Dental Hygiene - Nitrous Oxide Complete Examination
Questions and Answers
1. What is the one absolute contraindication for the administration of nitrous oxide?: Recent
eye surgery using ocular gas bubble.
2. What percentage of nitrous oxide to begin at?: 15%
3. What increments do you use to increase the nitrous oxide sedation level?-
: 5%
4. What should you instruct the patient about eating prior to the procedure?-
: To avoid fasting and heaving meals prior to procedure (eat light).
5. Should you have the patient remove their contacts prior to the procedure?-
: Yes
6. What are the 4 "a" properties nitrous oxide possesses?: Analgesic, Anxi- olytic, (slight
amnesia and weak anesthetic).
An analgesic agent- reduces intensity of pain but does not eliminate it
A weak anesthetic agent
An anxiolytic agent- has sedative effects; reduces anxiety
Has amnesia producing qualities- patient cannot recall severity of pain
7. What is nitrous oxide made from?: Ammonium nitrate
8. Is nitrous a solid, liquid or gas at room temperature?: Gas
9. What is nitrous oxides weight in comparison to air?: It is heavier than air.
10. ------- is defined as an unpleasant mental, emotional, physiologic sensa- tion derived from
a specific dental-related stimulus; identifiable source.: - Dental fear
11. -------- is nonspecific, unease, apprehension, or negative thoughts about what might
happen during a dental appointment; source unknown.: Dental anxiety
12. What could happen if the N2O tank is opened too quickly?: Opening the tank valves too
quickly could cause rapid pressure increase, increasing the temperature, which can cause a
chemical reaction resulting in fire or explosion.
13. 20% N20 and 80% 02 has the same analgesic effect as ----- mg morphine-
: 15mg
14. T/F
N2O should not be used in combination with local anesthetics.: False. N20/02 is used to
enhance local anesthetic, but should NOT be used to substitute local anesthetic.
15. N20 has a rapid onset of action (< 5 minutes) and quick recovery because
----------: It has low solubility.
16. The -------- and --------- control breathing automatically.: The Pons and medulla oblongata
17. Breathing is also controlled voluntarily by the ------------.: Cerebral cortex.
18. The upper respiratory system consists of what 4 things?: Nose, Na- sopharynx,
Oropharynx, and Laryngopharynx.
Nasopharynx: tonsils, adenoids, eustachian tubes
Oropharynx: entrance into larynx and esophagus
Laryngopharynx: starts at the epiglottis, which directs material into esophagus to avoid trachea;
contains the larynx; made of cartilage to protect larynx.
19. The lower respiratory system consists of what 4 things?: Larynx, Trachea, Bronchi and
Bronchioles.
Larynx: contains vocal cords, cough reflex; N20 sedation SHOULD allow cough reflex to remain
intact
Trachea: muscular tube bifurcates into R and L bronchi, contains carina (back up cough
mechanism)
Bronchi: R shorter than L, more foreign objects aspirated into R lung
Bronchioles: continuous division of the bronchi but w/o cartilage
20. CO2 and O2 are exchanged across capillary membranes in the alveoli by
-----------.: Passive diffusion.
21. The amount of air that enters or leaves the lungs during ONE respiratory cycle is ----------.
What
is
the
average
amount
in
milliliters
for
an
adult?:
TIDAL
VOLUME,
(avg.
adult
is 500
ml).
22. The amount of gas brought into the lungs each minute is referred to as.: MINUTE
VENTILATION.
23. When is a pulse oximeter mandated?: Use of pulse oximeter is not mandated for minimal
sedation, but is mandated for moderate sedation according to the ASA.
24. Nitrous oxide molecule displaces --------- in the lungs.: Nitrogen
25. --------- is when headaches, lethargy, and nausea occur because of de- creased O2
saturation levels in the blood, caused by the rapid exit of N20 on its termination.
How can you prevent this from happening?: Diffusion Hypoxia. (When N20 exits the lungs faster
than the N2 that replaces it which dilutes the supply of O2, and reduces the O2 blood saturation).
Administer 100% O2 afterward for five minutes to prevent this from occurring.
26. T/F
N20 alters mood and increases pain-reaction threshold but does not totally block pain
sensations.Peripheral vasodilatation is produced by N2O admin- istration - patient may
appear flushed. Little or no effect on respiratory or other body systems and there are no
significant drug interactions.: TRUE
27. What are the effects of N2O on the cardiovascular system, central ner- vous system and
the respiratory system?: Cardiovascular System: no negative effects, the extra 02 can be
beneficial.
