Anesthesia - Quiz 1

Endotracheal tube

A flexible tube is placed inside the trachea of an anesthetized patient and used to transfer anesthetic gases directly from the breathing circuit into the patient's trachea, bypassing the oral and nasal cavities, pharynx, and larynx.

High volume/low pressure ET tube cuffs

Typically found with PVC tubes. This style of cuff allows for a greater volume of air to be used and creates less pressure on the trachea.

Low volume/high pressure ET tube cuffs

Typically found with silicone ET tubes. This style of ET tube uses lower volumes of air to inflate and creates higher pressure within the ET tube cuff

Laryngoscopes

-used to help increase visualization of the larynx while intubating

-Used to depress the tongue and epiglottis

-Handle, Blade, Light source

-Miller blade (most common) are straight and Mcintosh blades are curved (Humans)

-not used in mature ruminants and horses

Anesthesia machine primary function:

To deliver precise amounts of oxygen and volatile anesthetic under controlled conditions to patients undergoing general anesthesia

The anesthetic machine consists of four main components:

-Compressed gas supply

-Anesthetic vaporizer

-Breathing circuit

-Scavenging system

Intermediate pressure zone

Regulators

-help to produce safe operating pressures and prevent fluctuations at the flowmeter

-reduce the pressure to 40-50 PSi, regardless of fluctuations in pressure within the tank

Flow meter in low pressure zone

-measures the rate of gas to the vaporizer and common gas flow outlet

-Helps to further reduce the pressure to 15 Psi which is a safe rate for patients

O2 flush valve

-This is a button that when activated delivers a large volume of pure oxygen at a flow rate of 35-75 L/min or approximately 40-50 Psi

-When this button is activated, oxygen bypasses the anesthetic vaporizer and oxygen flowmeter

Vaporizer

-convert the liquid anesthetic ( Isoflurane or Sevoflurane) into a saturated vapor

-The vaporized anesthetic can only exit the vaporizer via a carrier gas. This transports it from the vaporizer to the breathing circuit

Fresh gas inlet

-where the gases that have passed through the flowmeter, vaporizer, or O2 flush valve leave the anesthesia machine and enter the breathing system

-located near the inspiratory valve

The selection of the type of breathing circuit is based on what?

weight

Non-rebreathing system=

less than 5kgs

Rebreathing system=

greater than 5kgs

Dead space

the volume of air that is inhaled that does not take part in gas exchange. It is referring to the portions of the respiratory tract that are ventilated but not perfused by pulmonary circulation

Anatomic dead space

The volume of the airway involved in conduction including the mouth or nose all the way to the terminal bronchioles.

The structures included are mouth, nose, nasopharynx, larynx, trachea, bronchus, bronchioles, terminal bronchioles

Physiologic dead space

The collective sum of alveolar dead space and anatomic dead space. These gases do not help in oxygen (O2) and carbon dioxide (CO2) exchange

Alveolar dead space

The space found in the alveolar which contains air that is not used in O2 and CO2 exchange

Mechanical dead space

-the space where the inhalation and exhalation mix

-Created by the breathing circuit, ET tube, and any added adaptors and elbows

Effects of increased end tidal CO2:

-Respiratory acidosis

- Peripheral vasoconstriction/ vasodilation

- Increased intracranial pressures

Factors that can increase your mechanical dead space include:

- Old/ exhausted soda lime

- Sticky unidirectional valves

Non-rebreathing system

-Allows gases exiting the vaporizer to go directly to a connecting hose to deliver it to the patient bypassing the unidirectional valves and CO2 absorber canister

-connects directly to the fresh gas inlet

Unidirectional valves

-one-way valves, control the flow of gas to the

rebreathing circuit

-located inside clear plastic domes that allow the anesthetist to observe the action of the valves

Pop-off valve

-The point of exit of the anesthetic gas from the breathing circuit

-to allow excess carrier and anesthetic gases to exit from the breathing system and enter the scavenge system

Pop-off occlusion valve

temporarily prevents air from escaping from the pop-off valve while the button is pressed

Semi-closed pop off valve

This is used with medium and high flow techniques in which oxygen delivery exceeds oxygen consumption and excess gases are eliminated through the pressure relief valve

Closed pop off valve

This is used with low flow techniques in which oxygen deliver is calculated to meet metabolic needs

Reservoir bag

-should hold a volume of at least 5 times the patient's tidal volume

Tidal volume

the volume of air that moves in or out of the lungs during one breath

Small animal tidal volume

10-15 ml/kg

Pressure manometer

-Indicates the pressure of the gases within the breathing system, and by extension the pressure in the patient's lungs

-cm H2O

Small animal positive pressure manometer

10-20 cm H2O

Large animal positive pressure manometer

20-40 cm H2O

The pressure manometer reading should not exceed ______ when the small animal patient is bagged.

