nghiên cứu một số chỉ số chức năng tim - mạch, tâm - thần kinh của sinh viên đại học y thái bình ở trạng thái tĩnh và sau khi thi tóm tắt luận án tiếng anh

MINISTRY OF EDUCATION AND TRAINING MINISTRY OF DEFENSE VIETNAM MILITARY MEDICAL UNIVERSITY NGUYEN THI HIEN STUDY ON SOME CARDIOVASCULAR AND NERVOUS INDICATORS OF THAI BINH MEDICAL STUDENTS IN CONTROL AND EXAMINATION CONDITION Speciality: Physiology Code: 62 72 01 07 DOCTOR OF PHILOSOPHY DISSERTATION HAnOi - 2013 THE PROJECT COMPLETED In VIETNAM MILITARY MEDICAL UNIVERSITY Advisors: Assoc. Prof. PhD. Tran Dang Dong Assoc. Prof. PhD. Vuong Thi Hoa Reviewer 1: Assoc. Prof. PhD. Le Thu Lien Reviewer 2: Assoc. Prof. PhD. Le Van Son Reviewer 3: Assoc. Prof. PhD. Nguyen Trong Hung The doctoral dissertation has been defended at the Council Assessment of the dissertation at Vietnam Military Medical University at 8.30 am. - April 9th 2013. THE DISSERTATION AVAILABLE AT: - National Library of Vietnam - Library – Vietnam Military Medical University - Library – Thai Binh Medical University INTRODUCTION Students are high quality workforce for the society in the future, they are “life-sustaining element” in every country. Health care for students is the important task not only for the school but also for the society. This era, the era of integration with the global boom of science and technology, along with environmental pollution, internal factors in the human body also become stress agents (stressors). Stress affects all social classes, including students. There are many factors causing neuropsychological stress for students during the time at the university, especially for medical students. Apart from the common stressors of all students (living conditions, educational conditions…), medical students have to spend the longest time at the university with very large amount of theoretical and practical knowledge and many exams, therefore, they are under high-pressure that cause many psychological functional strain. In the world, many studies showed that stressors can alter the function of the immune system, nervous system as well as cardiovascular and endocrine system in human. Stress is a reality of life, hence we need to understand the responses to stresses of the human body in every stressful status. In doing this, we have to quantify stress levels by using objective measuring indicators. In Vietnam, there have been some studies on occupational stress of the scientists at the National Institute of Labor Protection, National Institute of Occupational and Environmental Health and some universities. However, very few studies have been conducted on the responses of the endocrine, cardiovascular and neurological systems of the individual to stress, including studies on students. From these reasons, we carried out the study "Study on some cardiovascular and nervous indicators of Thai Binh medical students in control and examination condition" with the following objectives: 1. Measuring some cardiovascular and neuropsychological indicators of Thai Binh medical students before examination (control condition). 2. Evaluating some cardiovascular and neuropsychological and endocrine indicators of Thai Binh medical students after intellectual activities (examination condition). 1 NEW SCIENTIFIC CONTRIBUTIONS OF THE DISSERTATION - Providing data of some cardiovascular and neuropsychological indicators of 600 male and female medical students from first year to fifth year in control condition. - Detecting changes of cardiovascular, neurological and endocrine function after intellectual activities (after examination) of medical students. After the exam, participants had cardiovascular strain indicator increased, ECG changed, cortisol level as well as catecholamine level elevated. - The results of the dissertation contributes to the development of some biological indicators and provides scientific evidences to propose solution to lessen stress, improve health and intellectual property of students. THE STRUCTURE OF THE DESSERTATION This desstertation consists of 152 pages: Introduction: 2 pages, Background: 41 pages, Methods: 20 pages, Results: 46 pages, Disscusion : 40 pages, Conclusion: 2 pages, Proposal: 01 page, 60 tables, 25 figures and 139 references. CHAPTER 1 BACKGROUND 1.1. Cardiovascular indicators 1.1.1. Heart rate and blood pressure Heart rate and arterial blood pressure are the simplest indicators to evaluate the operational capacity of the human body. These indicators are easy to measure, can be long-term or repeated measure. The variations of them are easily recognizable because when the labor intensity or the emotional level increased, those indicators rose follow. Stressful work causes increased heart rate, increased blood pressure by stimulating the adrenal sympathetic nervous system. Research of Droogleever on Dutch PhD students found that although blood pressure did not change significantly during the examination, but the density of peripheral Benzodiazepine receptor, allopregnanolon and cortisol level of these students increased significantly. Research of Makarenco on students during the stress test showed a decrease in the influence of parasympathetic nerve on heart rate and metabolic stimulation but found an increase of activity of the sympathetic nerve. In Vietnam, some authors have initially used the method that assess cardiovascular functions using heart rate and blood pressure in the job 2 with high neuropsychological stress such as work of pilots, soldiers, police, medical personnel, the commanders of the ship, the operators of automated machineries, the airport coordinators. 