Accelerated Pulse Wave Photo Plethysmography –

A Marker of Vascular Compliance and cardiac autonomic functions.

 

M.B.S. Sugunakar¹, Dr. K. N. Maruthy², Dr. Jaffer³, Dr. Srinivas⁴, Dr. Priscilla Johnson⁵*

¹M.Sc (Ph.D. Scholar), G.S.L. Medical College, Rajahmundry, A.P.

²Prof., Narayana Medical College.

³M.D, Associate Professor G. S. L. Medical College RJY.

⁴ Prof and HOD, GSLMC.

⁵M.D, DNB, Ph.D. Professor, Department of Physiology, Sri Ramachandra Medical College and RI,

 Porur, Chennai.

 

ABSTRACT:

The following study is conducted between three groups of subjects each group contains n=40 subjects. First the subjects were recruited to department of physiology for conducting study. Screening questionnaire was presented to the study subjects based on their responses according to the inclusion and exclusion criteria subjects were screened. The subjects who met the criteria’s for the study were recruited for the study and informed consent was obtained from the subjects after explaining the process of the study. The study questionnaire was given to the subject to collect the demographic, anthropometric data and socioeconomic status was evaluated by kuppuswami scale (1). The subjects were taken to the autonomic function testing lab in the department of physiology resting blood pressure was measured subject was connected to ECG apparatus to perform heart rate variability (HRV) analysis. The ECG data was acquired using audacity open source software. The data was analyzed using low pass filter at 40Hz and Accelerated pulse wave plethysmography was also obtained using APPG module with soundcard oscilloscope subsequent low pass filter 50Hz was applied and signal was analyzed angle was measured using image J software (2). Introduction: Accelerated photoplethysmography is a measurement tool which is used to evaluate "vascular retro gradation grade" and to detect "arteriosclerosis" by differentiating "volume capacity photoplethysmography" twice on fingertip (3) Aim: To evaluate the relationship between diastolic blood pressure and "arterial compliance" and "peripheral circulation status “using accelerated pulse wave plethysmography (APPG). Methodology: This study was conducted in healthy volunteers (n=40) and in hypertensive’s (n=120). Informed consent was obtained from the study participants and their blood pressure was recorded. Accelerated pulse wave plethysmography was obtained using APPG module with soundcard oscilloscope. Subsequent low pass filter 50Hz was applied and the signal was analyzed. The size of P1, P2, P3, the gradient of P1-P3 and the angle were measured and analyzed using image J software. Results: Rise in diastolic blood pressure leads to a shift in the angle between the P1 and P3 wave. Positive correlation was found between the diastolic blood pressure and the P1 P3 angular shift. (R= 0.2) and it was statistically significant (p <0 .05). Conclusion: This study indicates that rise in diastolic component of blood pressure is associated with more pronounced vascular changes which are detected as a shift in the angle of the APPG component. This non-invasive and cost-effective technique may pave way for early detection of vascular/cardiovascular disorders thereby preventing morbidity and mortality.

 

 

 

 

 

INTRODUCTION:

Background:

Globally, it has been estimated that hypertension accounts for 6% of deaths. In the United States, based on results of the National Health and Nutrition Examination Survey (4), 28.7% (age-adjusted prevalence) of U.S. adult individuals, have hypertension (5). Overall prevalence for hypertension in India is 29.8% (95% confidence interval: 26.7–33.0). The pathophysiological features such as elastin loss and fragmentation, increased collagen synthesis, endothelial dysfunction, and higher levels of inflammatory cytokines lead to stiffening of the wall of the aorta resulting in systolic hypertension (6).

 

In 1930, photoplethysmography technique was first explored to measure blood flow based on the optical properties of the vascular bed (7). Photoplethysmography is a wave form signal that indicates pulsation of chest wall and great arteries followed by heart beat, that is, the blood pressure and vascular diameter change with cardiac cycle, and these arterial pulsatile alterations propagating to peripheral vascular system mean "photoplethysmography ". (3) However, original photoplethysmography has a limitation to help us analyze the course of wave changes just because the original wave is flat. Therefore, the differentiated value of velocity pulse wave is applied in clinical fields to more specifically realize the process of pulse energy. This ultimate value is called "accelerated photoplethysmography” (APPG). Accelerated photoplethysmography is a measurement tool which is used to evaluate "vascular retro gradation grade" and to detect "arteriosclerosis" by differentiating "volume capacity photoplethysmography" twice on fingertip (8). Early detection of arteriosclerosis and the quantitative analysis of vascular retro gradation is made possible by using APPG which estimates "arterial compliance" and "peripheral circulation status (9)". The peripheral pulse waveform analysis using APPG can be used as a surrogate tool for assessing the aortic stiffness paving way to predict future undue cardiovascular disease events. Moreover, specific medication and management by patient' predisposition could be available, and medical approaches of this kind are to prompt the blood circulation and to rehabilitate the arterial compliance. Hence, this study was undertaken to estimate "arterial compliance" and "peripheral circulation status" using APPG in hypertensive’s and compare with healthy volunteers (10).

