Acute and chronic respiratory failure

Question 1

definition: respiratory failure

Answer 1

lung fails to

adequately oxygenate arterial blood and/or
prevents retention of CO2

Question 2

definition: acute on chronic respiratory failure

Answer 2

increase baseline oxygen requirements

increase CO2 above baseline enough to drop ph below 7.3

Question 3

what is a normal paCO2?

Answer 3

40 mm Hg

Question 4

what are two causes of hypoventilation?

Answer 4

medications

neuromuscular

Question 5

what are the four types of respiratory failure?

Answer 5

type I - hypoxemic
type II - hypercapnic
type III - perioperative
type IV - shock

Question 6

what are the causes of type I hypoxemic respiratory failure? which is most important? which is due to the environment?

Answer 6

V/Q mismatch (most important) 
R-L shunt 
alveolar hypoventilation 
diffusion defect 
inadequate FIO2 (environment)

Question 7

what are the causes of type II hypercapnic respiratory failure?

Answer 7

pump failure 
ventilatory effort (drive failure) 
increased CO2 production (sepsis, fever, burns, trauma) 
R-L shunt 
increased dead space

Question 8

what are the CV manifestations of tissue hypoxia?

Answer 8

mild and early - tachycardia, HTN

severe and late - bradycardia, hypotension

Question 9

what do B lines show on US?

Answer 9

pulmonary edema

Question 10

what is the initial support for hypoxic respiratory failure?

Answer 10

supplemental oxygen
IV access
vital sign monitoring (spO2, HR, BP, ECG)

Question 11

what is the goal for advanced support in hypoxic respiratory failure?

Answer 11

1. provide adequate oxygen delivery to tissues
2. optimize Hb, CO, lactic acid
3. treat underlying causes
4. mechanical ventilation
5. high flow nasal cannula
6. ECMO

Question 12

for every acute rise in CO2 of 10, how does the pH change?

Answer 12

decrease by 0.8

Question 13

for every chronic rise of CO2 of 10, how does the pH change?

Answer 13

decrease by 0.03

Question 14

what are the clinical manifestations of hypercapnic respiratory failure?

Answer 14

direct effects of hypercapnia (CNS)
respiratory acidosis with metabolic alkalosis
ventilatory pump failure
ventilatory drive failure

Question 15

management: hypercapnic respiratory failure

Answer 15

intubation and mechanical
noninvasive mechanical ventilation
treat underlying cause

Question 16

what is the most reliable way to restore alveolar ventilation in hypercapnic respiratory failure?

Answer 16

mechanical ventilation

Question 17

what is the result of hypercapnia from oxygen administration?

Answer 17

1. increased physiologic dead space from V/Q mismatch
2. attenuated hypoxic ventilatory drive
3. Haldane effect - oxygen released bound CO2 increasing paCO2

Question 18

what are the clues for chronic respiratory failure?

Answer 18

polycythemia 
elevated CO2 
normal pH with elevated paCO2 
elevated bicarb 
clubbing

Question 19

what are the important vaccines for adults in a respiratory context?

Answer 19

influenza
tetanus
pneumococcal

Question 20

oxygen therapy shows no improvement in what areas?

Answer 20

lung function

survival in patients with moderate / nocturnal hypoxemia

Question 21

what are the qualifications for oxygen therapy?

Answer 21

paCO2 less than 55 mm Hg or saO2 under 88%

paCO2 56-59 with cor P, edema, and/or secondary erythrocytosis