Photoplethysmographic Wave Research Articles

Effects of trigeminal neurostimulation on heart rate variability: comparing cutaneous (Tragus) and tongue (Antero-Dorsal mucosa) stimulation

BackgroundTrigeminal neurostimulation of the dorsal anterior mucosal surface of the tongue has been proposed to treat a variety of pathologies and to promote neuro-muscular coordination and rehabilitation. Dental ULFTENS can also be considered a form of trigeminal neurostimulation applied to the skin surface bilaterally at the level of the tragus. It has been used for years in dentistry for practical and diagnostic purposes. Previous work has combined the two stimulation techniques showing an efficacy in improving HRV in healthy young women of dental ULFTENS applied to the mucosal surface of the tongue. This work sought to assess whether there is a difference in HRV in relation to the site of application of dental ULFTENS (tragus vs. tongue). If effective in reducing the activity of arousal circuits, this tongue-level stimulation technique could have new clinical applications.Material and methodA new intraoral device allowed electrical stimulation of the dorsal anterior mucosa of the tongue in 80 healthy young women divided into two groups: TUD group (ULFTENS stimulation on the mucosa of the tongue) and Tragus group (stimulation with ULFTENS bilaterally in the area of the tragus). The effects on HRV were monitored by photoplethysmographic wave (PPG). The HRV parameters studied were RMSSD, HF, LF, LF/HF.ResultsOnly the TUD group showed a significant change in selected HRV parameters that was maintained even in the epoch after the end of electrical stimulation. This effect can be considered as a vagal activation and an increased of HRV parameter. The Tragus group did not show significant change in the direction of increased HRV but showed an opposite trend. There were no undesirable or annoying effects of stimulation.ConclusionStimulation of the dorsal anterior (trigeminal) mucosal surface of the tongue with ULFTENS applied with an intraoral device was shown to be able to increase HRV while the same stimulation on tragus area, according to traditional dental ULFTENS procedure, did not show the same effects.Clinical implicationsThis stimulation technique could be an aid in the diagnosis and treatment of disorders characterized by autonomic disequilibrium such as, in the dental field, TMDs.Trial registration“Effects of Trigeminal Neurostimulation on Heart Rate Variability: Comparing Tragus and Tongue Stimulation”. ID number: NCT06549205. Date of first registration: August 1st 2024. https://clinicaltrials.gov/study/NCT06549205?id=%09NCT06549205&rank=1.

Trigeminal electrical stimulation with ULFTENS of the dorsal anterior mucosal surface of the tongue: Effects on Heart Rate Variability (HRV).

Trigeminal electrical stimulation of the dorsal anterior mucosal surface of the tongue has demonstrated its efficacy in a variety of neurological disorders in which anatomical or functional alterations are present. The pathogenesis of such disorders is often linked to altered arousal circuits, and the benefits of tongue stimulation are attributed to the rebalancing of this system. Dental ULFTENS shows efficacy in acting on the muscular, autonomic system and control of the descending pathways that modulate pain. It is administered at the skin level in the area anterior to the tragus and not on the mucosal surface of the tongue. The use of this stimulation technique at the tongue level could have new applications and clinical results if it were able to reduce the activity of arousal circuits. A new intraoral device allowed electrical stimulation of the dorsal anterior mucosa of the tongue in 32 healthy young women. The effects on HRV were monitored by photoplethysmographic wave (PPG) and compared with a control group. The HRV parameters studied were RMSSD, HF, LF, LF/HF, REC, DET. The group of stimulated subjects showed a significant change in some of the HRV parameters that was maintained even in the epoch after the end of electrical stimulation. This effect can be considered as a vagal activation and a change of HRV trend. The control group of unstimulated subjects showed an opposite trend. There were no undesirable or annoying effects of stimulation. Stimulation of the dorsal anterior (trigeminal) mucosal surface of the tongue with ULFTENS applied with an intraoral device was shown to be able to increase HRV.

