Nitrous Oxide

What type of sedation is nitrous oxide

conscious sedation

safety record of nitrous oxide

impeccable safety record - longer than any other drug

describe color, taste, and smell of nitrous oxide

colorless, tasteless, sweet-smelling

does nitrous provide amnesia

mild - tends to shorten the perception of appointment length

who discovered the existence of nitrous oxide and oxygen in 1775

Joseph Priestly

who was the first to relate nitrous to dentistry, describing the effect as “overwhelming joy” and the “ideal existence”

Humphrey Davy

Who is the father of anesthesia and used N2O during an extraction

Horace Wells

when did dental schools begin teaching inhalation sedation

1950s and 60s

how long as N2O been in use compared to other drugs

longer than any other drug

who controls manufacturing of N2O

FDA

who packages and transports N2O across state lines

DOT

list other names of N2O

conscious sedation

relative analgesia

inhalation sedation

“laughing gas”

what percentage of manufactured N2O is used in dentistry

10%

List other uses of N2O

85-90% N2O is used in healthcare:

• emergency room

• managing pain of a heart attack (first drug of choice)

• podiatry

• dermatology

• labor and delivery

• endoscopy

Other uses:

• explosive agent in auto air bags

• propellant for whip cream

• increase racing engine performance and making silicon chips

what is the 1st way to control pain

remove painful stimuli

Term: anxiety

nonspecific feeling of apprehension, the source of which is vague (normal reaction to a threatening event)

N2O can assist in calming

term: fear

feeling of fright or dread related to an identifiable source

N2O may or may not be effective

term: phobia

irrational fear that results in avoidance

N2O not appropriate alone in treatment

list the physiologic effects of anxiety

“fight or flight” response: body releases adrenaline/epinephrine

• decreased salivation

• increased respiration

• increased BP

• increased HR

• increased blood glucose

• irritated GI

behavior and psychological effects of anxiety

• nervous laughter

• emotional outbursts

• crying/screaming (children)

• uncooperative behavior

• irritability

• anger

• decreased tolerance to painful stimuli

describe the relationship between anxiety and pain

anxiety lowers pain tolerance

anxiety increases the potential for an adverse event

• syncope - #1 medical emergency

• angina

• hypoglycemia

what is the first question of the assessing dental anxiety scale

1. if you had to go to the dentist tomorrow, how would you feel about it

   1. look forward to it

   2. wouldn’t care either way

   3. little uneasy

   4. afraid it would be unpleasant/painful

   5. very frightened of what the dentist would do

what is the second question of the dental anxiety scale

2. when you are waiting for your turn in the dental chair, how would you feel

what is the third question of the dental anxiety scale

3. when you are waiting while the dentist gets the drill ready, how you feel

what is the fourth question of the dental anxiety scale

4. waiting to have your teeth cleaned, how do you feel

   1. relaxed

   2. a little uneasy

   3. tense

   4. anxious

   5. so anxious I would break out in a sweat or feel sick

term: local anesthesia

loss of feeling or sensation in one part of the body

N2O does not cause patient to lose feeling

term: analgesia

diminution/elimination of pain in a conscious patient

N2O may cause some analgesia

term: sedation

partial or complete awareness of environment but with a significant decrease in anxiety and restlessness

N2O causes sedation

general anesthesia - drug induced loss of consciousness

• incapable of being aroused, even with painful stimulation

• impaired ability to maintain ventilatory function

deep sedation - drug induced state of depressed consciousness

uAccompanied by partial or complete loss of protective reflexes

uInability to continually maintain an airway independently

uInability to purposefully respond to physical stimulation or verbal commands

moderate sedation - drug induced depression of consciousness

ØRespond purposefully to verbal commands, either alone or accompanied by light tactile stimulation.

ØMaintain their airway without assistance

ØReflexes remain intact

minimal sedation: minimally depressed level of consciousness

uAble to independently and continuously maintain airway

uRespond to tactile stimulation and verbal commands

uProduces diminished pain and anxiety, and a depressed level of consciousness while remaining aware of surroundings

what type of sedation are RDHs allowed to practice

minimal to moderate

term: sophrology

the science of the spoken word; enhances N2Os relaxing effects

can oral premedication be used with N2O

yes

can N2O be used to substitute local anesthesia

no - only to enhance it

20% N2O and 80% O2 has the same analgesic affect as what

15 mg of morphine

what does N2O do the central nervous system

depresses it

what does N2O do to pain threshold

raises it

does N2O provide relative analgesia

yes

list all parts of the respiratory system involved in exchanging CO2 and O2 across capillary membranes in the lungs

1. nose

2. nasopharynx

3. oropharynx

4. larynx

5. trachea

6. lungs

List parts of the upper respiratory system

1. nose

2. Pharynx (includes naso, oro, and laryngo)

function of nose

warms, humidifies, and filters air

describe the pharynx

12-14cm long muscular tube divided into three regions

nasopharynx

uppermost part of the pharynx that extends from the lower skull to the soft palate

oropharynx

contains the tonsils and opening of the mouth and is a continuous structure from the oral cavity to the soft palate and the epiglottis

laryngopharynx

starts at the epiglottis to the cricoid cartilage and is an important part of respiration

