Analysis of influencing factors of sleep spindles / 临床神经病学杂志

Objective Sleep spindles play an important role in promoting cognition.This paper discusses the influencing factors of sleep spindles and provides objective evidence for clinical intervention and regulation of spindles to improve sleep and cognition.Methods Fifty patients with poor sleep quality were monitored overnight by sleep monitoring system,and physiological parameters of sleep structure,electroencephalography power spectrum,cardiovascular and respiratory function were obtained.The correlations between the parameters,age,sex and the spindle index and characteristics(frequency,duration and amplitude)of non rapid-eye-movement sleep(NREM)Ⅱphase were calculated.In Poincare diagram,SD1 represents the positive index of parasympathetic nerve activity,and SD2 represents the negative index of sympathetic nerve activity.Pulse transit time(PTT)decline index represents vascular sympathetic stability.Results SD1(β =-0.512,P＜0.05)and PTT decline index(β =-0.271,P＜0.05)were negatively correlated with spindle index respectively,while SD2 was positively correlated with spindle index(β =0.474,P＜0.05).The sleep change index,NREMⅠ phase proportion and cortical EEG microarousal index were negatively correlated with spindle index(r =-0.316,r =-0.359,r =-0.326;all P＜0.05).Age was negatively correlated with spindle index(β =-0.422,P＜0.05).δ power of deep sleep was negatively correlated with Spindle wave amplitude(β = 0.65,P＜0.001).No correlation was found between sex and sleep spindles.Conclusions The production of sleep spindles depends on good sleep and stable autonomic nerves.It is related to cognition and reflects the strength of synaptic connections,which provides evidence for clinical intervention and regulation of sleep spindles,and also provides a new physiological indicator for evaluating cognitive and brain function.

Pulse arrival time: Measurement and clinical applications

Pulse arrival time is the time elapsed between the R-wave of electrocardiogram and systolic peak in peripheral pulse obtained by any of the plethysmographic methods. Similarly, differential pulse arrival time, also known as pulse transit time, is the time elapsed between systolic peaks of proximal and distal peripheral pulse recordings in an extremity. Distance between the proximal and distal site in the extremity (in meters) divided by differential pulse arrival time (in seconds) gives arterial pulse wave velocity in the limb segment. Differential pulse arrival time has been used to discriminate between an aortic or arterial block from generalized atherosclerosis in aortic and arterial occlusive diseases for nearly four decades. All along there have been efforts to monitor beat-to-beat blood pressure with the help of these time intervals and other pulse parameters. Encouraging correlation has been observed with that obtained by Finapres. Recently pulse arrival time has been explored for the prompt detection of sudden hypertensive episodes during laryngeal microsurgery, for detection of mental stress, monitoring of baroreflex sensitivity, and real-time monitoring of blood pressure. This paper briefly describes the measurement technique of pulse arrival time and an overview of its clinical applications.

To Compare the Cardiovascular Reactivity to Mobile Games Induced Stress In Medical Students

Background: Students usually prefer to play games on theirmobile phones to avoid stress which is a major cause of CVDnowadays. CVR to stress can be assessed throughcardiovascular parameters such as blood pressure, heart rateand pulse transit time. The present study was conducted tocompare the Cardiovascular Reactivity (Heart rate, bloodpressure, pulse transit time) before, during and after playingmobile games and to compare cardiovascular parameters onthe 1st day and last day of study.Materials and Methods: This cross-sectional study wasconducted among 100 MBBS students in the age group of 19to 22 years at KD Medical College, Hospital and ResearchCentre, Mathura. Subjects over the period of 2 months wereselected for the study. The subjects were asked to have a lightbreakfast. Then in the sitting position; cardiovascularparameters and anthropometric data of the subjects weretaken 10 minutes before the game. All the rules of(CRASHLAND) mobile game were explained to the subjectsbefore letting him/her to start the game. After taking theseparameters the subject were asked to play the mobile game for30 minutes. Then the game was withdrawal and within 10minutes of interval; all these parameters were taken again. Ifany discomfort was reported by the subject then he/she wasexcluded from this study. Data was analyzed using SPSSversion 20. Variation of Cardiovascular Reactivity before,during and after playing mobile games were accessed byRepeated Measure ANOVA. Comparison of cardiovascularparameters on the 1st day and last day of study of a subjectwas accessed by Paired “t” Test.Results: A positive correlation was found between the BMIand various CVR parameters such as heart rate, SBP, DBP,MAP, pulse transit time, pulse wave velocity during and afterplaying the game. Repeated measure ANOVA analysed thatthere was no significant increase in pulse wave velocity of thesubject before, during and after playing mobile game. One wayANOVA analysed that there was significant increase in SBPand DBP of the subject, suggesting increased stressassociated with playing mobile games.Conclusion: Our study concluded that a positive correlationwas found between the BMI and various CVR parameters suchas heart rate, SBP, DBP, MAP, pulse transit time, pulse wavevelocity during and after playing the game.

