anaesthesia 1-10

Question 1

what are the four properties required for a general anaesthesia?

Answer 1

Amnesia (without memory)

Analgesia (without pain)

Muscle relaxation

Unconsciousness (without awareness)

Question 2

what does the theraputic index (TI) mean?

Answer 2

how dangerous a drug is (the difference between the dose required for desired properties vs the dose that could cause death)
- higher the theraputic index, the safer

Question 3

rank the following for theraputic index from high (safest) to low (dangerous)
- Inhalational (GA) inhalant agents
- sedatives
- injectable (GA) anaesthetic agents

Answer 3

sedatives < injectables < inhalants

Question 4

what are the five stages of anaesthesia?

Answer 4

1. The pre-anaesthetic period
2. Premedication
3. Induction
4. Maintenance
5. Recovery

Question 5

which anaesthetic phase?
1. The pre-anaesthetic period
2. Premedication
3. Induction
4. Maintenance
5. Recovery

Answer 5

1. The pre-anaesthetic period

Question 6

which anaesthetic phase?
1. The pre-anaesthetic period
2. Premedication
3. Induction
4. Maintenance
5. Recovery

Answer 6

2. Premedication

Question 7

which anaesthetic phase?
1. The pre-anaesthetic period
2. Premedication
3. Induction
4. Maintenance
5. Recovery

Answer 7

3. Induction

Question 8

which anaesthetic phase?
1. The pre-anaesthetic period
2. Premedication
3. Induction
4. Maintenance
5. Recovery

Answer 8

4. Maintenance

Question 9

which anaesthetic phase?
1. The pre-anaesthetic period
2. Premedication
3. Induction
4. Maintenance
5. Recovery

Answer 9

5. Recovery

Question 10

Which ONE of the following statements BEST describes general anaesthesia?
a. A state produced by injecting drugs into an specific area (i.e. skin) to prevent the patient feeling pain
b. A state of excitation in the brain that renders the patient unconscious but able to remember the events that occured
c. A state that renders the subject unable to feel or remember the negative events that occured
d. A pain free state that has minimal to no effects on consciousness or memory
e. A combination of drugs rendering the patient able to feel pain but with no memory of the event

Answer 10

c. A state that renders the subject unable to feel or remember the negative events that occured

Question 11

Which ONE of the following statements is MOST correct when describing the THERAPEUTIC INDEX?
a. Is the difference between the dose that results in a desired effect and the dose that causes death.
b. Percentage of inhalant that produces general anaesthesia
c. The sedative dose of a benzodiazepine
d. Difference between doses of different sedatives

Answer 11

a. Is the difference between the dose that results in a desired effect and the dose that causes death.

Question 12

The deeper the level of anesthesia, the greater the depression of the cardiopulmonary system…. what are the three “Hypo’s” that are therefore considerations for EVERY anaesthetic?

Answer 12

1. hypotension (low blood pressure)
2. hypoventilation (breathing too shallow/slow)
3. hypothermia (body temp drops)

Question 13

general anaesthetic agents.. propofol, alfaxalone, thiopentone, etomidate, halothane, isoflurane, sevoflurane: are they:
a. dissociative agents
b. hypnotic agents

Answer 13

b. hypnotic agents

Question 14

general anaesthetic agents - ketamine, tiletamine: are they…
a. dissociative agents
b. hypnotic agents

Answer 14

a. dissociative agents (K-hole)

Question 15

what is the difference between hypnotic agents and dissociative agents?

Answer 15

hypnotic - CNS depression, normal conscious and reflex messages cannot be processed
dissociative - CNS excitation, patient may appear conscious (blink and swallow)
*know the difference so you don’t keep patients too deep/light

Question 16

what is diastole vs systole?

Answer 16

diastole - relaxation (ventricles fill up)
systole - contraction (of ventricles)

Question 17

explain why bradycardia (low heart rate) is NOT the major contributor to anaesthetic induced hypotension?

Answer 17

CO = Heart rate (HR) x stroke volume (SV)
as the heart rate decreases, the stroke volume normally increases (more time for the heart to fill up with blood) so the stroke volume actually increases, meaning cardiac output stays the same. worry more if SV drops

Question 18

what does SAP, DAP, and MAP stand for?

Answer 18

SAP - systolic blood pressure (120 normally)
DAP - diastolic blood pressure (80 normally)
MAP - mean blood pressure (of SAP & DAP, normally 93)

Question 19

how low can MAP (mean (arterial) blood pressure) get before it’s considered critical?

Answer 19

MAP should be above 65, with a range of 60 - 70 mmHg

Question 20

what is the formula for arterial blood pressure (ABP)?

