Fingers Of Hand Research Articles

Finger contact keyboard for typing with tiny movement recognition

Hemiplegic patients often struggle with typing rapidly and accurately using a standard keyboard. This study developed a keyboard in continuous contact with the fingers, allowing for easier and more effective typing. With the proposed keyboard, the user types with their healthy hand and paralyzed hand. The hardware and software of the finger contact keyboard were investigated. In deciding the hardware, we measured the hand shape, finger speed, and muscle fatigue using electromyography, magnetic positioning sensors, and force sensors for eight participants. Using the Pareto solution, we optimized the keyboard’s structure to maximize finger movement speed and minimize muscle fatigue. As the software of the proposed keyboard, we developed an algorithm implementing a neural network to identify intentional typing and tested the algorithm on five participants. The highest average discrimination accuracy was 99.3% when the force threshold was approximately 1.32 N. The mean accuracy achieved using the neural network was 90.8%, which is higher than that achieved using the threshold algorithm (80.4%). In 40 trials, the proposed keyboard achieved the same accuracy and speed as the standard keyboard, and the input time for a patient with hemiplegia was reduced by 16.2%.

Multi-tactile sensor calibration via motion constraints with tactile measurements

This paper addresses a fundamental problem in multi-finger robot dexterous manipulation, Multi-Tactile Sensor Calibration (MTSC). It involves estimating the relative poses between multiple tactile sensors using their intrinsic measurements, crucial for coordinating multiple fingers in a dexterous robotic hand, especially when accurate encoders are unavailable. Unlike conventional multi-sensor calibration methods (like cameras), which rely on overlapping sensing regions and feature point matching, calibrating multiple tactile sensors presents unique challenges because these sensors cannot have overlapping sensing regions, precluding the use of shared key-points visible from different sensors. In this paper, we establish the theoretical basis for the MTSC problem, constructing constraint equations based on motions measured at multiple locations on the same grasped object from different tactile sensors. The key is that all these measurements correspond to a shared rigid body motion. A calibration scheme is proposed accordingly, with theoretical analysis conducted to enhance precision. Results in simulation, with objects of different shapes, confirm the validity of the proposed calibration approach. Furthermore, calibration of the relative pose between two GelSlim vision-based tactile sensors in real experiments demonstrates good agreement with the ground truth. The proposed theory and method not only shed light on explaining the accuracy gap between proprioception and tactile sensing in multi-finger manipulation but also pave the way for tactile-encoder-mixed or encoder-free solutions in dexterous multi-finger coordination.

Device for individual hand finger rehabilitation

Device for individual hand finger rehabilitation

Fabrication and testing of PVDF-Fish scales based sustainable piezoelectric impact sensor

Structural health monitoring is essential to modern infrastructure management, ensuring safety, optimizing costs, and enhancing structures' overall performance and reliability. Leftover fish scales (FS) in varying quantities (5, 10, 15, and 20wt.%) are reinforced into a polyvinylidene fluoride (PVDF) matrix to develop highly flexible piezoelectric composites, which are then assessed as impact sensors. The role of FS loading on the mechanical and dielectric behavior of PVDF is also investigated. PVDF with 10% FS loading showed maximum Ultimate tensile strength (UTS) and Elastic modulus (E) of 37MPa and 1192MPa, respectively. A 56% and 67% enhancement in UTS and E values over pure PVDF matrix is recorded. Piezoelectric nanogenerators (PENGs) are then fabricated to check the piezo response of composites under various loading conditions using a human hand (finger tapping, palm tapping, film twisting, and wrist pressing). The device with a maximum piezo response is further assessed for potential impact sensing under different impact loading conditions. The recorded results are analyzed statistically using the Weibull distribution approach to cater to the o/p voltage variations for each test load. The potential for sustainability and circular economies is significantly expanded with a cost-effective, highly sensitive piezoelectric impact sensor crafted from FS.

