Without reference, identify principles about
Anesthesia Units with at least 70 percent
accuracy.

Purpose of Anesthesia Units
◦ Supplies a set mixture of gases and anesthetic
vapors to the patient
◦ Helps the clinician control patient breath rates,
volumes, and pressures
◦ Monitors gas concentrations from the anesthesia
machine
◦ Provides patient monitoring
◦ Includes safety features to help protect the
patient
◦ Removes excess gases from the breathing system
and out of the anesthetizing location

Anesthetizing Locations
◦ An area used to administer any flammable or
nonflammable anesthetic agent such as the
operating room, delivery room, emergency room
and anesthetizing room
◦ Requirements for a nonflammable anesthetizing
area
◦ Areas must be clearly labeled “RESTRICTED TO
NONFLAMMABLE ANESTHETICS”
◦ Environments factors
 Humidity must be maintained at a minimum of
35%
 Ventilation requirements
Used to remove bacteria, anesthetic gases, and
maintain proper humidity
A positive pressure is maintained within the
anesthetizing area
 Temperature
Decreases metabolic rate of the patient
Decreases blood loss
Decreases infection by minimizing bacteria growth

Clinical Aspects of Anesthesia
◦ Definitions
 Anesthesia – the loss of the normal perception
of pain
 Anesthetic – a substance which produces
anesthesia
◦ Purpose of anesthesia – to remove the patient’s
sensitivity to pain during surgical procedures
◦ Types of anesthesia
 Local anesthesia
Applied only to the area of treatment
Patient remains conscious
 General anesthesia
Applied to the entire body
Usually results in loss of consciousness
Administered one of two ways
o Intravenous – the anesthetic is injected into the blood
stream
o Inhalation – the patient breathes a gas mixture containing
the anesthetic agent

Inhalation Anesthetics
◦ Delivered by inhalation
◦ May be gases or volatile liquids
◦ All common anesthetics in use today are nonexplosive and nonflammable
◦ Minimum alveolar concentration level (MAC)
 Concentration of any anesthetic agent in which
50% of the population will be anesthetized
 The MAC level must be exceeded to ensure
proper anesthesia
 Nitruous
It is colorless and odorless
Nitrous oxide is a gas at ambient temperature and
pressure
Kept as a liquid under pressure
Does not provide significant muscle relaxation
MAC = 105%
Frequently used in combination with the more potent
volatile agents
◦ Halogenated anesthetic agents
 Causes rapid, shallow breathing
 Relaxes skeletal muscles
 Halothane
Detrimental effect on rubber goods and some metals
MAC = 0.77%
 Isoflurane
Several side effects and is not popular
MAC = 1.77%
 Enflurane
Few side effects
MAC = 1.3%
 Deslurane
Will not evaporate at room temperature
Requires a special heated vaporizer
Low solubility in blood and body tissues causes a very
rapid wash-in and wash-out
MAC = 7.25%
 Aevoflurane
Low solubility in blood and body tissues
MAC = 1.7%

Stages of General Anesthesia
◦ Induction – start of administration of the
anesthesia agents (during induction it is very
important to remain as calm as possible)
◦ Excitement – the patient is delirious and
physiologically unstable
◦ Surgical Plane – the patient is insensible to pain.
Breathing is steady and automatic
◦ Danger – the patient is in danger of
cardiopulmonary arrest

Guidelines set by the manufacturer must be
strictly followed
◦ Recommendations before attempting
maintenance of this type of equipment
 All test equipment and ventilators are not the
same

Ventilator Operation is Usually
Unsupervised
◦ The calibrations are extremely critical to the
support of the patient's health and/or life

Anesthesia Unit Operation is Usually
Supervised
◦ The calibrations are extremely critical to the
support of the patients health and/or life
◦ Tolerances
 Are not as narrow as the ventilator due to the
constant supervision of the patient
 Still very real because of the drugs that are used
 A unit’s reaction to the changes in the patient’s
condition
Can cause under or over anesthetic dosage
Can lead to damage or death
◦ Tolerances
 Are narrower than most other devices in the
hospital (ex. +/- 1% instead of +/-3%)
 A units reaction to the changes in the patient's
condition
Can cause under or over ventilation
Can lead to injury or death

Test Equipment
◦ Calibrations are only as accurate as the
calibration of the test equipment

Calibration Items
◦ Pressure delivery
◦ Pressure sensing
 Peak
 Mean
 Peep
◦
◦
◦
◦
◦
◦
◦
◦
Overpressure
Volume delivered
Volume sensing
Breath rate
Oxygen blending
Assist sensitivity
Safety devices
Alarm limits

Anesthesia unit special items of concern
◦ Safety devices
 Proportioning system
Monitors the nitrous oxide flow to the oxygen flow to
maintain <3:1 ratio
Designed to prevent oxygen concentration from falling
below 25%
The kick-in point will
o limit nitrous oxide flow from increasing if nitrous oxide is
increased above 3:1
o increase oxygen flow if nitrous oxide is increased above 3:1
Below 25% oxygen is considered hypoxic
decrease nitrous oxide flow if oxygen is decreased
above 3:1
◦ Secondary gas shutoff
Monitors the oxygen source pressure
Controls nitrous oxide and air flows (secondary gases)
Will either
o Decrease flow of secondary gases in proportion to oxygen
pressure
o Shutoff flow instantly at a preset pressure
Either way the secondary gases will be completely cutoff before oxygen is depleted
 Vaporizer interlocks
Used on multiple vaporizer systems
Prevents more than one vaporizer from being turned on
at a time
◦ Alarm limits
◦ Common/fresh gas concentrations
 Ensure minimum oxygen content cannot be
adjusted to hypoxic levels
 Vaporizer
Calibration verification can only be performed
Use a Rankin gas analyzer
If verification falls outside of limits then vaporizer will
be sent to manufacturer for repair or replacement