Assessment of the PPG up-stroke time to predict peripheral lower limb arterial occlusive disease (PAOD): Application to the pOpmetre ®

Screening for peripheral lower limb arterial occlusive disease (PAOD) is a major challenge for the prevention, management and treatment of patients with arteriosclerosis. The Ankle Brachial Index (ABI) is the reference method, it requires expertise and time which are limiting factors for systematic screening. The analysis of a photoplethysmographic (PPG) wave form in the lower limb can be an interesting alternative. In a retrospective pilot study we analyzed the possibility of detecting PAOD by measuring the up-stroke time wave form (UTP) at the toe by PPG method. The ABI (minimum of 2 leg arteries) and the UTP (pOpmeter® - Axelife - France) were collected in 54 patients during a vascular assessment and presenting different stages of PAOD. Of the 108 lower limbs registered, 25 were excluded for technical difficulties (very severe PAOD, mediacalcosis, toe amputation). 83 lower limbs were analyzed. Mean age was 69 ± 12; 75% men, 28% diabetics, 47% hypertensive. 17% without PAOD (stage 0); 44% stage 1; 23% stage 2; and 2% Stage 3. The 200 milliseconds UTP threshold identifies PAOD from stage 1 with: sensitivity 77%, specificity 94%, a positive predictive value 96% and negative predictive value 68% (Yule Q = 0.96). UTP makes it possible to identify an PAOD in 100% of patients with mediacalcosis (ABPI > 1.4, n = 3, diabetic = 2). The UTP measured by PPG at the toe is a simple and rapid method (< 2 min) detects the PAOD stages 1 to 3 with 94% specificity, 77% sensitivity that must be improved by using other thresholds to optimize the test. These results have to be confirmed with a prospective study.

Blood Pressure Continuous Measurement through a Wearable Device: Development and Validation of a Cuffless Method.

The present study aims to develop and validate a cuffless method for blood pressure continuous measurement through a wearable device. The goal is achieved according to the time-delay method, with the guiding principle of the time relation it takes for a blood volume to travel from the heart to a peripheral site. Inversely proportional to the blood pressure, this time relation is obtained as the time occurring between the R peak of the electrocardiographic signal and a marker point on the photoplethysmographic wave. Such physiological signals are recorded by using L.I.F.E. Italia’s wearable device, made of a sensorized shirt and wristband. A linear regression model is implemented to estimate the corresponding blood pressure variations from the obtained time-delay and other features of the photoplethysmographic wave. Then, according to the international standards, the model performance is assessed, comparing the estimates with the measurements provided by a certified digital sphygmomanometer. According to the standards, the results obtained during this study are notable, with 85% of the errors lower than 10 mmHg and a mean absolute error lower than 7 mmHg. In conclusion, this study suggests a time-delay method for continuous blood pressure estimates with good performance, compared with a reference device based on the oscillometric technique.

Pulse decomposition analysis in camera-based photoplethysmography.

Imaging photoplethysmography (iPPG) is an interesting alternative to laser speckle contrast imaging for the analysis of spatio-temporal patterns in the cutaneous microcirculation. Recent years have witnessed the development of sophisticated techniques for the non-invasive extraction of vascular-related features. These techniques, referred to as pulse decomposition algorithms (PDA), most often involve the analysis of photoplethysmographic waves. This study validated the use of a multi-Gaussian (PDA) for the automatic mapping of iPPG pulse waveforms acquired with a standard camera. We show that iPPG-based PDA can reveal differences in skin perfusion in response to cold stimuli. The study thus proves the potential for morphological analyses of the iPPG pulse waveform.

Endothelial Dysfunction Evaluated using Photoplethysmography in Patients with Type 2 Diabetes

Background: Diabetes mellitus (DM) reduces life expectancy by a third, principally because of cardiovascular disease and endothelial dysfunction is considered to be one of the first manifestations of vascular disease. Photoplethysmography is a non-invasive technique to evaluate endothelial dysfunction based on the emission of infra-red light on the skin. Objective: To evaluate endothelial function by photoplethysmography in patients with type 2 DM without evidence of vascular disease. Methods: A cross-sectional study of patients with and without DM was undertaken. Endothelial function was evaluated using photoplethysmographic waves taking into consideration the shape of the curve and time of maximum amplitude/total time of the curve (TMA/TT) before and after ischemia induced by arterial obstruction. Results: In 174 subjects included, a greater basal TMA/TT index was found in diabetics, even after adjusting for age, hypertension, dyslipidemia and hypothyroidism. The percent change in amplitude post-ischemia compared to basal value was diminished in diabetics (p=0.030). Persons with diabetes, with and with not endothelial dysfunction, had comparable HbA1c concentrations; but diabetics with endothelial dysfunction, had lower serum concentration of HDL-C. (p=0.05) Conclusions: More endothelial dysfunction was found in patients with diabetes. While the control of diabetes did not influence endothelial dysfunction, it was associated with HDL cholesterol.

