Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Gravity Suits”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8Linked to original sources
PubMed1979

Evaluation of assisted positive pressure breathing on +Gz tolerance.

The effect of both assisted and unassisted positive pressure (PPB) breathing on +Gz tolerance was evaluated. A GOR (gradual onset rate = 0.1 G/s) acceleration profile was used to evaluate five different experimental conditions: 1) G-suit-only, 2) G suit + unassisted PPB, 3) G suit + PPB assisted by the English jerkin, 4) G suit + PPB assisted by the Canadian waistcoat, and 5) the Swedish counterpressure garment G suit combination. Acceleration tolerances for these experimental conditions (excluding the Swedish garment) with the subjects performing M-1 maneuvers were measured using an exhaustive ACM (Aerial Combat Maneuvers) acceleration profile. GOR tolerances were similar for both assisted and unassisted PPB with the pressure breathing experimental conditions providing a significant GOR tolerance increase over the G suit only condition. Assisted PPB increased ACM tolerances over both unassisted PPB and G suit only conditions. It appears that assisted PPB may offer a practical method for reducing the fatigue associated with exposure to high G.

Aerospace Medicine↗
PubMed1983

Effect of altitude change on MAST suit pressure.

Transport of patients involving changes in altitude has become commonplace in the treatment of trauma patients. Often these patients are treated with medical antishock trouser (MAST) suits initially and during transport. The effects of altitude changes on the pressures generated in MAST suits were systematically investigated. Jobst Standard Antishock Air Pants were applied to the lower half of a Resusci-Anne dummy and inflated to 30 mm Hg of pressure. In a simulation of patient transport, the inflated MAST suit and dummy were placed in a helicopter and ascended from 2,500 feet to 9,500 feet. Pressures increased to 84, 87, and 87 mm Hg in three separate trials. Intermittent MAST suit pressure readings at 1,000-foot increments in altitude showed a positive linear relationship. Three descending trials, in which the MAST suit was inflated to 60 mm Hg at 9,500 feet and the helicopter descended to 2,500 feet, were also done. Pressures dropped to 7, 8.5, and 8 mm Hg in the three trials. A positive second order relationship between MAST suit pressure and altitude was noted for the descending trials. It was concluded that MAST suit pressure is a function of altitude. Emergency medicine personnel should be aware of this, and should monitor patients accordingly when transporting through changes in altitude.

Altitude↗
PubMed1988

The antigravity suit in neurosurgery. Cardiovascular responses in seated neurosurgical patients.

The haemodynamic responses associated with inflation of the antigravity suit (G suit, aviation type) to 8.0 kPa were studied in a series of 40 patients who underwent neurosurgical operations in the sitting position. The study showed statistically significant increases in systolic arterial pressure (p less than 0.005) and mean central venous pressure (p less than 0.001) with inflation of the suit. The systolic arterial and mean central venous pressures remained significantly elevated immediately before deflation of the suit at the end of the operation (p less than 0.001 and p less than 0.005 respectively). The addition of 0.8-1.0 kPa positive end expiratory pressure during suit inflation was also investigated. A further increase in central venous pressure occurred but this did not achieve statistical significance.

Adult↗
PubMed1976

Physiological effects of sustained acceleration.

A review is given of the literature concerning the physiological and pathophysiological changes in humans, caused by sustained acceleration. After definition of the acting forces and an introduction into terminology, circulatory and respiratory mechanisms are described which are active under sustained acceleration. The origin of visual disturbances associated with acceleration is discussed. Acceleration tolerance is influenced by magnitude, duration, direction, and rate of application of G-forces together with environmental conditions and the condition of the subject. Acceleration protection may be achieved by technical devices (anti-g suits), voluntary manoeuvres and change of posture. Recent work dealing with high sustained +Gz (HSG) is reviewed and the associated problems are discussed.

Acceleration↗
PubMedDate not supplied

[Theoretical analysis of the efficacy of G suits during exposure to continuously increasing gravitational overloads].

