Surgical sedation and analgesia (adjunctive agent): Note: Minimal alveolar concentration, which can be considered the ED50 of inhalational anesthetics, is ~104% to 105%; therefore, delivery in a hyperbaric chamber is necessary to use as a sole agent for complete anesthesia. Use decreases requirements of other inhaled or IV anesthetics (Ref).
Procedural sedation: Inhalation: Concentrations of 30% to 50% nitrous oxide with oxygen (Ref).
General anesthesia: Inhalation: Concentrations of 50% to 70% via mask or endotracheal tube (Ref).
Dental sedation and analgesia: Inhalation: Concentrations of 30% to 50% nitrous oxide with oxygen (Ref).
There are no dosage adjustments provided in the manufacturer's labeling.
There are no dosage adjustments provided in the manufacturer's labeling.
Refer to adult dosing.
Refer to adult dosing.
There are no adverse reactions listed in the manufacturer's labeling.
Postmarketing:
Cardiovascular: Depression of myocardial contractility (Brodsky 1986), hypotension (Brodsky 1986)
Endocrine & metabolic: Homocystinemia (Zafirova 2018)
Gastrointestinal: Nausea and vomiting (including severe nausea and vomiting) (Myles 2014, Zafirova 2018)
Nervous system: Cognitive dysfunction (including psychomotor impairment and slowed reaction time) (Brodsky 1986), disorientation (Brodsky 1986), hysteria (Brodsky 1986), paresthesia (Brodsky 1986)
Otic: Increased middle ear pressure (with transient auditory impairment, hemotympanum, otalgia, and perforated tympanic membrane) (Brodsky 1986, Ohryn 1995), tinnitus (Brodsky 1986)
Respiratory: Atelectasis (Sun 2015), hypoxia (Brodsky 1986)
Although there are no contraindications listed in the manufacturer's labeling, use of nitrous oxide should be avoided in the following situations: patients with disorders of vitamin B12 deficiency, folate, or methionine synthesis or metabolism; patients having undergone vitreoretinal surgery and presence of intraocular gas bubble; and patients with pneumothorax, pneumocephalus, and closed dura, or those at high risk for vascular air embolus (ESA [Buhre 2019]; Fu 2002; Gropper 2020; Lee 2004).
Concerns related to adverse effects:
• Body space volume expansion: Both compliant (eg, bowel gas, pneumothorax) and poorly compliant (eg, middle ear) body spaces may be prone to changes in volume due to nitrous oxide transfer; avoid use in pneumothorax, pneumocephalus, middle ear surgery, or bowel obstruction (Miller 2010; Ohryn 1995; Sprehn 1992).
• Bone marrow suppression: Prolonged use may produce bone marrow suppression; patients with vitamin B12 deficiency (pernicious anemia) and those with other nutritional deficiencies (patients with alcohol use disorder) are at increased risk (ESA [Buhre 2019]).
• Nausea/vomiting: Occurs postoperatively in ~15% of patients (Sun 2015); risk may be reduced by antiemetics (Myles 2016).
• Neurologic effects: Prolonged use may produce neurologic dysfunction; patients with vitamin B12 deficiency (pernicious anemia) and those with other nutritional deficiencies (patients with alcohol use disorder) are at increased risk.
• Substance use disorder: May be associated with abuse and/or substance use disorder (Zafirova 2018).
Disease-related concerns:
• Vitreoretinal surgery: Detached retina and other ocular disorders treated with vitreoretinal surgery where intraocular gas was used: Nitrous oxide can increase intraocular pressure which may result in retinal artery occlusion, ischemia, or optic nerve damage and vision loss in these patients. Nitrous oxide should not be used in patients who have had an intravitreal gas bubble unless it can be confirmed that the bubble has been completely resorbed (Fu, 2002; Lee, 2004).
Other warnings/precautions:
• Handling: Never allow any unprotected part of the body to touch uninsulated pipes or vessels that contain cryogenic liquids.
