Finger recording electrode system for electrical impedance plethysmograph

System facilitates location of recording electrodes of impedance plethysmograph that is used for measuring flow of blood in finger segment; electrodes can be relocated accurately and volume of finger segment under study can be determined precisely. System minimizes movement artifacts in plethysmograph trace because finger segment is held firmly

New electrical plethysmograph monitors cardiac output

Four-electrode impedance plethysmograph measures ventricular stroke volume of cardiac output of humans. The instrument is automatic, operates with only one recording channel, and minimizes patient discomfort

Acoustic plethysmograph for measuring pulmonary function in mice

The traditional whole body plethysmograph (WBP) relies on pressure changes induced by a freely respiring animal inside a chamber. This pressure is a combination of a thermo-hygrometric effect (proportional to tidal volume) and a gas compression effect (related to lung mechanics). In order to measure either tidal volume or lung mechanics, it must be assumed that the other component is negligible. In this research, an acoustic WBP was developed that is capable of measuring the thoracic volume change of a mouse independent of the thermohygrometric effect. This allows independent measurement of tidal volume and specific airway resistance.;In the first phase of this research, the plethysmograph was designed to optimize measurement of the acoustic signal, which involved minimizing the WBP pressure. This plethysmograph was designed as a resonating cavity at a fixed frequency. It had a sharp resonant peak and was tuned so that changes in body volume produced nearly linear changes in sound amplitude. The plethysmograph was tested with a water filled balloon connected to a syringe pump. The volume of the balloon was varied as a triangle wave with amplitude of 250 mu L. The RMS error between measured and delivered volume was 4.43 mu L. A volume step test, performed to assess the response time of the system, showed that the plethysmograph responded in less than one millisecond.;Next, the plethysmograph was redesigned to provide a compromise between the acoustic measurement and the WBP pressure measurement. Similar to traditional methods utilizing a double chamber plethysmograph, these measurements were combined to estimate specific airway resistance (sRaw). To evaluate the system, six conscious A/J mice were individually placed in a chamber for a two-minute exposure to aerosolized methacholine chloride dissolved in saline (0, 5, 10, and 20 mg/mL) which is known to increase sRaw in mice. Following exposure, the mice were transferred to the acoustic plethysmograph for data collection. The mean baseline value of sRaw was 0.93 +/- 0.10 cm H 2O · sec. A dose-dependent increase in sRaw was shown, with an approximate tripling of sRaw at the highest dose. These results are comparable to those of other methods reported in the literature.;key terms. specific airway resistance, Helmholtz resonator, unrestrained plethysmograph, whole-body plethysmograph, acoustic plethysmograph

Supervised Release, Sex-Offender Treatment Programs, and Substantive Due Process

This Note argues that mandated PPG testing should be eliminated as a condition of federal supervised release. The test infringes on a constitutionally protected liberty interest against unwanted bodily intrusions and, as only the Second Circuit has held, any condition of supervised release that infringes on a constitutionally protected right may be mandated only where it is narrowly tailored to serve a compelling government interest. Because there are a number of viable, less intrusive alternatives, PPG testing as it stands today is not narrowly tailored enough to serve a compelling government interest

Readout electrode assembly for measuring biological impedance

The invention comprises of a pair of readout ring electrodes which are used in conjunction with apparatus for measuring the electrical impedance between different points in the body of a living animal to determine the amount of blood flow therebetween. The readout electrodes have independently adjustable diameters to permit attachment around different parts of the body between which it is desired to measure electric impedance. The axial spacing between the electrodes is adjusted by a pair of rods which have a first pair of ends fixedly attached to one electrode and a second pair of ends slidably attached to the other electrode. Indicia are provided on the outer surface of the ring electrodes and on the surface of the rods to permit measurement of the circumference and spacing between the ring electrodes

Development of limb volume measuring system

The mechanisms underlying the reductions in orthostatic tolerance associated with weightlessness are not well established. Contradictory results from measurements of leg volume changes suggest that altered venomotor tone and reduced blood flow may not be the only contributors to orthostatic intolerance. It is felt that a more accurate limb volume system which is insensitive to environmental factors will aid in better quantification of the hemodynamics of the leg. Of the varous limb volume techniques presently available, the ultrasonic limb volume system has proven to be the best choice. The system as described herein is free from environmental effects, safe, simple to operate and causes negligible radio frequency interference problems. The segmental ultrasonic ultrasonic plethysmograph is expected to provide a better measurement of limb volume change since it is based on cross-sectional area measurements

Apparatus for determining changes in limb volume

Measuring apparatus for determining changes in the volume of limbs or other boty extremities by determining the cross-sectional area of such limbs many comprise a transmitter including first and second transducers for positioning on the surface of the limb at a predetermined distance there between, and a receiver including a receiver crystal for positioning on the surface of the limb. The distance between the receiver crystal and the first and second transducers are represented by respective first and second chords of the cross-section of the limb and the predetermined distance between the first and second transducers is represented by a third chord of the limb cross section

Ventilatory Phenotypes among Four Strains of Adult Rats.

Our purpose in this study was to identify different ventilatory phenotypes among four different strains of rats. We examined 114 rats from three in-house, inbred strains and one outbred strain: Brown Norway (BN;n = 26), Dahl salt-sensitive (n = 24), Fawn-hooded Hypertensive (FHH: n = 27), and outbred Sprague-Dawley rats (SD; n = 37). We measured eupneic (room air) breathing and the ventilatory responses to hypoxia (12% O2-88% N2), hypercapnia (7% CO2), and two levels of submaximal exercise. Primary strain differences were between BN and the other strains. BN rats had a relatively attenuated ventilatory response to CO2 (P \u3c 0.001), an accentuated ventilatory response to exercise (P \u3c 0.05), and an accentuated ventilatory roll-off during hypoxia (P \u3c 0.05). Ventilation during hypoxia was lower than other strains, but hyperventilation during hypoxia was equal to the other strains (P \u3e 0.05), indicating that the metabolic rate during hypoxia decreased more in BN rats than in other strains. Another strain difference was in the frequency and timing components of augmented breaths, where FHH rats frequently differed from the other strains, and the BN rats had the longest expiratory time of the augmented breaths (probably secondary to the blunted CO2 sensitivity). These strain differences not only provide insight into physiological mechanisms but also indicate traits (such as CO2 sensitivity) that are genetically regulated. Finally, the data establish a foundation for physiological genomic studies aimed at elucidating the genetics of these ventilatory control mechanisms