A mathematical model of human circulation was employed to examine circulation responses to +GZ acceleration the value of which increased linearly at the rate 0.1 G/sec, using subjects having an anti-G suit on and sitting in a relaxed posture. It has been calculated that the anti-G suit can compensate as much as 83% of the increment of hydrostatic pressure in leg vessels and as much as 57% in abdominal vessels. The suit effect on resistance and capacity vessel properties makes an approximately equal contribution to an increase of the acceleration tolerance threshold. However the occlusion effect of the anti-G suit causes a significant increase of afterload.

Acceleration↗
PubMed1983

Antishock trouser inflation and pulmonary vital capacity.

Two models of antishock trousers were studied for the effect of their inflation on the pulmonary function of 20 healthy men. Vital capacity was measured for each model at pressures of 0, 30, 60, and 100 mm Hg. The antishock suit with the abdominal compartment extending over the entire abdomen decreased the vital capacity 13.8% with inflation to a pressure of 100 mm Hg. The antishock suit with a smaller abdominal compartment, considered the standard model, decreased vital capacity only 5% at the same pressure.

Adult↗
PubMed1984

George W. Crile: the pneumatic rubber suit.

Military antishock trousers (MAST) have been used in emergency care for only a little more than a decade. However, the initial report of the medical use of an inflatable compression garment appeared in 1903, when George W. Crile utilized a pneumatic rubber suit to augment the blood pressure of patients undergoing head and neck surgery. Technical difficulties occasionally produced precipitous deflation of the garment, but Crile maintained that the device was otherwise free of adverse effects. Since then, a number of complications have been ascribed to the suit, including reduction of vital capacity, metabolic acidosis, skin necrosis, renal failure, vascular thrombosis, and fascial compartment syndrome. None of these have occurred with sufficient frequency to substantially restrict the use of the suit. The mechanism by which the pneumatic garment produces an elevation in blood pressure-ascribed by Crile to elevation of peripheral resistance-continues to be a subject for research.

Animals↗
PubMed1979

Definitive control of bleeding from severe pelvic fractures.

Forty patients with severe pelvic fracture and extraperitoneal hemorrhage were reviewed. Eighteen patients seen prior to 1975 (group I) were clinically similar to 22 patients seen subsequently (group II). Major pelvic fracture hemorrhage was defined as bleeding in excess of 2,000 ml over and above initial resuscitation volumes. Ten of 22 group II patients met the criteria for continued extraperitioneal bleeding and were immobilized in an inflatable G-suit after surgically remediable lesions had been excluded. Ventilator support and hemodynamic monitoring were instituted and clinical response recorded. Prompt cessation of bleeding was observed in nine of ten patients. One patient required selective catheterization of a bleeding artery with subsequent embolic occlusion. Significant reductions in overall mortality and the frequency of shock related death were observed in group II patients. Sepsis was the leading cause of late death in survivors. Immobilization of pelvic fracture patients in the G-suit is recommended as a means of controlling continuing retroperitoneal hemorrhage when surgically correctable bleeding points have been dealt with. Failure of patients to respond promptly to the G-suit strongly suggests arterial bleeding amenable to selective catheterization and embolic occlusion.

Adolescent↗
PubMed1994

Cardiovascular responses with standard and extended bladder coverage G-suits during rapid decompression.

This study compared the cardiovascular responses of subjects exposed to 60,000 ft. rapid decompressions while wearing the Combined Advanced Technology Enhanced Design "G" Ensemble (COMBAT EDGE or CE) and the Tactical Life Support System (TLSS). Eight subjects were rapidly decompressed from 22,500 ft (6,858 m) to 60,000 ft (18,288 m), once wearing the CE ensemble and once wearing the TLSS ensemble. There were significant differences in heart rate, stroke volume, cardiac index, and mean arterial pressure (p < 0.0001), due to garment type, with TLSS providing better cardiovascular support. Oxygen saturation did not decrease to the same degree with CE as with TLSS (p < 0.0001). Both TLSS and CE provided sufficient physiological support to maintain oxygen saturations above 65% during the 3-min exposures to 60,000 ft altitude. Short-term physiological support at higher altitudes with greater PPB levels or longer duration excursions at 60,000 ft may not be possible without the greater G-suit bladder coverage and cardiovascular support provided by TLSS-type garments.

