Clinical and Therapeutic Evaluation of Hypertensives According to the Practice of Ambulatory Blood Pressure Measurement (ABPM) at the Bel Air International Clinic in Conakry from January 1, 2019 to November 30, 2022

Introduction: Ambulatory Blood Pressure Measurement (ABPM) is a non- invasive examination recommended for subjects at high cardiovascular risk, and those requiring a nocturnal drop in BP such as elderly and obese subjects, those with secondary hypertension or resistant, diabetics, subjects with metabolic syndrome or sleep apnea syndrome. The objective of this study was to evaluate the contribution of ABPM in the diagnosis and evaluation of the level of control of hypertension under treatment at the Bel Air international clinic. Materials and Methods: This is a retrospective, cross-sectional and descriptive study, carried out at the Bel Air International Clinic in Conakry (Guinea) between January 2019 and November 30, 2022. It included a consecutive series of 180 consenting patients recruited through an ambulatory measurement of 24-hour blood pressure from a FUGADA brand device. Results: We collected 180 patients, with a male predominance (sex-ratio M/F = 2.46). The mean age of the patients was 48.48 ± 14.23 years. The most represented age group was that of 32 to 42 years with 50 cases (27.8%) followed by that of 43 to 52 years with 42 cases or 23.3%. The indication was for diagnostic purposes in 106 cases 58.9%, the therapeutic evaluation in 58 patients (32.2%). The examination was prescribed by a cardiologist in 98 cases (54.4%), a general practitioner in 71 cases (39.4%), a neurologist in 11 cases (6.1%). In the therapeutic evaluation, high blood pressure was controlled in 24 patients (13.3%) and uncontrolled in 34 cases (18.9%). In the diagnostic indication, high blood pressure was confirmed in 79 cases (43.9%) with a statistically significant link (Chi2 = 4.57 and p-value = 0.032). The nycthemeral mean was 187.27 ± 26.22 mmHg for systolic blood pressure (SBP) and 110.37 ± 19.06 mmHg for diastolic blood pressure (DBP), during the day, 151.64 ± 21.45 mmHg for SBP and 71.59 ± 8.67 mmHg for diastolic blood pressure. During the study 65 patients (36.1%) were identified as dippers and 115 patients (63.9%) were no-dipping. The antihypertensive protocol used was monotherapy in 68 cases (37.8%), dual therapy in 46 cases (25.6%), triple therapy in 17 cases (9.4%). However 39 patients or 21.7% were not taking any antihypertensive. Conclusion: This preliminary study, despite the modest sample size, showed the importance of ABPM as a tool for diagnosis, monitoring of hypertensive patients and therapeutic adaptation. A large-scale national study would be necessary for the rational use of ambulatory blood pressure measurement in our context in order to improve the management of hypertensive patients.

Numerical analysis of stress distribution in the upper arm tissues under an inflatable cuff：Implications for noninvasive blood pressure measurement

An inflatable cuff wrapped around the upper arm is widely used in noninvasive blood pressure measurement.However, the mechanical interaction between cuff and arm tissues, a factor that potentially affects the accuracy of noninvasive blood pressure measurement, remains rarely addressed. In the present study, finite element（FE） models were constructed to quantify intra-arm stresses generated by cuff compression, aiming to provide some theoretical evidence for identifying factors of importance for blood pressure measurement or explaining clinical observations. Obtained results showed that the simulated tissue stresses were highly sensitive to the distribution of cuff pressure on the arm surface and the contact condition between muscle and bone. In contrast, the magnitude of cuff pressure and small variations in elastic properties of arm soft tissues had little influence on the efficiency of pressure transmission in arm tissues. In particular, it was found that a thickened subcutaneous fat layer in obese subjects significantly reduced the effective pressure transmitted to the brachial artery, which may explain why blood pressure overestimation occurs more frequently in obese subjects in noninvasive blood pressure measurement.