Delayed functional rescue of section of the flexor tendons of the last four (4) fingers at a gold miner in a Sahelian hospital in Niamey (Niger)

Introduction: Secondary reconstructions of flexor tendon section have become rare nowadays. We report the result of delayed functional rescue of a traumatic section of the hand flexor tendons in a young adult. Clinical case: This is a 20-year-old patient, admitted for inability to flex the last 4 fingers of the right hand. The interrogation revealed a history of open trauma to the hand from a stab dating back 3 months following a fight. The physical examination found a transverse scar located on the palmar aspect of the right hand measuring 6 cm in zone three (3) of Verdan. Exploration in the operating room revealed a complete section of the superficial and deep flexor tendons of the last four (4) fingers. An end-to-end suture of the tendons was performed using Kessler stitches using Nylon thread 4.0. After one (1) year and eight (8) months of follow up, we found an excellent result according to the IFSSH (International Federation of Societies for Surgery of the Hand) classification with a score of 88/100. Conclusion: Secondary repair of late flexor tendon ruptures by end-to-end suture gives good results and remains an alternative when a tendon graft is impossible. Keywords: Secondary suture, Flexor tendons, Hand, Niger.

Design and Optimization of Electromagnetically Driven End-Effector

The excellent flexibility and plasticity of a flexible robotic hand enable it to grip objects of various shapes and sizes. Currently, most of the flexible robotic hand fingers on the market use pneumatic drives. However, the unstable power of the pneumatic drive can cause the object gripped by the finger to slip. Additionally, the pneumatic pump can create noise pollution. To address these issues, a flexible end-effector is designed using an electromagnetic coil as the power source. The electromagnetic-driven end-effector has high precision and fast response, without the need for external devices. It only requires controlling the current to control the magnetic force of the electromagnet, thereby controlling the degree of end-effector bending. The finite element simulation is used to analyze the impact of the structural parameters of the end-effector on bending degree. And the optimal basic parameters of the end-effector are determined. Under the same intensity of the current, when the bottom layer thickness is 5 mm, end-effector knuckle spacing is 4 mm, the maximum angle of end-effector bending is reached.

EPID-33. EPITHELOID SARCOMA IN A LONG-TERM SURVIVOR OF AN ATYPICAL TERATOID / RHABDOID TUMOR WITH RHABDOID TUMOR PREDISPOSITION SYNDROME

Abstract INTRODUCTION Rhabdoid tumor predisposition syndrome (RTPS) predisposes to a high risk of developing Rhabdoid tumors in Brain, kidney; and is defined by a germline mutation in SMARCB1 (rarely SMARCA4) gene. The most frequent pediatric tumor associated with RTPS is atypical teratoid/rhabdoid tumor (ATRT), commonly diagnosed in children < 3 years of age. Epitheloid Sarcoma (ES) is a rare soft tissue sarcoma, arising in any age group and histologically defined by loss of SMARCB1 in tumor cells. METHODS We describe a long- term survivor of ATRT with RTPS presenting 12 years later with ES. Data was collected from medical chart review. RESULTS Our patient was diagnosed with ATRT and RTPS (SMARCB1) at 6 months of age and treated with chemotherapy as per ACNS0333 at diagnosis; by chemotherapy / focal radiation at first relapse and with alisertib on second relapse. At 10yrs of age she presented with multiple firm, skin-colored dermal nodules in both her hands (palms and fingers). She was diagnosed to have palmar warts and treated with topical cantharidin with a waxing and waning course. Subsequently the hand lesions were diagnosed as granuloma annulare and followed up with no therapy. At 12 years of age, lesion in tip of the right thumb increased in size and a punch biopsy was done which revealed ES with IHC showing loss of SMARCB1 in tumor cells. Staging CT of the chest showed multiple bilateral (b/l) small (<1cm) axillary lymph nodes with a negative PET scan. Bilateral axillary lymph node biopsies were negative for ES. She underwent excision of all the hand lesions with negative margins with no further therapy. CONCLUSION Based on our case and single case report in literature, we hypothesize that ES is likely a primary malignancy of RTPS and should be included in the spectrum of malignancies of RTPS.

Severe Flexor Digitorum Profundus Muscular Adhesion by Pseudo-Volkmann's Contracture without Fracture: A Case Report and Literature Review.

Volkmann's ischemic contracture is a condition characterized by permanent ischemic damage to muscles and nerves due to vascular insufficiency, resulting in flexion contractures of the affected limb. In contrast, pseudo-Volkmann's contracture presents with similar clinical features but lacks ischemic damage and has the potential for complete recovery. We report a case of a 39-year-old man who developed failure of extension in the middle and ring fingers of the left hand following blunt forearm trauma from a rolling machine. Despite no skin breakage or fracture, his symptoms progressively worsened over 2 months without treatment. Surgical exploration 2 years later revealed severe adhesions of the flexor digitorum profundus muscle at the myotendinous junction to the ulnar periosteum, with immediate recovery after release. This case highlights pseudo-Volkmann's contracture in an adult without fracture, likely due to blunt trauma causing delayed adhesion formation.

