Case Studies Flashcards

1
Q

What are some of the signs and symptoms of anaemia?

A

Yellow tacky mucous membranes, lethargic, galloping pulse, high respiratory rate

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2
Q

With a bounding pulse what is going on?

A

CO may be increased. Peripheral resistance is lower compared to normal. There is a larger difference between systolic and diastolic blood pressure

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3
Q

What causes icterus (jaundice)?

A

Increased RBC destruction, a bile duct obstruction, end stage liver cirrhosis

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4
Q

What can lead to bilirubin?

A

Increased destruction of RBCs, Biliary stasis, reduced functional hepatic mass, pancreatitis, hepatic neoplasia

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5
Q

In Harriet’s case, what is likely to have caused the icterus?

A

Increased destruction of RBCs

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6
Q

What occurs with IMHA?

A

IMHA antibodies are deposited on the surface of RBCs, antibody may be directed against the RBC proteins or against drug or viral antigens bound to RBC, which results in a type II hypersensitivity response, deposition of antibodies results in the lysis of RBCs by complement and phagocytosis, this results in greatly reduced RBC lifespan and the body’s response by increasing RBC production (regenerative response)

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7
Q

What does deposition of antibodies on RBCs also cause?

A

Agglutination (or rouleaux formation is common in horses and cats)

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8
Q

How do spherocytes form?

A

Damage from the antibody can result in a change in conformation–> normal biconcave appearance is altered and they become spherocytes

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9
Q

What is a Coombs test?

A

Looks for antibodies directed against RBCs

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10
Q

What are the two treatments for Harriet?

A

Blood transfusion and immunosuppressive treatment

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11
Q

What is stridor?

A

Shrill, harsh sound heard during inspiration in the case of a laryngeal obstruction (can cause whistling)

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12
Q

What is stertor?

A

Snoring, sonorous respiration usually due to a partial obstruction of the upper airway (roaring- made by air passing through a stenosed larynx- usually from laryngeal hemiplegia in the horse)

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13
Q

Why does expiration occur as the leading leg hits the ground at a canter and gallop?

A

Because impaction of the abdominal viscera on the diaphragm, flexion of the neck as the forelimbs hit the ground, transmission of force to the chest as the forelimbs strike the ground

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14
Q

What is recurrent laryngeal hemiplegia?

A

One side of the larynx is completely paralyzed (usually left). Degeneration of the recurrent laryngeal nerve that innervates the intrinsic muscles of the larynx. At exercise, negative pressure during inspiration pulls the paralysed left arytenoid cartilage into the laryngeal lumen, causing reduced airflow and turbulence (results in a noise)-whistle or roar

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15
Q

What is Hobday’s procedure?

A

removal of laryngeal ventricles and removal of vocal cords- in horses that don’t need to perform strenuously

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16
Q

In a horse that does need to perform strenuously, what is done?

A

ventriculectomy and laryngeal tieback procedure.

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17
Q

Which muscle abducts the larynx?

A

Dorsal Cricoarytenoideus muscle

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18
Q

Why is it likely that the left side is impacted and not the right commonly?

A

Left recurrent laryngeal nerve is longer than the right- it comes out of the brain stem with the vagus, around the base of the heart, and all the way back up to the larynx (a couple of meters long)

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19
Q

What is significant about the cricothyroideus muscle?

A

The only muscle not innervated by the laryngeal nerve in the larynx

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20
Q

If you halve the lumen of a tube, what are you doing to the flow?

A

Flow is reduced to 1/16th of the normal flow!!

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21
Q

During inspiration, what is the pressure like in the thorax?

A

Negative

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22
Q

What is alveolar dead space?

A

Volume compromising non-functional alveoli due to absent or poor blood flow

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23
Q

What is alveolar ventilation?

A

Amount of new air reaching the areas of gas exchange each minute (inspired gas minus dead space)

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24
Q

What is anatomic dead space?

