Lecture 28: Anesthesia in patients with respiratory disease

Question 1

How do opioids affect respiration

Answer 1

mild decrease in frequency and tidal volume

Question 2

how do alpha 2 agonists affect respiration

Answer 2

mild decrease in frequency

Question 3

respiratory depression from anesthetics are __dependent and __dependent

Answer 3

dose and speed

Question 4

what drugs when given too fast can easily cause apnea

Answer 4

propofol or alfaxalone

Question 5

no particular drug is contraindicated for respiratory disease therefore the key is

Answer 5

proper usage (speed and fosse) and close monitoring throughout peri-anesthesia period

Question 6

what position should you keep patients in with respiratory disease: sternal or dorsal

Answer 6

sternal

Question 7

define hypo ventilation

Answer 7

decreased alveolar ventilation volume

Question 8

what is formulae for minute volume

Answer 8

Tidal volume x RR

Question 9

define hypercapnia

Answer 9

amount of CO2 removed is inadequate causing accumulation, increase PaCO2

Question 10

patients with pulmonary pathology, hypo ventilation can occur even with adequate minute ventilation d/t __

Answer 10

inefficient alveolar gas exchange

Question 11

what is normal PaCO2

Answer 11

35-45

Question 12

what is normal ETCO2

Answer 12

30-40

Question 13

what do you do to fix hypo ventilation

Answer 13

Increase ventilation via increasing TV, RR or both

Question 14

what is permissive hypercapnia

Answer 14

PaCO2 up to 60mmHg

Question 15

PaCO2 up to 60mmHg is clinically acceptable in most cases except contraindicated when

Answer 15

brain tumor, moderate/severe metabolic acidosis

Question 16

why do you need to use caution when applying higher airway pressures in hypoventilating patients with pulmonary pathology

Answer 16

possible alveolar rupture—> pneumothorax

Question 17

what patients should you be particularly cautious about higher airway pressures for fixing hypoventilation

Answer 17

pulmonary bulla, pneumothorax, chest trauma (HBC)

Question 18

what is peak inspiratory pressure you can provide in healthy lungs vs those with pulmonary pathology

Answer 18

healthy: up to 20cm H20
Pathology: up to 10-15cm H20

Question 19

define hypoxemia

Answer 19

PaO2 <60mm Hg

Question 20

what are 5 causes of hypoxemia

Answer 20

1. Low FiO2
2. V/Q mismatch
3. Diffusion impairment
4. R-L shunt
5. Hypoventilation

Question 21

what causes of hypoxemia can be affected by pulmonary disease and give examples

Answer 21

1. Hypoventilation (ex: pneumothorax)
2. Diffusion impairment (ex: pulmonary edema)
3. V/Q mismatch:(ex: atelectasis)

Question 22

what causes of hypoxemia can be affected by anesthesia and recumbency

Answer 22

1. FiO2
2. Hypoventilation
3. V/Q mismatch

Question 23

what is normal pulse ox SPO2

Answer 23

98-100%

Question 24

what SPO2 value is true hypoxemia

Answer 24

<90%

Question 25

when patient is cyanotic SPO2 =

Answer 25

<85%

Question 26

how can you avoid hypoxemia before induction

Answer 26

pre-oxygenation for > or = 3mins

Question 27

how much time do you buy before hypoxemia with no pre-oxygenation, with flow by and with mask for 3 minutes

Answer 27

none: 30 secs Flow by: 66 sec Mask: 187 sec

Question 28

what things should you have with suspected difficult intubation

Answer 28

1. Several sizes of ET tubes 2. Long, skinny, stylet

Question 29

what is time limit until possible cerebral ischemia

Answer 29

3 minutes

Question 30

what capnograph show

Answer 30

left: normal Middle and right: obstruction

Question 31

what are some signs of airway obstruction

Answer 31

1. Abdominal breathing 2. Increased breathing effort 3. Increased resistance on reservoir bag 4. Increased peak inspiratory pressure

Question 32

what is the most critical period in patients with respiratory disease with anesthesia

Answer 32

anesthesia recovery

Question 33

what should you do/check before extubation

Answer 33

1. Check oral cavity for any fluid 2. Dexamethasone at least 5 minutes prior if inflammation expected

Question 34

describe room air challenge

Answer 34

try off oxygen to see if SPO2 maintain >95% if unsuccessful try to improve before extubation, if still unsuccessful supply oxygen after extubation

Question 35

what do reliable spo2 readings require

Answer 35

1. Matching pulse rate with HR 2. Consistent rhythm and wave form

Question 36

why may patients with severe pulmonary disease keep waking up under inhalant anesthesia

Answer 36

inefficient ventilation- needs to be inhaled to be absorbed in blood

Question 37

what other options besides inhalant can you consider for patients with severe pulmonary disease

Answer 37

1. TIVA - intermittent injections of propofol or alfaxolone - propofol infusion - alfaxalone infusion