1.1.2. Mathematical statistical indicator of heart rate In recent years, a number of authors have used the mathematical statistical indicators of heart rate (MSIHR) of Baevski to evaluate cardiac function. Baevski is the first author who launched the principle of the index of 100 consecutive RR intervals including: RR interval average (X), heart rate average (HRA), standard deviation, variation coefficient, mode (Mo), amplitude of mode and variation interval of RR max and RR min (DX). Stress index is calculated from above indicator (Stress index = AMo/2.DX.Mo). At a symposium "Application of mathematical methods to analyze heart rate" the report of Baevski, Zemaichiche, Zatsiorxki, Parin showed that MSIHR provides better information to assess the status of the body function, particularly in profession with high emotional stress. Recently, MSIHR method has been applied in Vietnam. Studies of Ta Tuyet Binh, Nguyen Thu ha, Tran Thanh Ha, Nguyen Khac Hai, Nguyen Ngoc Son showed that intellectual stress and acute stress cause stress index to increase and heart rate variation to decrease. 1.2. Some neuropsychological functional indicators Intelligence is the complex mental activity consisting of ability to learn, to use languages, to solve problems and ability to adapt to society. 1.2.1. Intelligence assessment tests The first scientist proposed the test ideas and coined the term "mental test" as Francis Galton (1822-1911). After that the intelligence assessment tests were alternately appeared such as: Binet-Simon (1905), Stanford-Binet test (1916), Wechsler scale (1939), Gille test (1944), Wisc test (1949) and Raven test (1960). Many intelligence tests have been widely used in countries around the world such as: Russia, USA, Poland, Germany and France. Raven test is officially used by UNESCO to diagnose human intellect since 1960. In Vietnam, before 1980s of twentieth century, there have been some researchs at Hanoi National University of Education applying intelligence tests in evaluating learning outcomes of students such as: study of Tran Ba Hoanh, study of Nguyen Long. From 1980s up to now, intelligence tests have been widely applied in our country. The two facilities have made important 3 contributions in this field are Institute of Education Sciences of Vietnam and Center for kid research in Hanoi. These facilities have done many researchs on intellect of primary, secondary, high school pupils as well as university students. 1.2.2. Attention, memory and thinking Attention, memory and thinking of human beings are active, complex processes that have important roles in learning and processing information in many different fields of activities. In Vietnam, Tran Thi Loan found the increase of attention ability of male and female pupils is also in the period of increase memory ability and in the period of development, improvement of structure and function of the brain. The study of Lai The Luyen showed the most clear appearance and the highest rank of stress on students was hard to focus and then hard to remember. According to J. Lazaus, stress causes memory injury, mental instability, inability to concentrate, hesitance, indecisive, lack of attention, empty-headed These symptoms usually appear. 1.2.3. Visual - motor reaction time, information processing speed Information comes to human in various ways, through many chanels: vision: up to 90%, hearing, touching To evaluate the reaction of the body, for instance: visual-motor reaction time, there has been a research of Z1 group in Vietnam Military Medical University based on computer processing technique. From the result of measuring visual-motor reaction time they calculated information processing speed. Result of the study of Do Cong Huynh showed that visual-motor reaction time lessen with age, greater age (less than 18) shorter reaction time. This proven that information processing speed is getting better due to age class. The study of Ta Thuy Lan, Tran Thi Loan, Mai Van Hung depicted similar result and reaction time in women was longer than that of men. 1.2.4. Research on the relation between EEG and intellectual activity Nervous-emotional stress induced by learning environment after intellectual activities caused changes in the functional state of the nerve cells. These changes appear early and can be seen on EEG results. Study of Vu Dang Nguyen showed EEG indicators changes depend on many factors causing nervous stress. Tran Thi Cuc reported that amplitude of alpha waves decreased, while the frequency and index of beta waves increased proportional to intellectual capacity when thinking. Thus the study of EEG changes at normal 4 and after intellectual work allows us to identify the intellectual performance of each individual. 