N20 sedation Flashcards
Nitrous Oxide N2 O
* happy/sad?
* emotions/inhibitions of pt?
- Nitrous Oxide a.k.a. laughing gas
- Nitrous oxide does NOT make a person happy or sad
- Decreases the inhibitions of the patient
- Increases the intensity of emotions
Physical properties n2o
- Only inorganic anesthetic gas in clinical use
- Colorless and odorless
- Capable of oxygen supporting combustion
n2o effects on pulmonary, cardio, and renal systems
Toxicity of n2o
- Prolong exposure Bone marrow depression, Neurological deficiencies peripheral
neuropathies and pernicious anemia
n2o production
Impurities of n20
- N2 (nitrogen), NO (nitric oxide), NO2 (Nitrogen dioxide), NH 4 ammonia
water vapor and CO (carbon monoxide)
most dangerous impurity of n2o
NO is most dangerous impurity
* Combine with Hg and prevent O 2 absorption and may also react with water vapor
to form acid = damage pulmonary epithelium = pulmonary edema
* NO is form when N2 O is heated above 450 0 C
n2o hydrous state
N20 is anhydrous
n2o Properties
* iritation, smell, color?
* CNS?
* Specific gravity?
* Wall of the cylinder maybe cold due to?
Properties
* Nonirritating, sweet-smelling, colorless gas
* ONLY nonorganic compound other than CO2 that has CNS depressant
properties
* Specific gravity if 1.53 vs air (1)
* Wall of the cylinder maybe cold due to heat needed for vaporization into
gaseous state
Solubility n2o
is n2o oxygen usable
n2o flammable/explosive
Potency of n2o
* compared to other anesthetic gases
* solubility compared to n2/o2
Potency
* Least potent of the anesthetic gases
* N2O is
* 35X more soluble in plasma than N2
* 100X more soluble in plasma than O2
cns depression with n2o+o2
N2O + O 2 = CNS depression
* Some patient may get delirium
* Very few people will get Stage III anesthesia ( surgical anesthesia)
Optimum concentration of N 2O for production of
analgesia while maintaining patient cooperation is?
Optimum concentration of N 2O for production of
analgesia while maintaining patient cooperation is
35%
n2o mixture similar to morphine?
20%:80% mixture N2O-O 2 = 10-15mg of morphine
special properties of n2o
concentration effect and second gas effect
Concentration Effect
- The higher the concentration of the gas inhaled, the more rapidly arterial tension of the gas increases
- Fresh gas will be pushed into the lungs from the anesthesia machine= increase arterial N 2 O arterial tension
- So its important to start the Nitrous slowly and not blast it high in the beginning
2nd Gas Effect
- Occurs when a second inhalation anesthetic is administered along with N 2O-O 2
- Extreme uptake of N 2O will form a vacuum at alveoli that forces other air ( in this case, other inhalational agent) into the lungs
how does n2o inhalation work
mechanism of n2o
analgesic and anxiolytic
What happen when the N 2O session is over
- N2O diffused out of the blood and into the alveoli as rapidly as it diffused into the blood during the induction
- If patient simply breath room air and not O2 Patient may get diffusion hypoxia
- Prevention: administer 100% O2 for 3-5 mins at the termination of the procedure
Diffusion Hypoxia
- As the N2O is rushed out of the body, it will take other airs out including CO2
- Lowering CO 2 tension in blood will cause respiratory depression
- S/s: Headache, Nausea, Lethargy hangover effect
N2O at CNS
- Actual mechanism of action is unknown
- Almost all form of sensation are depressed.
