blood gases Flashcards
1
Q
blood gases rely on
A
circulation of buffers in the blood, pulmonary, and renal systems that act together
2
Q
what is the air we breath in consist of
A
nitrogen, oxygen, small amount of water and CO2
3
Q
At sea level: atmospheric pressure is 760 mg and all the gases contribute the pressure in the proportion of contribution
A
partial pressure
4
Q
partial pressure depends on
A
diffusion
5
Q
When you breath in through your nose, vapor in your nose is added to bring relative humidity to 100% at RT
A
brings vapor pressure to 47 mm Hg
6
Q
when blood leaves the lungs have parital pressure of 100 mmHg the pressure in the lungs is now
A
40 mm Hg
7
Q
blood away from heart and tissues
A
arteries
-more oxygen rich, darker red
RBCs let go of oxygen and pick up CO2
8
Q
blood back to the heart
A
venial blood
9
Q
where is the biggest exchange of oxygen and CO2?
A
lungs
10
Q
____ has greater affinity for Hgb
A
CO2
11
Q
what factors affect movement across the membrane
A
- Partial pressure
- How well it can diffuse
- Affinity for oxygen
Number of RBCs
12
Q
In normal person 95% of Hgb in arterial blood is bound to oxygen
A
oxygen saturation rate
13
Q
if saturation rate dips below 95%=
A
hypoxia
-not enough oxygen
-not enough RBCs
-too much functional Hgb
14
Q
cyanotic
A
blue person
15
Q
what makes up total CO2
A
Bicarb, dissolved CO2, other small components
-if total CO2 is increased this also means bicarb
16
Q
hypercapnia
A
increased CO2 in arterial blood, not normal
-breath in too much CO2
17
Q
hypocapnia
A
decreased in CO2 in arterial blood
-due to hyperventilation
18
Q
partial pressure of oxygen
A
amount of oxygen in our blood stream
19
Q
partial pressure of CO2
A
amount of carbon dioxide in bloodstream
20
Q
% of Hgb that is carrying oxygen
A
oxygen saturation
21
Q
too much alkaline products
A
base excess
22
Q
deficient of acid products
A
base defect
23
Q
every gram of Hgb can carry ______ mL of oxygen
A
1.93
24
Q
oxygen disassociation curve
A
Plots oxygen saturation against partial pressure of oxygen
25
as you go to the right=
acid
Hgb will share more of its oxygen to the tissues
26
as you move to the left =
alkaline
hgb tends to keep oxygen and is less willing to share
27
what can cause shifts to left or right of curve
pH
28
what is the dissociation curve called
Bohr's effect
29
another factor affecting Hgb affinity for oxygen
2,3 BPG- bisphosphoglycerate
30
what is 2,3 BPG- biphosphoglycerate
byproduct of glucose, center of Hgb molecule
31
when 2,3 BPG is increased
T form- tight binding
decreased oxygen affinity- give oxygen away
32
when 2,3 BPG is decreased
relaxed form
increased oxygen affinity- more work
33
when there is a increase in CO2, H and Cl
decrease Hgb affinity for oxygen
34
Increases in temp, will make Hgb want to
get rid of oxygen
35
Decreases in temp will make Hgb want to
keep oxygen
36
shift to the right - share oxygen
* Decrease in pH
* Increase in temp
* Increase in BPG
* Increase in Hydrogen ions
37
in cases of anemia there are less RBCs to shift to right
fewer cells to carry oxygen and body needs it so RBCs willing to give up
38
shift to the left (overall)
* Increase in pH
* Decrease temp
* Decrease BPG
39
what shift has a more negative impact on a person , especially long term
left
40
parameters for blood transfusions
* Blood that sites on shelf loses 2,3 BPG (lowered) = Hgb keeps oxygen
* Only give blood if Hct <7
41
normal hydrogen con
35-45
42
normal pH
7.35- 7.45
43
2 main ways body gets ride of hydrogen; blood gases maintained
kidney and lungs
44
recongize Henderson-Hasselbalch equation
notes
45
normal ratio fo bicarb to carbonic acid
20:1
46
carbonic acid formula
(0.03 x PCO2)
47
formation of CO2
using fats, CHO, and protein
48
CO2 + H2O<---> H2CO3 <---> H+ + HCO3- driven by
carbnoic anhydrase enzyme
excretion of 20,000 moles of CO2/day
49
what is incomplete oxidation
nonvolatile acids
get rid through the kidney 50 mm of acid/day
50
what convert carbonic acid to Co2 so we can breath it out
lungs
51
most important buffering system in plasma
Bicarbonate/ carbonic acid system
-because of high concentration of bicarb
52
Bicarbonate/ carbonic acid system controlled by
lungs and kidneys
53
intercellular Hgb most important buffer
Hgb buffer system
54
how does Hgb buffer system work
As CO2 produced in tissues get picked by RBC combines with h2o through carbonic anhydrase and converted into hydrogen and bicarb
bicarb out and Cl in
55
what buffer system involves in chloride shift
Hgb buffer system
-negative out, negative in
56
in acidosis uses a lot of bicarb (negative), body will try to
get rid of negative - chlordie
57
phosphate buffer system
Uses phosphate to minimize pH changes in plasma and RBCs
58
most important buffering system in urine
phosphate buffer system
-exchange of hydrogen adn sodium ions
59
protein buffer
○ Plasma proteins to minimize pH changes in blood
○ At 7.4 most proteins negatively charged; bind with excess hydrogen ions to help keep us out of acidosis
60
in the lungs what is a normal byproduct
CO2
61
if more carbonic acid, more ___will be formed
CO2
body regulates this by breathing out
62
lungs respond to CO2 by either
increasing or decreasing breathing
63
if CO2 can't be expelled you will form