A Deep Learning-Based Continuous Blood Pressure Measurement by Dual Photoplethysmography Signals

This study proposed a measurement platform for continuous blood pressure estimation based on dual photoplethysmography(PPG)sensors and a deep learning(DL)that can be used for continuous and rapid measurement of blood pressure and analysis of cardiovascular-related indicators.The proposed platform measured the signal changes in PPG and converted them into physiological indicators,such as pulse transit time(PTT),pulse wave velocity(PWV),perfusion index(PI)and heart rate(HR);these indicators were then fed into the DL to calculate blood pressure.The hardware of the experiment comprised 2 PPG components(i.e.,Raspberry Pi 3 Model B and analog-todigital converter[MCP3008]),which were connected using a serial peripheral interface.The DL algorithm converted the stable dual PPG signals acquired from the strictly standardized experimental process into various physiological indicators as input parameters and finally obtained the systolic blood pressure(SBP),diastolic blood pressure(DBP)and mean arterial pressure(MAP).To increase the robustness of the DL model,this study input data of 100 Asian participants into the training database,including those with and without cardiovascular disease,each with a proportion of approximately 50%.The experimental results revealed that the mean absolute error and standard deviation of SBP was 0.17±0.46 mmHg.The mean absolute error and standard deviation of DBP was 0.27±0.52 mmHg.The mean absolute error and standard deviation of MAP was 0.16±0.40 mmHg.

Non-Contact Blood Pressure Measurement Based on IPPG

Blood pressure is an important physiological parameter to reflect human vital signs.In order to achieve the non-contact dynamic blood pressure acquisition based on ordinary optical camera,a theoretical understanding of the functional relationship between blood pressure and pulse wave signal conduction time.And through imaging photoelectric plethysmography(IPPG),pulse wave signal conduction time of forehead and hand was obtained with ordinary optical camera.First,the pulse wave conduction time was obtained by recording the video with an ordinary optical camera.Second,real-time blood pressure values were collected.Finally,based on the relationship between blood pressure and pulse wave conduction time,a non-contact blood pressure measurement prediction model was obtained through neural network fitting.So that non-contact blood pressure measurement with optical camera could be completed.The method in this paper has several advantages,such as low requirements on measuring equipment,low cost,and simple operation.It can let people get rid of the discomfort caused by measuring equipment such as cuff and can measure blood pressure at any time.The predicted blood pressure results were compared with an Omron wrist electronic sphygmomanometer.The calculated error of systolic blood pressure is-9.28%~3.16%,and the error of diastolic blood pressure is-9.84~4.35%.

Real-time human blood pressure measurement based on laser self-mixing interferometry with extreme learning machine

In this paper, we present a method based on self-mixing interferometry combing extreme learning machine for real-time human blood pressure measurement. A signal processing method based on wavelet transform is applied to extract reversion point in the self-mixing interference signal, thus the pulse wave profile is successfully reconstructed. Considering the blood pressure values are intrinsically related to characteristic parameters of the pulse wave, 80 samples from the MIMIC-II database are used to train the extreme learning machine blood pressure model. In the experiment, 15 measured samples of pulse wave signal are used as the prediction sets. The results show that the errors of systolic and diastolic blood pressure are both within 5 mm Hg compared with that by the Coriolis method.

Investigation on the relationship between overpressure and sub-harmonic response from encapsulated microbubbles

Sub-harmonic component generated from microbubbles is proven to be potentially used in noninvasive blood pressure measurement. Both theoretical and experimental studies are performed in the present work to investigate the dependence of the sub-harmonic generation on the overpressure with different excitation pressure amplitudes and pulse lengths. With 4-MHz ultrasound excitation at an applied acoustic pressure amplitude of 0.24 MPa, the measured sub-harmonic amplitude exhibits a decreasing change as overpressure increases; while non-monotonic change is observed for the applied acoustic pressures of 0.36 MPa and 0.48 MPa, and the peak position in the curve of the sub-harmonic response versus the overpres- sure shifts toward higher overpressure as the excitation pressure amplitude increases. Furthermore, the exciting pulse with long duration could lead to a better sensitivity of the sub-harmonic response to overpressure. The measured results are ex- plained by the numerical simulations based on the Marmottant model. The numerical simulations qualitatively accord with the measured results. This work might provide a preliminary proof for the optimization of the noninvasive blood pressure measurement through using sub-harmonic generation from microbubbles.