Absence of O2 in tissues It is a serious condition Presents as: Cyanosis Frequent, deep respirations

Anaesthesia Definitions Flashcards by Nia Wallace

What is Anoxia?

Absence of O2 in tissues

It is a serious condition

Presents as:
* Cyanosis
* Frequent, deep respirations

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What is Anaesthesia?

A state of reduced perception of pain
* Reversible suppression of the CNS
Sensations such as;
1. Touch
1. Temp
1. Pressure
1. Pain

Presents as:
* Loss of sensation
* Feeling in part or whole of body

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What is Local Anaesthesia?

Sensation loss
* That is induced in a restricted part of the body
* Where pain is not warranted

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What is General Anaesthesia?

Loss of pain over the whole body during unconsciousness of the brain
* Induced by a chemical agent
* Usually implies muscle relaxation

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What is Dissociative Anaesthesia?

Type of General Anaesthesia
* Provides good analgesia
* But only superficical sleep

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What is Regional Anaesthesia?

Loss of sensation produced by a nerve block agent
* Or possibly infiltratoin of a whole field area

This includes:
* Injection of an anaesthetic agent, around the spinal cord
* Otherwise known as an Epidural

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What is Analgesia?

Reduced perception of pain
* W/o loss of awareness

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What is an Analeptic?

Substance that reverses an anaesthetic state
* Stimulating the brain + restoring consciousness

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What is Apnoea?

Temporary cessation of breathing
* Px should be monitored closely

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What is an Arrhythmia?

Loss of normal regular heartbeat

Condition of sinus arrhythmia is considered a good feature on auscultation
When the Vagus Nerve accelerates the beat of Inspiration + slows or suppresses it on expiration
Also referred to as Dysrhythmia

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What is an Ataractic?

Medication that produces a state of calmness + freedome from anxiety
* Similar to a state producded by a tranquillizer

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What is an Agonist?

A drug that stimulates normal tissue activity
* May also be a muscle response to cause a specific movement

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What is an Antagonist?

A counteracting agent
Such as;
* The reversal of a sedative drug
* Term is also used to describe a muscle that has an opposite action to an agonist muscle

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What are Antisialagogues?

Drugs or substances that decrease the flow rate of saliva
* Opposing effect to Sialagogues

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What are Antihypertensive Agents?

Drugs that lower blood pressure
They include:
1. Angiotensin-Converting Enzyme (ACE) Inhibitors
1. Calcium Antagonists
1. Alpha-1-Antagonists
1. Beta-Antagonists
1. Diuretics

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What is Balanced Anaesthesia?

The use of several drugs in order to achieve:
1. Unconsciousness
1. Analgesia
1. Muscle relaxation

Use of analgesics + muscle relaxants in addition to General Anaesthetic Agents
Means that lower anaesthetic doses can be used
Preserving Vital Centre Activity

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What is Basal Narcosis?

Term used to indicate that a narcotic had been given
* Before inducing GA

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What is meant by the ‘Blood-Brain Barrier’?

(BBB)

The term given to the division between the body’s circulation + the brain substance
* It is only slightly permeable to electrolytes + other ionic solutions
* Many therapeutic substances with large molecules cannot readily reach the brain (for this reason)

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What is the Blood Brain Barrier only slightly permeable to?

Electrolytes + other ionic solutions

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Why is it that many therapeutic substances with large molecules can’t reach the brain?

Due to the Blood Brain Barrier (BBB)
+
That it is only slightly permeable to electrolytes + other ionic substances

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What is Bradycardia?

Abnormally low heart rate

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Why can Bradycardia be slightly desirable with some anaesthetics?

Ventricular filling + Stroke volume are increased, as cardiac work is lowered

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Why can Bradycardia be undesirable, under anaesthetics?

Can cause Hypotension
Which is often associated with Hypokalaemia

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(Surgically + Respiratory)

What is Dead Space?

Surgically
* It describes the poorly apposed gap in the tissues
* That is likely to fill with Serum or Blood
* When it becomes infected

In the Respiratory System
* It represents the part that contains air
* But does not exchange O2 + CO2 at an alveloar level

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Define **Anatomical**

Scientific study of the **structural internal anatomy** of the body

Define the term **Apparatus**

It describes: * Instruments * Implements * Machines * Structures * Tools Or * Processes * **For medical procedures that employ physical actions on portions of animal's body**, to: * Correct * Enhance * Inspect * Treat

Define the term **Physiological**

The scientific study of **bodily functions + biological processes** within the body

Define the term **Hypercapnia**

* **Excess CO2** in the **blood** * Also known as '**Hypercarbia**'

Define the term '**Hypertension**'

**Consistent high blood pressure** in the **arteries**

What are 3 potential **causes** of **Hypertension** during anaesthesia?

1. **Increased Cardiac Output** + **Systemic Vascular resistance** 1. **Inadequate anaesthesia** **causes** **Adrenaline release** 1. **Pain on recovery**

What pre-exisiting **disease** may cause **elevated systemic arterial pressure**, during anaesthesia?

Renal disease

What species of animal is **3x likely to suffer** from **Hypertension**, **than dogs**?

