Arterial Blood Gases

Front 1

External respiration

Back 1

-where the exchange of O2 and CO2 between the alveoli and pulmonary capillaries takes place

Front 2

gas transport

Back 2

-quantitative transport of sufficient volume of O2 from the pulmonary capillaries to its celllular destination

Front 3

internal respiration

Back 3

-the final phase in this process is the diffusion of O2 from small systemic capillaries in response to metabolic demand or needs

Front 4

anatomic shunt

Back 4

-2-3% of cardiac output
-blood delivered into left side of heart that does not come in contact with alveolar cap bed--->no gas exchange

Front 5

capillary shunt

Back 5

-AC unit in which there is no alveolar ventilation
-PNA, atelectasis, left-side heart failure

Front 6

relative shunt-

Back 6

-AC unit being properly perfused but not adequately ventilated

Front 7

relative deadspace

Back 7

-alveoli being over-ventilated

Front 8

true alveolar deadspace

Back 8

-alveolus that is ventilated but not perfused
-result of PE or decreased pulmonary perfusion

Front 9

blood pH

Back 9

-normal rage for pH in arterial blood is 7.35 - 7.45

Front 10

acid homeostasis

Back 10

-maintained by the kidneys and lung
-the lungs excrete volatile acids (those that can be converted from a liquid form to gaseous form to facilitate excretion)-carbonic acid
-kidneys excrete fixed acids such as sulfuric and phosphoric acid- cannot be converted into a gas- excrete in liquid state thru urine

Front 11

oxygenation

Back 11

-O2 molecules move from atm to pulmonary caps
-O2 from pul cap to cellular destination requires nml heme and CO
-diffusion of O2 form systemic caps is in response to cellular metabolis needs or internal respiration

Front 12

PaO2 in the adult

Back 12

-nml = 8 - 100
-mild hypoxemia = 60-79
-mod hymoxemia = 45-59
-severe hypoxemia = <45

Front 13

ssx of hypoxemia

Back 13

1. muscular incoordination
2. confusion
3. loss of judgement
4. extreme restlessness
5. combative behavior
6. tachycardia
7. mild HTN
8. peripheral vasoconstriciton
9. cyanosis
10. bradycardia, hypotension- bad

Front 14

ssx of hypercapnia

Back 14

1. progressive somnolence
2. disorientation
3. mucosal, scleral, conjunctival hyperemia
4. diaphoresis
5. tachycardia
6. HTN

Front 15

sampling sites for blood gases

Back 15

-radial artery
-dorsalis in neonatal
-sampling errors:
1. air contamination
2. venous admixtue
3. anticoag effects
4. changes due to metabolism
5. alterations in temp

Front 16

pH Sanz electrode

Back 16

-consists of a measuring and reference electrode measures the voltage change that develops when two solutions with differing [H+] exist on either side of a pH sensitive glass membrane

Front 17

pO2 clark electrode

Back 17

-measures the current produced by an oxidation reduction process that occurs in the presence of oxygen

Front 18

pCO2 servinghause

Back 18

-a modified pH electrode where CO2 from a sample moves across a silicone membrane in response to a pressure gradient undergoing a chemical reaction that produces [H+]

Front 19

point of care testing

Back 19

-measure blood gas and electrolytes all in one hand- held deivce
-eliminates some of the sequential steps involved in traditional analysis of specimens

Front 20

pulse oximetry

Back 20

-looks at a particular spectrum of light
-only arterial blood is pulsatile
-factors affecting accuracy:
1. diff types of heme
2. skin pigment
3. nail polish
4. ambient light
5. low perfusion signal
6. motion artifact

Front 21

alveolar-arterial gradient

Back 21

PAO2 = FIO2 (PB - PH2O) - PaCO2
-used to esimate the percent intrapulmonary shunt
-nml is 7-14
-

Front 22

arterial/alveolar ration

Back 22

a/A = PaO2/PAO2
-The lower limit of normal for PaO2/PAO2, regardless of FIO2, is 0.75 or greater
-The lower the PaO2/PAO2, the greater the cardiopulmonary abnormality

Front 23

Oxygen index

Back 23

-OI= (FIO2)(100)(MAP) /PaO2
-
Calculation that accounts for the amount of ventilatory support required to provide the level of oxygenation obtained
-An Oxygen Index of greater than 40 has been associated with mortality rates of 80% and is a common criteria for ECMO

Front 24

PaO2/FIO2 ratio

Back 24

-The normal PaO2/FIO2 ratio on room air (.21) is about 400 to 500 mmHg

Front 25

Rapid shallow breathing index

Back 25

-F/VT
-ratio of spontaneous frequency
-A f/VT less than 105 can be accurate and an early predictor of weaning outcome, and an f/VT of 80 is associated with an almost 95% posttest probability of successful weaning
-The ratio must be calculated during 1 minute of unsupported spontaneous breathing
-Discontinuation of ventilator support is likely to prove successful if f/VT is less than 100 breaths/min per liter within the first minute of a brief trial of fully spontaneous breathing

Front 26

the lungs excrete...

Back 26

-13,000 mEq/day of carbonic acid
-kidneys excrete only 40-80

Front 27

pH classification

Back 27

-nml = 7.35 - 7.45
-acidemia <7.35
-alkalemia >7.45

Front 28

clinical manifestations of an abnml pH

Back 28

-Low pH has a generalized depressive effect on the CNS and a pH <6.8 is generally incompatible with life
-High pH generally excites the CNS symptomized by tetany, cardiac arrhythmias and convulsions. A pH >7.8 is generally incompatible with life

Front 29

PaCO2

Back 29

-single best indicator of repsiratory acid-base control
-nml = 35-45
-respiratory acidosis >45
-respiratory alkalosis <35

Front 30

hypocarbia

Back 30

-Expected pH = 7.4 + (40 mm Hg – PaCO2) 0.01

Front 31

hypercardbia

Back 31

-Expected pH = 7.4 + (40 mm Hg – PaCO2) 0.01

Front 32

metabolic assessment

Back 32

-Plasma bicarbonate is a calculated value based on the measured pH and PaCO2
-Base excess/deficit calculations may assume a normal pH and PaCO2, and therefore not accurately reflect actual patient conditions

Front 33

base homeostasis

Back 33

-maintained by kidneys
-Base excess/deficit calculations may assume a normal pH and PaCO2,and therefore not accurately reflect actual patient conditions

Front 34

an increase in PaCO2 productions can occur...

Back 34

-after IV administration of (NaHCO3) to a patient who is unable to increase alveolar ventilation
-This occurs because bicarbonate is one of the factors in hydrolysis reaction, which in turn, has the effect of increasing dissolved CO2 and H2CO3 levels in the blood

Front 35

metabolic classification

Back 35

nml: BE 0 +/- 2; HCO3 24 +/- 2
metabolic acidemia: BE <-2; HCO3 <22
metabolic alkalemia: BE >+2; HCO2>26

Front 36

compensation assessment

Back 36

-Defined as a return of an abnormal pH toward normal by the component (organ system) that was not primarily affected
-When one of the acid- base components is abnormal and the other is normal, the condition is said to be uncompensated