Correlation And Risk Factors Between The Decline Rate Of Pulse Oxygen At Night And The Variability Of Intraurnal Blood Pressure In Elderly Hypertension Patients With Sleep Disordered Breathing

PurposeBy analyzing the correlation between nocturnal pulse oxygen decline rate and diurnal blood pressure variability in elderly patients with hypertension related to sleep breathing disorder,this paper discusses the risk factors of non dipper hypertension in the elderly,so as to provide theoretical and clinical basis for the prevention and early diagnosis and treatment of non dipper hypertension in the elderly at night.MethodPatients with hypertension admitted to the geriatrics department of our hospital from July 2019 to August 2021 were selected for night sleep breathing monitoring and 24-hour ambulatory blood pressure monitoring.After the occurrence of nocturnal apnea,the percentage of the decrease of pulse oxygen saturation（SpO2）per second in the oxygen reduction event is regarded as the decrease rate of pulse oxygen.According to the percentage of the decrease of circadian blood pressure（per）,it is divided into dipper hypertension group and non dipper hypertension group.The general data,respiratory disorder parameters,24-hour circadian blood pressure variability and clinical data of the two groups were compared.Pearson correlation analysis was used to evaluate the correlation between pulse oxygen decline rate and diurnal blood pressure variability.Multiple regression equation was used to analyze the risk factors affecting the formation of non dipper hypertension in the elderly.Main outcome measures:1.Correlation between nocturnal pulse oxygen decline rate and diurnal blood pressure variability in elderly patients with hypertension related to sleep breathing disorder;2.Risk factors of non dipper hypertension in the elderly.Secondary outcome measures:1.Differences in sleep breathing monitoring indexes and blood pressure variability between the two groups;2.The differences of carotid intima-media thickness and ventricular structure between the two groups;3.The differences of blood biochemistry and myocardial injury markers between the two groups;4.Early diagnostic value of blood biochemical indexes and respiratory disorder index in elderly non dipper hypertension related to sleep respiratory disorder.Results1.The short-term variability of nocturnal blood pressure in non dipper hypertension group was positively correlated with pulse oxygen decline rate,respiratory disorder index（AHI）,oxygen reduction index（ODI）,body mass index（BMI）and carotid middle thickness（CIMT）;It is negatively correlated with the lowest oxygen saturation（LSaO2）.2.The decrease rate of AHI,ODI,pulse oxygen decline rate,24-hour mean blood pressure and short-term blood pressure variability in non dipper hypertension group were higher than those in dipper hypertension group,and the level of LSaO2 was significantly lower than that in dipper hypertension group.The difference between the two groups was statistically significant（P<0.05）.3.The carotid intima-media thickness,ventricular septal thickness（IUS）,left ventricular posterior wall thickness（LVPW）,left ventricular diastolic diameter（LVD）and left ventricular systolic diameter（LVS）in non dipper hypertension group were significantly higher than those in dipper hypertension group,and the left ventricular ejection fraction（LVEF）was significantly lower than that in dipper hypertension group.The difference between the two groups was statistically significant（P<0.05）.4.Fasting blood glucose（FBG）,glycosylated hemoglobin（HbA1c）,homocysteine（Hcy）,total cholesterol（TC）,triglyceride（TG）,uric acid（UA）,Myoglobin（Myo）and N-terminal B-type natriuretic peptide（NT-proBNP）in non dipper hypertension group were significantly higher than those in dipper hypertension group.The difference between the two groups was statistically significant（P<0.05）.5.Multivariate logistic regression analysis was carried out with ODI,CIMT and pulse oxygen decline rate as independent variables and non dipper hypertension as dependent variables.Among the included independent variables,the final results showed that there were significant differences in ODI（OR=1.569;95%CI,1.423-2.566;P<0.05）,pulse oxygen decline rate（OR=1.120;95%CI,1.017-2.889;P<0.01）and CIMT（OR=0.983,95%CI,0.965-0.992,P<0.001）.It is suggested that ODI,CIMT and pulse oxygen decline rate are independently related to non dipper hypertension.6.ROC analysis showed that the area under the ROC curve of combined myo,NT proBNP and AHI in the classification of elderly non dipper hypertension was 0.884,the maximum value of yoden index was about 0.676,the corresponding sensitivity was 73.7%,the specificity was（1-0.061）=93.9%,and the 95%confidence interval was 0.809-0.960,It is suggested that Myo,NT-proBNP and AHI have important value in predicting the early diagnosis of nocturnal non dipper hypertension in the elderly.Conclusions1.SDB related elderly patients with non dipper hypertension had more severe hypoxia exposure.The night blood pressure variability,vascular structure and function,ventricular structure and function,glucose and lipid metabolism and myocardial injury were significantly higher than those in dipper hypertension group.2.The decrease rate of nocturnal pulse oxygen in SDB related elderly patients with non dipper hypertension is closely related to the degree of diurnal blood pressure variation.3.ODI,CIMT and pulse oxygen decline rate are important risk factors for non dipper hypertension in elderly patients with sleep disordered breathing.4.Myo,AHI and NT-proBNP have important value in predicting nocturnal non dipper hypertension in the elderly.