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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 Lungs Blood 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 (> 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 (>10/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 % 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 Always have an assistant present!
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….
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