An Association Between Left-Hand Digit Ratio (2D:4D) and Anthropometric Indexes in Chinese Children and Adolescents Aged 8-15 Years in Bengbu City.

The digit ratio (2D:4D) is a possible marker of prenatal hormone exposure. The purpose of this study was to explore the relationships between digit ratio (2D:4D) and anthropometric indexes in Chinese children and adolescents. This study is a cross-sectional study. A school-based survey among 685 children and adolescents aged 8-15 years were conducted by stratified cluster sampling. The length of index finger (2D) and ring finger (4D) of the left hand, height, sitting height (ST), weight, chest circumference (CC), waist circumference (WC), hip circumference (HC), and abdominal skinfold thickness (AST) were measured. Pearson correlation and multivariate linear regression were used to analyze associations between 2D:4D and above indexes. In girls, 2D:4D was positively related to WC, AST, waist-to-height (WHtR), waist-to-hip ratio (WHR) after adjusting for ages (p < 0.05). The WC, AST, WHtR, and WHR among girls with 2D:4D ≥ 1 were significantly higher than those among girls with 2D:4D < 1, respectively (p < 0.05). However, there was no correlations between digit ratio (2D:4D) and above anthropometric indexes in boys (p > 0.05). The 2D:4D was related to anthropometric indexes in girls, which suggests that the maternal prenatal hormone exposure might be related to the anthropometric indexes of their female offspring.

036. Sclerotic Therapy as The Management Of Arteriovenous Malformation on Hand: A Case Report

Background: An arteriovenous malformation (AVM) is an abnormal connection between arteries and veins, bypassing the capillary system. There are a number of consequences associated with this illness, such as bleeding and neurological impairments. The situation is complex, which emphasizes the necessity for individualized treatment plans. This case report a 18 years old female with AVM condition. Case: A 18 years old female was admitted to to Prof. IGNG Ngoerah General Hospital with a chief complaint of lump on the left finger. The lump on the left finger has been felt since &gt;10 years ago. The lump appeared suddenly and went bigger each day. Complaints worsened until the patient felt pain in the left finger. On examination of the local status, multiple masses were found on third and fourth digits of the left hand, with unclear border and vein ectasis. MSCT Angiography of the left superior extremity found a soft tissue image of hemangioma on the palmar aspect and interdigiti III-IV to the palmar-dorsal aspect of digit III and the palmar aspect of digiti IV of the left hand and multiple non-suspicious lymphadenopathy in the left axilla region. The scleroterapy treatment was performed and 3 months results shown decreased size of the masses without any complication. Conclusion: An arteriovenous malformation (AVM) of the left hand fingers is a rare case found in Prof Ngoerah Hospital. The sclerotic therapy found to be an effective management for this case.

Effectiveness of Finger Hand Relaxation and Progressive Muscle Relaxation Techniques on Anxiety in Pre-Operative Sectio Caesarea Patients

Background: Anxiety is a common thing that occurs in patients who will undergo surgery. The anxiety that occurs in preoperative patients can be felt from the time they are scheduled for surgery until the time of surgery arrives. Anxiety management can be done using pharmacological and non-pharmacological therapy. Purpose: The aim of this research is to analyze the effectiveness of finger grip relaxation techniques and progressive muscle relaxation on anxiety in pre-caesarean section surgery patients in the Kediri Regency Regional General Hospital. Method: This study used a Quasy-experiment With Pretest Posttest to determine the effect of finger grip and progressive muscle relaxation techniques. The sample selection in this study used a purposive sampling technique and a total of 56 patients were obtained who were divided into 2 groups, namely the finger grip intervention group and the progressive muscle intervention group. The pretest and posttest data for each group were then analyzed using the Wilcoxon Test to determine the effect and the Mann-Whitney Test to compare the posttest results of the 2 groups. Results: The results of the study showed that the Wilcoxon test in both intervention groups obtained a p-value &lt; α (0.05), which means that before and after the intervention, both progressive muscle relaxation and finger grip relaxation had an influence on the anxiety level of pre-caesarean section patients. For the results of the Mann-Whitney test, the p-value was 0.063 or p-value &gt; α (0.05), which means there was no significant difference between changes in anxiety whether those given progressive muscle relaxation intervention or finger grip relaxation. Conclusion: Finger grip relaxation techniques and progressive muscle relaxation techniques are both effective in reducing anxiety levels in pre-caesarean section surgery patients. So this non- pharmacological therapy can be an option for patients in dealing with anxiety problems before caesarean section surgery.

