A fast gas-mixing system for breath-to-breath respiratory control studies

1982 ◽  
Vol 52 (5) ◽  
pp. 1358-1362 ◽  
Author(s):  
P. A. Robbins ◽  
G. D. Swanson ◽  
A. J. Micco ◽  
W. P. Schubert
Keyword(s):  
High Voltage ◽  
Special Form ◽  
Low Voltage ◽  
Respiratory Control ◽  
Gas Mixing ◽  
Tidal Forcing ◽  
Mixing Chamber ◽  
Computer Controlled ◽  
End Tidal ◽  
Gas Fractions

A computer-controlled gas-mixing system that manipulates inspired CO2 and O2 on a breath-to-breath basis has been developed. The system uses pairs of solenoid valves, one pair for each gas. These valves can either be fully shut when a low voltage is applied, or fully open when a high voltage is applied. The valves cycle open and shut every 1/12 s. A circuit converts signals from the computer, which dictates the flows of the gases, into a special form for driving the valve pairs. These signals determine the percentage of time within the 1/12-s cycle each valve spends in a open state and the percentage of time it spends shut, which, in effect, set the average flows of the various gases to the mixing chamber. The delay for response of the system to commanded CO2 or O2 changes is less than 200 ms. The system has application for the manipulation of inspired gas fractions so as to achieve desired end-tidal forcing functions.

A digital system for generating dynamic sinusoidal gas concentration signals

1988 ◽  
Vol 65 (2) ◽  
pp. 945-949 ◽  
Author(s):  
S. A. Barton ◽  
L. Sutton ◽  
C. E. Hahn ◽  
A. M. Black
Keyword(s):  
Frequency Modulation ◽  
Pulse Frequency ◽  
Respiratory Monitoring ◽  
Gas Mixing ◽  
Pulse Frequency Modulation ◽  
Gas Concentration ◽  
Mixing Chamber ◽  
Computer Controlled ◽  
The Individual ◽  
Valve Switching

A computer-controlled gas-mixing system is presented. It is capable of mixing four gases, the concentration of three of which will follow a path to be determined by the user. For our purposes the output O2 fraction is maintained constant and the levels of Ar and N2O vary sinusoidally and independently, with periods between 0.25 and 30 min. A fourth gas, N2 is necessary to make the sum of the individual fractions 100%. The system uses banks of between one and four solenoid valves each linked via a sonic choke to a common mixing chamber. A regime of pulse frequency modulation is employed. All calculations and timing of valve switching are performed by a dedicated microcomputer built for the purpose. The device has been used to provide respiratory gas forcing functions for a program of research in respiratory monitoring.

Control of expiratory time in conscious humans

1995 ◽  
Vol 78 (5) ◽  
pp. 1910-1920 ◽  
Author(s):  
G. F. Rafferty ◽  
J. Evans ◽  
W. N. Gardner
Keyword(s):  
Auditory Feedback ◽  
Respiratory Control ◽  
Open Circuit ◽  
Respiratory Pattern ◽  
Control Mechanisms ◽  
Inspiratory Time ◽  
Expiratory Time ◽  
Small Influence ◽  
Computer Controlled ◽  
End Tidal

Combinations of 17 normal awake humans breathed mildly hyperoxic and hypercapnic gas mixtures via a pneumotachograph into an open circuit. Respiratory pattern was measured for each breath in real time by computer. Use of computer-controlled auditory feedback at a constant end-tidal PCO2 (PETCO2) allowed prolonged changes of 1) inspiratory time (TI) at constant inspired tidal volume (VTI), 2) VTI up and down in repeated steps at constant TI, and 3) expiratory time (TE) at constant VTI. The remaining variables were free to be determined by the subjects' automatic respiratory control mechanisms. We showed that TE changed in parallel with the change in TI despite constant VTI, TE did not change in response to step changes in VTI at constant TI, and large changes in TE had no influence on the subsequent TI, but VTI increased slightly as TE lengthened despite clamping. Time for expiratory flow (TE--end-expiratory pause) changed in parallel with TE in all protocols. Thus, in conscious humans, inspiratory timing has a direct influence on expiratory timing, independent of volume change and chemical drive, but expiratory timing has no influence on the inspiratory timing of the subsequent breath but has a small influence on volume.

Alterations in respiratory control during 8 h of isocapnic and poikilocapnic hypoxia in humans

1995 ◽  
Vol 78 (3) ◽  
pp. 1098-1107 ◽  
Author(s):  
L. S. Howard ◽  
P. A. Robbins
Keyword(s):  
Analysis Of Variance ◽  
Ventilatory Response ◽  
Acute Hypoxia ◽  
Respiratory Control ◽  
Companion Paper ◽  
Tidal Forcing ◽  
Nasal Catheter ◽  
The Subject ◽  
Per Se ◽  
End Tidal

