Chapter 172

The pneumatic antishock garment (PASG) is commonly used in the prehospital setting to transport patients with hypovolemic shock. It has also been used for nontraumatic causes of hemorrhage (pelvic fractures, ruptured ectopic pregnancy, and ruptured aortic aneurysms) and to stabilize extremity fractures. The most common PASG is the Military/Medical Antishock Trousers (MAST trousers). The PASG was initially designed in 1903 but did not see routine use until the Vietnam War.1

The PASG was primarily used for trauma victims with hypovolemic shock. Several studies have demonstrated an elevation of blood pressure and control of bleeding with the application of the PASG.2,3 The largest series reviewed the use of the PASG in 1120 patients. Approximately 84 percent of these responded with an increase in systolic blood pressure greater than 20 mmHg, a decrease in heart rate, or evidence of enhanced tissue perfusion.4 Recent controlled studies have questioned the efficacy of the PASG, especially in penetrating abdominal injuries and thoracic injuries.5,6 The Advanced Trauma Life Support course sponsored by the American College of Surgeons states that “the efficacy of PASG in-hospital or in the rural setting remains unproven and, in the urban pre-hospital setting, controversial.”7 The criteria for the application of the PASG have been revised and are noted in the “Indications” section below.

The mechanism of action of the PASG has been the focus of numerous experimental studies. The increase in blood pressure from the application of the PASG is due to enhanced venous return (autotransfusion), increased total peripheral vascular resistance, and reduced volume loss from hemorrhage control. Recent studies have demonstrated that the patient receives only a 4 mL/kg autotransfusion effect from the inflated PASG.8 Previous studies had suggested an autotransfusion up to 2000 mL.9

The predominant effect of the PASG is an increase in peripheral vascular resistance.10,11 The decreased diameter of blood vessels under the suit leads to increased preload, improved stroke volume, and increased cardiac output. This temporarily improves cerebral and coronary blood flow.

Control of hemorrhage is the third effect of the PASG. The compressive effect decreases blood flow, minimizes tears in the vessels, and allows clot formation to occur. Use of the PASG has been recommended as part of the initial management of major pelvic fractures prior to definitive intervention.12 The PASG offers several advantages in the treatment of pelvic fractures.12,13 It compresses the pelvic area and tamponades bleeding, immobilizes pelvic fractures, reduces bony displacement, and improves pelvic bone alignment. The PASG has been used in nontraumatic pelvic hemorrhage in the obstetric and gynecologic patient.13 Hemostasis is likely a result of the compressive effect on the blood vessels under the garment.

There are no absolute indications for the use of the PASG. Its original use as an adjunct to support a failing circulatory system still holds, even though it may ...

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