Social negotiation and “accents” in Western lowland gorillas’ gestural communication

Recent findings on chimpanzee infants’ gestural development show that they use some gesture types flexibly and adjust them depending on their interaction partner and social context, suggesting that gestural communication is partly learnt and partly genetically determined. However, how gesture types are shaped by social and demographic factors remains unclear. We addressed this question by focusing on gesture type morphology and conducted a fined-grained analysis of gestural form during intraspecific social-play interactions in two captive groups of Western lowland gorillas (Gorilla gorilla gorilla). We focused on the most frequent gesture types (beat chest, slap body, slap ground and touch body) produced by subadults (infants, juveniles and adolescents). We considered twelve morphological gesture characteristics (e.g., horizontal and vertical hand trajectories, fingers flexion and spread). Our multifactorial investigation shows that morphological characteristics of distinct gesture types can be shaped by social factors, namely signaller’s sociodemographic characteristics (group and kinship), signaller’s behavioural characteristics (body posture) and context-related characteristics (recipient’s sex, attentional state and position in the signaller’s visual field). We nurtured the lively debate concerning gesture origins by revealing the existence of “accents” in non-verbal communication and the highly variable adjustment of gestural form to different conspecifics and interactional characteristics, which supports the revised social negotiation hypothesis.

Two-Stage Flexor Tendon Reconstruction for Finger Contracture Secondary to Phlegmon: A Case Report

Flexor tendon reconstruction is a complex surgical procedure that requires great precision and specialized expertise. It remains a preferred treatment for patients with neglected lacerations of the digital flexor tendon and after the failure of flexor tendon repair. Improvements in tendon repair methods and follow-up techniques have enhanced outcomes after flexor tendon grafting. Case Presentation: A 14-year-old girl with a history of a phlegmon of the 4th finger of the right hand, treated with antibiotics and drainage. The evolution is marked after 2 years by the progressive development of a flexion contracture of the proximal interphalangeal (PIP) joint. On examination, there is a flexion attitude and an inability to extend the PIP joint without vascular or nervous disorders. A two-stage reconstruction was performed using the palmaris longus tendon as a graft. With a follow-up of 3 years, the girl has recovered complete flexion and has limited extension to 25° at the PIP joint. An arthrolysis was proposed, but the girl refused, and she is satisfied with the results.

Multidigit tactile perception II:perceptual weighting during integration follows a leading-finger priority.

When we run our hand across a surface, each finger typically repeats the sensory stimulation that the leading finger has already experienced. Because of this redundancy, the leading finger may attract more attention and contribute more strongly when tactile signals are integrated across fingers to form an overall percept. To test this hypothesis, we re-analyzed data collected in a previous study (Arslanova I, Takamuku S, Gomi H, Haggard P, J Neurophysiol 128: 418-433, 2022), where two probes were moved in different directions on two different fingerpads and participants reported the probes' average direction. Here, we evaluate the relative contribution of each finger to the percept and examine whether multidigit integration gives priority to the leading finger. Although the hand actually remained static in these experiments, a "functional leading finger" could be defined with reference to the average direction of the stimuli and the direction of hand-object relative motion that this implied. When participants averaged the motion direction across fingers of the same hand, the leading finger received a higher weighting than the nonleading finger, even though this biased estimate of average direction. Importantly, this bias disappeared when averaging motion direction across the two hands. Both the reported average direction and its systematic relation to the difference between the individual stimulus directions were explained by a model of motion integration in which the sensory weighting of stimuli depends on the directions of the applied stimuli. Our finding supports the hypothesis that the leading finger, which often receives novel information in natural hand-object interactions, is prioritized in forming our tactile perception.NEW & NOTEWORTHY The capacity of the tactile system to process multiple simultaneous stimuli is restricted. One solution could be to prioritize input from more informative sources. Here, we show that sensory weighting accorded to each finger during multidigit touch is biased in a direction-dependent manner when different motions are delivered to the fingers of the same hand. We argue that tactile inputs are weighted based on purely geometric information to prioritize "novel" information from the leading finger.

