China
Africa
Explore chapters and articles related to this topic
Signs of Pressure Sores
Published in J G Webster, Prevention of Pressure Sores, 2019
Lee et al (1979) used photoplethysmography to assess the healing potentials of pressure sores. The motivation behind their work was to objectively determine the need for surgery to treat a pressure sore, thus avoiding the risk and cost of unnecessary surgery. The study used measurements of blood flow around the ulcer to determine the skin’s potential for healing. Giltvedt et al (1984) developed a multiwavelength photoplethysmograph to detect simultaneous flow variations at levels of the dermis and deep vascular plexi. The principle of the multiwavelength device is that light of different wavelengths penetrates the skin to different depths. Thus two light sources emitting radiation at different wavelengths are reflected from blood vessels at different depths.
Non-invasive physiological monitoring
Published in John Edward Boland, David W. M. Muller, Interventional Cardiology and Cardiac Catheterisation, 2019
Mark Butlin, Isabella Tan, Edward Barin, Alberto P. Avolio
Regardless of the probe configuration, a photoplethysmography device can measure the short-term time-varying changes in the absorption of light, which is associated with blood volume in the tissue, and changes in the wavelength of light absorbed, which is associated with the oxygen saturation of haemoglobin. By shining light of two wavelengths (red light at approximately 660 nm and near-infrared at approximately 940 nm) into the tissue, the arterial oxygen saturation (SpO2) can be estimated, as light intensity in these two wavelength ranges differ between oxyhaemoglobin (HbO2) and haemoglobin (Hb). While this is a well-validated technique and in common usage in clinical monitoring, the use of the photoplethysmogram (the short-term time-varying signal associated with blood volume changes at the frequency of the cardiac cycle) has no standard for clinical measurement. However, it is commonly used for measurement of heart rate, as it is observed to be reliably in phase with a simultaneously-recorded electrocardiogram. The photoplethysmogram has been used experimentally for derivation of cardiac output, respiration, arterial compliance, endothelial function, Raynaud’s disease, and autonomic function assessment.9 However, these have not yet had an uptake in common clinical usage.
Cardiovascular and Related Complications of Diabetes
Published in Robert Fried, Richard M. Carlton, Type 2 Diabetes, 2018
Robert Fried, Richard M. Carlton
Vaginal photoplethysmographic measures of capillary engorgement were taken while participants individually viewed counterbalanced erotic, and non-erotic, videotape presentations. A plethysmograph reflects changes in volume. A photoplethysmogram is an optically obtained plethysmograph, often obtained by using a pulse oximeter that illuminates the skin and measures changes in light absorption reflecting blood vessel volume and changes in volume as blood pressure varies in the vessel.
Pilots’ mental workload variation when taking a risk in a flight scenario: a study based on flight simulator experiments
Published in International Journal of Occupational Safety and Ergonomics, 2023
Lei Wang, Shan Gao, Wei Tan, Jingyi Zhang
The experiment was run on a flight simulator equipped with X-Plane version 11.0. The simulator comprises a high-performance computer, three display screens, a flight control column, a throttle controller and a pair of rudder pedals (Logitech, Switzerland). The photoplethysmograph (PPG) sensor used to measure HRV was 43 × 25 × 12 mm3 in size with 24-bit resolution and a sampling frequency of 64 Hz (Kingfar, China). It uses an ear clip sensor, which is clamped on the earlobe and fixed on the collar with another clip. The relationship between the optical signal and blood flow was calculated using the transmission and reflection principle of the wavelength beam. The conversions from optical signals to electrical signals were then amplified to obtain the changes in volume, pulse and blood flow. The flight data were recorded by a module installed on X-Plane version 11, flight simulator software that recorded flight performance data every 200 ms. It can record a large number of flight parameters, including time, speed, weather, aircraft state (pitch, roll and headings) and position (latitude, longitude and altitude), etc. (Figure 1).
The intensity of oscillations of the photoplethysmographic waveform variability at frequencies 0.04–0.4 Hz is effective marker of hypertension and coronary artery disease in males
Published in Blood Pressure, 2020
Anton R. Kiselev, Anatoly S. Karavaev
Blood pressure variability is an important cardiovascular phenomenon. It is known that there is an association between blood pressure variability and cardiovascular outcomes and mortality [1,2]. At the same time, blood pressure variability has little association with other cardiovascular factors impacting the prognosis, such as atrial fibrillation [3]. Blood pressure variability is primarily caused by the vasomotor tone [4]. Taking into account that oscillations in blood supply in digital arteries contribute significantly to the photoplethysmographyc signal in fingers [5], we can be sure that it is possible to study the regulation of systemic blood pressure using photoplethysmographic waveform variability characterizing beat-to-beat amplitude variations of photoplethysmogram. It is known that there have been attempts to use photoplethysmographic morphological features for evaluating hypertension [6].
Prediction in obstructive sleep apnoea: diagnosis, comorbidity risk, and treatment outcomes
Published in Expert Review of Respiratory Medicine, 2018
Kate Sutherland, Fernanda R. Almeida, Philip de Chazal, Peter A. Cistulli
The simplest of PM devices (denoted type-4 devices by the AASM [45]) are most suitable for a P4 medicine approach as they have lowest cost and are easiest to use. Type 4 devices vary in the attachment point to the body. A representative sample of devices is shown in Table 1. Chest strap mount devices use a chest strap with an attached recorder. One such device measures respiratory effort and sound, with external sensors to measure nasal airflow and oximetry. It provides a range of outputs including AHI, Hypopnea Index (HI), flow limitation, snoring, and oxygen desaturation index (ODI) [46]. While the chest strap and external sensor combination may be less convenient for the patient than other type 4 devices, the accuracy is high. Wrist worn devices are more convenient to the patient and use a recorder on the wrist with finger mounted sensors. Examples include oximeters and peripheral arterial tone (PAT) devices. Oximetry is simple diagnostic device using the photoplethysmograph (PPG) and saturation signals derived from a standard fingertip mounted pulse oximeter. PAT devices have an inflatable fingertip cuff and by combining actigraphy and oximetry, detect sleep-related breathing disorders, and sleep architecture [47].