1.3. Emotional stress Emotional stress is a complex process related to social, psychological and physiological factors. According to Hans Selye, stress is the body's state arising when strongly affected by factors from outside or inside the body. In that state, body has to make sudden changes the biological activities, to ensure homeostasis. The non-specific responses of the body in a state of stress is considered as general adaptation syndrome. GAS leads the body to a three-stage response: Alarm, Resistance and Exhaustion. Hypothalamic-pituitary-adrenal axis (HPA axis) system is the basic theory of GAS. The activation of HPA and Sympathetic Adrenal Medullary (SAM) leads to increase the body protection activities, mobilizes energy to help the body in responses to stimuli which cause stress. Physiological responses to stress are not only non-specific, but also physiological changes depending on environment, working conditions, social factors, stress experiences of individual. Many hormones of the endocrine glands involve in reactions, in which cortisol and catecholamines are the most important hormones and considered as the indicators of stress. Learning stress can be seen as a good study model of natural stress of human. When students are stressed, the most clearly physical consequences of the students are difficult to concentrate, easy to tense and inactive to work. However, stress is not always cause negative impacts on the students. The presence of stress sometimes is necessary, which greatly affect the motivation and interest in their learning. CHAPTER 2 STUDY PARTICIPANTS AND METHODS 1.4. Study participants Study participants are 600 students from 1st year to fifth year of full-time training course of general medical doctor in Thai Binh Medical University. We did not choose 6th year students because they needed time to prepare for graduation. Average age of the students has been shown in the table 2.1. Table 0.1.Tuổi trung bình của sinh viên các năm thuộc trường ĐH Y Thái Bình Student Age 1st year 2nd year 3rd year 4th year 5th year X ± SD 21,76±1,21 22,31±0,82 23,49±1,30 24,61±1,07 25,52±0,91 5 Selection criteria: Participants having BMI, pulse, blood pressure, hearing and vision in the normal range, not suffering from acute or chronic diseases, especially cardiovascular, neurological and mental diseases; not using any neuroleptics or stimulants for 3 days before and during the study time; being voluntary to take part in the study and willingness to follow all study procedures. 1.5. Study methods Analytical cross-sectional study. 1.5.1. Sample size and sample selection According to Phan Van Duyet, Le Nam Tra et al, samplie size for the studies of biological indicators is as follows: 222 22 StdN NtS n + = With d= ±5% , confidence level: 99%, t= 2,58. CV = 20%, N=300, n was calculated: n= 78. - We selected 120 students in each year (60 males and 60 females), hence, the total of the students for 5 year (from first year to fifth year) was 600 students to measure biological indicators. - In measuring ECG, mathematical statistical indicators of heart rate (MSIHR) and endocrine level, we selected d=10%, p=0,05, t=1,96 and calculated n=15. - We selected 30 students for each year (15 males and 15 females), hence, the total of the selected students from first year to fifth year was 30 x 5= 150 (students). Having similar study results, these students were selected for the purpose of evaluating some indicators before examination (control condition) and after examination. In the total of 150 students we randomly chose 30 students (15 males and 15 females) to evaluate the changes of blood hormone level in control condition and after the examination. 1.5.2. Study indicators, measuring tools and methods - Pulse rate in quiet status. Use stopwatch. - Blood pressure in quiet status (mmHg). China sphygmomanometer was used and standardized with mercury sphygmomanometer before measurement, using the Korotkov method. Calculate Kerdo index. 6 - Assessment of cardiovascular function and vegetative nervous system by using mathematical statistical indicator of heart rate (Baevski RM et al.) on Cadiofax 3 channels ECG machine of Japan. - Assessment of intellectual capacity is determined by the ongoing test of Raven frame types A, B, C, D, E. - Visual-motor reflex time and information processing speed is measured on computer using software of testing physiological psychology written by Ngo Tien Dung, Do Cong Huynh et al. - Attention ability was assessed by the method of "Arranging the jumbled digits". - Logical thinking ability was assessed by method of "Finding the digit patterns". - Short-term memory was assessed by the method of "Look and remember digits" - Emotional stress was evaluated using Spielberger test. - EEG was recorded by Neurofax 9001 machine of NIHON KOHDEN, Japan. - Measuring serum cortisol levels on the Immulite 2000 machine of Siemens using immunoassay method, in the Department of Biochemistry, National Institute of Haematology and Blood Transfusion. - Measuring blood catecholamin levels using Smaznov method, in the Department of Biochemistry, Thai Binh Medical University. 