- Mild Depression on CNS at Cerebral cortex
- Area postrema (vomiting center) of Medulla is not affected unless hypoxia or anoxia is present
n2o at CV system
- No clinically significant effect
- Slight depression of myocardial contraction
- Slight increase in vascular smooth muscle to norepinephrine
n2oirritation at pulmonary system
- Not irritating to pulmonary epithelium
- Ok for Asthma
n2o at GI
no effect
n2o at renal
no efffect
n2o and hematopoesis
- Inhibits methionine synthetase> impair B12 metabolism > decreased Bone Marrow function = Pernicious anemia (Vitamin B12 anemia)
- Long term exposure ( > 24 hr exposure) = transient bone marrow depression
n2o and skeletal mm
Does not produce relaxation of skeletal muscle
o2 properties
- Clear colorless, odorless
- Specific gravity of 1.105
o2/n2o cylinders
colors/psi
Advantages of Inhalational Sedation:
* Onset?
* recovery?
* N2O metab?
* Able to?
* No?
* side effects?
* ADRs?
* Nitrous Does have?
- Onset of action is similar to IV sedation
- Fast recovery (3-5 mins)
- N2O is not metabolized by body
- Able to Titrate ( administer small incremental dose until the desired clinical action is obtained)
- No injection
- Few side effect
- No adverse reaction to body organ/ system
- Nitrous Does have analgesic properties (20% n2o=10-15mg morphine)
Disadvantages of n20 inhalation
Contraindications to inhalation sedation
- No absolute contraindication
- Claustrophobic patients
- Compulsive personality ( take charge)
- Children with severe behavior problems
- Upper respiratory tract infection
- COPD ( chronic bronchitis, Emphysema)
- Pregnancy
Indications of inhalation sedation
Armamentarium for inhalation sedation
Compressed-gas cylinders safety and psi
- Cylinder are designed to handle 1.66 times the usual pressure
- Example: Usual 2000 psi O 2 cylinder is designed to hold up to 3400 psi
Handling of cylinders
* Never use?
* Storage position?
* drop?
* temps to avoid?
* valves?
* “cracking”
- Never use grease, oil or lubricant
- Store in vertical position
- Don’t drop them
- Avoid heat and fluctuating temperature
- Close all valves tightly even when its “empty”
- “Cracked” cylinder before use= Let some gas out before connecting to the system
Cylinder sizes
- From a small A size to large HH size
- Portable Nitrous oxide unit uses “E cylinder for both Oxygen and N2O
O2 cylinder
- Full E Cylinder is about 1900 psi in gaseous state only
- Psi will decrease as O2 is being used
N2O cylinder
- Full E cylinder has gaseous 750 psi and liquid states
- 750 psi will stay there until the moment of empty tank
o2 cylinders per n2o cylinders
2.5
Regulator ( Reducing valves)
- Reduce incoming cylinder pressure to ~50psi
Reservoir bag
- 3 liter reservoir bag is commonly used in Dentistry
- Provide additional gas on demand if patient exceed the gas flow being delivered
- Monitoring respiration
Scavenging nasal hood
- Eliminate exhaled N2O from the ambient air
Preoperative instructions for inhalation
* food?
* flow rates? (adult vs kid)
* COPD and CHF with partial obstruction?
* Reservoir Bag?
- No heavy meal 4 hours prior to N2O-O2 sedation
- Determine proper flow rate for the patient
- 6L/min flow of 100% O2 for adult
- 3-5L/min for smaller pediatric patient
- COPD and CHF with partial obstruction may require larger volume
- Reservoir Bag
Minimum O 2 delivering to Nitrous
Oxide sedation patient is ?
Minimum O 2 delivering to Nitrous
Oxide sedation patient is 30%
Inhalational sedation technique, begin with? titration?
General Algorithm to a sedation appt
How do you determine the “right” flow volume
- Reservoir bag
- Reservoir bag remains partially inflated and deflates and inflates partially with
each breath usually indicates that the minute volume is adequate
Totally Deflated reservoir bag causes?
- Minute volume of gas is inadequate
- Large leak at the nasal hood
- Vacuum on the scavenging system is too high
Overly Inflated reservoir causes?
- Minute volume of gas is too great
- Hose obstruction
progression of n2o effects on pt
How do you know if you are “in the zone”?
proper level n2o?
- Relaxation of hands
- Slower verbal responses
- Difficulty in phrasing replies
- Slower physical responses
discharging the pt
primary determinant and vital signs
Complications of n2o