In the preceding companion paper (L. S. G. E. Howard and P.A. Robbins, J. Appl. Physiol. 78: 1092–1097, 1995), we showed that ventilation rises during 8 h of isocapnic hypoxia. In the present study we report the changes that occur in the ventilatory response to acute hypoxia (AHVR) over 8 h of both isocapnic and poikilocapnic hypoxia. Ten subjects completed the study. Each was seated inside a chamber in which the inspired gas could be controlled so as to maintain the desired end-tidal gases (sampled via nasal catheter) constant. Three 8-h protocols were compared: 1) isocapnic hypoxia, at an end-tidal PO2 of 55 Torr with the end-tidal PCO2 held at the subject's resting value; 2) poikilocapnic hypoxia, at the same end-tidal PO2; and 3) control, where the inspired gas was air. AHVR was measured before and at 20 min and 4 and 8 h after the start of the experiment. A sequence of hypoxic square waves and sawtooth inputs was imposed by an end-tidal forcing system, with the subject breathing through a mouthpiece. End-tidal PCO2 was held constant at 1–1.5 Torr above resting. Values for hypoxic sensitivity (Gp; 1.min-1.%-1) and hypoxia-independent ventilation (Vc; l/min) were calculated for each test of AHVR. Both Gp and Vc increased significantly during both hypoxic exposures in relation to control (P < 0.001, analysis of variance). Over the 8-h period, increases in Gp were 87% in isocapnic hypoxia and 44% in poikilocapnic hypoxia, and increases in Vc were 89% in isocapnic hypoxia and 84% in poikilocapnic hypoxia. There were no significant differences between the isocapnic and poikilocapnic exposures. We conclude that Gp and Vc rise mainly as result of hypoxia per se and not the associated alkalosis.

Low-Voltage Variable Gain Current Amplifier for High-Voltage Signal Processing

2009 ◽  
Vol 129 (8) ◽  
pp. 1511-1517
Author(s):  
Nicodimus Retdian ◽  
Jieting Zhang ◽  
Takahide Sato ◽  
Shigetaka Takagi
Keyword(s):  
Signal Processing ◽  
High Voltage ◽  
Low Voltage ◽  
Current Amplifier ◽  
Variable Gain ◽  
Voltage Signal

A Comparison of Physiological Demand between Self-Propelled and Motorized Treadmill Exercise

2018 ◽  
Vol 7 (4) ◽  
pp. 13-21
Author(s):  
Todd Backes ◽  
Charlene Takacs
Keyword(s):  
Respiratory Exchange Ratio ◽  
Treadmill Exercise ◽  
Cardiopulmonary Exercise Testing ◽  
Mean Value ◽  
The Self ◽  
Mixing Chamber ◽  
Wide Range ◽  
The Subject ◽  
The Mean ◽  
Computer Controlled

There are a wide range of options for individuals to choose from in order to engage in aerobic exercise; from outdoor running to computer controlled and self-propelled treadmills. Recently, self-propelled treadmills have increased in popularity and provide an alternative to a motorized treadmill. Twenty subjects (10 men, 10 women) ranging in age from 19-23 with a mean of 20.4 ± 0.8 SD were participants in this study. The subjects visited the laboratory on three occasions. The purpose of the first visit was to familiarize the subject with the self-propelled treadmill (Woodway Curve 3.0). The second visit, subjects were instructed to run on the self-propelled treadmill for 3km at a self-determined pace. Speed data were collected directly from the self-propelled treadmill. The third visit used speed data collected during the self-propelled treadmill run to create an identically paced 3km run for the subjects to perform on a motorized treadmill (COSMED T150). During both the second and third visit, oxygen consumption (VO2) and respiratory exchange ratio (R) data were collected with COSMED’s Quark cardiopulmonary exercise testing (CPET) metabolic mixing chamber system. The VO2 mean value for the self-propelled treadmill (44.90 ± 1.65 SE ml/kg/min) was significantly greater than the motorized treadmill (34.38 ± 1.39 SE ml/kg/min). The mean R value for the self-propelled treadmill (0.91 ± 0.01 SE) was significantly greater than the motorized treadmill (0.86 ± 0.01 SE). Our study demonstrated that a 3km run on a self-propelled treadmill does elicit a greater physiological response than a 3km run at on a standard motorized treadmill. Self-propelled treadmills provide a mode of exercise that offers increased training loads and should be considered as an alternative to motorized treadmills.

scholarly journals The third form electric organ discharge of electric eels

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jun Xu ◽  
Xiang Cui ◽  
Huiyuan Zhang
Keyword(s):  
High Voltage ◽  
Low Voltage ◽  
Electric Organ Discharge ◽  
Electric Organ ◽  
The Third ◽  
Electric Organs ◽  
Electric Eel ◽  
New Finding ◽  
Discharge Behavior ◽  
Unique Species

AbstractThe electric eel is a unique species that has evolved three electric organs. Since the 1950s, electric eels have generally been assumed to use these three organs to generate two forms of electric organ discharge (EOD): high-voltage EOD for predation and defense and low-voltage EOD for electrolocation and communication. However, why electric eels evolved three electric organs to generate two forms of EOD and how these three organs work together to generate these two forms of EOD have not been clear until now. Here, we present the third form of independent EOD of electric eels: middle-voltage EOD. We suggest that every form of EOD is generated by one electric organ independently and reveal the typical discharge order of the three electric organs. We also discuss hybrid EODs, which are combinations of these three independent EODs. This new finding indicates that the electric eel discharge behavior and physiology and the evolutionary purpose of the three electric organs are more complex than previously assumed. The purpose of the middle-voltage EOD still requires clarification.

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