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61 Cards in this Set

  • Front
  • Back
4 purposes of anesthetic equipment and breathing systems
1. Delivery of O2

2. Removal of CO2

3. Delivery of an inhalant anesthetic

4. Mechanism for artificial ventilation
4 basic components of the machine
1. Gas Source

2. Regulator

3. Flow meter

4. Vaporizer
Describe the overall function of an anesthetic machine
To deliver precise, but variable concentrations of O2 and anesthetics to the breathing system and patient
Describe the function of a pressure gauge
Reports the pressure of a tank, which allows one to asses content of a gas container
7) Describe the content and pressure in cylinders for O2 and N2O when full and when during in use
O2: Initial: 2200 PSIG----Pressure drops in proportion to volume

N2O:Initial: 750 PSIG----Pressure only begins to drop after all liquid is vaporized (about 25% of volume)
Purpose of a Diameter-indexed Safety System
prevent inadvertent interchange of gases while allowing for a rapid attachment of hoses to station outlets or large H cylinders
What is a Pin-index safety system?
Uses pins to prevent the inadvertent interchange of gases with small E cylinders
Explain the color coding on anesthetic equipment
O2: Green

N2O: Blue
Describe and locate hanger yokes on anesthetic machines
Used to attach small cylinders to anesthetic machines
4 basic parts of a flowmeter for oxygen
1. Control Knob
2. Glass Tube
3. Float/Indicator
4. Scale
Describe the proper way to read “floats” used in flowmeters
* Ball Float: Middle of the ball

* Bobbin Float: Top of the float
Describe the purpose and proper use of a flush valve
* Flush valves allow for O2 to bypass the vaporizer and go directly to the patient, allowing for the quick administration of O2 without anesthesia.
When should flush valves not be used?
They should not be used with a closed or non-rebreathing system due to risk of over pressuring the patients lungs.
the range of flow of O2 provided by a flush valve
They deliver O2 at 35-75 L/min.
Define the term vaporizer
An instrument that is designed to change a liquid anesthetic to its vapor and adds a controlled amount of the vapor to the flow of gas to the patient.
Explain why accuracy is needed for delivery of potent, volatile inhalants
When uncontrolled, the vapor pressure may produce a maximum concentration (ISO: 32%) that is much higher than than MAC (ISO: 1.4%)
Vapor Pressure
partial pressure of an anesthetic gas over the liquid in a closed container
What controlls vapor pressure?
controlled by temperature
Heat of Vaporization
Number of calories to convert 1 gm of liquid to it vapor; the process of vaporization causes cooling of liquid, thus constant heat must be supplied by another material
Specific heat
amount of heat needed to change the temperature of 1 gm of a substance 1*C; Metals with high specific heat provide heat at a constant temperature during vaporization
Thermal Conductivity
measure of heat transfer; metals with high thermal conductivity maintain constant temperature of vaporization
3 common metals in vaporizers due to their thermal conductivity and specific heat
1. copper
2. aluminum
3. brass
Explain why temperature and back pressure compensation are important.
* Temperature: The process of vaporization leads to a reduction in the anesthetic liquid’s temperature, which lowers Vapor pressure. Thus, temperature compensation of 15-35* C is desired to keep the vaporizer output constant

* Back Pressure: Artificial ventilation can causes back pressure to increase, which can lead to surges of output in the vaporizer---Compensation prevents back pressure from affecting vaporizer function
2 methods of output regulation for vaporizers
1. Measured flow
2. Variable bypass
Describe the measured flow method of output regulation for vaporizers
* Used in older vaporizers;

* Has two flow meters one before the vaporizers and one that bypasses the vaporizer (dilutes anesthetic gases);

* Flow compensation is manual
Describe the variable bypass method of output regulation for vaporizers
* Used in modern vaporizers

* Drug specific

* All gases enter vaporizer, however some bypass the vaporizer chamber

* Flow compensation occurs due changes in resistance to gas flow into the vaporization chamber as flow rate changes
2 methods of vaporization for vaporizers
1. Bubble-through

