Servo-controlled air pump for calibration of respiratory measurement systems.

We describe a servo-controlled piston pump driven by a stepping motor. The analogue controller is a single non-linear second-order feedback loop with adjustable speed and acceleration limits. This system, designed to simulate slowly-moving, active and non-linear systems, can be used as a low (0-6.

Automatic monitoring of breath-to-breath occlusion pressure and ventilatory parameters during CO2 rebreathing.

A computerized system for occlusion pressure measurement during a rebreathing test is described. The system is implemented on an Apple II microcomputer. A set of programs allows calibration, data acquisition during the experiment, and fast automatic processing of the various parameters of ventilation and occlusion pressure versus end tidal PCO2.

Effects of droperidol on respiratory drive in humans.

The sensitivity of the respiratory center following a single 0.3 mg X kg-1 iv dose of droperidol was determined in eight healthy volunteers by using carbon dioxide (CO2) rebreathing and mouth occlusion pressure measurements (P0.1).

Nonlinear fluid systems identified by random noise input.

The usual impedance measurement by Fourier analysis leads to undetectable errors when applied to nonlinear fluid systems where a nonlinear pressure drop p = K X V2 adds to the linear pressure-flow relationship, but processing series of impedance data with various input levels allows the measurement of such systems. This new method has been tested on simulations, nonlinear resistances, and intubation tubings. It gives accurate estimates of the nonlinear coefficient K together with the true linear impedance of the measured system.

Depression of respiratory drive by diazepam as premedication.

The respiratory effects of premedication with i.v. injection of diazepam have been assessed in 10 healthy patients awaiting minor operative procedures.