Adult↗
PubMed1976

Effect of sequential anti-G suit inflation on pulmonary capillary blood flow in man.

The hemodynamic effects of an anti-G suit, sequentially filled from below upward (M-aG), were compared to those of the standard USAF anti-G suit (S-aG) in 10 men supine and under +1 Gz stress produced by 90 degrees head up passive tilt. S-aG was found to fill from the abdominal bladder downward. The heart rate and the pulmonary capillary blood flow (Qc), as estimated by a nitrous oxide plethysmographic method, were used as criteria of effectiveness. Heart rate did not vary between the suits during the supine and upright studies. In the supine position, the first M-aG inflation induced a significant increase of Qc, 2.5 1 min above the Qc of the S-aG inflation. After 90 degrees head up tilt, M-aG inflation as associated with a significant increase of Qc, 1.7 1 min greater than the Qc produced by S-aG inflation. Since leg bladder inflation may play a critical role in high-G tolerance, the sequential filling from below upward of the anti-G suit may further increase the G protection compared to the standard garment. In addition, the modified anti-G suit may be a useful device for treatment of circulatory shock and postural hypotension when the venous return is decreased.

Acceleration↗
PubMed1994

[Amniotic embolism with favourable outcome].

A 31-year-old multiparous pregnant woman forced into labour with oxytocin, suffered a sudden circulatory collapse and, after the birth of her child, a defibrination syndrome with uterine haemorrhage. In the absence of a local cause, either placental or cervico-uterine, a diagnosis of amniotic fluid embolism was made. The time course was favourable, mainly thanks to the absence of acute pulmonary cardiogenic oedema and to the use of an anti-shock G suit. The authors point out the lack of actual in vivo paraclinical means for confirming the diagnosis.

Adult↗
PubMed1992

Cardiovascular responses to positive pressure breathing using the tactical life support system.

The improved protection afforded by the Tactical Life Support System (TLSS) vs. other partial pressure ensembles has not been reported with respect to the cardiovascular effects of positive pressure breathing (PPB). Nine seated subjects wearing TLSS were exposed to 30, 50, and 70 mm Hg PPB (breathing air) with four times this pressure in the G-suit. Experiments were conducted at ground-level in order, separated by 4 min rest and preceded by a 1-min control period. Stroke volume and cardiac output (SV, CO) and indexes (SI, CI) were determined by impedance cardiography. Mean arterial pressure (MAP) was directly related to PPB level, increasing by 23%, 32%, and 47% for each PPB level, respectively (p less than 0.01). HR, SV, and CO were unaffected after 4 min of 30, 50, and 70 mm Hg PPB. The results indicate that cardiovascular function decay is less severe than that reported using other PPB ensembles at similar PPB levels. Improved protection is most likely due to the greater pressurization of the G-suit and the 45% greater bladder volume in the leg bladders, leading to restored venous return and SV.

Adult↗
PubMed1980

Respiratory gas exchange during positive pressure breathing and rapid decompression to simulated altitudes of 18.3 and 24.4 km.

Respiratory gas exchange was studied, using the technique of mass spectrometry, during events of slow and rapid decompression of human subjects to simulated altitudes of 60,000 and 80,000 ft (18.3 and 24.4 km, respectively). Positive breathing pressures and G-suit counterpressures were employed in three series of decompression experiment. Low levels of inspired carbon dioxide and nitrogen reflected the rebreathing of gases throughout the experiments. Application of a positive breathing pressure of 70 torr, accompanied by a jerkin pressure equal to breathing pressure and a G-suit counterpressure of four times the breathing pressure on the trunk and limbs, respectively, maintained alveolar oxygen at physiologically safe levels during decompression to 60,000 ft (18.3 km) altitude. Similarly, 80 torr positive breathing pressure, in combination with four times the breathing pressure in the G suit, adequately satisfied the requirements for oxygen during rapid decompression to 80,000 ft (24.4 km) simulated altitude.