Pulse transit time technique for cuffl ess unobtrusive blood pressure measurement: from theory to algorithm

Cuffless technique holds great promise to measure blood pressure (BP) in an unobtrusive way, improving diagnostics and monitoring of hypertension and its related cardiovascular diseases, and maximizing the independence and participation of individual. Pulse transit time (PTT) has been the most commonly employed techniques for cuffl ess BP estimation. Many studies have been conducted to explore its feasibility and validate its performance in the clinical settings. However, there is still issues and challenges ahead before its wide application. This review will investigate the understanding and development of the PTT technique in depth, with a focus on the physiological regulation of arterial BP, the relationship between PTT and BP, and the summaries of the PTT-based models for BP estimation.

A new approach for blood pressure estimation based on phonocardiogram

Continuous and non-invasive measurement of blood pressure (BP) is of great importance particularly for patients in critical state. To achieve continuous and cuffless BP monitoring, pulse transit time (PTT) has been reported as a potential parameter. Nevertheless, this approach remains very sensitive, cumbersome and disagreeable in ambulatory measurement. This paper proposes a new approach to estimate blood pressure through PCG signal by exploring the correlation between PTT and diastolic duration (S21). In this purpose, an artificial neural network was developed using as input data: (systolic duration, diastolic duration, heart rate, sex, height and weight). According to the NN decision, the mean blood pressure was measured and consequently the systolic and the diastolic pressures were estimated. The proposed method is evaluated on 37 subjects. The obtained results are satisfactory, where, the error in the estimation of the systolic and the diastolic pressures compared to the commercial blood pressure device was in the order of 6 .48 ± 4.48 mmHg and 3 .91 ± 2.58 mmHg, respectively, which are very close to the AAMI standard, 5 ± 8 mmHg. This shows the feasibility of estimating of blood pressure using PCG.

Evaluación de la Presencia de Disautonomía en Pacientes con Parkinson mediante el Análisis de Señales Cardiovasculares / Assessment of the Dysautonomia Presence in Parkinson disease through Cardiovascular Signal Analysis

Resumen: En este trabajo se evalúa y compara la respuesta del sistema nervioso autónomo (SNA) en pacientes con enfermedad de Parkinson (EP) y sujetos sanos para detectar la posible presencia de disautonomía. Las señales de electrocardiograma y fotopletismografía fueron adquiridas durante las maniobras: reposo, cambio de postura (Post-CP), respiración controlada (RC) e hiperventilación (Hip.). El análisis de las señales incluyó índices de la variabilidad de la frecuencia cardiaca (VFC) lineales y no lineales, índices de la señal de tiempo de tránsito de pulso y la sensibilidad del barorreflejo (índice α). Los pacientes con Parkinson mostraron una alteración en la modulación simpática principalmente durante Post-CP y una deficiencia en la respuesta cardiovagal en RC. La entropía aproximada disminuyó significativamente en sujetos sanos respecto a pacientes con EP durante RC. El índice α fue menor en pacientes con EP con respecto a sujetos sanos durante todo el protocolo, lo cual sugiere una alteración en el control del barorreflejo en EP. Sin embargo, es necesario aumentar el número de sujetos con la finalidad de determinar grados de disautonomía. El protocolo diseñado para evaluar la presencia de disautonomía en mexicanos con EP a través de señales no invasivas aportó información sobre el comportamiento del SNA.