A

Volume of conducting airways where no gas exchange can occur

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25
What is apparatus dead space?
Volume of dead space contributed by an external breathing apparatus
26
What is hypercapnoea?
Abnormally high CO2 in the blood
27
Why is hyperventilation?
Increase in minute volume beyond what is necessary to maintain normal PO2
28
What is hypoventilation?
Abnormal retention of CO2 from insufficient airflow to the lungs
29
What is hypoxaemia?
Abnormally low PO2 in the blood
30
What is hypoxia?
Inadequate oxygen supply to the tissues
31
What is the minute volume?
Amount of air inspired or expired in a minute
32
What is tidal volume?
Amount of air inspired or expired with each normal breath
33
What is PO2 in the alveolar gas determined by?
Rate of uptake of O2 into the blood and rate of delivery of new O2 in the lungs by ventilation
34
What is the rate of removal of O2 from the lung governed by?
O2 consumption of the tissues, tends to vary little in resting conditions
35
What is alveolar O2 in mm Hg normally?
About 104 mm Hg
36
What is alveolar CO2 in mm Hg normally?
About 40 mm Hg
37
In a perfect lung, the PO2 of the arterial blood would be the same as that in alveolar gases. Why is this not the case even in a healthy animal?
98% of blood that enters the left atrium from the lungs passes through the alveolar capillaries and becomes oxygenated. The other 2% passes through the bronchial circulation where it is not exposed to air. This blood combines in the pulmonary veins with the oxygenated blood (venous admixture). This lowers the overall PO2 to about 95 mm Hg
38
So in a healthy, conscious animal breathing air, what is the alveolar to arterial oxygen tension different?
About 10 mm Hg
39
What causes the alveolar to arterial oxygen tension difference to increase?
Age, anaesthesia, diseases of the lung and some CV disorders
40
What is the PO2 in any part of the lung determined by?
The ratio of ventilation to perfusion
41
What is the Mean ventilation to perfusion ratio for the lungs in a healthy animal?
1.0
42
What happens with V/Q mismatch?
Impairment of O2 and CO2 transfer results
43
What is the most common cause of hypoxaemia?
V/Q mismatch (hypoxaemia is lack of oxygen in the blood)
44
What is shunting?
Blood passes through the pulmonary capillaries without oxygen uptake
45
What is dead space ventilation?
Ventilation is normal but blood flow is absent
46
What will cause alveolar O2 concentration to fall?
Increased O2 uptake, decreased alveolar ventilation (hypoventilation), decreased inspired O2 concentration
47
What factors influence the rate of transfer (Ficks Law)?
Surface area, tissue thickness, pressure gradient
48
The difference between alveolar gas and arterial PO2 will increase if:
The blood gas barrier is thickened, a low O2 mixture is inspired
49
Which shunts will increase the alveolar to arterial oxygen tension difference?
Bronchial veins, Right to left shunting in PDA, blood passing through collapsed (atelectasis) or unventilated (pulmonay oedema e.g.) alveoli, accidental intubation of just one bronchus
50
Are you able to correct the increase in alveolar to arterial oxygen tension difference resulting from shunting by administration of 100% oxygen?
NO
51
shunting is present, V/Q= 0 (blood passes through without oxygen uptake- 0/1- there is perfusion but no ventilation)
Alveolar Ventilation- absent Blood flow- present PO2- 40 PCO2- 45
52
If dead space ventilation is occurring and V/Q= infinity (no perfusion- 1/0)
Alveolar Ventilation- present Blood flow- absent PO2-150 PCO2- 0
53
V/Q= 1
Alveolar Ventilation- present Blood flow- present PO2-104 PCO2- 40
54
What do you monitor when the patient is under anaesthesia?
Arterial blood gases, pulse oximetry, end tidal CO2, arterial blood pressure, electrocardiography
55
Assuming the horse is breathing 100% oxygen at normal atmospheric pressure, what would you expect the PO2 to be?
500-600 mm Hg
56
What happens to a horse in dorsal recumbency?