carbonic acid, put body into acidosis
64
if too much carbonic acid =
more CO2
increase respiration
65
if hyperventilate too long=
put into alkalosis
CO2 being removed faster than hydrogen ions are being formed
if you do this too long, increase in carbonic acid
66
what is the first response for acidosis/ alkalosis
respiratory
-either breath faster or slower
-will change depth of breath
SHORT TERM
67
how does kidney respond to acidosis/ alkalosis
excreting or retaining bicarb
68
when in acidosis the kidney
retains bicarb (keep)
68
in alkalosis in the kidney
get rid of bicarb
69
where do you collect blood gases
arterial site
70
how should a specimen be kept until sample run
anaerobically- no air bubbles
71
areas to draw for gases
radial, brachial, femoral artery
72
most common area to draw
radial artery
73
best site to draw but most complications
femoral artery
74
what is allen's test
determine what hand is better for draw
thumbs press down
-release one side and hand returns pink= good
if not color returns= can't draw, decreased blood flow
75
what is blood gas drawn into
premeasured lithium, heparin syringe
-mixed to avoid clots
-immediately run or put on ice
76
if blood gas left at RT
cells will continue to use oxygen and produce CO2
-pH also decreased
77
if there is exposure to air
O2 increases
CO2 decrease
pH increase
78
when patients hyperventilate about getting blood gas drawn
decrease amount of CO2
pH increase
79
respiratory acidosis
pH of less than 7.35, CO2 greater than 45, Bicarb decreased
80
what causes respiratory acidosis?
○ Inability to get rid of CO2 (exhale)
§ Anything that stops my breathing
§ Pneumonia
§ Emphysema
§ COPD
Fluid in lungs
SHALLOW breathing
81
what does respiratory acidosis have an effect on
cardiovascular, nervous system, drowsy
treat by whatever is causing it ; give oxygen
82
when respiratory acidosis kidney compensates by
keep bicarb
83
Respiratory Alkalosis
pH greater than 7.45, CO2 less than 35
84
causes of Respiratory Alkalosis
Hyperventilating
○ Stress, anxiety, fear
○ Anxiety drugs
Pregnancy
85
in Respiratory Alkalosis kidneys
get rid of bicarb
treatment: breath in paper bag, CO2 coming right back at you
86
characteristics of metabolic acidosis
pH less than 7.35, bicarb less than 22
involves kidney
87
what metabolic processes can put you into acidosis?
diabetic keto acidosis
destruction of RBC, overdose aspirin, renal failure
88
seen in diabetic keto acidosis
anion gap increased
ketones
89
what specifically are you overdosing on when you overdose on aspirin
overdose on salicylates, lactic acid, salicylic acid
90
how to treat metabolic acidosis
treat the cause
if diabetic in DKA, give insulin
91
If in metabolic acidosis, respiratory system may try to help
body will try to hyperventilate and try to get rid of CO2
92
metabolic alkalosis
pH greater than 7.45, bicarb greater than 26
93
causes of metabolic alkalosis
losing too much acid
-prolong vomiting and/or diarrhea
-ingestion of antacids
-hyperaldosteronism
94
what is hyperaldosteronism
doesn't allow for sodium-hydrogen exchange, no buffering system
95
how will respiratory try to fix metabolic alkalosis
shallow breathing
-most difficult acid-base imbalance to fix
96
correction
when parameters are back to normal, we corrected
97
degrees of compensation
primary disorder is continuing but opposing system is beginning to adjust
98
compensation example
pH is within normal limits
only time we call compensation is when the pH is within normal limits
99
partially compensation
pH is not within normal limits but both components are in opposite directions
100
uncompensated
pH is not in normal limits, 1 component is abnormal and the other one is within normal limits
101
mixed component
both components are causing the problem
102
blood gas analyzers measures
PO2, PCO2, and pH
103
bicarb is measured as
total CO2
TCO2-1
104
what does blood gas calculates
carbonic acid and base excess
105
what do blood gas analyzers need to be set at to be accurate
37 degrees
every degree above 37- pH decreases by 0.015
every degree below 37, pH increase by 0.015
106
PO2 measurement
amperometric- currrent flow
based on same principle as ISE- selective membrane
107
PO2 electrode called
Clark electrode
reference solution KCL
108
sources of error on blood gas analyzer
protein buildup on membrane, O2 decrease
109
pre-analytical errors for blood gas analyzers
not left on ice
-cells use O2
-CO2 increase
-pH increase
bubble
-increase O2
-CO2 decrease
-ph increased
hyperventilating
-CO2 decrease
110
pH measurement in blood gas analyzer
glass electrode
potentiometric measurement- change in voltage
111
electrode used for pH measurement
calomel electrode
-mercury chloride in ti
112
PCO2 measurement in blood gas analyzer
potentiometric
severinghaus electrode
113
how is bicarb calcularted
HH equation
pKa assumed= 6.1 at 37 degrees
114
how is base excess/ deficiency calculated
Ph, CO2, Hgb
normal range -2 to +2
parameter of metabolic
115
above 2+ indicated
excess of bicarb = metabolic alkalosis
116
below -2 indicates
deficiency of bicarb = metabolic acidosis
117
when to do venial draws
emergency situations
patient's in ICU
118
differences in venial draws
oxygen saturation rate
pH- slightly lower
bicarb and CO2 -similar
