Military anti-shock trousers

Military Anti-Shock Trousers (MAST), also known as pneumatic anti-shock garments (PASG), are a specialized medical device used in the pre-hospital and emergency care settings. Their primary function is to stabilize patients who are experiencing severe hypotension (low blood pressure), particularly in cases of traumatic shock, by applying even pressure to the lower body and abdomen. This pressure helps in maintaining blood flow to the vital organs, especially the heart and brain, by counteracting the effects of shock on the body's circulatory system.

History

The concept of applying external pressure to the lower body to improve circulation and blood pressure in shock patients has been explored since the Korean and Vietnam wars. The development of MAST was a significant advancement in emergency medical care, particularly in the military context, where it was used to stabilize soldiers with traumatic injuries during transport to medical facilities. Over time, the use of MAST has expanded into civilian emergency medical services (EMS) for managing various types of shock, including hemorrhagic shock resulting from severe blood loss.

Design and Function

Military Anti-Shock Trousers consist of inflatable compartments that wrap around the patient's legs and abdomen. These compartments are connected to a pump that allows emergency medical technicians (EMTs) or paramedics to inflate them with air to a prescribed pressure. The inflation of these compartments exerts external pressure on the lower body, which can help to reduce bleeding and promote the return of blood to the central circulation, thereby improving blood pressure and circulation to critical organs.

Indications

MAST are primarily indicated for use in patients experiencing shock due to:

• Hemorrhage: Severe blood loss from traumatic injuries or internal bleeding
• Pelvic fractures: Stabilization of pelvic fractures to reduce hemorrhage
• Other conditions leading to hypotension where increasing peripheral vascular resistance can provide temporary stabilization

Contraindications

While MAST can be lifesaving, there are specific contraindications for their use, including:

• Pulmonary edema: The increased intrathoracic pressure can exacerbate the condition
• Congestive heart failure (CHF): The increased preload can worsen CHF
• Compartment syndrome: MAST can increase compartment pressures and worsen the condition

Complications

Potential complications from the use of MAST include:

• Compartment syndrome in the legs due to prolonged application
• Skin breakdown or necrosis if applied too tightly or for an extended period
• Delay in recognizing and treating underlying injuries due to the stabilization of vital signs

Current Use and Controversy

The use of Military Anti-Shock Trousers has become somewhat controversial in recent years. Advances in trauma care, including rapid transport to specialized trauma centers and improved fluid resuscitation techniques, have led to a reevaluation of their effectiveness and indications. Some studies suggest that while MAST can improve blood pressure in the short term, they may not have a significant impact on long-term survival rates and could potentially delay definitive care.

Conclusion

Military Anti-Shock Trousers have played a significant role in the management of traumatic shock in both military and civilian settings. However, their use must be carefully considered against potential complications and the availability of alternative treatments. Ongoing research and clinical judgment are essential to determine the most appropriate use of this device in emergency medical care.