Abstract: The goal of this work is to assess and to compare the autonomic nervous system (SNA) response in Parkinson's disease (EP) patients and healthy subjects in order to evaluate the possible dysautonomia presence. Electrocardiogram and photoplethysmography signals were acquired during the following maneuvers: rest, orthostatic change (Post-CP), controlled breathing (RC) and hyperventilation (Hip.). The signal processing was carried out by means of linear and no linear indices of heart rate variability (VFC), indices of pulse transit time (PTT) and baroreflex sensitivity (α index). Parkinson disease patients showed an attenuated sympathetic modulation mainly during Post-CP and the cardiovagal response resulted blunted during RC. Approximate entropy was significantly decreased in healthy subjects with respect to EP subjects during RC. In addition, the index α resulted in lower values in EP patients with respect to healthy subjects during the complete protocol, this result suggests that the baroreflex control in EP patients is blunted. However, is necessary to increase the number of subjects with the objective of determining levels of dysautonomia. The protocol designed to evaluate the dysautonomia presence in mexicans with EP through non invasive signals provides information about the SNA behavior.

The factors affecting pulse transit time during anesthesia / 临床麻醉学杂志

Objective To investigate the factors affecting pulse transit time during anesthesia. Methods Sixty cases of gastrointestinal surgery under general anesthesia were investigated.The pulse transit time (PTT),BP and HR were measured at the time before and after intravenous anes-thesia induction,and at the time before and after the injection of vasoactive drugs,respectively. Results Compared to at the time before injection,HR,SBP and DBP increased significantly,and PTT decreased significantly (P <0.01 )at the time after injection of atropine and ephedrine.Com-pared to at the time before injection,HR and PTT increased significantly,while SBP and DBP de-creased significantly (P < 0.01 )at the time after injection of nicardipine.While HR and PTT de-creased significantly,and SBP,DBP increased significantly (P <0.01 )with the injection of pheny-lephrine.Obvious negative correlation between SBP and PTT was observed before and after induc-tion;meanwhile,only weak correlation between DBP and PTT was observed,and no obvious correla-tion between HR and PTT was detected.SBP and PTT were well negatively correlated with the injec-tion of atropine,ephedrine,nicardipine or phenylephrine.Conclusion All the PTT changes during anesthesia were found to be negatively correlated with the systolic blood pressure.

Changes in pulse transit time according to target controlled infusion of propofol versus sevoflurane inhalation induction

BACKGROUND: Pulse transit time (PTT), the time it takes a pulse wave to travel from one arterial site to another, is a noninvasive indicator of arterial stiffness. The main objective of our study was to compare two common anesthetic techniques using PTT in order to explore which technique would bring more vascular distention. METHODS: Sixty female patients, ages 18-65, classified by ASA 1 or 2 undergoing general anesthesia, were randomly allocated into two groups, S and P. Group S (n = 30) was inducted with 2 mg/kg of propofol and remifentanil 5.0 ng/ml. Group P (n = 30) was inducted with propofol 4.0 ug/ml and remifentanil 4.0 ng/ml using a target controlled infusion (TCI) pump. Group S was anesthetically maintained with sevoflurane at 1.0 MAC and 1.0 ng/ml remifentanil while group P was anesthetically maintained with propofol 3.0 ug/ml and remifentanil 1.0 ng/ml for 10 minutes. PTT values were obtained by measuring the distance between the electrocardiographic R wave, which approximates the opening of the aortic valve, to the radial artery. Three consecutive values of prePTT, postPTT, and corresponding vital signs were measured and recorded before and 10 minutes after anesthetic induction. RESULTS: PrePTT in group S and group P was 240.18 +/- 3.66 and 239.32 +/- 3.69 ms, respectively. Ten minutes after anesthetic induction, postPTT in group S increased to 284.16 +/- 4.37 ms while postPTT in group P increased to 278.7 +/- 4.53 ms (P > 0.05). However, despite the slope of group S (43.98 +/- 22.18) being greater than group P (39.38 +/- 18.39), the difference between the two groups was statistically insignificant (P = 0.2239). CONCLUSIONS: Changes in PTT values were statistically insignificant regarding arterial distension in patients anesthetized with target controlled infusion of propofol compared to those with balanced anesthesia with sevoflurane.