• Oxygen use: Oxygen should be administered for several minutes before and after discontinuing nitrous oxide to prevent diffusion hypoxia (Gropper 2020).
Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Supplied in blue cylinders
Yes
Sedation and analgesia: Sedation, analgesia, and amnesia; principal adjunct to inhalation and intravenous general anesthesia.
The Institute for Safe Medication Practices (ISMP) includes this medication among its list of drug classes (anesthetic agent, general, inhaled and IV) which have a heightened risk of causing significant patient harm when used in error (High-Alert Medications in Acute Care Settings).
None known.
Note: Interacting drugs may not be individually listed below if they are part of a group interaction (eg, individual drugs within “CYP3A4 Inducers [Strong]” are NOT listed). For a complete list of drug interactions by individual drug name and detailed management recommendations, use the drug interactions program by clicking on the “Launch drug interactions program” link above.
Acrivastine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Alcohol (Ethyl): CNS Depressants may increase CNS depressant effects of Alcohol (Ethyl). Risk C: Monitor
Alizapride: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Amisulpride (Oral): May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Articaine: May increase CNS depressant effects of CNS Depressants. Management: Consider reducing the dose of articaine if possible when used in patients who are also receiving CNS depressants. Monitor for excessive CNS depressant effects with any combined use. Risk D: Consider Therapy Modification
Azelastine (Nasal): May increase CNS depressant effects of CNS Depressants. Risk X: Avoid
Benperidol: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Blonanserin: CNS Depressants may increase CNS depressant effects of Blonanserin. Management: Use caution if coadministering blonanserin and CNS depressants; dose reduction of the other CNS depressant may be required. Strong CNS depressants should not be coadministered with blonanserin. Risk D: Consider Therapy Modification
Brexanolone: CNS Depressants may increase CNS depressant effects of Brexanolone. Risk C: Monitor
Brimonidine (Topical): May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Bromopride: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Bromperidol: May increase CNS depressant effects of CNS Depressants. Risk X: Avoid
Buclizine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
BUPivacaine: Nitrous Oxide may increase adverse/toxic effects of BUPivacaine. Specifically, the risk of methemoglobinemia may be increased. Risk C: Monitor
Buprenorphine: CNS Depressants may increase CNS depressant effects of Buprenorphine. Management: Consider reduced doses of other CNS depressants, and avoiding such drugs in patients at high risk of buprenorphine overuse/self-injection. Initiate buprenorphine at lower doses in patients already receiving CNS depressants. Risk D: Consider Therapy Modification
BusPIRone: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Cannabinoid-Containing Products: CNS Depressants may increase CNS depressant effects of Cannabinoid-Containing Products. Risk C: Monitor
Cetirizine (Systemic): May increase CNS depressant effects of CNS Depressants. Management: Consider avoiding this combination if possible. If required, monitor for excessive sedation or CNS depression, limit the dose and duration of combination therapy, and consider CNS depressant dose reductions. Risk D: Consider Therapy Modification
Chloral Hydrate/Chloral Betaine: CNS Depressants may increase CNS depressant effects of Chloral Hydrate/Chloral Betaine. Management: Consider alternatives to the use of chloral hydrate or chloral betaine and additional CNS depressants. If combined, consider a dose reduction of either agent and monitor closely for enhanced CNS depressive effects. Risk D: Consider Therapy Modification
Chlormethiazole: May increase CNS depressant effects of CNS Depressants. Management: Monitor closely for evidence of excessive CNS depression. The chlormethiazole labeling states that an appropriately reduced dose should be used if such a combination must be used. Risk D: Consider Therapy Modification
Chlorphenesin Carbamate: May increase adverse/toxic effects of CNS Depressants. Risk C: Monitor
CNS Depressants: May increase adverse/toxic effects of CNS Depressants. Risk C: Monitor
Dantrolene: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Dapsone (Topical): May increase adverse/toxic effects of Methemoglobinemia Associated Agents. Risk C: Monitor
