L6 Nitrous Oxide Sedation Flashcards
What is nitrous oxide made of
Dinitrogen monoxide (g) Stored as a liquid
What are properties of N2O
- Analgesic (like morphine)
- Anxiolytic
- Colourless
- Non-flammable
- Slightly sweet
odour - Low solubility in blood
- Rapidly diffuses across membrane
- Excreted unchanged from lungs
What affects does nitrous have on BP and heart rate?
No change to BP (if at all a slight increase)
No effect on HR
Where does N2O act?
On opioid receptors in the mid-brain - same is morphine and heroin
Descending inhibitory pathway
Altering pain processing in the spinal cord
What do the effects of N2O feel like?
Alcohol
What is the common percentage of N2O
40-70%
Usually used with other things as well - ex. will not be used alone for GA
What is the onset time of nitrous?
2-5 minutes
What are potential uses for nitrous?
Start GA
Titrate GA
Anxiolytic
Reduce pain
What must be given in first and last 5 minutes?
Oxygen
What is a general effect of N2O?
Calm, comfortable, relaxed, reduced fear/anxiety
Aware patient, that responds, but has a glazed look in eyes
What are the general sensations people feel from nitrous?
- tingling extremities
- heaviness, heaven ness
- warmth
- Chills
- Floating sensation
- Vasodilation
Loss of gag reflex
What is involved in the metabolism of N2O
Oxidizes cobalt enzyme of vitamin b12
– b12 required for myelin sheath synthesis
Pressure volume problems
N2O pressure is 31x more than N2
N2O physically replaces N2 and increases the volume +/or pressure of that space
N2O 34x more soluble in blood, replacement of N2 faster than N2 is taken out, increasing pressure in air filled spaces
What are some benefits of nitrous?
Good for long procedure, good for pain and anxiety, quick and easy to reverse, easily titratable
Still lets people have protective reflexes, with few side effects
Is nitrous stored in body or metabolized by the liver?
Neither
99% eliminated through lungs without biotransformation
What are indications for nitrous?
Fearful anxious patient Special health care need Strong gag reflex Profound LA can't be obtained Lengthy procedure
What are contraindications for nitrous?
Lung issues Phychological issues Pregnancy Bleomycin sulfate (a cancer med for SCC) B12 efficiency Pulmonary hypertension Severe cardiac disease Claustrophobia Congestion, nasal probs Resp tract infections Full meal Cystic fibrosis Pneumothorax, middle ear probs, eye surgery, hyperthermia
What are the names of the nitrous machine we use?
Accutron or porter
What colour is the oxygen side?
White/green
What colour is the nitrous side
Blue
Requirements for nitrous
5 cases per year in log book, re-register q5yr
To certify in nitrous
6 cases and a 6 hour course
What is the minimum oxygen percentage delivery?
30%
What percentage of nitrous patients don’t receive enough sedation?
3%
Why do patients not achieve enough sedation?
Claustrophobia
Need more than the 70% nitrous system can deliver
Too fearful
Is vomiting possible from nitrous?
Yes, position upright, suction and assess for aspiration
What is diffusion hypoxia?
After sedation N2O leaves the body relatively unaltered through the lungs.
N2O will leave faster than N2 can replace it –> diluted supply of O2 and reducing O2 blood saturation
This is why we need 5 mins of Oxygen
Symptoms of acute nitrous exposure
Dizzy hard to breath headache nausea fatigue irritability loss of consciousness
Chronic exposure symptoms
tingling numbness mental performance manual dexterity adverse reproductive effects
What does it mean to minimize N2O pollution
Minimize talking Scavenge area of mixing unit Turn the tank off all the way cannot use any cracked stuff pressure test
Office air zones for nitrous
- patient zone - within 10 cm from nose
- operator zone - 36-72 cm away from pt nose
- operators zone - whole op with nitrous oxide use
- office zone - all areas outside of operators served by same ventilation system
What are the zones we’re concerned about?
2 and 3
What is the limit for nitrous use per day?
30 minutes to maintain a 25 ppm safety level
