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Physiological considerations concerning positive pressure breathing (PBG) during +Gz
J M Clere1, G Ossard, F Melchior
1Laboratoire de Medecine Aerospatiale, Centre D'Essais en Vol, Bretigny-sur-Orge, France.
The Physiologist
|February 1, 1993
Summary
Maintaining head arterial pressure is key to tolerating high G-force acceleration and preventing G-induced loss of consciousness (G-LOC). Positive pressure breathing (PPB) may help increase blood pressure to the brain during these exposures.
Area of Science:
- Aerospace Medicine
- Human Physiology
- Cardiovascular Regulation
Background:
- High Gz acceleration poses risks like blackout and G-induced loss of consciousness (G-LOC).
- Hydrostatic effects during acceleration reduce blood flow to the brain.
- Maintaining arterial pressure at head level is crucial for tolerance.
Purpose of the Study:
- To review methods for increasing arterial pressure to enhance Gz tolerance.
- To provide an overview of positive pressure breathing (PPB) and its effects.
- To discuss the side effects of PPB in the context of Gz acceleration.
Main Methods:
- Literature review of physiological responses to Gz acceleration.
- Analysis of methods to counteract hydrostatic pressure effects.
- Examination of positive pressure breathing (PPB) as a countermeasure.
Main Results:
- Elevating arterial pressure at heart level is essential for cerebral blood flow during Gz exposure.
- Shortening the heart-to-head blood column or increasing heart-level pressure are key strategies.
- Positive pressure breathing (PPB) is explored as a method to increase arterial pressure.
Conclusions:
- Understanding methods to increase arterial pressure is vital for improving Gz tolerance.
- Positive pressure breathing (PPB) is a potential countermeasure with associated side effects.
- Further research into optimizing PPB and other methods is warranted for aviation safety.