Improving Oxygenation & Management Of Ards

Front 1

Methods to Improve Oxygenation include:

Back 1

use of O2
PEEP (increasing MAP)
patient positioning

Front 2

Most common causes of hypoxemia include:

Back 2

hypoventilation
V/Q mismatch
diffusion defect
Shunt

Front 3

To prevent Oxygen Toxicity:

Back 3

keep FiO2 < 0.4 to 0.5 while keeping PaO2 between 60 -90 mmHg and the CaO2 at 20 mL/dL

Front 4

How do you calculate a desired FiO2

Back 4

Desired FiO2 = desired PaO2 x known FiO2 / known PaO2

Front 5

How do you calculate a desired FiO2 while taking the PaCO2 into account?

Back 5

kPaO2 x kFiO2 = dPaO2 x DFiO2

Front 6

what do you correlate the SPO2 with to correctly use it to titrate FiO2

Back 6

Correlate the SpO2 with the SaO2 from an ABG

Front 7

What are some hazards of long term use of 100% O2?

Back 7

tissue damage
absorption atelectasis which increases shunt and further contributes to hypoxemia

Front 8

What causes the PaO2 to remain low when on high FiO2 concentrations

Back 8

significant shunt
V/Q abnormalities
and/or
Diffusion defects

Front 9

Factors that affect MAP during PPV include:

Back 9

PIP
total PEEP
I:E ratio
RF
Inspiratory flow pattern

Front 10

How is MAP a major determinate of oxygenation in ARDS patients?

Back 10

MAP affects mean alveolar pressure & alveolar recruitment

Front 11

what are the goals of PEEP?CPAP therapy

Back 11

enhance tissue oxygenation
maintain PaO2 >60 mmHg w/SPO2 at or above 90% at acceptable pH
recruit alveoli & maintain in aerated state
restore FRC (increase SA)

Front 12

If PaO2 remains low despite high FiO2 this indicates:

Back 12

significant shunt
V/Q mismatch
diffusion defect

Front 13

Factors that can increase MAP include:

Back 13

PIP (PF), total PEEP (intrinsic & extrinsic), I:E ratio, RF,
inspiratory flow pattern, HFOV
APRV, IRV (inverse ratio ventilation) although not widely used today, Inspiratory pause

Front 14

Adverse effects of high MAP can result in:

Back 14

lung injury caused by airtrapping, overdistention & barotrauma(pneumothorax)
reduced venous return (preload), SV, CO & BP

Front 15

Goals of PEEP/CPAP therapy:

Back 15

enhance tissue oxygenation
maintain a PaO2 >60 mmHg with SpO2 ≥ 90% at acceptable pH
recruit alveoli & keep them in an aerated state
restore FRC (increase SA)

Front 16

Three PEEP Ranges:

Back 16

physiological PEEP 3-5 cmH2O
Therapeutic PEEP (increases oxygenation) ≥ 5 cmH2O
Optimum/Best PEEP
level at which the maximum beneficial effects of PEEP occur

Front 17

conditions that cause refractory hypoxemia include:

Back 17

increased shunt
V/Q mismatch
↓ FRC & C
diffusion defects

Front 18

maximum beneficial benefits of PEEP include:

Back 18

↑ oxygen transport
↑ FRC & C
↓ shunt

Front 19

ndications for PEEP/CPAP

Back 19

bilateral infiltrates on CXR
recurrent atelectasis w/low FRC
Reduced C
PaO2 < 60mmHg on FiO2 >0.50
P/F ratio <200 for ARDS, <300 for ALI
Refractory hypoxemia: PaO2 increases < 10 mmHg w/FiO2 increase of 0.2

Front 20

Refractory hypoxemia is identified as:

Back 20

PaO2 increases < 10 mmHg w/FiO2 increase of 0.2

Front 21

If PEEP is beneficial and has restored the FRC, what will the Static Compliance reflect?

Back 21

As FRC is restored, Static Compliance is increased

Front 22

If PEEP results in overdistended alveoli, what will the static compliance reflect?

Back 22

Static Compliance will decrease

Front 23

what are the clinical effects If PEEP increases the arterial to end tidal CO2 gradient above acceptable limit?

Back 23

then the level of PEEP is too high and will result in a decreased CO & an increase in dead space to tidal volume ratio.

Front 24

Arterial-Venous Oxygen difference – C[a-v]O2 reflects:

Back 24

oxygen utilization by the tissues

Front 25

an increase in C[a-v]O2 with an increase in PEEP may indicate

Back 25

hypovolemia, cardiac malfunction, decreased venous return and decreased CO from PEEP or increased VO2

Front 26

What is the normal C[a-v]O2

Back 26

5 vol%

Front 27

What is the minimal acceptable level of PvO2 and what does this represent?

Back 27

28 mmHg and this represents a SvO2 of about 50%

Front 28

Normal PvO2 =
Minimal acceptable level:

Back 28

Normal PvO2 = 35-40 mmHg
Minimum acceptable = 28

Front 29

Normal SvO2 =
Minimal acceptable:

Back 29

Normal SvO2 = 75%
Minimal acceptable = 50%

Front 30

A PvO2 of 28 mmHg gives what SvO2 percentage?