2. Flow over
Describe the bubble-through method of vaporization for vaporizers
* Used in older vaporizers

* Gases (O2) are dispersed through the anesthetic liquid by a bubble foot or dispenser (bubble up through the anesthetic liquid)
Efficiency of the bubble-through method of vaporization depends on what 3 things?
1. Bubble size
2. Depth
3. Rate of gas Flow
Describe the flow over method of vaporization for vaporizers
* Used in modern vaporizers

* Gas flow over the surface of anesthetic liquid

* Can increase the surface area by using wicks
What are NOT differentials for hypoxemia?
* Anemia
* Left to right shunt
* Immune-mediated hemolytic anemia
What is a NEGATIVE consequence of intermittent positive pressure ventilation (IPPV)?
Impaired cardiac function
What is an effect of hypoventilation?
Arrhythmia formation
What are 2 logical causes of hypoxemia?
* V/Q >1
* V/Q <1
Cyanosis is NOT a reliable sign of hypoxemia
Cyanosis is NOT a reliable sign of hypoxemia
What can occur in a patient that is hypoventilating (i.e. has CO2 retention)?
CO2 narcosis
What is the first thing you should do if the patient's oxygen saturation as measured by pulse oximetry starts to drop?
Check the placement of the sensor
What is NOT a clinical sign of hypoventilation on 100% oxygen?
What would be INAPPROPRIATE ventilation?
Mechanical ventilation with an inspiratory time of 4 seconds
Why is increasing respiratory rate possibly harmful to an anesthetized patient?
It can cause decreased venous return
Which value does NOT correspond with its correct description?
Metabolic acidosis: BE > -4 mEq/L
What 2 types of oxygen contribute to oxygen content?
Bound & dissolved
Pale mucous membranes is NOT a sign of hypoventilation
Pale mucous membranes is NOT a sign of hypoventilation
What is a POSITIVE effect of an elevated PaCO2?
Shifting the oxyhemoglobin dissociation curve to the right
When do patients buck the ventilator?
* When anesthesia is too light

* When they become hypercarbic

* When they become hypoxemic
What drug is contraindicated in stallions but not mares?
A patient with life threatening uncompensated systemic disease is which ASA classification?
Category IV
Based on the ASA patient classification scheme, a dog with a skin tumor who is otherwise healthy would be classified as:
Category II
Your job as an anesthetist is to “not kill anything”. Your yardstick for success will change as your knowledge base and skill improve.
Your job as an anesthetist is to “not kill anything”. Your yardstick for success will change as your knowledge base and skill improve.
An animal having a routine spay is a category
When is the MOST appropriate time to administer analgesia in relation to surgical procedures?
Before surgery
A hyper excitable state of the spinal cord that results in the volley of afferent impulses in the spinal cord activated by nociception is referred to as:
Behavior, physiologic response, expectations, response to therapy, and pain score are used to determine if a patient requires analgesic therapy.
Behavior, physiologic response, expectations, response to therapy, and pain score are used to determine if a patient requires analgesic therapy.
Precision vaporizers

* Patient does no breathing through the vaporization chamber

* High resistance; able to be used for all inhalant anesthetics; safer

* Need precision and high efficiency vaporizers
Non-precision vaporizers
* Patient breathes through the vaporization chamber

* Require a low resistance vaporizer; used with ether and methoxyflurane

* Increase patient ventilation  increase inspired anesthetic %
“heat sink”
vaporizer with lots of heavy metal that is thermo-stable
Differentiate between agent-specific and multipurpose vaporizers
* Agent-specific: made specifically for a single anesthetic agent; color-coded (safer machines)

Multipurpose vaporizers: Used in research setting mostly, accurate vaporizers, but require attention to flow rates
Breathing system
serves to deliver O2, remove CO2, deliver anesthetic, and act as mechanism for artificial ventilation
Rebreathing system
breathing system in which all or part of exhaled gases are retained within the system to be re-inhaled by the patient
Non-rebreathing system
breathing system in which no part of the exhaled gases are retained in system
Closed, low-flow, and semiclosed systems are types of rebreathing systems which differ on FGF rate
Closed, low-flow, and semiclosed systems are types of rebreathing systems which differ on FGF rate