Pharm
Nitrous Oxide
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Nitrous Oxide
, Laughing Gas
See Also
Nitrous Oxide Abuse
Indications
Procedural Sedation
(esp. pediatrics)
Low intensity procedures (e.g.
Lumbar Puncture
,
Laceration Repair
, minor
Fracture
reduction)
Moderate analgesia
Best used in combination with
Local Anesthesia
(e.g. local infiltration,
Hematoma Block
)
Contraindications (related to gas expansion risks)
Pneumothorax
Pulmonary Bleb
s
Bowel Obstruction
History
First used for
Anesthesia
in U.S. in 1845
Used in a majority of pediatric dental offices
Mechanism
Effects
Opioid
spinal modulators, GABA receptors,
NMDA
receptors
Also releases endorphins
Pharmacology
Excreted unchanged (not metabolized) primarily from lung
Onset: 2-3 minutes
Duration: 3-5 minutes
Rapidly off-loads with oxygen (often given for 5 minutes after procedure)
Effects
Mild anxiolysis: <50% Nitrous Oxide
Analgesia: 50-70% Nitrous Oxide
Adverse Effects
Light headedness
Somnolence
Confusion
Paresthesia
s
Nausea
or
Vomiting
(1-2% of cases)
Vomiting
is uncommon unless concurrent
Opioid
s are used
Inadequate sedation (1.2% of cases)
Airway obstruction or
Hypoxia
(0.25% of cases)
More common with concurrent
Opioid
s or
Benzodiazepine
s
Safety
Among the safest sedation agents with proper use and monitoring (ACEP, 1984)
Airway obstruction or
Hypoxia
is rare (0.25% of cases)
Very rare mortality (case reports)
No pregnancy data, and not recommended in first or second trimester
No delay in
Lactation
Preparation
Gene
ral equipment
Oxygen supply
Wall suction
Airway equipment
Educate patient on use of mask
Patient instructed to take deeper breaths if feels more pain
Nitrous Oxide delivery device
Nasal mask (may be scented)
Delivery mix: 50:50 to 70:30 mix of Nitrous Oxide and oxygen
Device should have audible alarms, flow control and scavenger functionality (suction)
Does not require a medical gas vacuum system
Dosing
Goal Nitrous Oxide effects (expect onset within 2-3 min of starting Nitrous Oxide)
Apathy
Somnolence
Still responds to verbal stimuli
Start with total liter flow estimation
Child: 4-5 L/min
Adult: 6-7 L/min
Watch reservoir bag while on oxygen only, and goal inflation is 2/3 full (not collapsed and not full)
Initiate Nitrous Oxide
Start 10-15% Nitrous Oxide and increase every couple of minutes to effect (see above)
Patient asked to breath normally through their nose and to relax
Prepare patient that they may have arms and legs
Titrate Nitrous Oxide
Stop agent for
Nausea
(and allow to dissipate over 2-3 minutes, and then re-start)
Decrease Nitrous Oxide if
Agitation
occurs
Oxygen reverses effects if too much sedation
Self-titration method
Patient holds mask to their own face
As sedation increases, the mask drops away
When they awaken again, they replace the mask to once again increase sedation
References
Acker, Koval and Leeper (2017) Crit Dec Emerg Med 31(4): 3-13
Cordle (2016) Nitrous Oxide Lecture, ACEP PEM Conference, attended 3/9/2016
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