Pain Pearls – Nitrous Oxide

Nitrous Oxide

Introduction to Nitrous in the ED

  • Tasteless colorless gas administered in combination with oxygen
    • Maximum concentration 70% N20
  • Absorbed via pulmonary vasculature and does not combine with hemoglobin or other body tissues
  • Rapid onset and elimination
    • <60 seconds
  • Analgesic and anxiolytic agent
    • Use along with local anesthetic or other non-opioid pain medications
  • Administered via facemask
  • Only monitoring needed is pulse oximetry
  • No NPO requirements, patient can drive after administration, no IV line needed, no RN necessary at bedside
  • Nitrous is NOT procedural sedation and should be thought of as a pain medication
  • Studies show it is similar to morphine 10 mg IM
  • It works only when the patient is breathing it in and stops working immediately when the gas is off


  • Severe COPD or asthma
  • Active Otitis Media/Sinusitis
  • Active Bowel Obstruction
  • 1st -2nd trimester pregnancy
  • Altered level of consciousness
  • Severe Psychiatric disease
  • EtOH
  • Head Injury
  • Complex Advanced Active Cardiac Disease

Indications (really any procedural pain)

  • Laceration repair
  • Incision & Drainage
  • Wound Care
  • Foreign body removal
  • Central Venous Access
  • Peripheral venous access
  • Fecal Disimpaction
  • Adjunct for
    • Dislocations
    • Splinting

Nitrous as an adjunct

  • If using nitrous to try and reduce a joint
    • Use IN ketamine
    • Intra-articular lidocaine
  • Concomitant admin of nitrous with opioids, benzos, or propofol is considered PSA
  • If giving an IV opioid you should wait 30-45 minutes before using nitrous to avoid excessive sedation or airway issues

What do we have?

Porter Standard Flowmeter

  • Stored in the trauma bay
    • Extra tank rack across from peds resus bed
  • Must use disposable breathing circuit
    • Located next to desk in trauma bay
    • There are adults small, youth medium, and peds small
Safety Features
  • Nitrous oxide flow stops if oxygen is shut off or supply becomes limited
    • Can never supply more than 70% nitrous oxide
  • Exhaled gas is scavenged away to avoid unnecessary exposure to providers

Getting started

  • Wheel to bedside
  • Plug green oxygen tube into oxygen port in the wall (may have to remove Christmas tree)
  • The gray tube scavenging tube plug into to the suction port in the wall
  • Breathing circuit only fits one way, push big lumen tube into top (by gray bag) and the clear little tube below breathing bag


  • Position the patient comfortably
  • Bring unit close to the patient so you can reach the dials
  • Make sure pulse oximetry is connected and you can see the waveform
  • Once the mask is on…
  • Set oxygen flow rate then titrate nitrous oxide to desired percentage
  • Watch gray breathing bag as a guide to adjust flow (titrate flow)
    • If bag is fully collapsing, increase overall flow
    • If bag is not moving, decrease overall flow
    • Once nitrous oxide percentage is set, regardless of flow rate, percentage stays the same

During The Procedure

  • Titrate nitrous oxide up and down as needed for “desired analgesia”, watch breathing bag to determine overall flow
  • Once procedure is complete, turn off nitrous oxide, allow patient to breath oxygen only for 60 seconds
    • Continue to watch breathing bag
  • Then remove mask completely

Your Done!!

  • Patient can be discharged with no driving or work restrictions
  • Throw away the breathing circuit
  • Return it to the trauma bay

  • Becker 2008
  • Babl 2015
  • Zhang 1999
  • Champman 1979
  • Jastek 1991

Special thanks to Dr. Alexis LaPietra for her contribution! Watch out for next times pain pearls…….. Haldol as an analgesic!!!

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