Comparative study of methodologies for pulse wave velocity estimation

Arterial stiffness, estimated by pulse wave velocity (PWV), is an independent predictor of cardiovascular mortality and morbidity. However, the clinical applicability of these measurements and the elaboration of reference PWV values are difficult due to differences between the various devices used. In a population of 50 subjects aged 20-84 years, we compared PWV measurements with three frequently used devices: the Complior and the PulsePen, both of which determine aortic PWV as the delay between carotid and femoral pressure wave and the PulseTrace, which estimates the Stiffness Index (SI) by analyzing photoplethysmographic waves acquired on the fingertip. PWV was measured twice by each device. Coefficient of variation of PWV was 12.3, 12.4 and 14.5% for PulsePen, Complior and PulseTrace, respectively. These measurements were compared with the reference method, that is, a simultaneous acquisition of pressure waves using two tonometers. High correlation coefficients with the reference method were observed for PulsePen (r = 0.99) and Complior (r = 0.83), whereas for PulseTrace correlation with the reference method was much lower (r = 0.55). Upon Bland-Altman analysis, mean differences of values +/- 2s.d. versus the reference method were -0.15 +/- 0.62 m/s, 2.09 +/- 2.68 m/s and -1.12 +/- 4.92 m/s, for PulsePen, Complior and Pulse-Trace, respectively. This study confirms the reliability of Complior and PulsePen devices in estimating PWV, while the SI determined by the PulseTrace device was found to be inappropriate as a surrogate of PWV. The present results indicate the urgent need for evaluation and comparison of the different devices to standardize PWV measurements and establish reference values.

Clinical applications of photoplethysmography in paediatric intensive care

The photoplethysmographic wave is displayed by most pulse oximeters. It may be used as a non-invasive alternative to invasive arterial blood pressure trace analysis for continuous haemodynamic monitoring in selected situations. Four cardiac patients treated in a tertiary neonatal-paediatric intensive care unit. Simultaneous monitoring of the photoplethysmographic wave, ECG, and invasive blood pressure. Photoplethysmography allows for monitoring pulse rate in patients with (possible) heart rate/pulse rate dissociation (pacemaker dependency, pulsatile ventricular assist device); monitoring sudden changes in heart beat volume, which are unrelated to respiration (pulseless electrical activity, pulsus alternans); and monitoring respiratory-dependent fluctuations of the plethysmographic wave (heart failure, hypovolaemia, asthma, upper airway obstruction, pericardial effusion). Deterioration, slowly evolving over time, may be detected by this method.

Accuracy of Pulse Oximetry in Sickle Cell Disease.

Pulmonary complications and hypoxemia are common in sickle cell disease (SCD) and may exacerbate microvascular occlusive phenomena. Thus, detecting hypoxemia is of particular importance in SCD. To assess the accuracy of pulse oximetry in the diagnosis of hypoxemia in SCD, we compared 22 pulse oximetric measurements of arterial oxygen saturation (SpO2) in adult patients with SCD and acute vasoocclusive crisis with simultaneously drawn arterial saturation (SaO2 = oxyhemoglobin divided by oxyhemoglobin plus reduced hemoglobin) measured by co-oximetry. We accepted SpO2 readings only if they were stable and characterized by strong and regular photoplethysmographic waves on the oximeter screen. To assess the position of these patients' oxyhemoglobin dissociation curves, we plotted arterial and venous oxygen saturation (SaO2 and SvO2 ) against oxygen tension. We found right-shifted oxyhemoglobin dissociation curves, with pH-corrected p50s ranging from 28 to 38 mm Hg. Pulse oximetry slightly overestimated oxyhemoglobin percentage (by an average of 3.4 percentage points), but it almost always accurately estimated SaO2 (underestimating on average by 1.1 percentage points). The error in SpO2 was never enough to classify a hypoxemic patient erroneously as normoxemic or a normoxemic patient as hypoxemic. We conclude that, as long as strong and regular photoplethysmographic waves are present, pulse oximeters can be relied upon not to misdiagnose either hypoxemia or normoxemia in SCD.