Central Nervous System (CNS): depresses the CNS, but no significant negative effects.
Respiratory System: may not be effective if the nasal passages are blocked;
non-irritating to mucous membranes.
28. N20 may interfere with what vitamin?: B12
29. T/F
N20 should not be used with bowel obstructions but is okay with ulcers.: True
30. Are there any contraindications for a pregnant women with N20?
Does N20 cross the placenta barrier?: You must obtain consent from their MD (not the
dentist!) if N2O must be used.
N2O does cross the placental barrier.
31. Are there any concerns of using N2O for people with: cancer, middle ear disturbances,
mind altering conditions, nutritional or eating disorders or people taking sedative hypnotic
medications for sleep induction?: YES:
Middle ear disturbances, mind altering conditions, people taking sedative hypnotic medications.
Pressure can affect middle ear and eyes; MD consult if infection, surgical proce- dures have been
done, etc.
Cancer: no negative effects, can provide additional comfort in final stages. Mind altering
conditions: must be used with caution or contraindicated-mental illness, mental retardation,
autism, Alzheimer's, drug and alcohol abusers (individual de- termination- see future slide on
indications).Nutritional/eating disorders: no effects. Can intensify sedative-hypnotic drugs. Can
enhance the effects of drugs to induce sleep or when drowsiness is a side effect (anti-histamines,
codeine, etc.).
32. ----------- regulates the N2O industry.: FDA
33. Under no circumstances should ---------------------- come in contact with the gas or gas
delivery system; potential explosion!: Grease, oil, or other lubricating substances.
34. List some indications for the use of N2O:: Mild anxiety/apprehension, Hy- persensitive gag
reflex, Cardiovascular disease (O2 enrichment coupled with stress reduction), Hypertension,
Asthma (stress induced for example), Cerebral palsy, Mental retardation, Allergy to local
anesthesia, Intolerance for long appoint- ments and Labor and delivery.
35. T/F
These are all relative precautions for the use of N2O:
Pregnancy, respiratory obstruction, anemia, COPD, psychological impair- ment,
methoglobinemia, emphysema, chronic bronchitis,: Pregnancy Consult with physician prior to
any nitrous use during pregnancy (high rate of sponta- neous miscarriage, especially during first
trimester). Respiratory obstruction such as a stuffy nose prevents patient from inhaling the
anesthetic. COPD/Emphy- sema/Chronic bronchitis** - compromises the patient's ventilation and
increases carbon dioxide partial pressure. Psychological impairment - these patients may
experience euphoria or altered state (evaluate prior to nitrous use if patient is on phenothiazines,
TCAs, lithium).
Not: anemia or methoglobinemia (abnormal breakdown of RBC).
36. T/F
These are all relative precautions for the use of N2O:
History of drug abuse or addiction, hemophilia, middle ear disturbances, multiple sclerosis,
epilepsy, communication difficulties, leukemia, bowel ob- struction,: FALSE
Relative precautions:
History of drug abuse or addiction, Middle ear disturbances and recent eye surgery(may prevent
high doses from being administered due to increased pres- sure in the ear or eye), Multiple
sclerosis, Epilepsy(can trigger a seizure), Com- munication difficulties, Bowel obstruction or
sinus blockage(because of expansive nature of gas in a confined air space).
Not: leukemia(cancer of the blood) or Hemophilia(Too long to clot).
37. T/F
These are all relative precautions for the use of N2O: Patient taking bleomycin sulfate,
Polycythemia vera, claustrophobia, cystic fibrosis, within
24 hours of scuba diving, increased intracranial pressure.: Bleomycin sul- fate(used to tx.
lymphomas and squamous cell carcinomas - may cause pulmonary
problems), Claustrophobia, Cystic fibrosis, Within 24 hours of scuba diving, In- creased
intracranial pressure
Not: Polycythemia vera(abnormal increase in RBC).
38. T/F
N2O has no negative effects on the endocrine system. It is okay to use with diabetics, people
with thyroid gland dysfunctions and adrenal dysfunctions.-
: True
39. T/F
N20 affects the liver in the presence of liver impairment.: False;N20 is not metabolized by the
liver, nor does it effect the liver in the presence of liver impairment.Ok to use with Hepatitis,
Jaundice and Cirrhosis.
40. T/F