Nitrous Oxide in Dentistry

Who discovered nitrous oxide?

Joseph Priestley (1733-1804)

Who identified nitrous oxide's analgesic properties?

Sir Humphrey Davy (1778-1829)

Who attempted the first dental use of nitrous oxide?

Dr. Horace Wells

Why is nitrous oxide ideal for inhalational anesthesia?

Analgesic, anxiolytic, amnestic, rapid onset/recovery, titratable, minimal side effects.

What are indications for nitrous oxide use in dentistry?

Pain/anxiety management, medically compromised patients, gag reflex management.

What percent of people avoid dental treatment due to fear?

40% (~35 million people)

What are some medically compromised conditions where N2O may help?

Cardiovascular disease, hepatic disease, epilepsy

What is the blood-gas solubility coefficient of N2O?

Low — leads to rapid onset and recovery

What is the MAC (Minimum Alveolar Concentration) of N2O?

105%, indicating it is not potent enough for general anesthesia alone

What is the 'second gas effect'?

High concentrations of N2O enhance the uptake of a more potent anesthetic (e.g., sevoflurane)

What is diffusion hypoxia and how is it prevented?

O2 dilution in alveoli post-procedure; prevent with 100% O2 for 3-5 minutes

How is N2O eliminated from the body?

Exhaled unchanged via the lungs

What is the primary site of action for N2O?

Cerebral cortex

What happens with N2O doses > 80%?

Slight myocardial depression

What does minimal sedation include according to VA regulations?

Anxiolysis, inhalation analgesia, or both

What are the required equipment features in VA for N2O-only sedation?

BP monitor, positive-pressure oxygen, hand respiratory bag, suction apparatus

How is nitrous oxide stored in E cylinders?

In liquid form

What color are nitrous and oxygen tanks in the U.S.?

N2O - Blue; O2 - Green

What is the purpose of the pin index safety system?

Prevents mixing up O2 and N2O tank connections

What is the initial N2O dose during administration?

20%, increasing by 10% every 2 minutes

What percent of patients respond well to 30% N2O?

80%

What should be done after N2O administration?

100% O2 for 3-5 minutes; assess vital signs and recovery

What is the Modified Romberg Test?

Eyes closed, feet together, touch nose with finger — tests balance post-sedation

What are signs of nitrous oxide overdose?

Restlessness, disorientation, unresponsiveness, sweating, nausea

How should an N2O overdose be managed?

100% O2, remove mask, reassure patient, use reservoir bag as needed

What are Stage I-IV of anesthesia?

I - Analgesia, II - Delirium, III - Surgical anesthesia, IV - Respiratory paralysis

What are symptoms of Guedel's Stage I (Sedation/Analgesia)?

Lightheadedness, numbness, warmth, euphoria

What are early excitement symptoms?

Hearing/vision changes, anxiety, hyperventilation, sweating

What are overdose symptoms (Guedel's Stage II)?

Nausea, amnesia, loss of airway, snoring, unresponsiveness

What are absolute contraindications for N2O?

Acute URI, nasal obstruction, active bronchitis, 1st trimester pregnancy, pneumothorax, bowel obstruction, inner ear infection

What are relative contraindications for N2O?

Pregnancy after first trimester, psychiatric instability, severe COPD, recent eye surgery (consult needed)

What is a major occupational exposure risk of N2O?

Spontaneous abortion, reduced fertility, birth defects, neurological damage

What is NIOSH's N2O exposure limit?

50 ppm over 8 hours; ideally under 25 ppm

How to minimize occupational N2O exposure?

Use scavenging systems, reduce patient talking, ventilate, calibrate equipment

What are side concerns of N2O use?

Hallucinations, dreams, potential for sexual misconduct accusations — always have an assistant present

What are advantages of N2O sedation?

Rapid onset/recovery, titration, no escort needed, low side effects

What are disadvantages of N2O sedation?

Requires cooperation, low potency, risk of abuse, space and equipment costs