Dorsal part of the lung becomes compressed by intestinal tract exerting pressure on the diaphragm. Compression and atelectasis of the alveoli and hence reduction in ventilation. Perfusion is increased though because pulmonary circulation is a low pressure system and therefore impacted by positional changes. Ventral part of the lung receives better ventilation but poorer perfusion.
57
What is a recruitment manoevre?
Increase pressure for a short period of time by the ventilator in order to re-expand the collapsed alveoli. Disadvantage to doing so is that it temporarily increases intrathoracic pressure which results in reduced venous return and reduced CO
58
What percentage of oxygen in blood is carried in the dissolved form?
2%
59
What percentage of oxygen in blood is combined with Hb?
98%
60
What would you expect the pulse oximeter to read if the horse had a PO2 of 188 mm Hg?
100%
61
What would you expect the pulse oximeter to read if the horse was standing on top of Mount Everest?
0-80%
62
The pulse oximeter does not provide information about how well the horse is ventilating. True or false?
True
63
What is capnograph?
Machine that measures CO2 in expired air
64
What is the primary driver to breathe arterial O2 or CO2?
Arterial CO2 (O2 only comes into play if the PO2 falls below 60 mm Hg)
65
The end tidal (last gas in expired breath) is virtually identical to the alveolar and arterial CO2. True or False?
True
66
What does the end tidal CO2 depend on?
The rate of production of CO2, the alveolar ventilation and the CO and pulmonary perfusion. Therefore monitoring CO2 tells us about metabolism, ventilation and circulation.
67
An end tidal CO2 value of 65 mm Hg may result from?
Increased metabolism or rebreathing CO2
68
An end tidal CO2 value of 25 mm Hg may result from?
Hypothermia or impending cardiac arrest
69
What is the shunt fraction in a horse under anaesthesia?
Normal up to 50% (normally 1-5%)- because of squish lungs
70
Right to left PDA causes what?
Hypoxaemia because it doesn't travel through the lungs
71
If blood pH increases during surgery, what do you do?
Increase breathing.
72
What two patterns can you see in Suki's radiograph?
Bronchial (involving the bronchi and peribronchial tissues) & Alveolar (increased opacity of the lungs- typically patchy in distribution)-- fluffly patches (alveolar) and trams and donuts (diffuse bronchial pattern)
73
Why can you not perform a respiratory functions test on an animal?
Cannot communicate with them to tell them to breathe in and out.
74
Why would you perform a bronchoscopy?
Can rule out FBs
75
Why would you perform a Bronchoalveolar lavage?
For cytology and bacterial culture.
76
What do neutrophils and eosinophils suggest with a bronchoalveolar lavage on a cat?
Feline chronic bronchial disease (feline asthma), underlying chronic inflammatory process and obstruction of airflow.
77
What are the major clinical signs of feline bronchial disease (feline asthma)?
Coughing, wheezing, dyspnoea
78
What causes feline bronchial disease (feline asthma)?
Genetics or inhalation of irritants- not known.
79
Compared to a normal cat, what does a cat with feline bronchial disease show in terms of TV, RR, MV, etc.?
Tidal volume- decreased; respiratory rate- decreased; minute volume- decreased; time associated with inspiration- similar; time associated with expiration- increased; Peak inspiratory flow- decreased; peak expiratory flow- decreased
80
What are the dogs used to treat chronic bronchitis in cats?
Beta 2 adrenoceptor agonists, phosphodiesterase inhibitors (breakdown cAMP keep airway dilated), and corticosteroids
81
What does wheezing mean?
Expiratory issue. With expiration, airways collapse a bit more, why it is more difficult to expire than inspire.
82
What is asthma?
Chronic inflammatory disease of the airways
83
What is Poiseuille's Law?
Airflow through a bronchus or bronchiole is proportional to the radius to the fourth power. Small changes in diameter have a huge effect on flow. Halve the diameter= 1/16th the flow.