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PREDICTIVE STUDIES VII (PS VII): Interactions of Hyperoxia, Exercise, and Immersion in Neurologic O2 Poisoning.
Major Category: Oxygen toxicity and oxygenation. Immersion. Exercise. (PS VII)
Subcategory 6: Development of on-line methods for measuring/monitoring physiological responses in fully immersed Subjects.

Stressors: N/A

Date: 1993

Expt. Title: Adaptation of Transcranial Doppler, EKG, impedance cardiograph, arterial blood sampling, control of bicycle ergometer pedaling rate and end-tidal PCO2 for measurement in fully immersed Subjects (Expt. 13.01).

Description:

A special computer program was developed to provide continuous data acquisition to an accessory computer from the Transcranial Doppler machine (not provided by manufacturer). Other programs were developed to playback, process and analyze the recorded data. Initial efforts to employ the Transcranial Doppler on immersed Subjects were unsuccessful. An initial problem involved a patient monitor (Siemens) used to acquire the EKG from the immersed subject. When the monitor was turned on, the TCD signals were completely obliterated. The problem was apparently due to digital signal processing within the unit’s electronics: emitted pulses from the monitor were sensed by the Transcranial Doppler’s electronics. This problem was resolved by using a simple analog EKG preamplifier to acquire the EKG. Another major problem was related to transmission and reception of doppler signals from moving water and air-water interface by the rear of the immersed doppler probe. Stabilization of the probe to the subject’s head in the face of subject and water movement had to be resolved. Audio feedback of pedal rate to the subject had to be developed, since visual feedback was not possible (facemask or goggles could not be employed). Special measures were taken to make possible acquisition of arterial blood samples and the EKG from immersed Subjects. No such measures were required for acquisition of impedance cardiograph signals during immersion.

07 February 2000 11:08:00 AM