Entonox Therapy for Acute Pain
50% Oxygen + 50% Nitrous Oxide
Self-administered pain relief for moderate to severe pain from trauma and burns
Contraindications - Do NOT Use If:
| Condition | Why |
|---|---|
| Allergy to nitrous oxide | Absolute |
| Head injury/altered LOC | Cannot self-administer safely |
| Maxillo-facial injury | Cannot seal lips around mouthpiece |
| Recent eye surgery | Gas expansion risk |
| Inhalation injury, O2 sat <95% | Need 100% oxygen |
| Chest injury/pneumothorax risk | Gas expansion risk |
| Severe COPD/emphysema | Respiratory depression |
| Pulmonary edema | Worsens condition |
| Abdominal distention | Gas expansion risk |
| Scuba diving last 24 hours | Decompression sickness risk |
| Pregnancy/nursing (relative) | Caution advised |
| Nitroglycerin in last 5 min | Drug interaction |
Indications
- Moderate to severe acute pain from musculoskeletal trauma
- Burns
Safety & Preparation
IMPORTANT: Invert tank 3 times to mix gases before use (prevents oxygen/nitrous separation below 10°C)
- Storage: Above 10°C (can transport horizontally, store vertically)
- No smoking near tank
- Use in ventilated space (not closed ambulances, helicopters, airplanes)
How to Administer
SFA, FR, EMR
Call for help; provide patient comfort measures
PCP, RPN, LPN, RN, and up
- Perform history and survey - ensure no contraindications
- Invert tank 3 times to mix gases
- Obtain baseline vitals including O2 sat
- Explain to patient (see below)
- Patient self-administers - inhale for pain relief, pause and restart as needed
- Discontinue if cyanosis develops
What to Tell the Patient
"This is Entonox - a mix of 50% oxygen and 50% nitrous oxide."
Common side effects:
- Light-headedness
- Slight nausea
- Things may seem funnier than usual
- Might feel "a little bit high"
"You can't overdose on Entonox alone. The gas and effect are gone within a few breaths after you stop."
Patient Instructions
- Hold mouthpiece like a whistle
- Breathe normally through your mouth
- Inhale to get pain relief
- Pause and restart at your own pace
- Continue until pain is manageable
Quick Reference
| Item | Details |
|---|---|
| Composition | 50% O2 + 50% N2O |
| Administration | Self-administered by patient |
| Onset | Rapid |
| Duration | While inhaling + few breaths after |
| Overdose Risk | Cannot overdose (self-limiting) |
⚠️ Report: Report every use of Entonox to team lead/medical director
Source: Odyssey Medical Consulting
Version: 2023-06-21