Measurement of respiratory pulse transit time variation as an intravascular volume index in simulated hemorrhage / 대한마취과학회지

BACKGROUND: We examined the usefulness of respiratory pulse transit time (PTT) variation as an intravascular volume index in young, healthy, spontaneous, paced breathing volunteers exposed to simulated central hypovolemia by lower body negative pressure (LBNP). METHODS: With paced breathing at 0.25 Hz, beat-to-beat finger blood pressure (BP), heart rate (HR), cardiac output (CO), stroke volume (SV), total peripheral resistance (TPR), and PTT were measured non-invasively in 18 healthy volunteers. Graded central hypovolemia was generated using LBNP from 0 to -20, -30, -40, and -50 mmHg. Respiratory PTT variation (PTTV) was calculated as the difference of maximal and minimal values divided by their respective means. Respiratory-frequency PTT variability (PTTRF) using power spectral analysis was also estimated. RESULTS: During LBNP, SV, CO and PTTRF decreased, but PTT, PTTV and TPR increased significantly. PTTV did not correlate with SV changes (r = -0.08, P = 0.52), but PTTRF (r = 0.58, P < 0.01) and PTT (r = 0.43, P < 0.01) did during progressive hypovolemia. CONCLUSIONS: PTTRF is more applicable to the changes in intravascular volume than PTT and PTTV, suggesting spectral analysis of PTT might be used as a dynamic preload index in patients with spontaneous and paced breathing condition, which needs further studies.

Development of a Wearable Pulse Transit Time Monitoring Device / 대한의료정보학회지

OBJECTIVES: We have developed a non.intrusive continuous PTT monitoring system, using a wearable device and wireless communication technology. METHODS: Pulse transit time (PTT) is a non.invasive measurement that shows promise in the continuous monitoring of blood pressure (BP) and the assessment of arterial stiffness. It has potential applications in wearable health monitoring devices. Generally, PTT is measured from the electrocardiogram (ECG) Rwave to a characteristic point on the peripheral pulse by photoplethysmography. However, for home healthcare applications, a system needs to be wearable and wireless. ECG and PPG were sampled at 1200 Hz and transmitted to a personal computer (PC) using Bluetooth communications. Heart rate (HR) and PTT were calculated by the PC from the signals received and waveforms of ECG, PPG, PTT and HR were displayed. RESULTS: In this study, we implemented a system that could be adapted to the wrist and measured ECG and a Photoplethysmogram (PPG). CONCLUSIONS: The wearable continuous PTT monitoring system developed in this study could be useful in home cardiovascular healthcare.

The Changes of Differences of Pulse Transit Time between Toe and Finger in General and Epidural Anesthesia / 대한마취과학회지

BACKGROUND: Pulse wave velocity (PWV) and pulse transit time (PTT) are influenced by the arterial wall stiffness and compliance. Also, the PTT is dependent on blood pressure changes that can be accompanied by the anesthesia. The simply measured PTT has difficult to discriminate the arterial compliance changes from blood pressure changes. Therefore, we investigated that the differences of PTT between toe and finger as an independent parameter on blood pressure. METHODS: Eighteen patients scheduled for elective lower abdominal gynecologic surgery were studied. General anesthesia was achieved with sevoflurane and epidural block was done with 0.2% ropivacaine and fentanyl 100microgram via epidural catheter inserted into L1 - L2 epidural space. PTT was measured in a finger (PTTf) and a toe (PTTt) by the time difference between the ECG R wave and the pulse wave of PPG. Blood pressure and PTT was measured at three instances such as preinduction (Pre), 5 minutes after intubation (Int5) and 30 minutes after injection of epidural dose (Epi). The time delay of PTT between toe and finger (PTTt-f) was measured. RESULTS: PTTf and PTTt was prolonged at Int5 and Epi. But the PTTt-f was not different between the Int5 and Epi because of prolonged PTTf caused by the blood pressure decrement after the epidural block. CONCLUSIONS: PTTf, PTTt and PTTt-f can be a one of the convenient measurement of the arterial compliance but it was suggested that there need to be a parameter less dependent on the blood pressure changes.

