Chapter 21 - N2O-O2 Flashcards
- The reservoir bag monitors which of the following?
a. Depth of respiration
b. Rate of oxygen flow
c. Need to adjust the Lpm
d. a and c
d. a and c
- Nitrous oxide sedation may be contraindicated in patients with which of the following conditions?
a. Recovered alcoholic
b. Hypoxic-driven COPD
c. Cystic fibrosis
d. all of the above
d. all of the above
(recovered alcoholics may relapse; COPD pts may have respiratory issues that may be further compromised; CF pts may incur emphysematous bullae)
- Which of the following reactions would indicate that a patient is being over-sedated?
a. giggling
b. ringing in the ears
c. unresponsiveness
d. tingling in the toes
c. unresponsiveness
- The effects of adequate sedation may include which of the following?
a. Relief of anxiety
b. Heaviness of the legs
c. Warm, flushed feeling
d. All of the above
d. All of the above
5, Most patients will achieve the desired level of sedation at what percentage of nitrous oxide?
a. Less than 10%
b. 10%-20%
c. 15%-40%
d. Greater than 50%
c. 15%-40% for most pts
others may be hypo- or hyper-responders
- Oxygen is delivered for 3-5 minutes after dental sedation in order to:
a. Prevent diffusion hypoxia
b. Bleed nitrous oxide from the hoses.
c. Allow recovery and the return of reflexes
d. b and c
d. b and c
N2O concentrations used in dentistry do not cause DIFFUSION HYPOXIA; O2 delivery is provided to eliminate N2O from hoses and to allow time for recovery and the return of reflexes
Q21-1: Define sedation.
A21-1: A state of calm induced by a drug or other tranquilizing substance.
Q21-2: What is the intended level of sedation with the use of nitrous oxide-oxygen (N2O-O2) in dentistry?
A21-2: Minimal sedation
Q21-3: Discuss the effects and anticipated patient response with the use of N2O-O2 in dentistry.
A21-3: Minimal level of sedation.
- pt able to respond normally to tactile stimulation and verbal commands
- pt able to independently maintain an open airway
- diminished pain and anxiety
- depressed level of consciousness with awareness of surroundings
Q21-4: What are some limitations and precautions with the use of N2O-O2 sedation in dentistry?
A21-4:
* variable effects on indiv. pts; ineffective for some
* increases costs
* requires:
- education to safely administer & monitor
- routine equipment monitoring/maintenance
- monitoring to prevent environmental exposure
Q21-5: Discuss diffusion hypoxia related to the use of N2O.
A21-5:
* may occur when excess N2O diffuses out of the blood & displaces O2 in the lungs
* usually w/ extraordinary percentages of N2O
* with N2O percentages used in dentistry, diffusion hypoxia does not occur.
Q21-6: Discuss the effects of N2O-O2 sedation on the central nervous system AT NORMAL SEDATION LEVELS.
A21-6:
- produces a variable degree of amnesia, distortion of spatial orientation, and sleepiness
- minimal effect on the ANS
- may enhance the CNS depressant effect of drugs (barbiturates, tranquilizers, narcotics, recreational)
Q21-7: What are the effects of N2O-O2 sedation on the cardiovascular system at normal sedation levels?
A21-7: No-to-minimal effect on the heart’s contractility, output, stroke volume, rate, or rhythm, and blood flow.
Q21-8: What is the FDA pregnancy category for N2O?
A21-8:
FDA pregnancy category C.
Considered a relative contraindication.
Q21-9: Define and discuss minimum alveolar concentration (MAC).
A21-9:
MAC represents an adequate dose (of gas in the alveoli) to achieve general anesthesia for 50% of the population. This is assigned a value.
Q21-10: What is the typical MAC of N2O?
A21-10: At typical sedation concentrations in dentistry of 0.3–0.5 MAC (30% to 50%), N2O produces mild analgesic effects that will still require the use of local anesthesia.
Q21-11: Summarize adverse reactions to N2O-O2 sedation.
A21-11: Although rare in occurrence, adverse reactions to N2O-O2 sedation include:
* Dizziness
* Increasingly rigid movements
* Unresponsiveness
* Sweating
* Nausea and vomiting
* Dilated pupils
Q21-12: What is the leading cause of dissatisfaction with N2O-O2 administration?
A21-12: Nausea and vomiting, especially during pediatric care.
Q21-13: Provide some common indications for dental N2O-O2 sedation.
A21-13:
* Apprehensive patients
* Restless, anxious, or young children
* Long procedures
* Hyperactive gag reflexes
* Temporomandibular disorders
Q21-14: Provide examples of absolute contraindications to the use of N2O-O2 sedation.
A21-14:
* Active respiratory infection (URI, TB, flu, etc.)
* Advanced (hypoxic driven) COPD (absolute in dentistry; relative in medicine)
* Intraocular gas injection (within 8–12 weeks)
* Latex allergy (exception with non-latex systems)
* Pregnancy (first trimester)
* Recent tympanic membrane graft
* Severe psychoses (in dentistry; relative in medicine)
* TX involving injection or pathology that causes pockets of gases into a body cavity (e.g. diverticulitis)
Q21-15: Provide examples of relative contraindications to the use of N2O-O2 sedation.
A21-15:
* Certain mental/psychological disorders
* Claustrophobia
* Contact lenses
* CNS depressant use (incl. OTC & herbs)
* Cystic fibrosis
* Dry air-induced asthma
* Susceptibility to Vitamin B12 deficiency
* Latex sensitivity
* May be CI in patients receiving bleomycin
* Middle ear issues (blocked eustachian tubes)
* PTSD [can be positive or negative experience]
* Pregnancy (second or third trimester)
* Recovering/recovered alcoholic
* Substance abuse
* Use of colostomy bags or bowel obstructions
Q21-16: What chemical is used to manufacture nitrous oxide?
