N623 Assess Critically Ill - 2009Umbsrnas

Front 1

Equation and normal value for tidal volume

Back 1

VT = VE/RR

Norm = 500ml

Front 2

Peak Inspiratory Pressure

Back 2

Direct measure.

Norm = 10-100 cmH2O

Front 3

What happens during inspiration?

Back 3

diaphragm and chest muscles contract --> increase intrathoracic volume & decrease intrathoracic pressure-->air moves down the gradient and into the lungs

Front 4

What happens during expiration?

Back 4

Passive. Muscles relax, lungs recoil --> decrease intrapulmonary volume & increase intrapulmonary pressure --> air moves out of lungs

Front 5

Perfusion zones:
zone 1
zone 2
zone 3

Back 5

zone 1- low flow Pa<PA>Pv

zone 2 - Pa>PA>Pv

zone 3 - Pa>PA<Pv

Front 6

Plateau Pressure

Back 6

direct measure

<30 cmH2O

Front 7

Airway resistance

Back 7

Raw= (PIP-Pplat)/Flow

opposition of flow of gas.

Front 8

What causes increased airway resistance?

Back 8

small ETT
mucous plug
water in vent tubing
pt biting on the tube
high flow rate

Front 9

What is the truest measure of lung compliance?

Define it.

Back 9

Static Compliance. It reflects the elastic recoil of the lungs. Must use a breath hold maneuver.

Cst=exhaled VT/(Pplat-PEEP)

norm= 70-100 ml/cmH2O

Front 10

What is dynamic compliance?

Back 10

exhaled VT/(PIP-PEEP)
norm = 50-80 ml/cmH2O

measures distensibility of lung and its resistance to gas flow.

Front 11

Why is dynamic compliance always smaller than static compliance?

Back 11

because PIP is higher than plateau pressure.

Front 12

a/A ratio

Back 12

arterial-alveolar ratio = PaO2/PAO2

norm = 0.8

Low a/A ratio (<0.6)=shunt, V/Q mismatch or diffusion defect

Front 13

What is the measure for preload in the right and left heart?

Back 13

right heart: CVP, RAP, RVEDP, RVEDV

left heart: PAWP, LVEDP, LVEDV

Front 14

What is the measure for afterload in the right and left heart?

Back 14

right: PVR, PVRI
PVR=pulmonary vascular resistance

left: SVR, SVRI

Front 15

PaO2/FiO2 ratio

Back 15

reflects the status of oxygenation

norm = 550 mmHg

Front 16

A-a gradient

Back 16

PAO2-PaO2

indicates efficacy of gas exchange.

Front 17

arterial oxygen content

Back 17

CaO2 = (Hgb x 1.36 x SaO2) + (PaO2 x .0031)

norm = 19-20 ml/dl

Front 18

What causes an increase in CaO2?

Back 18

any conditions that increase Hgb, SaO2 and PaO2

Front 19

What is oxygen delivery?

When is it decreased?

Back 19

DO2 = CaO2 x CO x 10
norm = 1000ml/min

Decreased with decreased CO as in heart failure or valve disease, decreased Hgb as in anemia.

Front 20

What is oxygen consumption?

Back 20

VO2 = CO x (CaO2-CvO2) x 10

norm = 200-250 ml/min

The amount of O2 used by the tissues in one minute.

Front 21

What would cause an increase in VO2?

Back 21

increase oxygen demand as with exercise, fever, increased CO, shivering

Front 22

What is oxygen extraction?

Back 22

The difference between arterial and venous oxygen concentrations. It is the amount of oxygen used by the tissues.
norm = 4-6 ml/dl

Front 23

What are the normal ABG parameters?

Back 23

pH = 7.35-7.45
PCO2 = 35-45
PO2 = 80-100
HCO3 = 22-26
BE = +/- 2
O2sat= 95-100%

Front 24

Name some conditions that result in a left shift in the oxyhemoglobin dissociation curve?

Back 24

hypothermia, chronic acidosis, multiple transfusions (decreased 2,3 DPG)

Front 25

Normal Hgb and Hct values.

Back 25

Hgb: males 13-18 gm/dl
females 12-16 gm/dl

Hct: males 39-55%
females 36-48%

Front 26

What is Qs/Qt?

Back 26

It is the amount of blood passing through the lungs and not coming into contact with ventilated lung tissue...no gas exchange occurring.
Normal is 3-5%

Front 27

What can cause an increased CVP?

