Introduction
If you’ve been around EMS long enough, you’ve probably heard of anti-shock pants—the pneumatic trousers also called PASG or MAST. A couple decades ago, they were everywhere. Today? Not so much. Most systems pulled them out because survival benefits were never clear, and the risks became hard to ignore.
So why are we still talking about them in 2025? Because in some situations—pelvic fractures with shock, postpartum hemorrhage when you’re hours from a hospital, or long rural transports—PASG might still buy you precious time.
This isn’t an academic history lesson. It’s a straightforward field guide: when to use PASG, when not to, how to inflate safely, what numbers to watch, and what recent evidence says.
When to Use PASG (Indications)
Think of PASG as a tool to squeeze blood from the legs and belly back up into the chest, giving the heart and brain more to work.
Here’s the quick look:
| Scenario | Use PASG? | Why |
|---|---|---|
| Pelvic fracture + low BP | ✅ Yes | Can help stabilize until binder/definitive care |
| Severe hypotension (MAP <60) | ✅ Yes | Only if chest is clear |
| Postpartum hemorrhage (PPH) | ✅ Yes | Solid evidence in low-resource OB settings |
| Abdominal trauma with bleeding | ⚠️ Caution | Might increase abdominal pressure |
| Long bone fractures / crush injuries | ❌ No | No proven benefit |
| Chest trauma / thoracic bleeding | ❌ No | Can make bleeding worse |
| Pregnant >20 weeks | ❌ No | Contraindicated |
| Pulmonary edema / CHF | ❌ No | Can push patient into failure |
| Abdominal evisceration | ❌ No | Contraindicated |
| Head injury with high ICP | ❌ No | Contraindicated |
Bottom line: It’s a niche tool. It’s either for shock where you can’t control bleeding yet, or for PPH in places where blood and surgery aren’t ready.
When Not to Use PASG (Contraindications)
If you remember nothing else: don’t put PASG on chest injuries, pregnant women past 20 weeks, or patients with pulmonary edema.
Other big red flags:
- Eviscerated abdominal organs
- Known head injury with high intracranial pressure
- Limbs already showing ischemia or compartment risk
- No reason to leave PASG inflated more than 45 minutes
Gear You’ll Need
- PASG suit (with separate leg and abdominal compartments)
- Pump or inflation unit with PSI gauge
- Blood pressure cuff
- Monitor if you’ve got one (SpO₂, heart rate)
- Timer/clock
Nice extras:
- Laminated “PSI ranges” quick card
- Contraindications checklist card
How to Apply: Step-by-Step
This is where most mistakes happen—wrong order or overinflation. Keep it simple.
Inflation sequence and pressures:
| Step | What to Do | Pressure |
|---|---|---|
| 1 | Assess patient, rule out contraindications, record baseline vitals | — |
| 2 | Place garment under patient, cover legs + abdomen | — |
| 3 | Inflate legs first | ~40 mmHg |
| 4 | Inflate abdomen last | 20–30 mmHg |
| 5 | Recheck vitals—BP, pulse, comfort | — |
| 6 | Secure tubing, prep for transport | — |
| 7 | Deflate slowly (reverse order: abdomen first, then legs) under medical control | — |
Tips:
- Inflate gradually—don’t crank it up all at once.
- Stay under 40 mmHg for legs, 30 mmHg for abdomen.
- Deflate slowly. Drop everything at once and you’ll crash the patient.
Complications & Risks
This is the reason PASG mostly disappeared:
- Compartment syndrome in the legs
- Ischemia if left too long
- Breathing trouble from diaphragm pushed up
- Hidden bleeding in chest/upper abdomen gets worse
- Rebound hypotension if deflated too quickly
Time limit: keep inflation ≤45 minutes, max 1 hour.
What 2024–2025 Evidence Says
- Trauma/Polytrauma: Studies still show no real survival benefit. Fluids + pelvic binders win.
- Postpartum hemorrhage (PPH): Best evidence here. WHO supports PASG in low-resource settings where surgery/blood isn’t available.
- Rural/remote transport: Can hold MAP stable for ~30–45 minutes.
- Military use: Very rare, only as last resort.
Guideline updates:
- NAEMSP and Ontario EMS (2024): PASG = reserve device, not first-line.
- Only use with online medical direction if possible.
PASG vs Other Options
| Tool | Strengths | Weaknesses |
|---|---|---|
| PASG | Temporary BP support + pelvic compression | Ischemia, no survival proof |
| Pelvic binder | Simple, cheap, effective | No systemic BP support |
| IV fluids | Boost BP, widely available | Dilutional coagulopathy |
| TXA | Real survival benefit | Needs IV |
| Blood transfusion | Definitive | Needs facility & blood products |
FAQs
Q: Do EMS kits still stock PASG?
A: Most don’t. Some rural and military units still keep one.
Q: How long can I leave it inflated?
A: Aim for 30–45 minutes max. After an hour you’re asking for ischemic damage.
Q: Can I use PASG in pregnancy?
A: No. Contraindicated beyond 20 weeks.
Q: Is PASG really useful in PPH?
A: Yes—in rural/low-resource obstetrics it can save lives.
Q: How do I deflate?
A: Slowly, in reverse order: abdomen first, then legs. Never all at once.
Conclusion
PASG is not the superstar it once was. But it’s also not completely dead. If you’re working in rural EMS, low-resource obstetrics, or rare trauma scenarios with delayed definitive care, PASG might still be the tool that buys your patient enough time.
Key reminders:
- Know the indications and contraindications.
- Stick to the PSI numbers and sequence.
- Keep time short.
- Deflate slow.
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