Daridorexant: May increase CNS depressant effects of CNS Depressants. Management: Dose reduction of daridorexant and/or any other CNS depressant may be necessary. Use of daridorexant with alcohol is not recommended, and the use of daridorexant with any other drug to treat insomnia is not recommended. Risk D: Consider Therapy Modification
DexmedeTOMIDine: CNS Depressants may increase CNS depressant effects of DexmedeTOMIDine. Management: Monitor for increased CNS depression during coadministration of dexmedetomidine and CNS depressants, and consider dose reductions of either agent to avoid excessive CNS depression. Risk D: Consider Therapy Modification
Difelikefalin: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Difenoxin: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Dihydralazine: CNS Depressants may increase hypotensive effects of Dihydralazine. Risk C: Monitor
Dimethindene (Topical): May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Dothiepin: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Doxylamine: CNS Depressants may increase CNS depressant effects of Doxylamine. Risk C: Monitor
DroPERidol: May increase CNS depressant effects of CNS Depressants. Management: Consider dose reductions of droperidol or of other CNS agents (eg, opioids, barbiturates) with concomitant use. Risk D: Consider Therapy Modification
Emedastine (Systemic): May increase CNS depressant effects of CNS Depressants. Management: Consider avoiding this combination if possible. If required, monitor for excessive sedation or CNS depression, limit the dose and duration of combination therapy, and consider CNS depressant dose reductions. Risk C: Monitor
Entacapone: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Esketamine (Nasal): May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Flunarizine: CNS Depressants may increase CNS depressant effects of Flunarizine. Risk X: Avoid
Flunitrazepam: CNS Depressants may increase CNS depressant effects of Flunitrazepam. Management: Reduce the dose of CNS depressants when combined with flunitrazepam and monitor patients for evidence of CNS depression (eg, sedation, respiratory depression). Use non-CNS depressant alternatives when available. Risk D: Consider Therapy Modification
HydrOXYzine: May increase CNS depressant effects of CNS Depressants. Management: Consider a decrease in the CNS depressant dose, as appropriate, when used together with hydroxyzine. Increase monitoring of signs/symptoms of CNS depression in any patient receiving hydroxyzine together with another CNS depressant. Risk D: Consider Therapy Modification
Isoflurane: Nitrous Oxide may increase therapeutic effects of Isoflurane. Specifically, isoflurane MAC values may be decreased. Isoflurane may increase CNS depressant effects of Nitrous Oxide. Risk C: Monitor
Ixabepilone: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Kava Kava: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Ketotifen (Systemic): May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Kratom: May increase CNS depressant effects of CNS Depressants. Risk X: Avoid
Lemborexant: May increase CNS depressant effects of CNS Depressants. Management: Dosage adjustments of lemborexant and of concomitant CNS depressants may be necessary when administered together because of potentially additive CNS depressant effects. Close monitoring for CNS depressant effects is necessary. Risk D: Consider Therapy Modification
Levocetirizine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Lisuride: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Local Anesthetics: Methemoglobinemia Associated Agents may increase adverse/toxic effects of Local Anesthetics. Specifically, the risk for methemoglobinemia may be increased. Risk C: Monitor
Lofepramine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Lofexidine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Loxapine: CNS Depressants may increase CNS depressant effects of Loxapine. Management: Consider reducing the dose of CNS depressants administered concomitantly with loxapine due to an increased risk of respiratory depression, sedation, hypotension, and syncope. Risk D: Consider Therapy Modification
Magnesium Sulfate: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Melitracen [INT]: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Mequitazine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Metergoline: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Methotrexate: Nitrous Oxide may increase adverse/toxic effects of Methotrexate. Risk X: Avoid