Aerospace Medicine↗
PubMed1998

Male/female SACM endurance comparison: support for the Armstrong Laboratory modifications to the CSU-13B/P anti-G suit.

BACKGROUND: The standard anti-G suit (CSU-13B/P) was designed based on male body structure. Females differ from males with respect to body proportionality. In Armstrong Laboratory (AL) studies, females have terminated centrifuge simulated air combat maneuvers (SACM) because of anti-G suit (CSU-13B/P modified according to original T.O. 14P3-6-121)(OTO) discomfort. AL modifications to the suit have since been adopted in the OTO in an attempt to provide females a best-fit suit (AL Mod). The study examined male/female SACM endurance with females wearing both the OTO and the AL Mod suits. METHODS: There were 6 females and 8 males who performed a +5.0 to +9.0 Gz SACM to fatigue using the anti-G straining maneuver with anti-G suit inflation. The females performed in both the OTO and AL Mod suits while the males performed in the OTO suit only (OTO was their best-fit suit). RESULTS: Wearing the OTO, males performed the SACM significantly longer than the females, three of whom reported severe suit discomfort. However, when the females wore the AL Mod suit, their SACM endurance almost doubled over their OTO performance and none reported suit discomfort. When wearing their best-fit suits, there was no significant gender difference in SACM endurance. CONCLUSIONS: These data support the efficacy of the AL modifications to the CSU-13B/P anti-G suit through greatly improved performance during the +5.0 to +9.0 SACM in females. These data also suggest that, in the small sample examined, when fitted with a best-fit anti-G suit, females can endure the +5.0 to +9.0 SACM to the same degree as males.

Acceleration↗
PubMedDate not supplied

[The antigravity suit, chamberless type, as a means of increasing orthostatic tolerance after water immersion hypokinesis and acceleration].

Orthostatic tolerance after 7-day dry immersion and head-to-feet acceleration was investigated on test subjects with and without an antigravity suit of bladderless type. With the suit on, the 20 min tilt test at 70 degrees prior to immersion induced less marked changes than without the suit. When the suit was on, cardiovascular reactions to tilt tests after immersion and acceleration improved. The maximum heart rate decreased from 135 +/- 4 to 101 +/- 5 beats/min (p less than 0.01), minimum stroke volume increased from 29 +/- 2 to 41 +/- 3 ml (p less than 0.05), and pulse pressure grew. Thus, an antigravity suit may help increase initial orthostatic tolerance and maintain it after the combined effect of simulated hypogravity and acceleration.

Acceleration↗
PubMed1986

Application of the medical anti-shock trouser (MAST) increases cardiac output and tissue perfusion in simulated, mild hypovolaemia.

We have studied the haemodynamic effects of the application of the medical anti-shock trouser (MAST) in 10 healthy subjects in the semi-upright position in order to simulate mild hypovolaemia. Left ventricular end diastolic dimension (EDD) was measured by M-mode echocardiography and cardiac output (CO) by the Doppler ultrasound technique. Forearm blood flow (FBF) was measured by plethysmography and blood pressure (BP) by the standard cuff technique. Systematic increases in MAST pressure of up to 80 mm Hg were applied. EDD increased to a maximum of 9.3% (p less than or equal to 0.01) which was associated with a maximum increase in CO of 31.7% (p less than or equal to 0.05). FBF increased by a maximum of 54.2% (p less than or equal to 0.001) whilst BP increased by a maximum of 12% (p less than or equal to 0.001). These results demonstrate that the application of the MAST is an effective means of transferring blood to the central circulation by compression of the capacitance vessels resulting in significant increases in cardiac output and tissue perfusion. At high pressures there was evidence of compression of resistance vessels, which may be useful in reducing blood loss. The ease and rapidity with which his suit can be applied suggests that it may be useful in the short term treatment of hypovolaemia.

Adult↗