***acts as a valve separating the trachea from the upper digestive tract, which is essential for effective cough maneuvers and in preventing aspiration during swallowing

list the parts of the lower respiratory system

1. trachea

2. carina

3. bronchi

4. bronchioli

5. alveolar ducts

6. alveolar sacs

trachea

11cm long muscular tube that is contiguous with the larynx

bifurcates into the right and left bronchi

carina

located at the junction of the trachea and the left and right bronchi

**** acts as the secondary backup reflex-defensive cough initiation cough mechanism

if an object is inhaled, which bronchi is it more likely to get lodged in

right bronchi because it is shorter than the left

bronchioli

smaller subdivisions of the branched bronchial tree

alveolar ducts

finer ramification of the air passages at the ends of the respiratory bronchioles

1.5 to 2 million per lung

alveoli sacs

distal ends of the alveolar ducts that contain alveoli

300 million in adults

where does gas exchange occur over the capillary membranes

alveoli area

describe the density of the aveoli area

very dense - reason why N2O onset is rapid

what part of the brain controls involuntary breathing

medullary center

describe how inspiration occurs

accomplished by diaphragm and external intercostal muscles

describe how expiration occurs

passively as the chest wall and lungs recoil

term: tidal volume

volume of each breath, ebb and flow of respiration

what does tidal volume

depends on physical characteristics of the individual

male lungs are 25% larger than female lungs

what is the average tidal volume

500 ml

average respiration rate

12-15 breaths per minute

term: minute volume

amount of air exhaled in one minute

how is minute volume calculated

tidal volume X respiration rate

what is used to determine N2O/O2 flow rates

minute volume

consequences of too little gas mixture (in regard to minute volume)

act of breathing will be difficult and produce a suffocating feeling

consequences of too much gas mixture (in regard to minute volume)

waste gases and pollute the environment, exposing personnel to trace gases and drying patient’s eyes

normal minute volume in adult

6-7 liters

what does the amount of gas capable of dissolving in blood depend on

partial pressure and solubility

describe partial pressure of N2O and O2 in the lungs

high partial pressure - move freely across cell walls into the blood

solubility of N2O

poor solubility in blood and rapidly leaves when partial pressure is higher than that of surrounding tissues

how long does it take for primary saturation of blood and brain

3 to 5 minutes

what does N2O displace in the lungs

N2

how much more soluble is N2O than N2

35X more soluble

what does N2O do to blood vessels

peripheral vasodilation (flushing of the skin)

list the tissues that receive more N2O/O2 due to their greater blood flow

brain

heart

kidney

liver

where is N2O excreted

from the lungs

composition of ambient air

79% nitrogen

21% oxygen

0.04% carbon dioxid

what is ambient air

the air we breathe

list the physical and chemical properties of N2O

• colorless

• sweet smelling

• non-irritating to body tissues

• comes as compressed liquid and gas in a cylinder

• gas at room temperature

• specific gravity = 1.53

• nonflammable but supports combustion (do not use with grease/oil)

is N2O good for asthma patients

yes

what happens if you open the tank valves too quickly

cause a rapid pressure increase, increasing the temperature, which can cause a chemical reaction resulting in fire or explosion

explain the biotransformation of N2O

not metabolized

excreted by lungs

describe potency of N2O

least potent of all inhalation anesthetics

what is the minimum alveolar concentration of N2O

104% - can’t produce profound surgical anesthesia

what is a potential consequence of N2O

negative effect on b12 and plays a role in DNA synthesis via the enzyme methionine synthetase; has a synergistic effect on bone marrow

list disadvantages of N2O

• cost of equipment

• takes up quite a bit of space in the operatory

• not for everyone

• patient cooperation needed

• weak agent

• potential for abuse

• occupational hazard

list the indications for N2O

• management of fear and anxiety (mild to moderate)

• gaggers

• for local anesthesia injection

• pain management for some procedures (probing and/or initial debridement)

• medically compromised patient (stress reduction)

• long appointments

what vitals needs to be taken before sedation

BP, pulse, and respiration

pre-procedure instructions for patients under 14

• no clear liquid for 2 hours

• no non-human milk for 6 hours

• no meals for 6 hours

restrictions for patients over 14

none; however, heavy meals should be avoided and contact lenses must be removed in all patients

list absolute contraindications

none

list relative contraindications

• pregnancy (especially during 1st trimester)

• communication barrier

• nasal obstruction

• COPD

• cystic fibrosis

• emotional/mental instability

• epilepsy (can trigger a seizure)

• negative past experience with N2O

• extremely claustrophobic patients

list effects on cardiovascular system

negative:

• none

positive:

• decreased anxiety

• increases pain threshold

• provides more O2 than air

OK for patients with heart murmurs, heart disease, hypertension

what is the most common cause of problems with N2O

oxygen deficit (stress increases cardiac demands)

Effects on respiratory system

decreased respirations (secondary effect due to stress reduction through decreasing anxiety and pain)

do NOT use on patients who have:

• moderate to severe COPD

• infectious diseases (air-borne)

• pneumothorax

• cystic fibrosis

• sinus infections or nasal obstruction

effects on CNS

unknown mechanism of action

depressed

memory affected to a minimal degree

diminished ability to concentrate

good with stroke and Parkinson’s patients for stress reduction

is it safe to use on hepatitis patients and alcoholic patients

yes - not safe to use on substance abusers

gastrointestinal system effects

do not use in someone with bowel obstruction due to gas expansive nature

OK to use on someone with ulcers