A21-16: ammonium nitrate
Q21-17: What color are nitrous oxide tanks painted in the U.S.?
A21-17: Blue in the U.S.
Q21-18: What is the percentage of liquid and vapor contained in nitrous oxide tanks when full?
A21-18: 95% liquid, 5% vapor when full
Q21-19: What psi is maintained in a nitrous oxide tank until the liquid has evaporated?
A21-19: N2O tanks maintain constant pressure of approx. 750 psi until all the liquid has evaporated, making residual volume difficult to determine.
Q21-20: What color are oxygen tanks painted in the U.S.?
A21-20: green iIn the U.S.
(most of the rest of the world: white.
Canada: green with a white top.)
Q21-21: What is the percentage of vapor contained in oxygen tanks when full?
A21-21: 100% gas (vapor) when full
Q21-22: What is the amount of pressure in an oxygen tank when full?
A21-22: approximately 2200 psi
Q21-23: List the components of sedation delivery systems.
A21-23:
Manifolds
Copper tubing
Latex or nonlatex hoses
Pin index safety systems
Regulators
Flow meters
Reservoir bags, conduction tubing, and breathing apparatus
Q21-24: What are the two types of N2O-O2 delivery systems for use in dentistry?
A21-24: central supply & portable machines.
Q21-25: What is a Diameter-Index Safety System?
A21-25:
- on central supply systems
- to help prevent switching gases to the operatory
- consists of a manifold, copper tubing, and hoses
Q21-26: What is the name of the safety system used only for portable equipment?
A21-26: Pin index safety systems
Q21-27: What are scavenger systems?
A21-27:
- eliminate residual gases
- usually operate via a separate suction system that is part of the office suction system.
Q21-28: Why is copper tubing required in central supply delivery systems?
A21-28: Copper tubing is required in central supply because it does not support combustion.
Q21-29: Describe and discuss the purpose of a pin index safety system.
A21-29: arrangement of holes and pins ensure that tanks are correctly attached to the corresponding gas yolks on the stands
Q21-30: What is the function of the regulator?
A21-30:
- found on portable & central delivery systems
- reduce gas pressures from tanks before gas is delivered into the tubing and pipes
Q21-31: Describe the function of a flow meter.
A21-31:
floating balls inside calibrated glass tubes (usually colored green for O2 and blue for N2O) provide visual indications of the volumes of the gases delivered.
Q21-32: What is the purpose of a reservoir bag?
A21-32:
- provide a volume of gas necessary for each breath (bags refill from the continuous flow of gas delivered by the machine betw. pt’s inhalations)
- provide mechanisms for monitoring breathing and evaluating whether more or less gas is needed during administration.
Q21-34: What is time-weighted dosimetry?
A21-34: inexpensive method for monitoring individual exposure to trace gas by wearing a badge for a specified time period before being submitted for analysis
allows for continuous monitoring & easiest when N2O-O2 sedation is used intermittently
Q21-35: What is the percentage of N2O where most patients reach adequate sedation levels?
A21-35: Most patients reach adequate sedation levels between 15% and 40% N2O, although there are no set concentrations to achieve specific levels of analgesia.
Q21-36: List the five main steps for administering N2O-O2 sedation.
A21-36:
1) Patient assessment and informed consent
2) Pre-sedation preparation
3) Incremental induction & sedation monitoring
4) Initiating and monitoring recovery
5) Documentation
Q21-37: What are the common symptoms of sedation?
A21-37:
* Feeling of warmth
* Sense of relaxation
* Feeling of heaviness of the extremities
* Sense of tingling of the extremities
Q21-38: What are the signs of optimal N2O sedation?
A21-38:
* sense of relaxation and well-being
* sense of comfort & awareness of surroundings
* able to respond rationally and coherently
* able to acknowledge reduced anxiety and fear
* dreamy look & big smile
* tingling or heaviness of extremities
* slight ringing in ears; increased hearing range
* vital signs should remain normal
Q21-39: What are symptoms of excessive N2O sedation?
A21-39:
* Uncontrolled laughter
* Sweating
* Nausea
* Marked lethargy, closing mouth frequently
* Unresponsiveness, unaware of surroundings, fixed stare
* Dysphoria (an emotional state marked by anxiety, depression, and restlessness)
* Inability to follow commands
* Dilated pupils
* Agitated, combative behavior
* Hallucinations
Q21-40: Summarize the incremental induction steps.
A21-40:
* Establish tidal volume: 100% O2 for 2 minutes
Inducing Sedation/Analgesia:
* 10% N2O for 1 minute
* 20% N2O for 1 minute
* 25% N2O for 1 minute
* Up 5% each minute until level achieved (not to exceed 70% N2O)
Initiating and Monitoring Recovery:
* Administer 100% O2 for 3–5 minutes
Q21-41: Discuss possible causes of long-term occupational risk of exposure to N2O.
A21-41:
-impossible to prevent trace amounts even w/ proper maintenance & use
- long-term occupational exposure risk increases w/ inadequate ventilation, incorrect administration, poorly maintained equipment
Q21-42: Discuss the differences between administering and monitoring N2O-O2 sedation.
A21-42:
- Administering: dispensing, applying, or offering of N2O analgesia to a dental patient
- Monitoring: observing/evaluating pts (clinical, electronic, & mechanical means) & by recognizing/ reporting adverse reactions/complications to supervising dentists
List 4 levels of sedation
General Anesthesia
Deep Sedation
Moderate Sedation
Minimal Sedation