Answer 20

arterial blood pressure (ABP) = cardiac output (CO) x systematic vascular resistance (SVR)

Question 21

Everything other than the alveoli are CONDUCTING AIRWAYS and DO NOT participate in gas exchange. These structures make up…
a. physiological dead space
b. anatomical dead space

Answer 21

b. anatomical dead space

Question 22

Gas exchange occurs in the alveoli, but poorly perfused alveoli also DO NOT participate in gas exchange. This is known as:
a. physiological dead space
b. anatomical dead space

Answer 22

a. physiological dead space

Question 23

does anaesthesia add to…
a. physiological dead space
b. anatomical dead space
c. both

Answer 23

c. both - this is known as “equipment dead space” (all the tubes) and “anaesthetic induced physiological dead space (low BP meaning low alveoli blood perfusion = less gas exchange)

Question 24

true or false - you need to keep an eye on brachycephalic patients during premedication, induction, recovery if your GA/sedative drugs cause muscle relaxation (which most do).

Answer 24

true - excessive relaxation of the muscles that hold the respiratory tract patent can result in upper respiratory tract obstruction and death

Question 25

true or false - The correct definition of HYPOVENTILATION is "an increase in the level of carbon dioxide in the arterial blood" (defined as an elevation in PaCO2 > 45 mmHgz)

Answer 25

true - this then results in acidosis as the additional carbon dioxide is transported in the blood dissolved in water in the form of CARBONIC ACID.

Question 26

what is IPPV?

Answer 26

intermittent positive pressure ventilation - manual breathing

Question 27

how is IPPV different to natural negative pressure breathing?

Answer 27

positive intrathoracic pressure instead of negative, which is also applied to all thoracic structures - can collapse veins

Question 28

Identify ways of minimising the negative impact of IPPV?

Answer 28

get your values right

Question 29

Identify THREE negative consequences of endotracheal intubation?

Answer 29

1. cooling of the patient 2. drying of the airway 3. tracheal mucosal hypoperfusion (from the cuff) and increase the risk for tracheal strictures

Question 30

Based on the information provided in the table to the left, which ONE of the following statements would be FALSE? a. Effort should be made to protect the eyes from mechanical damage when a patient is anaesthetised b. Chest wall exertion is decreased when a patient is at a deeper plane of anaesthesia c. Eye position is likely to change as depth of anaesthesia changes d. General anaesthesia consistently preserves the patient's ability to protect their airway from foreign material e. A drug combination used to produce anaesthesia is likely to produce hypothermia and reduce salivation

Answer 30

FALSE - d. General anaesthesia consistently preserves the patient's ability to protect their airway from foreign material

Question 32

You have given a dog some medetomidine (a sedative drug) and he is lying in lateral recumbency. You want to remove a small lump from the skin of his forelimb. You have prepared the site for removal of the mass and start to make an incision with a scalpel blade. Which of the following is the next most likely scenario. a. The dogs heart rate decreases from 100 to 40 beats per minute. b. The dog sits up and bites you c. The dog stays in lateral recumbency and its respiratory rate stays the same as what it was before d. Nothing happens, the dog is very stoic and you could have removed the mass without any drugs

Answer 32

b. The dog sits up and bites you - it's a sedative

Question 33

Which ONE of the following statements about the cardiac cycle is TRUE? a. Diastolic blood pressure will be normal even in the face of cardiac arrhythmias b. Systole is the relaxation phase of the cardiac cycle c. The systolic phase lasts the majority of the cardiac cycle d. An adequate diastolic period is important for myocardial perfusion

Answer 33

d. An adequate diastolic period is important for myocardial perfusion

Question 34

Which ONE of the following statements is MOST correct? a. Arterial blood pressure has no correlation to tissue perfusion b. Mean arterial blood pressure lies half way between SAP and DAP c. Under anaesthesia, MAP must be greater than 90 mmHg to ensure tissue is perfused adequately d. MAP is the most import determinant of tissue perfusion e. Systemic vascular resistance (SVR) must be high if arterial blood pressure is within a normal range

Answer 34

d. MAP is the most import determinant of tissue perfusion

Question 35

Which ONE of the following statement is MOST correct? a. When HR is low CO will always be low b. CO can be maintained with an augmented SV during drug induced bradycardia c. HR should be maintained at normal or high rates during anaesthesia in order to protect against myocardial hypoxia d. During anaesthetic-induced hypoventilation, CO is generally decreased.

