ARDS

Question 1

ARDS (acute respiratory distress syndrome)

Answer 1

diffuse lung injury with non-cardiogenic pulmonary edema; disruption of alveolar-capillary membrane (alveoli filling with fluid)

Question 2

4 hallmark features of ARDS

Answer 2

1. bilateral patchy infiltrates on chest XR
2. no s/s of HF (PAWP 18 or less)
3. no improvement in PaO2 despite increasing O2 delivery
4. acute onset

Question 3

PaO2/FiO2 ratio

Answer 3

look at PaO2 on ABGs and divide by % of O2 pt is receiving; ex: PaO2 83 and 45% FiO2 = 83/0.45 = 184.4

Question 4

Berlin criteria: timing

Answer 4

within a week of clinical insult/worsening symptoms

Question 5

Berlin criteria: chest x-ray

Answer 5

bilateral opacities not explained by effusions, lobar collapse, or nodules

Question 6

Berlin criteria: origin of edema

Answer 6

respiratory failure not fully explained by HF or fluid overload; need echocardiography

Question 7

Berlin criteria: mild ARDS

Answer 7

2005

Question 8

Berlin criteria: moderate ARDS

Answer 8

1005

Question 9

Berlin criteria: severe ARDS

Answer 9

PaO2/FiO2 with PEEP >5

Question 10

risk factors for ARDS

Answer 10

sepsis, pneumonia, trauma, aspiration, multiple transfusions, fat embolism, or pancreatitis

Question 11

direct lung injury

Answer 11

lung epithelium sustains a direct insult

Question 12

indirect lung injury

Answer 12

insult occurs elsewhere in body and mediators are transmitted via bloodstream to lungs

Question 13

examples of direct injury

Answer 13

aspiration, pulmonary infections, pulmonary contusions, toxic inhalation, drug overdose, burns, near drowning

Question 14

examples of indirect injury

Answer 14

sepsis, hyper-transfusion of blood, trauma, pancreatitis, cardiopulmonary bypass, shock, DIC

Question 15

ARDS pathology

Answer 15

injury –> inflammatory response –> damage to alveolar-capillary membrane –> increased vascular permeability –> protein rich fluid –> decreased gas exchange –> respiratory failure

Question 16

exudative phase

Answer 16

within 72 hr, capillary membranes begin to leak - protein rich fluid fills the alveoli - hyaline membrane formed -disrupts gas exchange

Question 17

fibroproliferative phase

Answer 17

day 7-10 after onset until 1 mo, alveolar cells damaged and surfactant production declines, VQ mismatch, hypoxemia, pulmonary htn develops and increase in R vent afterload and R sided HF

Question 18

resolution phase

Answer 18

after around 21 days, altered healing process - development of fibrotic tissue in the ACM, structural and vascular remodeling takes place to reest. the ACM

Question 19

complications of ARDS

Answer 19

right to left shunting, ineffective surfactant activity, increased pulmonary vascular resistance, altered lung compliance (increased work of breathing)

Question 20

physical assessment

Answer 20

Restlessness, disorientation, change in LOC, CXR normal in early stage and infiltrates develop in about 24hr, resp. distress with dyspnea, tachycardia and hypoxia that doesnt respond to O2 therapy and PEEP, crackles/rhonchi, refractory hypoxemia, develops into metabolic acidosis and increased lactate levels, hypotension

Question 21

A-a gradient

Answer 21

PAO2 minus PaO2, should be less than 15, greater than 15 is hypoxia

Question 22

PAO2

Answer 22

alveolar oxygen tension; normal is 104 mmHg

Question 23

PaO2

Answer 23

arterial oxygen tension; normal is 95 mmHg

Question 24

what does an increased A-a gradient indicate?

Answer 24

shunting

Question 25

histology with ARDS

Answer 25

alveolar inflammation, thickened septum from protein leakage, congestion and decreased alveolar volume

Question 26

reducing ventilator related lung injury

Answer 26

low tidal volume and setting PEEP higher

Question 27

appropriate vent tidal volume for ARDS

Answer 27

4-6ml/kg

Question 28

appropriate FiO2 for ARDS

Answer 28

less than 60 to minimize O2 toxicity

Question 29

appropriate PEEP for ARDS

Answer 29

5-15 cm H2O to prevent alveolar collapse

Question 30

permissive hypercapnea

Answer 30

PaCO2 60-100 (lower respiratory rates), this protects lungs from ventilator related injury

Question 31

high frequency oscillatory ventilation (HFOV)

Answer 31

when pt doesnt respond to AC or PRVC; uses very low tidal volumes at very high rates, constant airway pressure and prevents complete alveolar closure

Question 32

inhaled nitric oxide

Answer 32

controversial, vasodilator with no systemic effects that reduces pulmonary arterial pressure

Question 33

inverse-ratio ventilation (IRV)

Answer 33

prolonging inspiration time to prevent complete exhalation (I:E on vent)

Question 34

ECMO/bypass

Answer 34

allows lungs to rest by providing complete pulmonary and cardiac support; bleeding is a common complication

Question 35

goal of ARDS therapy

Answer 35

treatment of the underlying cause, cardio-pulmonary support, specific therapy targeted at lung injury and supportive therapy

Question 36

additional support options

Answer 36

bronchodilators, administer exogenous surfactant, sedationi/neuromuscular blocking agents, nutritional support, monitor vials and UOP

Question 37

sepsis treatment

Answer 37

empirical antibiotics, c&s and change antibiotics as needed, avoid nephrotoxic drugs, enteral feedings preferred

Question 38

when is prone positioning most beneficial?

Answer 38

the first 36hr

Question 39

when would you consider prone positioning?

Answer 39

low TV and PEEP not successful, PaO2/FiO2 below 100 (severe ARDS), would want to maintain for 18-20 consecutive hours