Introduction to Nitrous Oxide Practice Flashcards

A set of vocabulary-style flashcards covering the history, physical properties, physiological effects, contraindications, and safety features of nitrous oxide based on the lecture transcript.

Analgesic

The term meaning pain reliever.

Horace Wells

A dentist who, in 1844, discovered nitrous oxide and used it as a general anesthetic.

Doctor Riggs

The dentist who removed one of Horace Wells' mowers using only nitrous oxide.

PSI of Nitrous Oxide

At room temperature in a steel cylinder, nitrous oxide creates a pressure of $750\,\text{PSI}$ (pounds per square inch).

Physical Appearance and Scent

Nitrous oxide is tasteless, odorless (though some say sweet-smelling), and colorless.

Ammonium Nitrate

The substance that is heated to produce nitrous oxide.

Combustion

Nitrous oxide is not a flammable gas on its own, but it will support combustion due to its oxygen atom.

Morphine Equivalence

$20\%$ nitrous oxide is equivalent to the analgesic effect of $10\,\text{mg}$ of morphine delivered intravenously.

Naloxone

A narcotic antagonist that can block the analgesic effects of nitrous oxide, proving the drug bonds to opioid receptors.

Inhibitory Neurons

The specific neurons nitrous oxide works on to increase endorphin levels and turn down neurotransmitters for consciousness and pain.

Cutaneous Vasodilation

A normal pharmacologic effect of nitrous oxide that causes the face to flush and the patient to sweat.

Primary Saturation

The amount of time it takes to saturate the blood with nitrous oxide, which is approximately $3$ to $5\,\text{minutes}$.

Metabolism

Nitrous oxide is not metabolized by the body or the liver at all; it passes through unchanged.

Blood Gas Coefficient

A measure of solubility in the blood; nitrous oxide has low solubility, meaning it is quick on and quick off.

Diffusion Hypoxia

A theoretical event where nitrous oxide leaves the blood so quickly it pushes oxygen out of the alveoli; it is prevented by giving $100\%\,O_2$ for several minutes after the procedure.

Gag Reflex

Nitrous oxide is used to turn down this specific reflex in hyperactive patients during dental procedures.

Eustachian Tube Dysfunction

A contraindication for nitrous oxide use because the gas can accumulate in the middle ear and increase pressure, potentially popping an eardrum.

Bullous Emphysema

A contraindication for nitrous use because the gas can diffuse into and expand lung blebs ($\text{bubbles}$), potentially causing them to pop and lead to pneumothorax.

Hyperventilation Cycle

A state where patients blow off too much $CO_2$ and their blood $pH$ rises above $7.4$; it can be treated by breathing into a paper bag to increase inhaled $CO_2$.

Vitamin B12 Deficiency

A condition associated with chronic recreational abuse of nitrous oxide that leads to permanent neural damage and neuropathies.

Pin Index System

A safety feature using specific metal pins that ensure an oxygen cylinder cannot be accidentally attached to a nitrous oxide inlet.

Oxygen Fail-Safe

A safety mechanism that automatically turns off all gas if the oxygen cylinder becomes empty.

Double Lumen Scavenger System

A breathing apparatus design that picks up exhaled gas in an outer rim and sends it to the sewer to prevent clinicians from breathing the patient's nitrous oxide.

50 parts per million

The research-proven limit for nitrous oxide exposure in a clinical environment to ensure personnel safety.

Titration

The process of adjusting the concentration of nitrous oxide (starting at $20\%$, then $25\%$, etc.) until the desired clinical endpoint is reached for the patient.