Cats!

Define the term **Hypotension**

Consistently **low** **blood pressure**, in the **arteries**

What 4 potential **causes** of **Hypotension**, **during** **anaesthesia**?

1. **Decreased** **cardiac output** + **Systemic vascular resistance** 1. **Fluid** or **blood loss** 1. **Anaesthetic agents** (Depress HR + Contractility) 1. **Volatile agents** (Cause vasodilation)

Define the term **Hypothermia**, in relation to anaesthesia

Abnormally low core body temp * Can occur due to: 1. **Surgery or post-op** 1. Px who is in **shock**

Define the term **Hypoventilation**

**Inadequate ventilation** from **shallow respiration** I.e; Inadequate gas exchange * Removal of CO2 + uptake of O2

# (Under anaesthesia) What 2 things can **Hypoventilation** lead to?

1. **Hypercapnia**/carbia 1. **Acidosis**

What can **cause** **Hypoventilation** during Anaesthesia?

1. **Anaesthesia overdose** * Resulting in an *insufficent respiratory rate* 2. **Compression of the chest** * Resulting in *reduced Tidal Volume* 3. **Mechanical dead space** * Resulting in *reduced Alveolar perfusion*

Define the term **Hypoxia**

Abnormally **low O2 tension** in the **Arterial Blood** | Or 'Diminished blood O2'

What does Hypoxia lead to?

**Reduced avaliability** of **O2** in the **tissues**

What **state** must be guarded against, during + after GA?

Hypoxia

What is the difference between **Hypoxia** + **Tissue** Hypoxia?

Hypoxia * Abnormally **low O2 tension** in the **Arterial Blood** Tissue hypoxia * **Active** tissues are **deprived** of O2 * As a **result** of **inadequate O2** of **Haemoglobin**

Define the term **Minute Volume** (MV)

The volume of **air** or **gas inhaled** **in 1 minute**

How do you calculate **Minute Volume** (MV)?

TV x BW x RR | Tidal Volume x Body Weight x Respiratory Rate

What does **MV determine**?

The **amount of gas** the patient will **require**, when **using an anaesthetic circuit**

What is a **Muscle Relaxant** and How does it work?

A **centrally acting** muscle relaxant will **block** the: 1. **Inter-neuronal pathways** in the **spinal cord** 1. **Midbrain Reticular Activating System**

Do some Muscle Relaxants have sedative effects?

Yes

What **class** of **Muscle Relaxant Anticonvulsants** have a **direct action** on the muscle?

Hydantoin deratives

Define the term **Neuroleptanalgesia**

It's a **form** of **chemical restraint**, similar to GA

What is one way to create **Neuroleptanalgesia**?

Combinations of: **Analgesia** + **Neuroleptics**

Define the term **Oxygen Flux**

The **volume** of **O2** **reaching peripheral tissues per 1 minute** * Cardiac output x O2 content of blood

What can you do it there is an **Oxygen Flux**, during anaesthesia?

* **Reduce** O2 flux + **subsequent lowered % saturation** of **O2** * By Haemalglobin, causing > Lung disease ## Footnote *While direct Haemoglobin may cause > Severe anaemia*

What is Premedication?

* Drugs given prior to another agent * Usually to counter side effects (Often pain)

Give 3 example scenarios of the use of premedicants

1. **Antiemetic** **prior** to **Chemotherapy** 2. Widespread use of **Sedatives** + **Analgesics** 3. **Antisialagogues** **prior** to **anaesthesia**

Define the term '**Respiratory Acidosis**'

**Pulmonary retention** of **CO2**

What may cause **Respiratory Acidosis** during anaesthesia?

Result of **impaired ventilation** or **respiratory arrest**

Define the term Respiratory **Alkalosis**

**Excessive loss** of **CO2**

What may cause **Respiratory Alkalosis** during anaesthesia?

**Hyper**ventilation

What is a sedative?

* Drug used to relax the patient, prior to surgery * To help relax the brain, during times of excitement * Often used prior to surgery

Describe the term **Surgical Anaesthesia**

**State** of **insensibility enabling** the performance of surgery

What **3** things can be **used in combination** to provide **Surgical Anaesthesia**?

1. **Unconsciousneess** 2. **Analgesia** 3. **Muscle relaxation**

Define the term **Tachycardia**

Abnormally elevated heart rate

Name **3 states** which may be **caused** by **moderate Tachycardia**, during anaesthesia?

1. Hypo**tension** 2. Hyper**capnia** 3. Hypo**glycaemia**

Why might **Hypotension**, **Hypercapnia** + **Hypoglycaemia** be seen as **desirable** during anaesthetic?

As they preserve blood pressure

List 4 causes of Tachycardia

1. **Pain** * May cause heart to become Hypoxic 2. **Stress** * Release of Adrenaline, Epinephrine 3. **Hypotension** 4. **Drugs** * Such as Atropine

List 2 **non-medical** causes of Tachycardia?

1. Exercise 2. Excitement

Define the term **Tidal Volume**

* The volume of **air** that **passes in** **+ out** **of** the **airways** * **During** **1** normal **respiratory cycle**