Acute Respiratory Distress Syndrome

Front 1

The 3 steps O2 is involved in?

Back 1

Oxygenation
Oxygen Delivery
Oxygen Consumption

Front 2

Kickers for Oxygenation?

Back 2

Getting O2 from the alveoli to the pulm cap and binding to Hb

Front 3

What is the condition caused by inadequate oxygenation?

Back 3

Hypoxemia

Front 4

Kickers for O2 delivery?

Back 4

Rate of O2 transport from lungs to peripheral tissues

Front 5

Kickers for O2 Consumption?

Back 5

Rate at which O2 is removed from blood for use by tissues

Front 6

how is Hypoxemia usually represented (test-wise)?

Back 6

PaO2 < 60

O2 sat < 90%

Front 7

What is SaO2 representative of?

Back 7

% of RBC's whose Hb is bound to O2

Front 8

what is PaO2?

Back 8

Amount of O2 dissolved in plasma

Front 9

Normal PaO2:FiO2 ratio?

Back 9

300-500 mmHg

Front 10

What does a PaO2:FiO2 ratio of less than 300 represent? less than 200?

Back 10

< 300 = abnormal gas exchange

< 200 = severe hypoxemia

Front 11

Possible Causes of Hypoxemia?

Back 11

Hypoventilation
Diffusion Defect
Ventilation-Perfusion Defect
Shunt
Low FiO2 (high altitude)

Front 12

Mechanism of Hypoventilation-induced hypoxemia?

Back 12

Alveolar CO2 tension increase causes O2 tension decrease

Front 13

Common causes of hypoventilation hypoxemia?

Back 13

CNS Depression
Obesity (pickwickian)
Impaired Neural Conduction (ALS)
Muscular Weakness (MD)
Poor Chest Wall Elasticity

Front 14

What is a ventilation-perfusion defect?

Back 14

Imbalance of blood flow and ventilation

Front 15

Two main types of V-Q mismatch?

Back 15

Blocked alveolus
Blocked Capillary (dead space ventilation)

Front 16

Common causes of V-Q mismatch?

Back 16

ARDS
OPD
Pulmonary Vascular Disease

Front 17

Type of shunt leading to hypoxemia?

Back 17

Right to Left

Front 18

Types of R--->L shunt?

Back 18

Physiological
Anatomic

Front 19

Mech for Physiologic Shunt?

Back 19

Non-ventilated alveoli are perfused

Front 20

causes of Phys Shunts?

Back 20

Atelectasis
Pneumonia
ARDS

Front 21

Anatomic Shunt Mech?

Back 21

Alveoli are bypassed

Front 22

Causes for Anatomic Shunts?

Back 22

Intra-cardiac Shunts
Pulmonary A-V Malformations
Hepato-Pulmonary Syndrome

Front 23

What is the mech for a diffusion defect?

Back 23

Screwed up movement of O2 from alveolus to capillary

Front 24

Typical general cause of Diffusion defect?

Back 24

Alveolar/Interstitial Inflammation and Fibrosis

Front 25

Specific causes of diffusion defects?

Back 25

Late ARDS
Sarcoidosis
Pulm Fibrosis

Front 26

Special type of hypoxemia diffusion defect leads to?

Back 26

Exercise-Induced hypoxemia

since blood starts moving faster and there isn't enough time for adequate oxygenation

Front 27

When is just about the only time you'll deal w/ reduced PiO2?

Back 27

High Altitude

Front 28

Appearance of ALI-ARDS on CXR?

Back 28

BIlateral Widespread Infiltrates

Front 29

Effect of ARDS on pulmonary arterial pressure?

Back 29

normal pressures

Front 30

PaO2/FiO2 ratio in ARDS vs ALI?

Back 30

ARDS < 200

200 < ALI < 300

Front 31

Difference in ALI and ARDS?