Pulse oximetry for assessment of pulsus paradoxus: a clinical study in children

To evaluate the relationship between intraarterial measured pulsus paradoxus (PP) and photoplethysmographic wave changes. Tertiary pediatric intensive care unit. 62 nonintubated children with or without respiratory disorders. Prospective, clinical study. Simultaneous paper recordings of photoplethysmographic wave, arterial blood pressure, breathing cycle and electrocardiogram. The respiratory dependent changes of the plethysmographic respiratory wave (delta pleth, mm) were defined as the difference between the highest value of the upper peak of the wave (in expiration) and the lowest value of the upper peak (in inspiration). In each patient, ten consecutive breaths were averaged for analysis. Five recordings could not be evaluated (movement artifacts). In 57 children (median age 2.4 years, range 7 days to 17 years), the photoplethysmographic fluctuations (delta pleth, mm) correlated with PP (mm Hg). r = 0.85; 95% confidence interval (CI), 0.76 to 0.91. The sensitivity to detect a PP of > 10 mmHg with a plethysmographic fluctuation of > 8 mm was 89% (95% CI, 77 to 100%) and the specificity was 90% (95% CI, 79 to 100%). Pulse oximetry appears to be a rapid and easily performed, noninvasive method for the objective estimation of the degree of PP.

The importance of presynaptic beta receptors in Raynaud's disease

The purpose of the present study was to investigate the effect of atenolol, a β1-selective blocker, along with flunarizine, a calcium antagonist, in the management of Raynaud's disease. Forty patients with Raynaud's disease were randomized into a trial in which atenolol (50 mg daily) was given with flunarizine (10 mg daily). During the trial all patients were subjected to finger photoplethysmography and were given a diary to note daily the number and duration of the crises and presence or absence of pain and paresthesia. The association of atenolol with flunarizine caused an 80% reduction in the number of vasospastic crises, a significant increase (p < 0.001) in the photoplethysmographic wave amplitude, and complete disappearance of pain and paresthesia. These results were not observed in patients treated with a placebo. Flunarizine reinforces the action of atenolol in causing a decrease in vasoconstriction in patients with Raynaud's disease, as observed previously by us, in that it acts directly on the β-presynaptic receptors or on the calcium slow channels connected to the β-receptors. The present study confirms that the principal role in the physiopathologic progression of Raynaud's disease seems to be played by a modification of the β-presynaptic receptors in the nerve endings of the peripheral vessels.

Variations hémodynamiques induites par la laparotomie en chirurgie aorto-iliaque

A haemodynamic study was carried out on 53 patients undergoing elective surgery of the abdominal aorta in order to assess the haemodynamic changes consequent to abdominal manipulations prior to aortic clamping. Surgery was carried out under general anaesthesia and ventilation was controlled. The following parameters were monitored : mean arterial pressure (P̄a), cardiac index (CI), systolic index (SI), systemic vascular resistances (Rsa), pulmonary vascular resistances (Rpa), heart rate (f C). Cutaneous circulation was monitored using a photoplethysmographic transducer. The following haemodynamic pattern was seen as the peritoneal cavity was opened and traction on the mesenter was applied : CI +40.7 %; f C +28.61 %; SI +9.85 %; Rsa −39.16 %; Rpa −28.43 %; P̄a −15.7 %. The recording of the facial cutaneous photoplethysmographic wave showed an increase of 50 %. In some extreme cases, a state of cardiovascular collapse with marked cutaneous erythema strongly resembling anaphylactic shock ensued. The physiopathology of these cardiovascular reactions is unclear, but the haemodynamic pattern as well as the cutaneous vasodilation suggest a stimulation of both vagal and sympathetic nervous systems and the release of vasoactive substances into the general circulation.