Nitrous Oxide & Oxygen Sedation - Physical Properties

1. Chapter 5
Based on
Handbook of Nitrous Oxide & Oxygen Sedation, 3rd edition
Morris S. Clark
Ann L. Brunick
Nitrous Oxide & Oxygen Sedation

2.  The activity or fate of
drugs over a period of
time
 Process of
 Absorption
 Distribution
 Localization
 Biotransformation
 Excretion

3.  Study of
 Biochemical and physiologic effects
 Mechanism of action
 Correlation of action and effects with chemical structure
 Effects of the actions of drug

5.  Dinitrogen monoxide
 Oxidizing gas
 Heat of compression - sudden release of pressure can
cause heat and explosion
 Found naturally in environment
 Used in healthcare, processing, manufacturing, and racing

6.  Manufacturing
 Cooking
 Propellant
 When used for sedation
 oxygen is mandatory
 Minimum of 30% oxygen at all times = Fail Safe System

7.  Difference between
partial pressures of gas
and liquid
 Nitrous vs blood
 Indicates how quickly
agent will cross alveolar
membrane

9.  Indicates how quickly equilibration occurs
 High solubility – immediately diffuse into blood
 Insoluble - Equilibrium will be achieved quickly
 Blood brain barrier crossed
 Rapid onset

11. 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

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

13.  High concentrations of nitrous 70% given
 Alveolar partial pressure reached rapidly
 Increased volume of gas inspired
 Negative pressure draws more gas into lungs and
increases volume
 Rapid uptake allows a second gas to be drawn in faster
 Second gas effect
 Nitrous is difficult to use at high altitudes
 Must increase concentration of nitrous due to pressures

14.  Biochemical and physiologic effects
 Potency of anesthetic measured my
 MAC minimum alveolar concentration
 Amount of drug necessary to prevent movement in 50 %
subjects responding to surgical incision

17.  Lease potent of all inhalation anesthetics
 Nitrous alone will not produce profound surgical
anesthesia
 Safety
 High MAC
 Low blood gas partition coefficient
 Low solubility

18.  Halothane 0.75%
 Sevoflurane 1.7%
 Nitrous 104%

19. Mfg & Distribution

20.  Nitrous = blue tank
 Oxygen = green tank
 No grease, oil or other lubricating substance to be used
 Nitrous is an oxidizer
 Heat of compression will ignite lubricants
 Nitrous oxide Will support combustion
 Fire hazard and explosion can occur

21.  Oxidizing agent
 Will support combustion

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

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

25. Open Valve Slowly
Do not use organic
lubricants on
fittings
Explosive Potential