20

Carbon dioxide absorber canister

The part of a rebreathing circuit that holds the carbon dioxide absorbent granules. These granules, primarily made of calcium hydroxide, remove expired CO2.

Active scavenge

-Require a vacuum and duct system

-Usually have a scavenge interface to regulate the vacuum

Passive scavenge

-Uses the positive pressure of the gases in the anesthetic machine to "push" gas into the scavenger

-Activated charcoal canister is an absorbent that binds halogenated gas anesthetics to its surface

When should the activated charcoal canister be replaced?

after weight gain of 50g

List the five components that should be included in the pre-anesthetic assessment.

Signalment, History, Physical exam, Diagnostics, ASA status

Why is it important to assess a patient’s medical history before administering anesthesia?

to make sure the patient has not had any complications or reactions to being put under anesthesia

List three components of a physical examination

Mucous membranes, hydration status, temperature

What diagnostic tests are commonly ordered prior to anesthesia, and what information do they provide?

CBC (hematocrit; platelet count), Serum chemistry (plasma proteins, electrolytes, BUN, Creatinine, Glucose, ALT, ALK), Diagnostic imaging (Radiographs, CT, shows broken bones, masses, or displaced organs, MRI, Ultrasound)

Hyperthermia

ILLNESS, HEATSTROKE, STRESS, high body temp

Hypothermia

ILLNESS, AGE, BODY CONDITION, low body temp

Pulse deficit

WHEN HEART RATE IS HIGHER THAN ACTUAL PALPABLE PULSE

Briefly describe the ASA status system, and how is it used to assess anesthetic risk in animals.

-this is a scale to describe a patient's anesthetic risk (American Society of Anesthesiologists)

-Scale 1= Minimal risk

-Scale 2= Slight risk

-Scale 3= Moderate risk

-Scale 4= High risk

-Scale 5= Extreme risk

What does a pale or white mucous membrane indicate, and what might it suggest about an animal’s condition?

This indicates anemia, poor perfusion, or vasoconstriction and it is caused by blood loss, shock, decreases in peripheral vessel blood flow

What does a cyanotic (blue) mucous membrane suggest, and what might it suggest about an animal’s condition?

This indicates that the patient is not getting enough oxygen and it can be caused by hypoxemia

What could a yellow (icteric) mucous membrane indicate in an animal, and what might it suggest about an animal’s condition?

This indicates bilirubin accumulation and is caused by hepatic or biliary disorder and/or hemolysis

How much of the patient's body weight is water?

60%

This solution contains water and small molecular weight solutes and is routinely used in anesthetized patients.

Crystalloid solutions

Blood volume for dogs and large animals.....

80-90 ML/KG

Blood volume for cats....

40-60 ML/KG

Homeostasis

THE CONSTANT STATE WITHIN THE BODY CREATED AND MAINTAINED BY NORMAL PHYSIOLOGICAL PROCESSES

COMPONENTS OF EXTRACELLULAR FLUID

NA, CL, HCO3

COMPONENTS OF INTRACELLULAR FLUID

K, MG, PROTEINS, AND PHOSPHATES

List 2 of the principle rules for homeostasis.

electroneutrality and osmotic pressure

List two signs of dehydration and two signs of overhydration.

Overhydration= ocular/nasal discharge and coughing

Dehydration= dry or tacky gums and loss of skin elasticity

What solution can be used with blood transfusions?

Normal saline solution

When do we use Hypertonic Saline solutions?

-HYPOVOLEMIC, TRAUMATIC, OR ENDOTOXIC SHOCK

• PROFOUND HEMORRHAGE

When do we use Dextrose solutions?

-neonatal, hypoglycemic, or debilitated patients

-diabetes mellitus

-hyperkalemia therapy

Isotonic Crystalloid Administration rate in dogs and large animals:

5 ML/KG/HR

Isotonic Crystalloid Administration rate in cats and horses:

3 ML/KG/HR

Hypertonic saline administration rate for dogs and large animals:

4-5 ML/KG

Hypertonic saline administration rate for cats and horses:

2-4 ML/KG

Please name two different types of colloid solutions used in veterinary medicine and when to use these solutions.

-We use Synthetic colloid solutions when shock, hypotension, and blood loss are present.

-We use Blood products when anemia, hypoproteinemia, coagulation disorders, and thrombocytopenia are present.

Colloid administration rate for dogs and large animals:

-10-20 ML/KG/DAY

-5 ML/KG BOLUS

Colloid administration rate for cats and horses:

-5-10 ML/KG/DAY

-2-3 ML/KG BOLUS