Massive Increase of Totkas on Indian Social Media

Currently, the world is experiencing revolutionary changes. It is becoming more magical and unreal due to great expansion and revolutionary inventions of internet and technology. Currently, people like brief and effective messages in the fast and furious world. Reading bulky books has become a difficult task for them as they are pacing with time in their tightly-packed and roughlyplanned life which is full of accidental events. Their busy schedule is reflected on their faces. Their communication, verbal or non-verbal is influenced largely by their stress and tension in current times. People like messages of social media in multiple forms. Social media literature is now available easily at a click of mouse or with the use of any finger of hand and scrolling any platform like YouTube, Twitter, Facebook etc. People like such literature because they can pass time reading or watching it anytime at any place including toilet or a place of worship

Comprehensive Medical and Psychological Rehabilitation in War Trauma (clinical case)

The purpose of the work was to analyze a clinical case of the course of war trauma and presents the experience of providing comprehensive medical and psychological clinical rehabilitation to a patient who suffered as a result of a terrorist attack. Patient D., 65 years old, sustained a mine-blast injury (MBI) to the right upper limb extremity during shelling. The optimal restoration of the functions of the upper injured limb and the patient's health (physical, somatic, mental) was carried out according to the algorithm of comprehensive medical and psychological clinical rehabilitation. As a result of the course of comprehensive medical and psychological clinical rehabilitation, significant positive dynamics was observed, including a decrease in edematous, painful, and inflammatory syndromes. The range of motion in the right upper limb and cervical-thoracic spine increased. Supination and pronation of the right hand became clearer and less painful (from 8 to 2 points), movement in the fingers of the right hand increased and became more steady, a clear pulsation appeared in the area of the skin defect on the right forearm, regression of pain in the elbow and shoulder joints on the right was noted, and the patient began to walk without a mobilization bandage. The course helped to reduce anxiety (from -1.82 to 0.85), asthenic symptoms (from 0.48 to 3.71), obsessive-phobic symptoms (from -1.96 to 1.74), and autonomic disorders (from -0.83 to 2.03). Low cortisol levels (61 nmol/l) in against acute stress indicated the development of post-traumatic stress disorder. Upon completion of the rehabilitation course, cortisol levels rose to a healthy level (246 nmol/l), indicating the effectiveness of the process of restoring the psychophysiological state and adapting to a stressful situation. War trauma is a complex and severe condition that requires an integrated approach to treatment and rehabilitation, covering not only physical but also psychological and social aspects of patients' health.

Modeling the Dynamics of Prosthetic Fingers for the Development of Predictive Control Algorithms

In the field of biomechanical modeling, the development of a prosthetic hand with dexterity comparable to the human hand is a multidisciplinary challenge involving complex mechatronic systems, intuitive control schemes, and effective body interfaces. Most current commercial prostheses offer limited functionality, typically only one or two degrees of freedom (DoF), resulting in reduced user adoption due to discomfort and lack of functionality. This research aims to design a computationally efficient low-level control algorithm for prosthetic hand fingers to be able to (a) accurately manage finger positions, (b) anticipate future information, and (c) minimize power consumption. The methodology employed is known as model-based predictive control (MBPC) and starts with the application of linear identification techniques to model the system dynamics. Then, the identified model is used to implement a generalized predictive control (GPC) algorithm, which optimizes the control effort and system performance. A test bench is used for experimental validation, and the results demonstrate that the proposed control scheme significantly improves the prosthesis’ dexterity and energy efficiency, enhancing its potential for daily use by people with hand loss.

Modular soft pneumatic actuator mimics elephant trunk locomotion

Robots support and facilitate tasks in all life fields. Soft robots specifically have the advantages of inherent compliance, safe interaction and flexible deformability. Soft pneumatic network (Pneu-Net) is a soft pneumatic actuator (SPA) composed of network of chambers that is actuated by pneumatic power. Soft Pneu-Net fits the human interface applications perfectly. In this paper, a bio-inspired modular based design for Pneu-Net actuator is developed. The actuator mimics the elephant trunk curling to be employed for rehabilitation of human hand fingers. The actuator is an integrated four Pneu-Net modules actuator which is attached to hand’s finger. The main introduced advantages in the new developed actuator are: providing four degrees of freedom (DoF) essential for finger’s motion by single compound actuator and developing a methodology for a modular soft Pneu-Net actuator that is efficiently reproducible. The actuator’s design is developed using computer aided design (CAD) software SOLIDWORKS. The design is simulated using finite element modeling (FEM) software ABAQUS. Fabrication process uses 3D printed molds. Soft material is molded in the 3D printed molds, forming actuator’s modules. Actuator’s modules are integrated by adhesion using the soft material. A proposed non-standard hyper-elastic material biaxial tension test is introduced as a quick material properties identification method that can produce a test table used for material identification in the FEM. Enhanced version for the actuator uses reinforcement fibers. Results show advances for the reinforced actuator, as it limits the unwanted actuator’s strain and deformation. The reinforced actuator shows improved energy efficiency reaches to 46%.