Methotrimeprazine: CNS Depressants may increase CNS depressant effects of Methotrimeprazine. Methotrimeprazine may increase CNS depressant effects of CNS Depressants. Management: Reduce the usual dose of CNS depressants by 50% if starting methotrimeprazine until the dose of methotrimeprazine is stable. Monitor patient closely for evidence of CNS depression. Risk D: Consider Therapy Modification
Methoxyflurane: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Metoclopramide: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
MetyroSINE: CNS Depressants may increase sedative effects of MetyroSINE. Risk C: Monitor
Minocycline (Systemic): May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Moxonidine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Nabilone: May increase CNS depressant effects of CNS Depressants. Risk X: Avoid
Nalfurafine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Nitric Oxide: May increase adverse/toxic effects of Methemoglobinemia Associated Agents. Combinations of these agents may increase the likelihood of significant methemoglobinemia. Risk C: Monitor
Noscapine: CNS Depressants may increase adverse/toxic effects of Noscapine. Risk X: Avoid
Olopatadine (Nasal): May increase CNS depressant effects of CNS Depressants. Risk X: Avoid
Opicapone: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Opioid Agonists: CNS Depressants may increase CNS depressant effects of Opioid Agonists. Management: Avoid concomitant use of opioid agonists and benzodiazepines or other CNS depressants when possible. These agents should only be combined if alternative treatment options are inadequate. If combined, limit the dosages and duration of each drug. Risk D: Consider Therapy Modification
Opipramol: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Orphenadrine: CNS Depressants may increase CNS depressant effects of Orphenadrine. Risk X: Avoid
Oxomemazine: May increase CNS depressant effects of CNS Depressants. Risk X: Avoid
Oxybate Salt Products: CNS Depressants may increase CNS depressant effects of Oxybate Salt Products. Management: Consider alternatives to this combination when possible. If combined, dose reduction or discontinuation of one or more CNS depressants (including the oxybate salt product) should be considered. Interrupt oxybate salt treatment during short-term opioid use Risk D: Consider Therapy Modification
OxyCODONE: CNS Depressants may increase CNS depressant effects of OxyCODONE. Management: Avoid concomitant use of oxycodone and benzodiazepines or other CNS depressants when possible. These agents should only be combined if alternative treatment options are inadequate. If combined, limit the dosages and duration of each drug. Risk D: Consider Therapy Modification
Paliperidone: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Paraldehyde: CNS Depressants may increase CNS depressant effects of Paraldehyde. Risk X: Avoid
Perampanel: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Periciazine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Pipamperone: May increase adverse/toxic effects of CNS Depressants. Risk C: Monitor
Piribedil: CNS Depressants may increase CNS depressant effects of Piribedil. Risk C: Monitor
Pizotifen: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Pramipexole: CNS Depressants may increase sedative effects of Pramipexole. Risk C: Monitor
Prilocaine: Methemoglobinemia Associated Agents may increase adverse/toxic effects of Prilocaine. Combinations of these agents may increase the likelihood of significant methemoglobinemia. Management: Monitor for signs of methemoglobinemia when prilocaine is used in combination with other agents associated with development of methemoglobinemia. Avoid use of these agents with prilocaine/lidocaine cream in infants less than 12 months of age. Risk C: Monitor
Primaquine: Methemoglobinemia Associated Agents may increase adverse/toxic effects of Primaquine. Specifically, the risk for methemoglobinemia may be increased. Management: Avoid concomitant use of primaquine and other drugs that are associated with methemoglobinemia when possible. If combined, monitor methemoglobin levels closely. Risk D: Consider Therapy Modification
Procarbazine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Rilmenidine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Ropeginterferon Alfa-2b: CNS Depressants may increase adverse/toxic effects of Ropeginterferon Alfa-2b. Specifically, the risk of neuropsychiatric adverse effects may be increased. Management: Avoid coadministration of ropeginterferon alfa-2b and other CNS depressants. If this combination cannot be avoided, monitor patients for neuropsychiatric adverse effects (eg, depression, suicidal ideation, aggression, mania). Risk D: Consider Therapy Modification
ROPINIRole: CNS Depressants may increase sedative effects of ROPINIRole. Risk C: Monitor