Back 30

PvO2 of 28 mmHg gives a SvO2 of 50%

Front 31

How are PaO2 and PVO2 affected with increases in PEEP

Back 31

PaO2 and PVO2 improve with no net change to P(a-v)O2

Front 32

What does an improvement in PaO2 & PvO2 with increased PEEP indicate?

Back 32

improved oxygen transport with no change in CO and level of shunt is decreased

Front 33

if PEEP increases PaO2 & PvO2, decreases net C(a-v)O2 & improves DO2 (if VO2 constant) what does this suggest about CO

Back 33

increased CO

Front 34

If PEEP decreases PvO2 and there is an increase in C(a-v)O2 what does this indicate about CO and DO2?

Back 34

decreased CO and DO2

Front 35

When cardiac function is impaired, but high levels of PEEP are required to ensure adequate oxygenation, what can be done?

Back 35

inotropic agents can be administered and/or vascular volumes can be increased to maintain cardiac function

Front 36

How does the application of PEEP affect vasculature pressures?

Back 36

vascular pressures increase w/application of PEEP

Front 37

If PCWP rises markedly as PEEP is increased, this can be sign of:

Back 37

lungs may be overinflated and PEEP may need reduced

Front 38

What is PEEP induced relative hypovolemia;

Back 38

When PEEP rises, the PCWP can be markedly decreased because pulmonary blood flow is reduced due to decreased venous return to the right side of the heart;

Front 39

DO2 reflects......

Back 39

cardiac & pulmonary function as well as carrying capacity of the blood.

Front 40

Equation to calculate oxygen delivery

Back 40

DO2 = CO x CaO2

Front 41

What is the normal value for oxygen delivery per min?

Back 41

1000 mL/min

Front 42

Examples of Inotropic agents that can be used to enhance cardiac function

Back 42

dopamine, hydrochloride

Front 43

A low CaO2 can be improved by:

Back 43

increasing PEEP
increasing FiO2
normalizing Hb levels (blood transfusion if anemic)

Front 44

Contraindications of PEEP

Back 44

Relative Contraindication:
Hypovolemia (fix before initiating PEEP)
Absolute Contraindication:
significant pneumothorax or tension pneumothorax

Front 45

Define Overdistention, or overstretch

Back 45

increases alveolar wall tension or elevates the distending pressure above normal

Front 46

associated with increased levels of inflammatory mediators

Back 46

Overdistention

Front 47

Define Hyperinflation

Back 47

Hyperinflation is gas overfilling, it is a higher-than-normal ratio of gas to tissue.

Front 48

Factors that influence CO

Back 48

preload, afterload & contractility

Front 49

define preload

Back 49

end diastolic volume

Front 50

RVEDP is an indicator of

Back 50

right ventricular preload

Front 51

LVEDP is an indicator of

Back 51

left ventricular preload

Front 52

what other measurement indicates the RVEDP

Back 52

the CVP or RAP can be used to estimate the RVEDP

Front 53

LVEDP can be estimated by what other parameter

Back 53

PCWP is an indicator of LVEDP

Front 54

Define afterload

Back 54

the impedence the L/R ventricles must overcome to eject blood

Front 55

afterload is represented by

Back 55

SVR and PVR

Front 56

The SVR represents

Back 56

the afterload the left ventricle must overcome to eject blood into the systemic circulation

Front 57

The PVR represents

Back 57

the afterload the right ventricle must overcome to eject blood into the pulmonary circulation

Front 58

What are the 4 ports of the Swan Ganz catheter

Back 58

proximal port
distal port
thermistor port
inflation lumen

Front 59

what does the proximal port measure

Back 59

RAP/CVP
fluids can also be given

Front 60

what does the distal port measure

Back 60

PCWP/LVEDP

Front 61

what does the thermistor port measure

Back 61

CO

Front 62

What is the function of the inflation port

Back 62

this is the balloon that is injected with 1-2 mL of air

Front 63

with insertion of the swan ganz what are the pressures as it is advanced

Back 63

RA = 2-6 mmHg
RV = 20/5 or 20/0
PA = 25/10 (has dichrotic notch)
PCWP = 4-12 mmHg

Front 64

What is the Swan Ganz used for

Back 64

aggressive fluid management
to monitor the R/L side of the heart in critically ill patients

Front 65

What can be used to measure mixed venous blood

Back 65

Swan Ganz

Front 66

What are two indicators of preload

Back 66

LVEDP & RVEDP

Front 67

what does a high LVEDP indicate

Back 67

high LVEDP indicates that heart is unable to pump all the blood out which results in pulmonary edema

Front 68

What is a normal SV

Back 68

60-130 mL/beat
average 70 mL/beat

Front 69

What is avg. CO

Back 69

5L

Front 70

what ejection fraction value indicates that patient is excercise intolerant

Back 70

EF < 30% (heart unable to pump out enough O2)

Front 71

What does the SVR represent

Back 71

left ventricular afterload

Front 72

what is a normal SVR

Back 72

900-1400 dynes

Front 73

what is the fick equation
(gives CO)

Back 73

CO = VO2/CaO2 - CvO2

Front 74

What factors influence CO

Back 74

HR, preload, contractility and afterload

Front 75

How is pulse pressure calculated

Back 75

Pulse pressure = difference between systoli and diastolic pressures

Front 76

what is the primary influence on pulse pressure

Back 76

stroke volume and arterial compliance

Front 77

what is the normal PA

Back 77

25/10