Nitrous Oxide Nitrous Oxide Sedation in Pediatric Sedation in Pediatric

DentistryDentistry

Dr.S.E.Jabbarifar 2009

History of N2O

Dr. Horace Wells

1793 - Joseph Priestly invented N2O

Initially used as an anesthetic agent in 1844.

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.

Purpose of Nitrous Oxide Sedation

Reduce fear, apprehension, or anxiety

Raise pain reaction threshold Reduce fatigue

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

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

Fear Reduction and N2O

Increase Pain Reaction Threshold

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Pain

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old

Pain

To

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10

20

30

40

50

m Amps

% Nitrous Oxide

NO Concentration vs. Pain Threshold and Tolerance

Four Stages of Anesthesia

Analgesiapatient is conscious reflexes are intact

Delerium Surgical Anesthesia Respiratory Paralysis

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

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.

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

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

N2O Should Not Be Used To:

Control defiant or uncontrolled behavior

Control pain by replacing local anesthesia

Replace poor techniques of behavior management

Uptake and Saturation of N2O

Blood

Tissue Saturation

PROBLEMS!!!

Less Uptake N2O from Lungs

Lungs

Effective PP in Brain

Increase Lung N2O Concentration

Highly Perfused Tissues

Signs of Saturation

Reminding child continuously to hold mouth open

No response to questions Agitation Sweating Nausea Unconsciousness

Monitor Frequently

Reduce N2O Dosage...

with lengthy administration (> 30 min.).

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

Elimination of N2O

Rapid Primarily through the lungs Small amount through skin, sweat

glands, urine, and intestinal gas

Diffusion Hypoxia

High outpouring of N2O Dilutes available oxygen in lungs

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

Effects on Systems

CNS - primary system effected by N2O

Respiratory respiratory rate increasedecrease tidal volumeN2O potentiates respiratory depression

with concommitant use of narcotics, barbiturates, or other sedatives

Effects on Systems

Cardiovascularnormally, no meaningful changes in

heart rate or pressuremyocardial depression with cardiac

decompensation (congestive heart failure)

patients with ischemic heart disease without decompensation may benefit from N2O

Myocardial Depression with N2O Use in CHF Patients

2.2

2.4

2.6

2.83

3.2

3.4

3.6

100% O2 50% N2O

Cardiac Index

Normal LVEDP Elevated LVEDP

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

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.

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

Chronic Exposure Disorders

Reproductive Hematologic Immunological Neurological Liver Kidney

Neurological Symptoms of Chronic Exposure

Loss of concentration Numbness and

paresthesia Ataxia Impotence Loss of bladder control Loss of bowel

sphincter control

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)

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)

Safe Concentrations of N2O

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

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 N2Oeffective regardless of heating and air

conditioning system in useable to achieve N2O standards recommended

by NIOSH and OSHA

Controlling N2O in the Operatory

Monitoring N2O concentrationAir samples from two areas

room air - infrared spectrophotometerworker breathing zone - passive dosimeter

Howard, JADA, March 1997

Controlling N2O in the Operatory

Engineering controls Inspection

equipment for wear, cracks, tearstest connections

Scavenging systemno system currently accepted by ADAflow rate of 45 L/min vacuum rate

Howard, JADA, March 1997

Controlling N2O in the Operatory

VentilationFresh air inlets - ceilingReturn air vents - floor levelLocation of ventilation system exhaustAir exchange rate (>10/hr)

Howard, JADA, March 1997

Controlling N2O in the Operatory

Work Practices Inspect equipment every dayUse scavenging system Instruct patient to refrain from mouth

breathing and talkingBag should collapse and expand as the

patient breathesAfter administration, flush the system

100% O2.Howard, JADA, March 1997

Howard, JADA, March 1997

Controlling N2O in the Operatory

Maintenance Inspect and test for leaks (soap)Document results of tests and actions

takenAll repairs done by authorized dealers

N2O Scavenging Factors of scavenging effectiveness

auxilliary evacuation rate of evacuation of scavenging deviceoperatory ventilationuse of air sweep fans reduced concentration of delivered N2Opoor patient behaviorcertain procedures (local anesthesia) improper administration loose connections

N2O Scavenging - Device

Preparation of Patient

Patient in reclined position Use TSD Describe sensations in advance

This is how its gonna be, kid...

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

Administration of N2O

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

Hallucinations

Complications/Precautions

Always have an assistant present!

Complications/Precautions

Mild rhinitis or colds are not absolute contraindications

Contraindicated in patients with a depressed respiratory systemchronic emphysema tuberculosismultiple sclerosis remember, N2O will potentiate drugs that

depress the respiratory system

Complications/Precautions

Contraindicated in patients with blocked eustachian tube, pneumothorax, pneumoperitoneum, and pneumopericardium

Contraindicated in the first trimester of pregnancy

Complications/Precautions

Other possible contraindications:severe cardiac diseasehyperthyroidismuncontrolled diabetessickle cell anemiasevere asthmatic conditions

See Ya Next Time….