Estimation of Continuous Blood Pressure with Amplitude of Photoplethysmogram and Pulse Transit Time of Finger and Toe / 대한마취과학회지

BACKGROUND: The amplitude (AMP) of Photoplethysmogram (PPG) is used as a marker of vasodilatation. The pulse transit time (PTT), which shows a good correlation with blood pressure (BP), is not strong enough to detect the changes in BP. This study examined the sensitivity of the combined effect of the finger and toe AMP, and the PTT of PPG as a marker of the changes in BP during general anesthesia. METHODS: Forty patients receiving maxillofacial surgery under general anesthesia were enrolled in this study. During surgery, the intra-arterial BP, ECG, finger and toe PPG signals were measured. Using the R-wave from the ECG, the AMP and PTT was derived from PPG data. The correlation between BP and PPG parameters (AMP and PTT) were compared. New parameters that show high correlation with the BP were found. Regression equations for calculating the BP using the PPG parameters were formulated. RESULTS: The new parameter, log (fingerAMP/toeAMP), showed the highest correlation in each patient (mean correlation coefficient in the systolic BP: -0.846, diastolic BP: -0.858). However, when the data from all 40 patients were combined, the correlation coefficient of the toe PTT was highest (systolic BP: -0.726, diastolic BP: -0.646). The regression equation showed the highest correlation between the actual BP and calculated BP when the toe PTT and log (fingerAMP/toeAMP) were included. CONCLUSIONS: The AMP of the toe and finger PPG can be used to estimate the invasive continuous blood pressure.

HypnoPTT in the diagnosis of the sleep respiratory disease in children / 中国耳鼻咽喉头颈外科

OBJECTIVE To explore a more effective method of detecting sleep respiratory events in children. METHODS Thirty-eight children were tested with HypnoPTT and 31 with polysomnography (control). The test parameters and operative methods were compared. RESULTS In addition to the parameters comm.on to both HypnoPTT and polysomnography, inspiratory flow limitation and spontaneous microarousal can be measured using HypnoPTT and fewer electrodes were needed. CONCLUSION HypnoPTT is a convenient method characterized by less sleep disturbance and credible results, rendering it is especially suitable for pediatric cases. Pulse transit time is a useful parameter for diagnosing the sleep respiratory disease.

Effects of Enflurane on Pulse Transit Time / 대한마취과학회지

BACKGROUND: In Anesthetic state, many hemodynamic parameters including blood pressure, heart rate and arterial compliance are changed. Moreover pulse transit time (PTT) is influenced by heart rate, blood pressure changes, and the compliance of the arteries. METHODS: In this study, we investigated PTT changes in patients under enflurane anesthesia. PTT of the finger was measured by photoplethysmography (PPG) and electrocardiography (ECG). PTT values were calculated as the time interval between the peak of the ECG R wave and the peak of the second derivatived of the PPG in the finger tip. RESULTS: ECG amplitude and heart rate increased reflecting hemodynamic chnages after enflurane anesthesia, and the PTT increased after enflurane anesthesia treatment by 16.68 ms (n = 24). Moreover, PTT was found to be inversely proportion to aging. CONCLUSIONS: The increase of PTT in the finger due to relaxation of the arterial wall muscle after enflurane anesthesia was used as an indicator of sympathetic block on muscle tone. This result suggests that PTT is strongly related with anesthetic state. And PTT may be one of useful surrogative methods for anesthetic monitoring, but PTT is unfortunately only qualitative.