This document provides information on nitrous oxide and oxygen sedation. It discusses the different levels of sedation including minimal sedation using less than 50% nitrous oxide and moderate sedation using over 50% nitrous oxide. It emphasizes the importance of careful titration to achieve the intended level of minimal sedation and outlines recommendations for patient monitoring, recovery, and record keeping when using nitrous oxide sedation.

1. Nitrous Oxide & Oxygen Sedation
Review
Based on
Handbook of Nitrous Oxide & Oxygen Sedation, 3rd edition
Morris S. Clark
Ann L. Brunick

2. Minimal Sedation
Minimal sedation
Titration of Drug
Less than 50% nitrous
Risks are minimal
Adverse effects are minimal

3. Minimal sedation
 Anxiolysis
 Drug induced state
 During which patient responds normally to
verbal commands
 Cognitive functions & coordination may be
impaired
 Respiration and CV functions unaffected
 Nitrous oxide < 50%

4. Moderate Sedation
 Drug induced
 Depression of consciousness
 Patients respond purposefully to verbal commands
 May need stimulation to respond
 No intervention is required to maintain airway
 Spontaneous respiration
 CV function of normal
 Nitrous oxide > 50%

5. Advanced airway management
 May be needed for moderate that
can fall into deep QUICKLY
 Positive pressure ventilation
 Ambu bag mask
 Nasotracheal tube
 Oropharyngeal tube

7. Patient self-medication
Sometimes they tell you
& some times they ….. dont

8. You Must Be Prepared
For The Next Deeper Level … or More
Drugs Are Additive

9. Analgesic Properties
 20 % nitrous = 15 mg. MORPHINE
 20% Nitrous - 80% Oxygen
 1 L/min nitrous to 4 L/ min oxygen
 1 L / 5 L - 20%
 1.5 L nitrous / 6 L tidal volume
 25% nitrous
 Would Your Patient React
 To 15 mg. Morphine? Absolutely!!!!!
 Patients will tell you they don’t feel the effect
 Wait longer for the effect

10.  Will raise patients pain threshold
 Nitrous will manage both fear and pain
 Will produce a sense of well-being
 Will manage MILD fear
Analgesic Properties

11. Desirable Characteristics
 Recovery
 With 100% oxygen for minimum of 5
minutes
 Recovery time may vary
 Elimination
 Rapidly eliminated from body by
respiratory system
 Acceptance
 Patients accept nitrous very well

12. Pre and Post Oxygenation

13. Patient Comfort

15. Relatively insoluble
 Blood gas partition coefficient .47
 Remains unchanged
 Does not combine with blood
 Does not disassociate
 Uptake by body is limited
 Equilibrium is achieved quickly
 Peak clinical effects seen 3-5 minutes after initiation
Nitrous oxide

16.  N2O 31 times greater than Nitrogen
 Therefore
 Nitrous oxide rapidly replaces nitrogen
 Occupies the space of nitrogen
 Increases volume and pressure of that space
Partial pressure

17.  Least potent of all inhalation anesthetics
 Nitrous alone will not produce profound surgical anesthesia
 Safety
 High MAC
 Low potency
 Insoluble
Nitrous MAC 104%

18. Nitrous oxide
 Pressure of cylinder is 750 psig
 Will remain constant until almost
empty (20%)
 Drop in dial pressure not
proportional to contents

19. Tank Pressure
Oxygen Nitrous

20. Nitrous Oxide
 Nitrous is a liquid in tank
 Is vaporized by ambient room
temperature
 Heat transfer process
 Tank becomes cool
 Frost may be seen on tank

21. Do not use organic lubricants on fittings
Explosive
Potential

22. Reservoir Bag
 Source of additional gas
 Mechanism to monitor patient
respiration
 May provide positive pressure
oxygen in emergency
 Use ambu bag mask

23. Nasal Hood
 Gas delivered to patient thru nasal
hood
 Designed to fit snugly over patient’s
nose
 Gas should not leak out

24. Scavenging capability
 Nasal hood
 has suction to remove exhaled nitrous
oxide
 Provide fresh gas to patient
 Provides nitrous oxide / oxygen
 provides removal of nitrous to outside

25. Safety Features
 Fail Safe – ensures no nitrous will be
delivered unless oxygen is flowing
 Minimum of 30% oxygen at all times
 Ambient air 21% oxygen
 30% allows for calibration error
 Pin Index safety system
 Oxygen can only be attached to oxygen yoke

