The Space Activity Suit: An Elastic Leotard for Extravehicular Activity

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Fig. 3. Lateral trunk flexion in the 60 mm.Hg assembly.

to write on a tablet, to fasten and unfasten Swagelok connectors and other small items of hardware and to operate the controls of an oscilloscope, electronic amplifiers, and similar laboratory instrument None of these requests caused any great problem al-though the cloth of the gloves reduced his tactile sense, as would any cloth glove of equal weight. There was no striking diminution of dexterity because of the elastic garment.

These simple tests of mobility and dexterity are sufficient to show that the SAS is qualitatively different from full pressure suits and partial pressure suits.

Circulatory Effects—Positive pressure breathing was adjusted to match the applied elastic counterpressure of the prototype garments, namely 30 mm.Hg with a, single layer, 60 mm.Hg with two layers, and 100 mm.Hg with the three layer assembly. In the four different wearing trials the subject was usually quite active. However, in one portion of the 90-minute trial at 60 mm.Hg pressure, the subject was purposely kept still in a vertical position to see whether blood pooling was a specific problem. For 15 minutes the subject leaned against the ladder at an angle of 70° from horizontal, and he was asked to relax and remain as quiet as possible. This was intended to be an exaggerated duplication of the conditions leading to parade ground faint. There was no noticeable change in pulse rate; the subject felt perfectly well and the blood pres­sure measurements did not change during this period.

Blood pressure measurements showed that the ar­terial pressure increased in the amount that positive pressure breathing was applied. Our subject normally had a standing resting arterial pressure of 130/85. With one suit layer and 30 mm.Hg of PPB the read­ing was 170/125. With 60 mm.Hg positive pressure and a 60 mm. garment assembly, his standing resting pressure was 180/150. With 100 mm.Hg PPB and elastic pressure applied, his standing resting pressure was 230/180.

Fig. 4. Climbing an extension ladder in the 60 mm.Hg as­sembly.

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