 

METHODOLOGY:

This study was conducted in healthy volunteers (n=40) and in hypertensive’s (n= 40 in three different grades of hypertensive’s) based on the following selection criteria: age group of ≥ 30 years and ≤ 60 years; male and female participants and hypertensive’s under medical management not less than five years. Participants were excluded if they were pregnant or had history of chronic endocrine disorders. Informed consent was obtained from the study participants. General information was collected using a questionnaire, anthropometric measurements were measured and their blood pressure was recorded. Accelerated pulse wave plethysmography was obtained using APPG module with soundcard oscilloscope. Subsequent low pass filter 50Hz was applied and the signal was analyzed. The size of P1, P2, P3, the gradient of P1-P3 and the angle were measured and analyzed using image J software.

 

RESULTS:

The descriptive characteristics of the study group are given in Table 1.

 

The mean SBP of male healthy volunteers was 116 ±3.5mm Hg and that of females was 121.5±18.0mm Hg. The mean SBP of Grade I hypertensive males was 126 ±16.9 and that of females was 131.7±9.4mm Hg. The SBP of Grade II hypertensive males were 137.4±17.7 and that of females was 142±19.9. The mean SBP of Grade III hypertensive males were 177.6±10.6mm Hg and that of females was 170±19.3mm Hg. Though the mean SBP was higher in females when compared with males, the MAP was higher in males when compared with females. DBP was highest in Grade III and it was higher in Grade II and Grade III male hypertensive’s when compared with females. The mean P1 P3 angle as recorded in APPG was lower in Grade II and Grade III hypertensive’s when compared with the healthy controls. P=0.004 Table 2

 

Table 1: Descriptive characteristics of the study group

Variable		Healthy control	Grade I	Grade II	Grade III
		Frequency (%)	Frequency (%)	Frequency (%)	Frequency (%)
Age	30 - 45	10.52632	14.61988	8.187135	9.356725
	46 - 60	12.8655	9.356725	14.61988	9.94152
Gender	Male	14.61988	12.8655	12.2807	11.11111
	Female	9.94152	13.45029	16.95906	10.52632
Literacy status	Yes	12.2807	11.11111	15.78947	11.11111
	No	12.2807	14.03509	13.45029	10.52632
Socioeconomic status	LIG	11.69591	13.45029	18.71345	8.187135
	MIG	16.95906	15.20468	12.8655	11.11111
Smoking status	Yes	5.847953	12.8655	5.847953	8.77193
	No	18.71345	12.2807	23.39181	12.2807
Alcoholic status	Yes	19.88304	15.78947	23.39181	12.8655
	No	2.923977	9.356725	5.847953	8.187135

Table 2: Comparison of Blood pressure and P1 P3 angle in APPG in hypertensive’s and controls

GENDER	GRADE	SBP ± 23.7	DBP ± 11.1	MAP ± 15.2	APPG ± 6.7
females	1	131.7	86.1	92.6	44.4
males	1	126.0	83.8	93.9	45.5
females	2	142.0	87.6	102.6	45.8
males	2	137.4	89.0	103.0	47.6
females	3	170.0	96.7	121.1	56.8
males	3	177.6	105.0	128.8	52.3
females	CNTRL	121.5	76.7	91.5	48.1
males	CNTRL	116.0	74.8	88.5	47.8

 

Fig 1: shows the relationship between DBP and the P1 P3 angle in APPG in hypertensives and controls.

 

Fig. 2 shows the correlation between DBP and P1 P3 angle in AP\PG. As DBP increases there is a fall in the angle P1 P3 angle in APPG which is statistically significant with a negative correlation coefficient R= 0.2 P-Value is .008723. The result was significant at p < 0 .05.

 

Fig. 2: Correlation between DBP and APPG

 

DISCUSSION:

From the above it was evident that the relationship between the diastolic blood pressure and APPG are negatively correlated with an R value of -0.47. These results shows that the PPG which was already a indicator of the vascular health (11) There are certain research evidences that the flow profile of the vascular bed changes according to the ongoing atherosclerotic changes and pronounces inflammatory effects (12) the cardiovascular parameters oscillations were found to have relation with autonomic nervous system and found to have many diagnostic importance in the evaluation of the cardiovascular diseases (13) there are many evidences showing the PPG as a derivative and showing the diagnostic importance of the tool which was used as a purpose of evaluating the cardiovascular diseases. PPG was mainly used as a non invasive technique to determine the vascular condition (3). PPG is a key clinical tool to determine the important parameters like HRV, R-R interval, SDNN, LFnu, and important autonomic parameters. In this study we have tried to establish a relationship between a non invasive parameters like blood pressure and PPG to evaluated the vascular health even further simplifying the diagnostic tool like one finger PPG (11). By doing this study we can assume a relationship between two important parameters like PPG and DBP there by establishing a confidence in a very simple non invasive diagnostic tool like PPG for further diagnostic purpose for evaluating the CVD (7).

 

CONCLUSION:

The study indicated that more pronounced vascular changes were associated with raise in diastolic component of blood pressure. Rise in diastolic blood pressure leads to positive shift in the angle R=0.2 p-Value is .008723 between the P1 and P3 wave indicated that dilation capacity is inversely related to vascular tone. Many endocrine and physiological factors are related to change in vascular tone. This study indicates that rise in diastolic component of blood pressure is associated with more pronounced vascular changes which is detected as a shift in the angle of the APPG component. This non-invasive and cost-effective technique may pave way for early detection of vascular/cardiovascular disorders thereby preventing morbidity and mortality.

 

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Received on 10.02.2020            Modified on 01.04.2020

Accepted on 06.05.2020         © RJPT All right reserved