26. Safety Features
 Fail Safe – ensures no nitrous will be
delivered unless oxygen is flowing
 Minimum of 30% oxygen at all times
 Ambient air 21% oxygen
 30% allows for calibration error
 Pin Index safety system
 Oxygen can only be attached to
oxygen yoke

27.  Amount of air per minute entering alveolar units
 Less than minute volume
 Not all air enters alveoli
 Conduction or dead space
 Subtract dead space from tidal volume and multiply by respiration rate
 (Tidal Volume – Dead Space) x Respiration Rate
Alveolar Ventilation

28. Gas Exchange
 Dependent on partial pressure of gas in
 Lung / alveoli
 Blood
 Amount of gas dissolving in blood depends
on its
 solubility
 partial pressure
 Moves from high to low pressure /
concentration
 Rate of dissolving depends on pressure
gradient

29. Gas Exchange

30.  Amount of gas absorbed by blood determined by its solubility
 Low solublity = high diffusion rate (RAPID)
 Little gas is absorbed by blood elements
 Rapid onset due to rapid diffusion and low solubility
 Rapid rate is the same when pressure gradient is reversed
 Rapid Recovery
Gas Exchange

31.  Rapid Diffusion due to low solubility
 N2O exits rapidly
 More rapid than Nitrogen replacing it
 Supply of O2 is diluted
 Reducing PO2 saturation
 Pulse oximetry : oxygen saturation = oxyhemoglobin
 Amount of oxygen carried in blood
 100% Oxygen 3-5 minutes after nitrous prevents this
Diffusion Hypoxia

34.  Nitrous level greater than 50%
 Practitioner is responsible for intended level and next level of sedation
 Intended level is minimal < 50%
 Next level is Moderate
 Some patients are hyper-responders
 Some patients take medications and effect is additive
 Pre procedural fasting may be needed if moderate sedation is used to prevent
aspiration
Moderate Sedation
By using >50% you are responsible for DEEP Sedation
Advanced Airways & Resuscitation

35. Target Level
Minimal Sedation < 50%
Responsible For Moderate

37. Responsible for Deep Sedation
Protective Reflexes & Spontaneous Breathing Lost
Advanced Airway Rescue Needed
If Moderate Sedation
Occurs

38.  Head tilt - chin lift
 Positive pressure ventilation
 Full face mask and ambu bag
 Aspiration of vomitus is unlikely
 If protective reflexes are intact
 If vomiting occurs
 suction pharynx
 Oxygen 100%
 DC dental care
Airway Management - BLS

39.  Used for moderate sedation
 Intentionally or unintentionally
 Light meal with no fried or fatty foods
 Within 6 hours
 No liquids 2 hours prior
Pre-procedural Fasting

41. Possible Contraindications
Medical Consult / Delay
Pregnancy
Sinus
Infection
Ear infections
Debilitating
CV Disease
Phobia Bronchitis
Mental
Illness
Late Stage
HIV
COPD TB
Bowel
Obstruction
Alcohol or
Drug Abuse

42. Absolute
Contraindications
COPD
Hypoxic Drive
Cystic
Fibrosis
Ophthalmic
Surgery
Pneumothorax
Latex
Allergy

43. ASA Classification
II - Mild systemic disease
mild to moderate disturbance
under good control
no significant compromise to normal
activity
Appropriate candidate for N2O2

44. ASA Classification
III - Severe systemic disease
Major systemic disturbance
Difficult to control
Significant compromise to normal
activities
N2O2 - only after medical consult

45. Vital Signs
Pre operative, intraoperative, postoperative
is considered Standard of Care
height, weight, body temperature (medical / hospital)
blood pressure, pulse, respiration - PO2
pain level

46. Minimal Sedation
Vital sign requirements
BP, pulse, respiration, PO2
preoperative = baseline to compare to post op
postoperative = objective measurement of recovery

47. ADA Recommendations
Focused physical evaluation prior to minimal sedation
Operator must be prepared to handle
the next deeper level of sedation than intended
Verbal & written instructions before sedation admin.
It is not necessary to fast before nitrous sedation – minimal
sedation
ASA guidelines - no fatty foods prior, clear liquids
light meal 1 - 2 hours prior

48. Moderate Sedation
Clear liquids 2 hours prior (water / juice / no pulp)
Non human milk - 6 hours prior
Light meals - 6 hours prior (toast & clear liquids)
gastric emptying
prevent aspiration of vomit