Learning to Play Guitar with Robotic Hands

AbstractPlaying the guitar is a dexterous human skill that poses significant challenges in computer graphics and robotics due to the precision required in finger positioning and coordination between hands. Current methods often rely on motion capture data to replicate specific guitar playing segments, which restricts the range of performances and demands intricate post‐processing. In this paper, we introduce a novel reinforcement learning model that can play the guitar using robotic hands, without the need for motion capture datasets, from input tablatures. To achieve this, we divide the simulation task for playing guitar into three stages. (a): for an input tablature, we first generate corresponding fingerings that align with human habits. (b): based on the generated fingerings as the guidance, we train a neural network for controlling the fingers of the left hand using deep reinforcement learning, and (c): we generate plucking movements for the right hand based on inverse kinematics according to the tablature. We evaluate our method by employing precision, recall, and F1 scores as quantitative metrics to thoroughly assess its performance in playing musical notes. In addition, we conduct qualitative analysis through user studies to evaluate the visual and auditory effects of guitar performance. The results demonstrate that our model excels in playing most moderately difficult and easier musical pieces, accurately playing nearly all notes.

Relationship Between Finger Photoplethysmographic Pulses and Skin Blood Perfusion.

Introduction Photoplethysmography (PPG) measures are important in monitoring peripheral oxygen saturation (SpO2). Another parameter is a derived quantity referred to as the peripheral perfusion index (PPI). It is calculated as the ratio of the peak-to-peak pulse amplitude of a PPG signal (PAPPG) to the non-pulsating part of the total PPG signal. The PPI has been used as a marker of blood perfusion states in a variety of clinical settings but has not been systematically and directly compared to measures of local blood perfusion. This study's purpose was to investigate this issue to provide initial data on the relationship between finger skin blood perfusion, measured by laser Doppler blood perfusion flux (LDF) and PAPPG. Methods Ten subjects (five male), recruited from medical students with an average age of 26 years, participated.While supine for 30 minutes, skin blood perfusion was recorded using laser Doppler flux (LDF) on the ring finger pulp of the non-dominant hand, and the photoplethysmography pulse (PPG) was recorded from the index finger of the same hand. The recorded data was searched sequentially manually to locate the first 30-pulse sequence in which the PPG amplitude of at least six PPG pulses was less than or equal to 60% of the maximum pulse amplitude in the sequence. The primary PPG parameter of interest was PAPPG. For the LDF signal, the pulse amplitude is designated as PALDF, the total LDF for each pulse is designated as LDFTOT,and the LDF pulsatile component is designated as PF. To investigate the relationship between LDF parameters and PAPPG a linear regression analysis of each 30-pulse sequence was done with PAPPG as the independent variable and each of the three LDF parameters individually (PALDF, LDFTOT, and PF) as dependent variables. Results There was a statistically significant direct relationship between PAPPG and all three measures of blood perfusion (p<0.05). Correlation coefficients (R) varied among subjects but within-subject variations versus PAPPG were similar, having mean values that ranged from 0.665 to 0.694. The results also provided evidence in support of a direct relationship between the LDF pulsatility index, defined as the ratio of PF to its mean value., and PAPPG (R=0.779). Conclusions When finger PPG pulse amplitudes are measured in individual subjects there is a moderate-to-strong correlation between the PPG pulse amplitude changes and skin blood perfusion changes. This fact impacts the confidence in using the widely available PPG parameter, peripheral perfusion index, as an indicator of changes in tissue perfusion.However, differences in the PPG pulse amplitude among subjects were less reliable indicators of differences in blood perfusion among subjects. The findings also indicate that a related parameter, the LDF pulsatility index, is also highly correlated with the PPG pulse amplitude and may serve as a useful parameter for future clinical investigations.