Acute Respiratory Failure

Question 1

Define acute respiratory failure

Answer 1

The inability of the respiratory system to meet oxygen/ventilation demands

Question 2

What are the two types of ARF and what is the difference?

Answer 2

Type One: Hypoxic RF - oxygenation failure- PaO2<60 mmhg
Type Two: Hypercapnic RF- ventilation failure w/ or w/o hypoxemia- PCO2>50mmhg

Question 3

Describe the general Pathophysiology behind hypoxia

Answer 3

CNS >PNS > Thoracic bellows > supper airways > lungs

Question 4

What are five mechanisms of hypoxemia

Answer 4

1. Inadequate o2 at the alveolar level
2. Ventilation perfusion abnormality
3. Intracardiac/Intra pulmonary
4. Diffusion abnormality
5. Low pulmonary arterial oxygenation

Question 5

What is normal air composition of O2?

Answer 5

21%

Question 6

What is alveolar partial pressure of o2 PAO2

Answer 6

Driving force of O2 diffusion
O2 moves from alveolar membranes to pulmonary capillary walls to arteriolar blood flow and erythrocytes- peripheral tissues

Question 7

What is the A-a gradient and what does it incite

Answer 7

PAO2-PaO2
The larger the gradient indicates pathology hindering O2 transfer

Question 8

How much does 1l of O2 increase the inspired O2

Answer 8

4%

Question 9

What does 2, 3 DPG do?

Answer 9

Stabilize hemaglobin increasing O2 at tissues

Question 10

What is the Bohr effect?

Answer 10

O2 association with hgb is inversely affected by acidity and PCO2 concentration

Question 11

What does a left shift in the oxyhemoglobin curve mean and what can cause it?

Answer 11

Hgb has greater affinity for O2
Causes: Alkalemia, hypothermia, hypo metabolism, abnormal hgb

Question 12

What does a right shift in the oxyhemoglobin curve mean and what causes it?

Answer 12

Hgb has lesser affinity for O2
Causes: Acidemia, hyperthermia, hyper metabolism, chornic hypoxemia, hypercapnea

Question 13

How to use PaO2 to determine if someone is oxygenating?

Answer 13

PaO2 = Fio2 x 5

Question 14

What are the benefits and draw backs of SaO2

Answer 14

Reflects oxyhemaglobin but is not impacted by anemia or CO poisoning

Question 15

What is the pH and CO2 in hypercapnic RF

Answer 15

pH <7.35
PaCO2>50

Question 16

What are three general causes of increased CO2

Answer 16

Increased CO2 production
Deceased total tidal volume
Increased dead space ventilation

Question 17

What are causes of increased CO2

Answer 17

Exercise, fever, sepsis, burns, trauma, excessive carb intake, hyperthyroidism

Question 18

How do you determine the causes of dead space disease?

Answer 18

A-a gradient >10mmhg is parenchymal lung process

Question 19

What are five causes of decreased tidal ventilation

Answer 19

Compromised neuromuscular sequence
CNS depressants
Neuromuscular transmission disorders
Abnormal respiratory mechanisms

Question 20

What is the Hallmark feature of inadequate ventilation

Answer 20

Elevated PaCO2 w/wo hypoxemia

Question 21

S/s of hypercapnic RF

Answer 21

Abnormal RR, irregular respirations, gasping, nasal flaring, accessory muscle use, lethargy, coma, seizures, tremors

Question 22

What are risk factors for hypercapnic RF

Answer 22

Post-op, preexisting chronic illness, malnutrition, advanced age, morbid obesity, chronic bronchitis, cigarette smoking