49. Informed Consent
Understand the purpose of the procedure
How it will be accomplished and what to expect
Benefits & risks of sedation
Opportunity to ask questions
Competent patient or legal guardian

50. Titration
Method of delivering incremental amounts of drug
Until desired endpoint is reached
Given until patient is relaxed and comfortable

51. N2O
Objective
Patient COMFORT
Ask them if they are comfortable
Are we ready to begin
or do you feel like you need a little more relaxation?
Remember - MINIMAL SEDATION
Less than 50% N20

52. Key To Success
Titration of N2O
Careful observation of the patient
Complete recovery

53. BEGIN WITH
OXYGEN
Start with 6-7 L/min. 100% oxygen
start with more to avoid suffocating feeling
Flush the system with O2 until bag is inflated 2/3
Have patient place nasal hood & adjust hoses
Determine minute volume - Tidal Volume

54. Minute Volume
Ask patient to breathe thru their nose - not mouth
Ask patient if they are able to breathe easy
Adjust flow to patient comfort & bag is 2/3 full
You will see bag inflate and deflate

55. N2O
Administration
Maintain minute flow thru the procedure
Each time N2O is added
O2 will have to be decreased
Keeping minute volume constant

56. Dual Tube
Flowmeters
Total liters flow is calculated
By adding both sides of the flowmeter
At the level of the middle of the floating ball

57. Flowmeters
The number associated with the floating
ball
Does NOT indicate N2O %
That is calculated as a percent of
total

58. % Nitrous
Calculation
Divide the L/minute of Nitrous
by the TOTAL L/minute
2L nitrous / 7L min = 28.5%
Appendix E

59. Standard of Care
The technique of titrating N2O is recognized as the
standard of care
SLOW titration of small doses of drug
Is important to prevent over sedation

60. Recommended
Regimen
Begin with approximately 10% to 15%
.5L N2O .5/6= 8%
Add N2O increments every few minutes
Suggested increments of 5% - 10 %
.5 - 1.0 L nitrous increments

61. Recommended
Regimen
Wait at least 2 minutes after a dose delivered
Before adding next increment
When sedation is becoming evident
Wait longer for the drug to take full peak effect
Before adding another dose to avoid over
sedation

62. Recommended
Regimen
Ask patient to breathe thru their nose and keep their lips
sealed
Talking and verbalizing to operator will alter sedation
Contaminates room air with nitrous

63. Goal
Patient comfort
Titrate to a level of sedation that is
Determined by patient comfort and relaxation
Minimal Sedation <50%

64. Intraoperative
Monitoring
Cumulative effects of N2O will be seen
as duration increases
Sedation may deepen and result in uncomfortable
symptoms
Reduce nitrous and adjust oxygen
Periodically ask patients how they feel
Titration to comfort
Minimal Sedation

65. Intraoperative
Monitoring
Decrease N2O incrementally for non stimulating phases of
care
Add oxygen as you diminish nitrous
If nearing completion of care you may terminate N2O
When you terminate N2O
Deliver 100% Oxygen for at least 5 minutes
At established minute volume

66. Recovery
Recovery /emergence is a mirror image of induction
Patient returns to original emotional state
N2O has rapid onset and emergence

67. Recovery
Post operative oxygenation
100 % oxygen
Minimum of 5 minutes
Or longer as needed by patient assessment

68. Recovery
Assess patient response to questions
Ask how they feel before removing nasal hood
Should indicate they feel fine, not drowsy, light
headed, groggy, dizzy or nauseated
If ANY indication of not feeling normal continue O2

69. Recovery
Continue 100% Oxygen as long as is necessary

70. Adequate
Recovery
Patient alert and oriented
Vital sign values stable and WNL
Patient states the feel normal

71. Recovery
Simple hand-eye coordination
instruct patient to place one finger on tip of nose
If this simple skill cannot be completed
continue oxygen until recovered

72. Recovery
ONLY after patient is recovered and feels normal
May the oxygen and nose piece be removed

73. Recovery Time
Minimum of 5 minutes
Each patient will differ due to biovariability
It may take longer for some

74. Record Keeping
ASA classification
Indications for nitrous use
Medical history and medications
Fasting status
Preoperative, intraoperative, and post operative vitals

75. Record Keeping
Patients minute volume
Peak percentage of nitrous
Duration of nitrous administration
BP, HR, Respiration Rate, PO2
Adverse reactions
Assessment of recovery
Oxygen time and patient response