13. Ventilation in Small Mammals

Question 1

LO1. define 5 causes of hypoxemia

Answer 1

1. ventilation - perfusion mismatch (most common)
2. low FiO2
3. hypoventilation
4. anatomic shunt
5. diffusion impairement

Question 2

LO2. hypoxemia v. hypoxia

Answer 2

hypoxia - dec. oxygen in tissues

hypoxemia can lead to hypoxia

Question 3

LO3. indications for controlled ventilation

Answer 3

hypoventilation
intra-thoracic surgery
intracranial disease
pt given neuromuscular blocking agents

Question 4

LO4. physiologic effects of IPPV

Answer 4

• volutrauma or barotrauma
• decreased compliance over time
• dec. venous return -> dec. BP

Question 5

LO5. classification of ventilators

Answer 5

1. power source (electric/gas)
2. major control variable (volume, pressure)
3. drive mechanism (dual circuit with belows usually)
4. cycling mechanism (most time cycled)
5. bellows configuration (ascending/descending)

Question 6

minute ventilation

Answer 6

tidal volume x respiratory rate

Question 7

expiration is _____ in small animals.

Answer 7

passive

Question 8

low V/Q mismatch

Answer 8

physiologic shunt (atelectasis, GDV/extended abdomen) no gas exchange with normal blood flow

Question 9

deadspace ventilation

Answer 9

no blood flow to alveolus

Question 10

ventilation - perfusion mismatch usually ______ after anesthesia

Answer 10

resolves

Question 11

Low FiO2 causes

Answer 11

• nitrous oxide doesn’t need carrier gas (can forget to add O2)
• modern machines have O2 sensors to prevent this from happening (vet machines not necessarily)

Question 12

may delay effects of apnea/hypoventilation by _________ of oxygen.

Answer 12

passive insufflation 
(preoxygenate)

Question 13

Anatomic shunt

Answer 13

R>L shunt (classic PDA)

- doesn’t resolve like the physiologic shunt

Question 14

diffusion impairment most common disease?

Answer 14

pulmonary fibrosis - westies

least common cause of hypoxemia

Question 15

4 types of hypoxia

Answer 15

1. circulatory (cardiac arrest)
2. anemic
3. cytotoxic (cyanide)
4. hypoxemic

Question 16

peak inspiratory pressure should not exceed?

Answer 16

20 cm H20

Question 17

PEEP, keeps pressure always above ___.

Answer 17

zero

Question 18

inspiratory:expiratory ratio

Answer 18

1:2 is normal

Question 19

how to set up ventilator

Answer 19

1. turn tidal vol down
2. empty bag and attach ventilator to where bag was
3. close pop off valve
4. attach scavenger
5. set rates, slowly increase to desired volume(15 ml/kg) and 10-12 cm H20.