Nitrous Oxide Sedation in Pediatric Dentistry Dr.S.E.Jabbarifar 2009
History of N2O • 1793 - Joseph Priestly invented N2O • Initially used as an anesthetic agent in 1844. Dr. Horace Wells
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
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.
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 Highly Perfused Tissues Blood Lungs Less Uptake N2O from Lungs Effective PP in Brain PROBLEMS!!! Increase Lung N2O Concentration Tissue Saturation
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 increase • decrease tidal volume • N2O potentiates respiratory depression with concommitant use of narcotics, barbiturates, or other sedatives
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
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 Uh, whaa ja’ say????
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 N2O • effective regardless of heating and air conditioning system in use • able to achieve N2O standards recommended by NIOSH and OSHA
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
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
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
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
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
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
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
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 system • chronic emphysema • tuberculosis • multiple 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 disease • hyperthyroidism • uncontrolled diabetes • sickle cell anemia • severe asthmatic conditions