Mech ventilation Dr Ambrisko

Question 1

What defines ventilation

Answer 1

PaCO2

Question 2

What defines oxygenation

How is it monitored

Answer 2

PaO2 or SpO2

arterial blood gas or pulse oximetry

Question 3

What is considered hypoxemia

Answer 3

PaO2 <60 mmHg ⇔ SaO2 < 90%

Question 4

How can oxygenation be improved?

How can good oxygenation be insured in most circumstances?

Answer 4

When breathing 100% O2 it CANNOT be improved by MORE ventilation

Could be improved by special respiratory manoeuvers

Use 100% oxygen

Question 5

What does resistance & compliance limit?

Answer 5

flow & volume respectively!

Question 6

what is the respiratory cycle

Answer 6

Inspiration

inspiratory flow time

inspiratory pause

Expiration

expiratory flow time

expiratory pause

Question 7

what is mechnical ventilation (MV)

Answer 7

artificial ventilation where mechanical means is used to assist or replace spontaneous breathing

provided by a ventilator or a person

Question 8

What are the types of ventilation

Answer 8

Spontaneous - pt determines when & how

Assisted - pt derermines when, ventilator determines how

Mandatory (or controlled) - ventilator determines when & how

Question 9

What is IPPV

Answer 9

Intermittent Positive Pressure Ventilation

positive pressure only during inspiration (no PEEP)

Question 10

what is IMV

Answer 10

Intermettent Mandatory Ventilation

predetermined # of positive breaths but pt can breath inbetween freely

Question 11

what is CPAP

Answer 11

Continuous Positive Airway Pressure

spontaneous breath w/ positive pressure during both inspiratory & expiratory phases

can prevent lung collapse

Question 12

what is PIP

Answer 12

Peak Inspiratory Pressure

highest pressure during inspiration

inflates alveoli, opens atelectasis, causes barotrauma

Question 13

what is PEEP

Answer 13

Positive End Expiratory Pressure

positive pressure maintained during expiration

pressure keeps alveoli open (prevents re-collapse of alveoli)

Question 14

Indications for PEEP

Answer 14

open thorax

lung parenchymal dz

following alveolar recruitment maneuver

Question 15

indications for MV under anesthesia

Answer 15

in intubated pt that breathe 100% O2 used to DECREASE PaCO2

(to tx hypoventilation)

Question 16

specific indications for MV under anesthesia

Answer 16

neuromuscular blockade

throacic sx

control of ICP

chest wall or diaphragmatic trauma

Question 17

Side effect of MV

how to tx side effects

Answer 17

may cause hypotension in hypovolemic pt

Volume loading

change ventilator settings

turn off ventilator

Inotropic drugs (e.g. dobutamine)

pneumothorax & lung injury

Question 18

Effects of hypercapnia

Answer 18

Direct effects of CO2:

• peripheral vasodilation*
• decr myocardial contractility (inotropy)*
• incr ICP*
• bradycardia*

Indirect effects of CO2 (via catecholamine release):

• tachycardia*
• incr myocardial contractility*

Question 19

ventilating healthy lungs

Answer 19

TV: 10-15 ml/kg

for ruminants: 6-10 ml/kg

RR: 10-15(20) breath/min

Inspiratory time: 1-2 sec

PIP: 10 cmH2O if BW <10kg

20 cmH2O if BW >10kg

PEEP: 0-2 cmH2O

Question 20

How is manual ventilation performed

Answer 20

1. close pop-off
2. squeeze reservoir bag until desired pressure reached
3. release bag so pt passively expire
4. open pop-off
5. repeat cycle q 6 secs (10/min)

Question 21

What are respiratory assist devices

Answer 21

ambu bag

demand valve

Question 22

modes of MV

Answer 22

volume controlled

pressure controlled (preffered)