Back 31

Differ only in severity of Hypoxemia (i.e. ARDS is most severe ALI)

Front 32

Mechanisms of ALI/ARDS?

Back 32

Acute alveolar/capillary membrane injury
Lung Infl
Inc Permeability of lung

Front 33

Sx's of ARDS?

Back 33

Rapid onset of dyspnea w/in a day of initiating event
Tachypnea, Resp Distress, labored breathing
Dry Cough
Cyanosis
Tachycardia
Diffuse Rales

Front 34

Almost all ARDS pts require what?

Back 34

Mechanical Ventilation

Front 35

CXR in ARDS?

Back 35

Diffuse/patchy bilateral infiltrates --> confluent central infiltrates
Air bronchgrams
Inc Interstitial Edema
Normal Heart Size

Front 36

clincal course of ARDS?

Back 36

Initial Phase for 3-7 days
Subsequent phase

Front 37

Components of Initial Phase of ARDS?

Back 37

Acute Pulm Decompensation
CXR w/ diffuse infiltrates
Mechanical Ventilation

Front 38

Subsequent Phase kickers?

Back 38

Less CXR changes
Ventilator Dependent
Complications

Front 39

Typical complications of ARDS?

Back 39

Baratrauma
Biotrauma (proteins attack lung)
Infections
Multi-System Organ Failure

Front 40

What is DAD?

Back 40

Diffuse Alveolar Damage

Front 41

Pulmonary Effects of ARDS in chron. order?

Back 41

1. Inflammatory injury to alveoli by pro-infl cytokines
2. Interstitial edema-->alveolar filling and collapse
3. V-Q mismatch
4. Impaired gas exchange, stiff lungs difficult to ventilate

Front 42

Major causes of Lung Injury?

Back 42

Pneumonia 40%
Sepsis 22%
Aspiration 15%
Trauma 8%
Transfusion 5%

Front 43

Who is at higher risk of ARDS?

Back 43

boozers

Front 44

when is ARDS mortality higher?

Back 44

with indirect causes as opposed to direct pulmonary causes

Front 45

Indications for Mechanical Ventilation?

Back 45

RR > 30
FiO2 >.6 and SaO2< 90%
Patient's breathing failing

Front 46

ARDS Rx?

Back 46

Mech Vent
Keep SaO2 > 90%
Maintain BP w/ drugs
Fluid therapy to maintain normal volume
Keep Hb about 8 gm%
Sedate pts if necessary
Nutritional support
Glucose control

Front 47

What preventions are important in Rx of ARDS?

Back 47

Ventilator Associated Pneumonia
DVT prophylaxis
GI prophylaxis (ulcer)

Front 48

what do you have to worry about with ventilation when only one lung is screwy?

Back 48

you can blow out the good lung

Front 49

How much Ventilation do you use?

Back 49

6 mL/kg/min based on Ideal body wt
Use lowest Positive End Expiratory Pressure (PEEP)
Keep PaO2 > 60, SaO2>90%

Front 50

How does a blow out feel?

Back 50

Crunchy

Front 51

How often does barotrauma occur?

Back 51

15% of pts on low tidal volume

Front 52

What are blow-outs associated w/?

Back 52

Higher levels of PEEP

Front 53

Clinical findings w/ Barotrauma?

Back 53

Pneumothorax
Subcu Emphysema
Pneumomediastinum
Interstitial Emphysema
Rarely air embolism

Front 54

Mediator of MOSF?

Back 54

Induced by cytokines and inflammatory proteins?

Front 55

Organs involved w/ MOSF?

Back 55

Kidney
Liver
CNS
Hematologic

Front 56

mortality for ARDS?

Back 56

60%-->35% (falling)

Front 57

Mortality w/ ARDS increases w/?

Back 57

Age
Sepsis
Pre-existing/Co-existing organ dysfxn

Front 58

how long does it take most patients to regain normal pulmonary fxn after ARDS?

Back 58

6-12 months