Answer 35

b. CO can be maintained with an augmented SV during drug induced bradycardia

Question 36

Which ONE of the following statements about pulmonary physiology is TRUE? a. The main determinant of ventilation under anaesthesia is the partial pressure of oxygen in the arterial blood b. Anaesthetic induced ventilatory impairment is minimal when acepromazine is used in the anaesthetic protocol c. Ketamine anaesthesia is associated with increased minute volume and overall hyperventilation d. Anaesthetic-induced ventilatory impairment is common and you should always be prepared to assist the patient using IPPV

Answer 36

d. Anaesthetic-induced ventilatory impairment is common and you should always be prepared to assist the patient using IPPV

Question 37

Which ONE of the following statements BEST defines HYPOVENTILATION? a. The product of respiratory rate and tidal volume is less than 200 mL/kg/min b. A respiratory rate that is less than 5 breaths per minute c. A tidal volume of less than 12 mL/kg d. An inspiratory pressure that is less than 10 cmH2O e. An arterial carbon dioxide pressure greater than 45 mmHg

Answer 37

e. An arterial carbon dioxide pressure greater than 45 mmHg

Question 38

Which ONE of the following statements is TRUE? a. Intrathoracic pressure during normal tidal breathing is always negative b. Only the diaphragm is affected by anaesthesia so chest exertion should be normal even at deep planes of anaesthesia c. Cartilaginous structures in the respiratory system will prevent airways from collapse during normal tidal breathing d. General anaesthesia preserves normal breathing, ventilation and gas exchange

Answer 38

a. Intrathoracic pressure during normal tidal breathing is always negative

Question 39

what are the two main reasons for pre-anaesthetic fasting?

Answer 39

1. reduced risk of vomiting and regurgitation 2. decreasing abdominal content (less pressure on diaphragm when dorsally recumbent)

Question 40

what should a dog's ideal fasting period look like?

Answer 40

- give a WET food meal of half metabolic energy requirements (MER) - fast 4-6 hours (not 12)

Question 41

what is the difference between vomiting, regurgitation and gastoesophageal reflux (GOR)?

Answer 41

vomiting - active process, food leaves mouth regurgitation - passive process, food leaves mouth GOR - passive, food/fluid moves out of the stomach but does not exit the oral cavity (less easily detected)

Question 42

which is NOT one of the three main factors you can use to avoid GOR (gastro-oesophageal reflux?) a. treat the underlying medical cause if the GIT is treatable (brachycephalics get gastrointestial disease from their upper airway obstructive disorders, can look into BOAS surgery) b. AVOID fasting patients longer than 6-12 hours c. don't put brachycephalics under anaesthesia d. use drugs in the preanaesthetic period that would reduce the impact of GOR

Answer 42

c. don't put brachycephalics under anaesthesia - not really avoidable

Question 43

which drug does NOT increase GOR risk? a. propofol b. morphine c. atropine d. peri-operative NSAIDs e. full opioid agonists f. ketamine

Answer 43

f. ketamine (not on the list anyway)

Question 44

Even a seemingly normal patient should undergo a thorough examination and history check before anaesthesia... what do you need?

Answer 44

a. history (previous health) b. present medications (2-3 days before anaesthesia, incl. premed drugs (trazodone, gabapentin, omeprazole), esp non-steroidal anti-inflammatory drugs (NSAIDs) and steroids, as they can cause significant morbidity) c. previous anaesthetics (drugs used, anything that went badly) d. physical exam - minimum of TPR, heart/lung auscultation, CRT and MM, bloodwork (PCV, TPP)

Question 45

when do you need ancillary (supportive) examinations for anaesthesia?

Answer 45

non elective, young or old patients. concentrate on body systems most likely effected by injury that has occured

Question 46

how do you make the anaesthetic considerations list? *do this prior to assigning an ASA grade, example given is for a cat with a fractured skull

Answer 46

order them so top considerations are at the top of the list, every patient has hypoventilation, hypotension, hypothermia, but additionally there can be pain haemorrhage, chronic pain, and acute pain

Question 47

The ASA categories of anaesthetic risk provide a framework for assessment of potential morbidity occurring during a procedure. what are the six different categories?

Answer 47

I, II, III, IV, V, E

Question 48

what is Acetaminophen's common name?

Answer 48

paracetamol - don't give to cats

Question 49

why do NSAIDS (non-steroidal anti-inflammatory drugs) cause renal failure with hypotension?

Answer 49

NSAIDs inhibit the production of prostaglandins (through blockade of cyclo-oxygenase enzyme system), which play a crucial role in both homeostasis and inflammation. Prostaglandins help maintain renal blood flow during hypotension, making anesthesia a greater risk to renal function if NSAIDs are administered.

Question 50

what are the two main behaviour modification drugs (for anxious/aggressive pets)

Answer 50

- gabapentin - trazodone