ALT), aspartate aminotransferase(AST), and gamma-glutamyl transferase(GGT) levels were systematically measured. OSA patients were divided into three gruops according to the apnea-hypopnea index(AHI), primary snoring group(<5 events/hour), mild/ moderate group(15–29events/hour), and severe group(≥30 events/hour).Results Elevated liver enzymes were present in 42.3% of OSA patients(32.4% in mild/moderate group; 51.0% in severe group) and in 28.1% patients without OSA. Patients with OSA had higher body mass index(BMI)(P<0.01). In the bivariate correlation, the liver enzymes level was negatively correlated with age and lowest Sa O2(L-Sa O2), and was positively correlated with BMI, oxygen desaturation index(ODI), percent of total time with oxygen saturation level <90%(TS90%), AHI, cholesterol(TC) and triglyceride(TG). In logistic regression analysis, Age, BMI, TS90%, TC and TG were included in the regression equation. In logistic regression analysis with hyperlipidemia as the dependent variable, Age, BMI and abnormal liver function were included in the regression equation.Conclusions Our data suggest that OSA is a risk factor for elevated liver enzymes. The severity of OSA was correlated with liver enzyme levels, we hypothesize that hypoxia is one of main causes of liver damage in patients with OSA. There is a relationship between abnormal liver function and blood lipid metabolism, hyperlipidemia aggravates liver injury, and liver injury also causes dyslipidemia.