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首页> 外文期刊>Aviation, space, and environmental medicine. >G-protection mechanisms afforded by the anti-G suit abdominal bladder with and without pressure breathing.
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G-protection mechanisms afforded by the anti-G suit abdominal bladder with and without pressure breathing.

机译：带有和不带有压力呼吸的抗G服腹部膀胱提供的G保护机制。

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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.
机译：背景：气动抗G服的腹部膀胱提供的G保护作用通常归因于G引起的心脏心脏移位和腹腔静脉血积的反作用。该研究检查了腹部膀胱是否还可以通过其他机制提供G保护。方法：每位受试者在放松坐下时都暴露于+ Gz负荷下，穿着全身覆盖的抗G服，改良后可分别对腹部和腿部膀胱加压。在两个实验系列（N = 8，N = 14）中，受试者以气道正压（PPB）呼吸。在第三系列中，五名受试者在大气压下呼吸。胸腔内压力通过食管导管估计。结果：在高G负荷下PPB期间，有腹腔压力高于无加压腹腔的情况。在14位受试者中，有7位在给腹部膀胱加压时PPB期间，基底胸腔内压力超过了气道压力。在高G负荷下，该受试者亚组（55 +/- 23 mmHg）的平均动脉压反应高于气道压力超过胸腔内压力（41 +/- 27 mmHg）的受试者。在没有增加G负荷的情况下，如果没有PPB，有压力的情况下的胸腔内压力梯度要比没有压力的膀胱要高。讨论：在PPB期间，腹腔膀胱起到气道反压的作用，从而促进压力从气道传递到胸腔，从而改善对G的保护。还似乎在几个人中，压力可能从腹部膀胱传递到胸腔和心脏。

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