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G-protection mechanisms afforded by the anti-G suit abdominal bladder with and without pressure breathing.
KTH, School of Technology and Health (STH), Environmental Physiology.
KTH, School of Technology and Health (STH), Environmental Physiology.
KTH, School of Technology and Health (STH), Environmental Physiology.
2011 (English)In: Aviation, Space and Environmental Medicine, ISSN 0095-6562, E-ISSN 1943-4448, Vol. 82, no 10, 972-7 p.Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: G protection afforded by the abdominal bladder of a pneumatic anti-G suit is usually attributed to counteraction of G-induced caudad displacement of the heart and pooling of blood in the abdominal veins. The study examined whether the abdominal bladder might provide G protection also via other mechanisms.

METHODS: Each subject was exposed to +Gz loads while sitting relaxed, wearing a full-coverage anti-G suit modified to permit separate pressurization of the abdominal and leg bladders. In two experimental series (N = 8, N = 14), subjects were breathing at positive airway pressure (PPB); in a third series, five subjects were breathing at atmospheric airway pressure. Intrathoracic pressures were estimated by use of esophageal catheters.

RESULTS: During PPB at high G loads, intrathoracic pressure was higher with than without the pressurized abdominal bladder. In 7 of the 14 subjects, basilar intrathoracic pressure exceeded airway pressure during PPB when the abdominal bladder was pressurized. The mean arterial pressure response at high G loads was higher in this subset of subjects (55 +/- 23 mmHg) than in the subjects in whom airway pressure exceeded intrathoracic pressure (41 +/- 27 mmHg). Without PPB at increased G load, the intrathoracic pressure gradient was higher with than without the pressurized abdominal bladder.

DISCUSSION: During PPB, the abdominal bladder acts as an airway counterpressure, thereby facilitating pressure transmission from the airways to the thorax and hence improving G protection. It also appears that in several individuals, pressure may be transmitted from the abdominal bladder to the thorax and heart.

Place, publisher, year, edition, pages
2011. Vol. 82, no 10, 972-7 p.
Keyword [en]
anti-G suit, G load, G tolerance, transdiaphragmal pressure, transpulmonary pressure
National Category
Physiology
Identifiers
URN: urn:nbn:se:kth:diva-44489DOI: 10.3357/ASEM.3058.2011ISI: 000295187000007PubMedID: 21961402Scopus ID: 2-s2.0-80054787870OAI: oai:DiVA.org:kth-44489DiVA: diva2:450728
Note
QC 20111021Available from: 2011-10-21 Created: 2011-10-21 Last updated: 2017-12-08Bibliographically approved

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