Back 27

Increases in preload such as hypervolemia,tricuspid insuff.

Increases in afterload such as ARDS, COPD, LVF, PE

Front 28

What can cause an increased PAWP?

Back 28

hypervolemia, LVF, pneumothorax, cardiac tamponade

Front 29

What's the significance of arterial-venous O2 content difference (Ca-vO2)?

Back 29

It represents tissue O2 consumption and estimates CO.

If Ca-vO2 is increased, then CO is decreased or metabolism has increased.

If Ca-vO2 is decreased, then CO is increased or metabolism is decreased.

Front 30

O2ER

Back 30

O2 Extraction Ratio

Norm = 25%

indicator of O2 supply/demand.

Front 31

cardiac output

Back 31

CO = SV x HR

norm = 4-8 L/min

indicates pump efficacy and is a determinant in tissue perfusion.

Front 32

True or False

Plateau pressure is always lower then peak inspiratory pressure.

Back 32

True.

Front 33

What is PEEP and why do we use it?

Do all vented patients require PEEP?

Back 33

PEEP is positive end expiratory pressure, the airway pressure in the lungs at end-expiration that aid in maintaining the alveoli open. PEEP is applied to vented patients to increase oxygenation and aid in alveoli recruitment.

All vented patients need PEEP.

Front 34

What are some complications of a high PEEP?

Back 34

decreased CO,
increased chest pressure at end expiration,
increased intrapulmonary shunting,
barotrauma resulting in decreased lung compliance

Front 35

How is oxygen carried in the blood?

Back 35

O2 is dissolved in the plasma (PaO2).

O2 is bound to Hgb (SaO2)

Front 36

List causes for a low SvO2.

Back 36

1. decreased O2 supply to the tissues as in low Hgb, hemorrage, or low CO.

2. increased O2 use by the tissue as in fever, pain, stress.

Front 37

What are the components of oxygen delivery?

Back 37

Oxygen dissolved in plasma (PaO2); oxygen bound to Hgb (SaO2); delivered by work of heart (CO).

So, CaO2 x CO x 10

norm = 1000 ml/min

Front 38

How much delivered O2 is used by the tissue under normal circumstances?

Back 38

25%

Therefore if DO2 is 1000ml/min, 25% of that is 250 ml/min, the amount of O@ consumed by tissue or VO2.

Front 39

What is an easy way to estimate PaO2 based on patient's age?

Back 39

PaO2 = 110 - 1/2 pt's age

normal should be 80-100 mmHg

Front 40

What is the significance of SvO2?

Back 40

It is an early indicator of a threat to tissue oxygenation. Normal is about 75% which means 25% O2 has been used by the tissues and 75% is in reserve for times of increased need.

Front 41

What parameters are used to assess the adequacy of oxygenation?

Be able to define each.

Back 41

PaO2 & PvO2
CaO2 & CvO2
SaO2 & SvO2

Front 42

What parameters are used to assess efficiency of oxygenation?

Be able to define each.

Back 42

PaO2/PAO2 ratio
PaO2/FiO2 ratio
Qs/Qt
O2ER
DO2
VO2

Front 43

What are the normal pulmonary pressures during systole, diastole and mean?

Back 43

SBP 15-25 mmHg

DBP 8-15 mmHg

mean 10-20 mmHg

Front 44

What is the significance of the A-a gradient?

What factors increase it?

Back 44

A-a gradient (aka anatomic shunt) is a method to analyze efficacy of oxygen diffusion. The greater the gradient the greater the diffusion defect. Factors that can increase the defect are atelectasis, pulmonary edema, pneumonia

Front 45

What is PAO2/PaO2 ratio?

List components, norms, causes of increase and decrease.

Back 45

PaO2/PAO2 norm = 0.8
this is an estimation of intrapulmonary shunting. A decrease in the ratio indicates a greater shunt. Causes are atelectasis, PE, pulmonary edema. An increase in the ratio would be caused by an improvement in any of the disease processes that decrease the ratio.

Front 46

PaO2/FiO2

Back 46

This is an estimate of intrapulmonary shunting. Norm = 550.
For every 100 mmHg there is a 5% shunt. Anything that causes injury or inflammation to the lung will cause shunting, such as ARDS, PE, aspiration.