APPLICATION OF USAF G-SUIT TECHNOLOGY FOR CLINICAL ORTHOSTATIC HYPOTENSION - A CASE-STUDY

Introduction: The purpose of this study was to determine the effective ness of a USAF anti-gravity suit (G-suit) on the stability of a patien t with chronic orthostatic hypotension. Methods: A 37-yr-old female wi th a history of insulin-dependent diabetes mellitus (IDDM) and symptom atic orthostasis was evaluated and the results were compared with thos e of non-diabetic controls, matched for age, height, and weight. Cardi ac vagal tone was assessed by determination of standard deviation of 1 00 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). Hea rt rate and blood pressure were recorded in response to the Valsalva m aneuver (VM) performed at an expiratory pressure of 30 mmHg to assess integrated baroreflex responses. Blood pressures and heart rate were m easured 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). Results: The IDDM patient had minimal baseline card iac 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 = 6 7.2 +/- 7.1 ms). Carotid-cardiac baroreflex response was virtually non -existent in the IDDM patient (Gain = 0.06 ms . mm Hg-1) compared to t he control subjects (4.4 +/- 0.8 ms . mm Hg-1). VM responses corrobora ted the lack of cardiac baroreflex response in the IDDM patient, while blood pressure changes during the VM were similar to those of the con trols. 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 d uring standing. Conclusion: These results demonstrate successful appli cation of Air Force technology as a useful alternative to pharmacologi c intervention in the treatment of a patient with autonomic dysfunctio n leading to supine hypertension and orthostatic hypotension.