inhalation sedation Flashcards
Properties of Nitrous Oxide
Rapidly absorbed but relatively insoluble in blood.
- quick onset
- quick recovery - leaves circulation and exhaled through lungs
Properties of Nitrous Oxide
Weak Anaesthetic:
- wide margin of safety - little effect on the respiratory system and excreted unchanged so suitable for pts with liver or kidney disease.
- loss of consciousness extremely unlikely
(not suitable to anaesthetise so will still require LA)
Nitrous Oxide Mechanism of Action
- anxiolysis - enhances activity of GABA receptors (similar to benzodiazepines) to stabilise nerve cell membrane.
- analgesia - mediated through interaction with opioid receptors.
- euphoria - dopamine release but has a mixed response (subjective to the individual).
Plane I of Analgesia - 5-25% NO
- relaxation and general sense of wellbeing
- paraesthesia
- feeling of suffusing warmth
- alert and readily responds to questions
- slight reduction in spontaneous movements
- decreased reaction to painful stimuli
- normal pulse, blood pressure, respiratory rate, reflexes and pupil reactions
Plane II of Analgesia - 20-55% NO
- marked relaxation and sleepiness
- detached from environment
- altered senses
- possible dreaming
- widespread parasthesia, moderate analgesia
- reduced gag reflex
- delayed response to questions
- vital signs and laryngeal reflexes should be unaffected
Plane III of Analgesia - 50%+ of NO
- marked relaxation and sleepiness, glazed appearance
- complete analgesia
- nausea and dizziness common
- pt may vomit
- unresponsive to questions
- may lose consciousness and enter stage 2 of general anaesthesia
Positives of Nitrous Oxide
- anxiolysis
- mild analgesia
- hypnosis
- euphoria
- rapid induction and recovery
- minimal metabolised
Negatives of Nitrous Oxide
- systemic toxicity - long term occupational exposure can lead to haematological, neurological and reproductive side effects.
- environmental effect - 300x more impact on global warming than CO2.
Ways to minimise nitrous oxide pollution:
- active scavenging systems (miniscav)
- room ventilation - 15 changes of room air per hr.
- floor level extractor fans
- correct technique:
- check pt is continuing nasal breathing
- monitor mask seal
- use lowest amount required for tx
- rubber dam - regularly serviced equipment
Patient Suitability
- mild to moderate dental anxiety
- some degree of cooperation
- > 5 years old (needs to sit by themselves in the dental chair)
- acclimatisation prior to sedation
- able to understand the same language
Contraindications
- URTI (upper respiratory tract infection)
- blocked nose
- chronic respiratory disease
- mouth breathers
- pre-cooperative children
- unable to speak and understand the same language
- moderate to severe learning disabilities
- first trimester of pregnancy
- upper anterior apicectomy
Information for Patients and Parents
- clear description of IHS using nitrous oxide and oxygen
- pt remains awake throughout procedure
- LA will still be used
- show the nasal hood
- explain how they will feel
- breathing exercises to practice prior to appt
- alternative options
Pre-op Instructions
(verbal and written instructions should be given re. post-op care)
- light meal 2 hours before appt
- children to be accompanied by responsible adult
- transport home - car or taxi
- no bike riding/machinary op for rest of the day
- adult supervision for the rest of the day, don’t return to school
IHS Consent Process
- carried out prior to the day of appt
- consent form 2 on clinic
- signed by adult with PR
- info given verbally and in written format
- discuss other options
- confirm tx to be undertaken with NO and O2 +/- LA
Pre-Op Machine Checks
- done each day/session to make sure machine is working correctly to confirm safety
- check reservoir bag is inflating with no leaks
- start with 100% O2, then 50% to check flow readings correspond
- remove O2 supply and check NO flow immediately stops