Rotigotine: CNS Depressants may increase sedative effects of Rotigotine. Risk C: Monitor
Sodium Nitrite: Methemoglobinemia Associated Agents may increase adverse/toxic effects of Sodium Nitrite. Combinations of these agents may increase the likelihood of significant methemoglobinemia. Risk C: Monitor
Suvorexant: CNS Depressants may increase CNS depressant effects of Suvorexant. Management: Dose reduction of suvorexant and/or any other CNS depressant may be necessary. Use of suvorexant with alcohol is not recommended, and the use of suvorexant with any other drug to treat insomnia is not recommended. Risk D: Consider Therapy Modification
Thalidomide: CNS Depressants may increase CNS depressant effects of Thalidomide. Risk X: Avoid
Trimeprazine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Valerian: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor
Zolpidem: CNS Depressants may increase CNS depressant effects of Zolpidem. Management: Reduce the Intermezzo brand sublingual zolpidem adult dose to 1.75 mg for men who are also receiving other CNS depressants. No such dose change is recommended for women. Avoid use with other CNS depressants at bedtime; avoid use with alcohol. Risk D: Consider Therapy Modification
Zuranolone: May increase CNS depressant effects of CNS Depressants. Management: Consider alternatives to the use of zuranolone with other CNS depressants or alcohol. If combined, consider a zuranolone dose reduction and monitor patients closely for increased CNS depressant effects. Risk D: Consider Therapy Modification
Infertility has been reported following prolonged occupational exposure. This risk is related to dose and duration of exposure and is decreased with proper administration procedures (Becker 2008; Rooks 2011; Zafirova 2018).
Nitrous oxide crosses the placenta.
Concentrations of nitrous oxide in the fetal circulation are ~80% of those in the maternal plasma. The half-life in the neonate is ~3 minutes and it is quickly eliminated from neonatal lungs with the onset of breathing (Rooks 2011).
Spontaneous abortion and congenital abnormalities have been reported in health care providers following prolonged occupational exposure (Becker 2008; Brodsky 1986; Rooks 2011). However, these adverse events are related to dose and duration of exposure and risks are decreased with proper administration procedures (Rooks 2011; Zafirova 2018). Short duration of exposure to the pregnant patients during obstetric procedural anesthesia is not associated with an increased risk of adverse events to the fetus (Neuman 2013).
Nitrous oxide is used in labor analgesia, as well as occasionally postpartum (ACOG 2019b; Collins [AWHONN 2018]; Likis 2014; Rooks 2011; Rosen 2002) and may be used when needed for dental treatments that cannot be postponed during pregnancy (or delayed until after the first trimester) (Becker 2008).
ACOG recommends that pregnant patients should not be denied medically necessary surgery, regardless of trimester. If the procedure is elective, it should be delayed until after delivery (ACOG 2019a).
Nitrous oxide administration may be considered an aerosol-generating procedure; therefore, use in labor analgesia may be of concern in patients with confirmed or unknown COVID-19 infection (Khan 2021; Pavlidis 2021).
Nitrous oxide was not found to influence the initiation or continuation of breastfeeding when used during labor (Zanardo 2017).
The Academy of Breastfeeding Medicine recommends postponing elective surgery until milk supply and breastfeeding are established. Milk should be expressed ahead of surgery when possible. In general, when the child is healthy and full term, breastfeeding may resume, or milk may be expressed once the mother is awake and in recovery. For children who are at risk for apnea, hypotension, or hypotonia, milk may be saved for later use when the child is at lower risk (ABM [Reece-Stremtan 2017]).
General CNS depressant action; may act similar to inhaled general anesthetics by stabilizing axonal membranes to partially inhibit action potentials leading to sedation; may partially act on opiate receptor systems to cause mild analgesia; central sympathetic stimulating action supports blood pressure, systemic vascular resistance, and cardiac output; it does not depress carbon dioxide drive to breath. Nitrous oxide increases cerebral blood flow and intracranial pressure while decreasing hepatic and renal blood flow; has analgesic action similar to morphine.
Onset of action: Inhalation: 2-5 minutes
Absorption: Rapid via lungs; blood/gas partition coefficient is 0.47
Metabolism: Body: <0.004%
Excretion: Primarily exhaled gases; skin (minimal amounts)