Haemodynamics: flow, pressure and resistance
Neil Herring, David J. Paterson in Levick's Introduction to Cardiovascular Physiology, 2018
Plethysmography is a non-invasive technique that measures blood flow in a human limb, foot or digit (Figure 8.5). To measure forearm blood flow, an inflatable cuff is wrapped around the upper arm, overlying the brachial vein, and is inflated suddenly to 40 mmHg. This arrests the venous drainage out of the arm, but not the arterial inflow; so, the forearm begins to swell with blood. The initial rate of swelling equals arterial inflow. The swelling is measured by recording the limb circumference, using an electronic strain gauge device wrapped around the forearm. In former years, limb swelling was measured by displacing air or water out of a rigid jacket around the limb, called a plethysmograph (‘fullness record’), hence the method’s gargantuan name.
Lung volumes
Lara Wijayasiri, Kate McCombe, Paul Hatton, David Bogod in The Primary FRCA Structured Oral Examination Study Guide 1, 2017
Describe how body plethysmography may be used to measure RV and FRC. The subject sits inside an airtight chamber equipped to measure pressure, flow or volume changes.The subject inhales or exhales to a particular volume (usually FRC), and then a shutter drops across their breathing tube.The subject makes respiratory efforts against the closed shutter, causing their chest volume to expand and decompressing the air in their lungs.The increase in their chest volume slightly reduces the box volume and thus slightly increases the pressure in the box.The most common measurements made using the body plethysmograph are thoracic gas volume and airway resistance.
Disordered and offensive sexual behaviour
John C. Gunn, Pamela J. Taylor in Forensic Psychiatry, 2014
Although sex offending is usually about more than sex, it should not be forgotten that sex is one of its inherent components. Assessment of sexual interest and arousal is therefore important. In theory, the most accurate way to do so would be through self report, but unfortunately self report is often highly unreliable. The extent to which sexual arousal to specific stimuli can be demonstrated with special tests is also problematic. The penile plethysmograph (PPG), for example, which directly measures penile responses to sexual cues in pictures or audiotapes, can provide clear evidence of arousal, but it has a high false negative rate (Kalmus and Beech, 2005). Techniques based on viewing time have also been developed, but so far appear to work best in respect of arousal to children (especially boys), and less well in respect of other types of deviant arousal; false negatives are also common here (Abel et al., 1998; Letourneau, 2002; Glasgow et al., 2003; Laws and Gress, 2004). Virtual reality protocols with which to evaluate sexual preferences are in their infancy, but have the potential to make laboratory investigations less artificial (Renaud et al., 2002). The best use of the PPG is as an aid to treatment, the results can be discussed with the patient and used to inform psychotherapy in its different forms. It is also helpful in getting a patient beyond the stage of denial.
Sexual vs. Nonsexual Currently Most Upsetting Trauma: A Fresh Look at Attenuation of Sexual Response, Alcohol Intoxication, and Post-Traumatic Stress
Published in The Journal of Sex Research, 2018
Elizabeth R. Bird, Martin Seehuus, Julia R. Heiman, Kelly Cue Davis, Jeanette Norris, William. H. George
Participants then watched three short films: a neutral 2.5-minute bird documentary (BBC) followed by two three-minute erotic films (New Era Productions; VCA Productions). Erotic film content depicted a man and a woman participating in consensual kissing, oral sex, and vaginal intercourse. The first film ended with the couple engaging in penile–vaginal intercourse; the second film began with the woman performing oral sex on the man. Two films were shown to mitigate the risk that sexual responding would be film specific. During pilot testing, the films induced equivalent levels of self-reported sexual arousal (George, 2004). They were shown consecutively without an intertrial interval. During the neutral and erotic films, genital sexual arousal was measured using vaginal photoplethysmography (Sintchak & Geer, 1975). The plethysmograph is the size of a small transparent tampon, which the participant inserts into her vagina while in a private room. Before beverages were administered, the experimenter instructed the participant on how to insert the plethysmograph. Written instructions were also provided. After the beverages were consumed, the experimenter instructed the participant to insert the device. Participants were left alone to insert the device. Baseline readings were checked for quality before proceeding with data collection. Researchers communicated with participants via intercom. After obtaining a 1-minute baseline reading, the participant was shown the neutral film.
Reliability and minimal detectable change of thoracoabdominal mobility measurements using photogrammetry
Published in Physiotherapy Theory and Practice, 2018
Karine J. Sarro, Camila L. Mombrini, Thais B. Tonole
There are several resources to assess thoracoabdominal movements, such as respiratory inductance plethysmography (Watson, Poole, and Sackner, 1988); magnetometry (Mead, Peterson, Grimby, and Mead, 1967); and optoelectronic plethysmography (Aliverti, Dellacà, and Pedotti, 2001). Optoelectronic plethysmography, which incorporates multiple dedicated cameras and special software and hardware to collect kinematic data of chest wall motion, is considered by researchers the first-choice method to measure chest wall volume. However, methods based on special equipment have a high cost, which hinders their popularity and use on a regular basis in most physical therapy clinics. For these reasons, these methods have been useful specifically in research environments, and simple and inexpensive methods to assess thoracoabdominal mobility have been more attractive within clinical practice.
Comparative safety evaluation of riot control agents of synthetic and natural origin
Published in Inhalation Toxicology, 2018
Ravindra M. Satpute, Pramod K. Kushwaha, D. P. Nagar, P. V. L. Rao
During the study, all the respiratory variables, such as normal respiration (N), airway obstruction (A), tidal volume (VT), respiratory frequency (f), flow at 50% of VT during expiration (VD), time of inspiration (TI), time of expiration (TE), pulmonary irritation (P), sensory irritation (S) were measured. The inspiration and expiration of the mouse caused small changes in air pressure inside the plethysmograph, which was sensed by differential volumetric pressure transducer (Grass model, PT-5, MA, USA) connected to the plethysmograph with a silicone tube. The transducer was connected to a low level D.C. preamplifier (Grass model 7PIG, MA, USA) of the polygraph (Grass model 7 D, MA, USA) to amplify, condition, and record respiratory signals. The respiratory signals were also recorded intermittently as upward deflection (inspiration) and downward deflection (expiration) during the experiment to obtain typical respiratory pattern on an oscilloscope (Agilent infiivision, CA, USA). The amplified signals were also fed to a computer through analog to digital converter card (Keithley metrabyte, Model DAS-16, MO, USA) for computing the respiratory parameters. The respiratory signals were recorded at every 15-s interval and were computed using a computer program capable of characterizing the respiratory variables and the breathing pattern (Vijayaraghavan et al., 1993, 1994). Sigma Plot 2.0 (SPSS, Chicago, IL) was used for plotting the graphs.
Related Knowledge Centers
- Arm
- Lung
- Chronic Obstructive Pulmonary Disease
- Functional Residual Capacity
- Helium Dilution Technique
- Compliance
- Leg
- Impedance Cardiography
- Venous Thrombosis
- Penile Plethysmography