1.5.3. Study procedures Step 1. Study location, training to unify process and data collection techniques. Step 2. Measuring selected indicators in control condition. - 600 students were measured the selected indicators such as: pulse, blood pressure, ECG, visual – motor reflex time, guiding for memory, attention, thinking, Spielberger and Raven test. Indicators in control condition were measured at the time of student learning and living in normal life, far from the exam at least 1 month. Every 30 students were measured each time. - 150 students were selected in the total 600 students, (30 students for each year unit). Data of ECG and 100 RR intervals of EEG were collected for the first time (10 students/time of recording ECG and EEG). In addition, blood of 30 students was taken to measure hormone for the first time. Step 3. Measuring selected indicators of 150 students after the examination. These indicators were measured right after the exam. We chose the examination with 60 minutes length (3-4 credits) and 4 students per each class 7 of examination. Each morning 3 classes had examinations; therefore, data of only 12 students were collected. Time of measuring indicators was shown in the following diagram (Figure 2.1): Figure 2.1. Study diagram of the students after examination Pulse, blood presssure were recorded at 4 working stations; visual-motor reflex time were evaluated on 4 computers; 100 RR intervals of EEG were recorded on 2 machines; blood sample for cortisol and catecholamin were also taken at 4 working stations. Time of finishing all above indicators in 12 minutes (right after the exam), later, the students took attention, memory, thingking and emotional tests. * ECG were recorded after finishing another examination of 60 minutes length. We chose students who finished the examination after 45, 50, 55, 60 minutes. Time of ECG is 5 minutes after students out of examination room. * In order to avoid confounding factors, we measured indicators in control condition at the weekend, in the quiet room with fresh air Examination room was professionally designed, effects of outside factors were eliminated, air conditioned. When indicators were measured after the exam, facilities were arranged next to examination room. Room for measuring indicators was quiet and air-conditioned. Data processing: Data were processed using biostatistical methods. CHAPTER 3 STUDY RESULTS 1.6. Some cardiovascular indicators of Thai Binh medical University students Results of cardiovascular indicators have been shown in table 3.1, 3.2 and figure 3.1. Table 3.1. Some cardiovascular indicators of the students ( X ± SD) Sex Indicators Males n=300 Females n=300 p Pulse rate (beats/minute) 79.85±9.02 79.81±9.02 >0.05 Systolic blood pressure (mmHg) 116.03±20.14 107.60±11.86 <0.05 2 ’ Examination Pulse, Blood pressure Visual-motor reflex time EEG Blood sample 60 ’ 3 ’ 5 ’ 6 ’ 11 ’ 1 ’ 12 ’ 2 ’ 8 [...]... cardiovascular functional strain among third-year students of Thaibinh Medical University”, Journal of Physiology Vietnam, 12(2), pp.1 5-2 1 2 Nguyen Thi Hien, Vuong Thi Hoa (2008) “Study on state-anxiety trait and personality types among third-year students of Thaibinh Medical University”, Journal of Practical Medicine, 629,pp.34 3-3 47 3 Nguyen Thi Hien, Vuong Thi Hoa, Tran Dang Dong (2012) “The effect... conclusion on this issue 1.11.3 Thinking, attention and memory ability of the students The results of our study showed that the memory, attention and thinking ability of female and male students were similar (p> 0.05), and mostly attaining good and excellent levels In which, attention ability of the fourth year students was significantly higher than that of the others (p0.05 2nd (2) n=120 10.83±2.73 11.38±3.17 >0.05 3rd (3) n=120 10.98±3.15 11.25±2.87 >0.05 4th (4) n=120 10.55±2.89 11.48±2.55 >0.05 5th (5) n=120 11.77±2.89 12.38±7.15 >0.05 Total (n=600) 11.06±2.84 11.49±4.10 >0.05 (p ( 1-2 ), p( 1-3 ),p( 1-4 ),p( 1-5 ), p( 2-3 ), p( 2-4 ), p( 2-5 ), p( 3-4 ),p( 3-5 )... speed in our study is higher in comparison with that of Nguyen Thi Ngoc Thanh’s study This is probably due to the difference in age and environment At the age of 20 the coordination of activities of nervous-muscle reached the level 19 of completeness, the speed of synaptic neurotransmission is faster, thus shortening VRMT in comparison with that of the younger 1.11.2 Intellectual capacity according to... remarkably increased (p . Vietnam Military Medical University at 8.30 am. - April 9th 2013. THE DISSERTATION AVAILABLE AT: - National Library of Vietnam - Library – Vietnam Military Medical University - Library – Thai Binh. physiological psychology written by Ngo Tien Dung, Do Cong Huynh et al. - Attention ability was assessed by the method of "Arranging the jumbled digits". - Logical thinking ability. because they needed time to prepare for graduation. Average age of the students has been shown in the table 2.1. Table 0.1.Tuổi trung bình của sinh viên các năm thuộc trường ĐH Y Thái Bình Student Age 1st