Elizondo L L, Doerr D F, Sims M A, Hoffler G W, Convertino V A
Clinical Science Division, Brooks Air Force Base, TX 78235-5117, USA.
Aviat Space Environ Med. 1996 Apr;67(4):344-50.
The purpose of this study was to determine the effectiveness of a USAF anti-gravity suit (G-suit) on the stability of a patient with chronic orthostatic hypotension.
A 37-yr-old female with a history of insulin-dependent diabetes mellitus (IDDM) and symptomatic orthostasis was evaluated and the results were compared with those of non-diabetic controls, matched for age, height, and weight. Cardiac vagal tone was assessed by determination of standard deviation of 100 R-R intervals (R-R SD). We assessed the carotid-cardiac baroreflex response by plotting R-R intervals (ms) at each of eight neck pressure steps with their respective carotid distending pressures (mm Hg). Heart rate and blood pressure were recorded in response to the Valsalva maneuver (VM) performed at an expiratory pressure of 30 mmHg to assess integrated baroreflex responses. Blood pressures and heart rate were measured during three 5-min stand tests to assess orthostatic responses: a) without G-suit; b) with noninflated G-suit; and c) with inflated G-suit (50 mm Hg).
The IDDM patient had minimal baseline cardiac vagal tone (R-R SD = 8.5 ms) compared with the average response of a control group of 24 subjects with orthostatic stability (R-R SD = 67.2 +/- 7.1 ms). Carotid-cardiac baroreflex response was virtually non-existent in the IDDM patient (Gain = 0.06 ms.mm Hg-1) compared to the control subjects (4.4 +/- 0.8 ms.mm Hg-1). VM responses corroborated the lack of cardiac baroreflex response in the IDDM patient, while blood pressure changes during the VM were similar to those of the controls. Upon standing, the IDDM patient demonstrated severe orthostatic hypotension (90 mm Hg SBP) and tachycardia without the G-suit. The G-suit, with and without pressure, reduced hypotension and tachycardia during standing.
These results demonstrate successful application of Air Force technology as a useful alternative to pharmacologic intervention in the treatment of a patient with autonomic dysfunction leading to supine hypertension and orthostatic hypotension.
本研究的目的是确定美国空军抗荷服（G 服）对慢性直立性低血压患者稳定性的有效性。
对一名 37 岁、有胰岛素依赖型糖尿病（IDDM）病史且有症状性直立性低血压的女性进行评估，并将结果与年龄、身高和体重相匹配的非糖尿病对照组进行比较。通过测定 100 个 R-R 间期的标准差（R-R SD）来评估心脏迷走神经张力。通过绘制八个颈部压力水平下各自的颈动脉扩张压力（毫米汞柱）对应的 R-R 间期（毫秒）来评估颈动脉-心脏压力反射反应。在呼气压力为 30 毫米汞柱时进行瓦尔萨尔瓦动作（VM）以评估综合压力反射反应，记录心率和血压。在三次 5 分钟站立试验中测量血压和心率以评估直立性反应：a）不穿 G 服；b）穿未充气的 G 服；c）穿充气的 G 服（50 毫米汞柱）。
与 24 名具有直立稳定性的对照组受试者的平均反应（R-R SD = 67.2±7.1 毫秒）相比，IDDM 患者的基线心脏迷走神经张力极小（R-R SD = 8.5 毫秒）。与对照组受试者（4.4±0.8 毫秒/毫米汞柱）相比，IDDM 患者的颈动脉-心脏压力反射反应几乎不存在（增益 = 0.06 毫秒/毫米汞柱-1）。VM 反应证实了 IDDM 患者缺乏心脏压力反射反应，而 VM 期间的血压变化与对照组相似。站立时，IDDM 患者在不穿 G 服时表现出严重的直立性低血压（收缩压 90 毫米汞柱）和心动过速。G 服无论是否充气，在站立期间均可减轻低血压和心动过速。
这些结果表明空军技术成功应用于治疗导致仰卧位高血压和直立性低血压的自主神经功能障碍患者，是药物干预的一种有用替代方法。
