MAST Pants

Anatomy and Physiology

The MAST device is applied approximately 1 inch inferior to the costal margin and covers the abdomen, pelvis, and lower extremities.

Indications

Currently, there are no widely accepted indications for using these devices. Specifically, the American College of Surgeons’ Advanced Trauma Life Support and American College of Emergency Physicians’ guidelines do not recommend using them.

Traditional Indications

• Hypotension associated with suspected pelvic or femur fractures
• Ruptured abdominal aortic aneurysm
• Stabilization of pelvic and femur fractures

Contraindications

Contraindications include:

• Congestive heart failure (CHF)
• Myocardial infarction
• Stroke
• Pregnancy
• Thoracic hemorrhage
• Diaphragmatic injury
• Head injuries
• Abdominal injury with evisceration
• Uncontrolled bleeding above the level of the garment
• Impaled object to the abdomen or lower extremity

Equipment

A list of equipment includes:

• Medical anti-shock trousers
• Pump or inflation device
• Sphygmomanometer
• Stethoscope

Personnel

Only medical professionals who have received appropriate training should deploy the MAST device. These professionals include physicians, nurses, and emergency medical personnel. Only 1 trained person is required to apply the MAST device.

Preparation

Place the MAST device on a stretcher or long backboard before transferring the patient. Transfer the patient to the stretcher or backboard and perform a physical examination to identify contraindications for MAST application or injuries the device covers once inflated. Apply and inflate the MAST device if no contraindications exist.

Technique or Treatment

Steps to treat MAST pants include:

1. Evaluate the need for MAST by assessing injuries and obtaining vital signs.
2. Unfold MAST and lay it flat on a backboard or stretcher before moving the patient.
3. Perform a secondary survey to identify injuries that the device covers, dressing wounds as necessary. Remove all clothing and foreign objects as the device presses them into the patient’s skin.
4. While maintaining spine immobility, place the patient on the MAST device so that the top of the garment is approximately 1 inch inferior to the costal margin.
5. Secure and fasten the leg sections. Ensure all creases are removed.
6. Secure and fasten the abdominal section (unless contraindicated). Ensure all creases are removed and that the garment has not changed position relative to the patient’s chest wall.
7. Attach the pump and check all valves for closure.
8. Inflate leg compartments.
9. Re-assess the patient and obtain repeat vital signs.
10. If the patient’s systolic blood pressure is between 100 to 110 mm Hg, ensure valves are closed and continue to monitor the patient’s blood pressure. Do not attempt to increase the systolic blood pressure beyond 110 mm Hg.
11. If the patient’s systolic blood pressure is not 100 to 110 mm Hg, inflate the abdominal compartment (unless contraindicated).
12. Continue monitoring the patient's systolic blood pressure, adding air to the device as needed to maintain a systolic blood pressure between 100 to 110 mm Hg.
13. Remove MAST only when the patient has been adequately resuscitated and under the direction of a physician in a controlled setting.

Complications

The complications that can manifest with MAST pants are as follows:

• Lower extremity ischemia
• Compartment syndrome
• Respiratory failure
• Increased intracranial pressure
• Acute kidney injury
• Metabolic acidosis

Clinical Significance

MAST devices are still discussed in protocols and textbooks for several EMS agencies in the United States. However, most hospital systems and EMS agencies have abandoned the use of these devices due to the paucity of supporting evidence and the relatively high cost compared to other treatment modalities. There are no widely accepted indications for MAST use, and doing so falls outside the standard of medical care in most developed nations. As of the writing of this topic, there is insufficient evidence to support the continued use of these devices.

Enhancing Healthcare Team Outcomes

An evidence-based team approach involving clinicians in MAST use is recommended. Resuscitation of critically ill patients is a topic of constant scrutiny and frequent disagreement among leaders in the field, and many studies have been published on this topic each year. The MAST device is an example of 1 of the many practices that were once the standard of care but expired as medical knowledge advanced. It is the responsibility of medical professionals to advance the knowledge and tools available to provide the best medical care. As medical knowledge and technology advance, so should the standard of care medical professionals provide their patients.