The Influence Of The Level Of The Blood Pressure In Inter-arm Blood Pressure Difference Of The Patients With Hypertension

Background：Blood pressure difference between arms is frequently encounteredin various general populations. In recent years, more and more researchers payattention to this phenomenon, and they call it “inter-arm blood pressure difference”（IAD）.The IAD includes the inter-arm systolic blood pressure difference （sIAD）and the inter-arm diastolic blood pressure difference（dIAD). Many researchers havecarried out some researches about it. The scholars generally think sIAD and dIADshould be no more than10mmHg, so they generally define the abnormal IAD aswhich is more than10mmHg.Objectives：To investigate the magnitude of the IAD among citizens andmeasure prevalence of IAD>10mmHg in patients with high blood pressure; toidentify what factors are associated with the difference between patients; to observewhether the abnormal IAD is reproducible.Methods：We enrolled414patients receiving treatment for hypertension in theSecond Hospital Affiliated to Nanchang University, and age range is27～86years，(mean age61.34±13.26,200men and214women). All patients may have Sinusrhythm, eliminate atrial fibrillation, sinus arrhythmia, frequent premature beats, acutemyocardial infarction, aortic coarctation, congenital heart disease, severe heart failure,paralysis, too thick of upper arm circumference and pulseless. We measured thepatients’ both arm blood pressure simultaneously and calculated the absolutedifference in blood pressure between arms at the time of admission, antihypertensivetreatment and discharge respectively. More over, at the time of admission, patients aredivided into hypertension class1, class2and class3according to the blood pressurelevel. We also recorded the patient’s blood lipids, blood glucose, echocardiography,carotid ultrasound, as well as general information including age, gender, history ofdiabetes. Casual BP reading was measured in a lying position after10minutes rest forfour times，using all automated electro—sphygmomanometer (Omron HEM-7012).The relationship between inter-arm difference and various factors was analyzed usingUnivariate Analysis. The data from subjects whose absolute systolic BP (SBP) difference was greater than10mmHg were analyzed using Multivariate LogisticAnalysis.Results：(1) Mean blood pressure of414patients with hypertension on admission was(SBP/DBP) right arm163.72±18.36mmHg/86.23±12.91mmHg, left arm159.73±18.22mmHg/86.57±13.38mmHg. Admission sIAD/dIAD was5.74±5.17mmHg/2.81±2.60mmHg, the prevalence of sIAD≥10mmHg and dIAD≥10mmHg were18.36%and2.90%.(2) sIAD one-way analysis of variance and multivariate linear regression analysisboth prompt blood pressure level of hypertensive patients is the main factor of sIAD.The χ~2test of sIAD≥10mmHg showed, sIAD≥10mmHg was significantlyassociated with blood pressure levels and left ventricular diastolic dysfunction (P<0.05), multivariate logistic regression analysis showed sIAD≥10mmHg iscorrelated to blood pressure levels (OR=1.702) and left ventricular diastolicdysfunction (OR=2.409).(3) Univariate analysis of the diastolic blood pressure difference between the armsshowed that left ventricular hypertrophy is the impact factor (P <0.05). Formultivariate analysis, there is no variable selected for multiple regression equation.The χ~2test of dIAD≥10mmHg showed dIAD≥10mmHg has no significantrelationship (P>0.05) with hypertension levels, age, cholesterol levels, diabetes, leftventricular diastolic dysfunction and so there.(4) Mean blood pressure of414patients on admission, treatment and discharge was:163.72±18.36/86.57±13.38mmHg,147.69±15.31/79.16±11.69mmHg,135.35±11.66/74.45±9.58mmHg, and the mean sIAD were5.74±5.17mmHg,4.52±4.05mmHg,3.68±3.43mmHg, so abnormal sIAD detection rates were18.36%(76/414),5.80%(24/414),2.41%(10/414). The results indicate that afterantihypertensive treatment, the average blood pressure of all414patients decreasedsignificantly compared to the time of admission, and the average sIAD and abnormalsIAD detection rate decrease with the decrease in the level of blood pressure.(5) In this study, there is a total of76patients with sIAD≥10mmHg when onadmission, by repeated measurement of the change of the mean sIAD1,2,3of thesepatients when on admission, treatment and discharge, it shows for all76cases, the difference in systolic blood pressure between the three groups was statisticallysignificant (F=36.337, P <0.05). Further pair wise comparison between differenttime for each group, it suggests that the difference of systolic blood pressure was alsostatistically significant (P <0.05). There are12patients with dIAD≥10mmHg whenon admission. By repeated measurement of the mean abnormal dIAD, we found thatthe difference between different groups is statistically significant (F=12.316, P<0.05). Further pair wise comparison between different time for each group, thedifference of dIAD≥10mmHg is significant between before treatment and ontreatment(P <0.05), but between on treatment and after treatment, the difference is notstatistically significant (P>0.05).Conclusions: Bilateral blood pressure measurements should become a routinepart of cardiovascular assessment in primary care. The results suggest that there isconsiderable Blood Pressure (BP) difference between the right and left arms and thatlarge difference of the absolute SBP is associated with decrease of LVDF and thelevel of the blood pressure.