Nitrous Oxide/Oxygen Inhalation Sedation in the Pediatric Patient

nitrous oxide indications

-reduce anxiety

-increase pain threshold

-suppress gag reflex

-increase tolerance for longer appointments

-eliminate need for sedative premedication

-potentiate effects of sedative premedication

physical properties of nitrous oxide

-a non-flammable, sweet-smelling gas

-relatively insoluble

-stable

-stored in BLUE cylinders

chemical properties

-nitrous oxide is inert

-quickly absorbed from the alveoli of the lungs and physically dissolved in the blood

-eliminated unchanged from the body

-gas is rapidly excreted form the lungs when the concentration gradient is reversed

mechanisms of action

-analgesic effect: initiated by neuronal release of endogenous opioid peptides with subsequent activation of opioid receptors and descending GABBA receptors and nonandrenergic pathways that modulate nociceptive processing at the spinal level

-anxiolytic effect: activation of the GABBA receptor either directly or indirectly through the benzodiazepine binding site

CNS pharmacology

-CNS depressant

-weak anesthetic potency- MAC >100% (minimum alveolar concentration- percent of population that would reach a state of GA)

-relatively potent analgesic

-response to suggestion enhanced

-cough reflex moderately suppressed- important to have rubber dam on

cardiovascular effects

-parallels inhaling 100% oxygen

-slight decrease in heart rate

-no evidence of increased myocardial irritability

-no change to slight decrease in blood pressure

respiratory effects

-slight stimulation- resulting in increased tidal volume

-sense of smell decreased

diffusion hypoxia

-upon termination of nitrous oxide administration, outpouring of nitrous oxide into the lungs can dilute the amount of oxygen available to the patient

-danger is probably insignificant in healthy patients

-recommended that pts receive 100% oxygen for 3-5 minutes at the termination of N2O use to prevent possibility

GI effects

-nausea and vomiting

-very low incidence

-#1 side effect

-very low incidence

-usually, no special eating instructions prior to administration

-correlation with fluctuating concentrations of N2O?

contraindications

-COPD- bronchitis, emphysema

-URI/maxillofacial deformities or nasal obstructions

-acute otitis media or recent middle ear surgery

-severe emotional disturbances

-claustrophobia or irrational fear of “gas”

-pregnant patients- especially in first trimester

-treatment with bleomycin sulfate

-methylenetetrahydrofolate reductase (MTHFR) deficiency

-cobalamin deficiency (vitamin B12)

advantages

-rapid onset and recovery

-ease of dose control (titration)

-limited physiologic effects

-analgesic

-suppression of gag reflex

-potentiation

disadvantages

-weak agent

-lack of patient acceptance- pt has to be somewhat compliant

-patient must be able to breathe through nose

-inconvenience when working on maxillary anterior teeth

-potential chronic toxicity

-potential for abuse

-necessary equipment

-potentiation

equipment

-numerous types of machine available

-fail-safe mechanism: minimum 30% O2

-audible or visual alarm if O2 interruption

-flush lever

-pin-indexed yoke system

-gas cylinders color coded (green- oxygen, blue- nitrous oxide)

safety issues for dental personnel

-chronic exposure (>8 hrs per week):

-increases in liver, kidney, and neurologic diseases

-increase in spontaneous abortion

-increase in congenital abnormalities

minimizing risk

-good scavenging system

-adequate circulation of room air

-limiting speech and mouth breathing of patient

-proper size nasal hood

-? use in uncooperative child

potential for abuse

-real concern in profession

-secure safely

-common signs of abuse: parasthesia or clumsiness of hands and legs, loss of balance, unsteady gait

patient selection

-medical history and physical exam

-parental informed consent

-mild-moderate anxiety

-strong gag reflex

-some pts with special health care needs: capacity to be compliant and follow directions

-when unable to get profound LA

-cooperative child undergoing lengthy procedure

administration

-prior to seating patient:

-make sure equipment is set up and working properly

-select nasal hood of proper size

-have pt use restroom if necessary

-make sure an assistant is in room at all times during use!

-introduce child to equipment (slowly)- use TSD

-make adjustments to ensure mask fits snugly but comfortably

-establish a total liter per minute of gases first with 100% O2: 3-7L/min depending on size of pt

-encourage pt to breathe through nose, keep reminding them verbally

-slow induction ideal, rapid induction what actually happens

-during induction, explain what the child might be feeling (tingling, numbness, sensation of warmth/floating, feeling of heaviness, droning sounds, hearing distinct but distant)

-watch pt for signs of proper level of sedation (therapeutic nitrous oxide levels usually between 30-50%, do NOT exceed 50%, watch for signs of nausea)

-upon termination of procedure: 100% O2 for 3-5 minutes, have child sit up in chair for several minutes

important notes

-nitrous oxide is NOT a substitute for traditional behavior management techniques

-should be considered an adjunct to aid in the management of the mild to moderately anxious patient who is capable of cooperating in the dental chair

-can make the good patients better