Nitrous Oxide Sedation in Pediatric Dentistry

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Nitrous Oxide Sedation in Pediatric Dentistry
Dr.S.E.Jabbarifar 2009

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History of N2O

• 1793 - Joseph Priestly invented N2O
• Initially used as an anesthetic agent in 1844.

Dr. Horace Wells
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N2O Commonly Used (and misused)
88 of Pediatric Dentists use N2O, and about 58
of general dentists use N2O.
Deadheads inhaling N2O from a balloon.
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Purpose of Nitrous Oxide Sedation

• Reduce fear, apprehension, or anxiety
• Raise pain reaction threshold
• Reduce fatigue

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Fear Reduction N2O

• One group treated with behavior management only
  other group with behavior management and N2O.
• Dental treatment of highly fearful children is
  carried out more successfully with N2O during the
  first few sessions.
• N2O is thus a valuable aid for making highly
  fearful children treatable quickly.

Veerkamp, et al, J Dent Child, May-June 1993
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Fear Reduction N2O

• When highly anxious children are treated with
  nitrous oxide for a number of consecutive
  sessions, their anxiety remains significantly
  lower during a following control period, even
  without use of nitrous oxide.

Veerkamp, et al, J Dent Child, Jan-Feb 1995
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Fear Reduction and N2O
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Increase Pain Reaction Threshold
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Four Stages of Anesthesia

• Analgesia
• patient is conscious
• reflexes are intact
• Delerium
• Surgical Anesthesia
• Respiratory Paralysis

The patient is unconscious in Stages 2, 3, and 4.
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Analgesia

• In analgesia stage, the patient is conscious, has
  all vital reflexes intact, can communicate and
  cooperate with the dentist, and quickly returns
  to a normal state following a few minutes of
  oxygenation.

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Four Plateaus of Analgesia

• Paresthesia - tingling of hands, feet
• Vasomotor - warm sensations
• Drift - euphoria, pupils centrally fixed,
  sensation of floating
• Dream - eyes closed but will open in response to
  questions, difficulty in speaking, jaw sags open

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N2O Should Be Used To

• Ease fears and anxieties
• Aid in the treatment of special patients
• Increase tolerance for longer appointments
• Raise the pain reaction threshold

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N2O Should Not Be Used To

• Control defiant or uncontrolled behavior
• Control pain by replacing local anesthesia
• Replace poor techniques of behavior management

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Uptake and Saturation of N2O
Highly Perfused Tissues
Blood
Lungs
Less Uptake N2O from Lungs
Effective PP in Brain
PROBLEMS!!!
Increase Lung N2O Concentration
Tissue Saturation
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Signs of Saturation

• Reminding child continuously to hold mouth open
• No response to questions
• Agitation
• Sweating
• Nausea
• Unconsciousness

Monitor Frequently
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Reduce N2O Dosage...

• with lengthy administration (gt 30 min.).

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Inhalation Analgesia Permits - State of Nebraska

• Portable oxygen tank
• Delivery system that delivers a maximum of 80
  N2O
• Medical history
• Physical evaluation ("...vital signs such as
  pulse, blood pressure, respirations, temperature
  and weight..."
• Oral pharyngeal airways available
• Emergency drugs

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Elimination of N2O

• Rapid
• Primarily through the lungs
• Small amount through skin, sweat glands, urine,
  and intestinal gas

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Diffusion Hypoxia

• High outpouring of N2O
• Dilutes available oxygen in lungs

Ventilate the patient for 3 to 5 minutes to
prevent diffusion hypoxia!
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Effects on Systems

• CNS - primary system effected by N2O
• Respiratory
• respiratory rate increase
• decrease tidal volume
• N2O potentiates respiratory depression with
  concommitant use of narcotics, barbiturates, or
  other sedatives

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Effects on Systems

• Cardiovascular
• normally, no meaningful changes in heart rate or
  pressure
• myocardial depression with cardiac decompensation
  (congestive heart failure)
• patients with ischemic heart disease without
  decompensation may benefit from N2O

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Myocardial Depression with N2O Use in CHF Patients
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Effects on Systems

• Fetal
• 1967 (Vaisman) - report showing increased
  incidence of spontaneous abortion among femal
  Russian anesthesiologists
• 1980 (Cohen, et al) - report showing increased
  spontaneous abortion rates (2.3) for DAs and
  unexposed wives of DDSs who used N2O in their
  practices also higher rates of liver, kidney and
  neurological disease

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Effects on Systems

• Fetal (cont.)
• 1992 (Rowland, et al.) - demonstrated reduced
  fertility among female DAs exposed to ambient
  levels of unscavenged N2O for longer than five
  hours per week the concentration and length of
  exposure that produce any of these effects remain
  undocumented.

