Modeling of the Physiological Responses to Non-Linear G-suit and Positive Pressure Breathing Schedules


  1. Fraser, W.D.
  2. Lu, Z.
  3. Askari, V.
  4. Kapps, A.
Corporate Authors
Defence and Civil Inst of Environmental Medicine, Downsview ONT (CAN)
Heart level blood pressure responses to G-suit pressures (2-8 psi) with and without Positive Pressure Breathing (5-60 mm Hg) at +1Gz were investigated in this paper for six test subjects. Various models were developed and tested to simulate these responses. The results show that a single-zero, two-pole, output-error model is suitable for characterizing the blood pressure responses to G-suit and Positive Pressure Breathing (PPB) pressures. A single-input model is used for the case of G-suit pressure with and without synchronized PPB, whereas a double-input model is used for the case of G-suit pressure with asynchronic PPB. The suitability of the models developed to high +Gz environment is investigated based on the data from a prior centrifuge test of one subject. Special dynamic indices are used to quantify the characteristics the blood pressure responses. Significant variations in the dynamic indices of individual subjects and the same subject observed at different time instances are seen. These variations indicate that a fixed standard G-suit pressure schedule might not necessarily be capable of providing adequate Anti-G protection for all subjects and even for the same subject at different time instances. The models developed in this paper can be used in an adaptive feedback control system for real-time identification and update of subject's Anti-G protection requirements. TRUNCATED
Positive Pressure Breathing (PPB);Anti-G suits;G-suits
Report Number
DCIEM-98-P-89 — Paper
Date of publication
01 Mar 1999
Number of Pages
Hardcopy;Document Image stored on Optical Disk

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