| BackgroundCardiovascular autonomic neuropathy(CAN)is a dysfunction of the autonomic nerves innervating the heart caused by a variety of primary and secondary etiologies.CAN has an insidious onset and is an independent risk factor for silent myocardial infarction,malignant arrhythmia and even sudden cardiac death,which will seriously affect the prognosis.At present,the only clinical examination recommended as the"gold standard" by guidelines is the cardiovascular reflex tests(CARTs),considered to be sensitive,specific and reproducible.During CARTs,subjects are required to complete a battery of maneuvers,and changes in heart rate and blood pressure upon standard physiological stimuli being carefully observed.However,the current examination process relies heavily on judgment and measurement by human,and the lack of objective monitoring on whether the actions are standardized affect the accuracy and precision of the examination results.At the same time,manual data measurement and analysis are time-consuming and tedious,which limits the clinical application and promotion to a certain extent.How to build a smart evaluation system for CARTs and truly achieve standardized stimulation is still worth exploring and thinking.Objectives:1.To design a cardiovascular autonomic evaluation system that can detect instantaneous parameters in real-time,ensuring the maneuvers performed by subjects are standardized,and can quickly analyze the results automatically.In addition,studies are carried out to verify the measurement performance of the system.2.To verify the reliability of the new evaluation system and explore the impact of the equipment on examination efficiency.Methods1.Find the technology that allows parameters collecting and elaborating in realtime,and establish the special interactive function module for each action.After the design is completed,the measurement performance of each functional unit of the evaluation system was tested in the laboratory.2.Trial one included 106 subjects who underwent examinations both by automatic(using the new evaluation system)and synchronous(simultaneously conducted with automatic but manually recording and measurement electrocardiography(ECG))methods,6 of whom underwent repeated examinations,and another 44 additionally underwent examinations by manual method(traditional instrument manual measurement).Measure the level of agreement of the continuous indexes between automatic and synchronous methods,and between automatic and manual methodsheart rate response to standing(R30:15),Valsalva ratio(VR),rate response to deep breathing(I-E),blood pressure response to standing(△SBP),and blood pressure response to handgrip(△DBP).Interclass correlation(ICC)and Kappa value were used for agreement analysis.Coefficient of variation(CV)was used as a measure of reproducibility.Record and compare the time required for examination,measurement and diagnosis between methods.3.Trial two enrolled 25 subjects for CARTs by automatic and synchronous methods,in which the synchronous method used an improved method of strictly manual marking events on ECG.level of agreement was measured between these two methods.Results1.An intelligent and real-time sensor monitoring interactive cardiovascular autonomic evaluation system is designed,integrated with microprogrammed control unit(MCU)and Bluetooth technology.2.The average detection rate of R waves in the standard ECG database by the ECG module of the evaluation system was 99.13%,the overall sensitivity was 99.68%,and the positive predictive value was 99.44%.The measurement accuracy of the blood pressure measurement module,the insufflation pressure measurement module and the grip strength measurement module all meet the standard requirements.3.In trial one,there was moderate to substantial agreement between heart rate continuous indexes acquired from automatic method and synchronous method(ICC for R30:15 was 0.616,p<0.001;ICC for VR was 0.805,p<0.001,ICC for I-E was 0.733).There was poor to moderate agreement between the automatic method and the manual method(ICC for R30:15 was 0.598,p<0.001;VR was 0.632,p<0.001;ICC for I-E was 0.466,p=0.0065,ICC for △SBP to standing was 0.193,p=0.0714;ICC for △DBP was 0.368,p=0.0078).The Automatic method and the Synchronizing method had moderate agreement(Kappa was 0.581,p<0.001)for the two-category diagnosis(i.e.CAN positive and CAN negative),and the five-category diagnosis(i.e.normal,early involvement,definite involvement and severe involvement)was highly consistent(Kappa=0.628,p<0.001).While the five-category diagnostic agreement between the Automatic method and the Manual method was poor(Kappa was 0.261,p=0.0059).4.Consistency of R30:15,VR and I-E measured by automatic and synchronous methods in Trial II,ICC were 0.930(95%confidence interval 0.849-0.968,p<0.001),0.988(95%confidence interval 0.967-0.995),respectively,p<0.001)and 0.889(95%confidence interval 0.889-0.984,p<0.001).Trial Ⅱ Kappa was 0.8253(p<0.001),0.8983(p<0.001),and 0.7953(p<0.001)for categorical variables examined individually.For the categorical diagnosis of CARTs,the automatic method and the simultaneous method had strong consistency in the two-category diagnosis(Kappa=0.621,p=0.0017)and the five-category diagnosis(Kappa=0.799,p<0.001).5.In repeated measurements performed by automatic method and the synchronous methods,the CV of R30:15 measured by the automatic method was 3%～19%,the CV of VR is 3%～11%,and the CV of I-E is 4～20%;R30 measured by the synchronous method:The CV of 15 is 6%～15%,the CV of VR is 4%～12%,and the CV of I-E is 11～35%.There was a significant difference in the coefficient of variation of I-E between the two methods(p=0.044).6.The new evaluation system automatically analyzed the data,manually reviews and generates a test report immediately after the CARTs test,taking an average of 1.02±0.07min,which is 10.7min(91.3%,p<0.0001)less than the manual analysis after the manual method.Conclusion1.The measurement accuracy of accessories of cardiovascular autonomic nerve function detection system is in line with relevant technical standards.They can monitor physiological parameters in real time,guide maintenance and record the whole process,truly realizing"standardized stimulation".2.The results of the cardiovascular autonomic evaluation system are in good consistency with the synchronous method,and the results are highly accurate.3.The application of cardiovascular autonomic evaluation system has greatly improved the efficiency of CARTs. |