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Chronic Exposure to N2O
Long-term (chronic) exposure to nitrous oxide in
sufficient concentrations can produce
irreversible, toxic changes, and should be a
concern for dental personnel working in
environments in which nitrous oxide is
administered to patients.
Howard, JADA, March 1997
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Chronic Exposure Disorders

• Reproductive
• Hematologic
• Immunological
• Neurological
• Liver
• Kidney

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Neurological Symptoms of Chronic Exposure
Uh, whaa ja say????

• Loss of concentration
• Numbness and paresthesia
• Ataxia
• Impotence
• Loss of bladder control
• Loss of bowel sphincter control

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Safe Concentrations of N2O

• OSHA - not established
• NIOSH - recommended exposure limit (REL) 25ppm
  during administrations
• ACGIH (American Conference of Governmental
  Industrial Hygienists) 50 ppm threshold limit
  value (TLV) over 8 hour TWA (time weighted
  average)

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Safe Concentrations of N2O
Nitrous Oxide Guidance ADA met with OSHA's
second in command, Deputy Assistant Secretary
James Stanley, Sept. 18 after learning that a
draft OSHA "technical guidance" document on
anesthetic gases apparently imposes on dental
offices a nitrous oxide level of 25 ppm, a level
technologically out of reach and far below that
associated with adverse health effects. ADA
pointed out that the Association's expert panel,
which met Sept. 12 and 13 and included an OSHA
engineer, agreed the 25 ppm level is unjustified
by scientific data. ADA will submit written
comments on the OSHA draft by the end of October.
(September 26)
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Safe Concentrations of N2O

• ADA - has not proposed a permissible exposure
  limit, but emphasizes the routine use of
  scavenging equipment

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N2O Scavenging

• Developed out of a concern regarding possible
  health consequences and psychomotor influences
• ADA states that scavenging equipment should be
• used to reduce ambient N2O
• effective regardless of heating and air
  conditioning system in use
• able to achieve N2O standards recommended by
  NIOSH and OSHA

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Controlling N2O in the Operatory

• Monitoring N2O concentration
• Air samples from two areas
• room air - infrared spectrophotometer
• worker breathing zone - passive dosimeter

Howard, JADA, March 1997
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Controlling N2O in the Operatory

• Engineering controls
• Inspection
• equipment for wear, cracks, tears
• test connections
• Scavenging system
• no system currently accepted by ADA
• flow rate of 45 L/min vacuum rate

Howard, JADA, March 1997
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Controlling N2O in the Operatory

• Ventilation
• Fresh air inlets - ceiling
• Return air vents - floor level
• Location of ventilation system exhaust
• Air exchange rate (gt10/hr)

Howard, JADA, March 1997
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Controlling N2O in the Operatory

• Work Practices
• Inspect equipment every day
• Use scavenging system
• Instruct patient to refrain from mouth breathing
  and talking
• Bag should collapse and expand as the patient
  breathes
• After administration, flush the system 100 O2.

Howard, JADA, March 1997
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Controlling N2O in the Operatory

• Maintenance
• Inspect and test for leaks (soap)
• Document results of tests and actions taken
• All repairs done by authorized dealers

Howard, JADA, March 1997
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N2O Scavenging

• Factors of scavenging effectiveness
• auxilliary evacuation
• rate of evacuation of scavenging device
• operatory ventilation
• use of air sweep fans
• reduced concentration of delivered N2O
• poor patient behavior
• certain procedures (local anesthesia)
• improper administration
• loose connections

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N2O Scavenging - Device
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Preparation of Patient

• Patient in reclined position
• Use TSD
• Describe sensations in advance

This is how its gonna be, kid...
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Administration of N2O

• Medical history vital signs
• 5 - 6 liters O2
• Increase N2O gradually watch for stages of
  analgesia
• Maintenance about 20 - 40
• Reduce N2O with long procedures
• Record N2O levels in the chart
• 3 - 5 minute O2 flush
• Rapid induction (surge) technique

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Administration of N2O
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Complications/Precautions

• Vomiting - due to
• overdosage
• prolonged administration
• pre-existing GI infection, influenza
• history of motion sickness or vomiting (use
  anti-emetic)
• impurities in the delivery system (rare)
• If vomiting occurs, turn patient to the side and
  use HVE
• Prevent vomiting by close observation of patient

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Hallucinations

• Complications/Precautions

Always have an assistant present!
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Complications/Precautions

• Mild rhinitis or colds are not absolute
  contraindications
• Contraindicated in patients with a depressed
  respiratory system
• chronic emphysema
• tuberculosis
• multiple sclerosis
• remember, N2O will potentiate drugs that depress
  the respiratory system

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Complications/Precautions

• Contraindicated in patients with blocked
  eustachian tube, pneumothorax, pneumoperitoneum,
  and pneumopericardium
• Contraindicated in the first trimester of
  pregnancy

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Complications/Precautions

• Other possible contraindications
• severe cardiac disease
• hyperthyroidism
• uncontrolled diabetes
• sickle cell anemia
• severe asthmatic conditions

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See Ya Next Time.