Chapter 6 Oxygen and Carbon Dioxide Transport
what are the two forms O2 is carried in the blood
1 as dissolved O2 in the blood plasma 2 chemically bound to hemoglobin
normal CaO2 is
20 vol%
The ratio of HCO3- to H2CO3 is
20:1
how many mL of O2 are extracted form each 100 mL of blood for tissue metabolism
20vol%-15vol%=5vol% or 5ml
normal HCO3- arterial venous
22-28 Meq/L arterial 24-30 mEq/L venous
normal O2ER is
25%
each RBC contains approximately how many hemoglobin molecules
280 million
about what % of Qt is shunted
3%
hemoglobin constitutes about what percent of RBC
33%
Normal Pco2 arterial and venous
35-45 torr arterial 42-48 torr venous
normal pH arterial and venous
7.35-7.45 arterial 7.30-7.40 venous
Normal Po2 arterial and venous
80-100 torr arterial 35-45 torr venous
what is your PAO2 stand for and the equation
PAO2= [(Pb-PH20)FIO2]-(PCO2x1.25) Amount of O2 in the Alveoli
the H2CO3 concentration can be determined by
PCO2x0.03
the amount of O2 bound to Hb is directly related to the
PaO2
anemic hypoxia
PaO2 is normal but the O2 carrying capacity of the Hb is inadequate
shunt equation is
Qs/Qt=CcO2-CaO2/CcO2-CvO2
Factor that increase the C (a-v)O2 ,ERO2, VO2 and decrease Svo2
Seizures hyperthermia exercise decreased cardiac output(Qt for VO2 remains the same) shivering periods of increased O2 consumption(doesn't apply to VO2) (SHEDS P) (For O2 ER anemia &Decreased arterial O2)
when the pulmonary capillary blood is in excess of the alveolar ventilation this condition causes pulmonary relative shunting
V/Q mismatch
O2 consumption equation is
V2O = QT [ C(a-v) O2 x 10 ] Normal 250mL O2/Min
hypoventilation is caused by
COPD CNS depressant Head trauma neuromuscular disorders (myasthenia gravis or Guilain barre syndrome)
content of the arterial blood O2
Cao2:[ (Hbx 1.34 xSao2) + (Pao2 x 0 .003)]
content of the venous blood O2
Cvo2[:( Hb x 1.34 x Sv O2 ) + (PvO2 x 0.003)]
Total O2 delivery equation
DO2=Qt x (CaO2 x 10): 5L x (20vol%x10)=1000mL/min
name the tree transport for CO2 in the RBC
Dissloved in the RBC 5% or 10ml combine to Hb 21% or 42 ml (carbomino Hb) HCO3- 63% or 126ml
most CO2 that is produced at the tissue cell is carried to the lungs in the form of
HCO3- by the RBC
the fact that deoxygenated blood enhances the loading of CO2 and oxygenation of blood enhances the unloading of CO2 is called the
Haldane effect
the quantity of oxygen that dissolves in the plasma at a given temperature is proportional to partial pressure of gas is a function of what law
Henry's law
Second part of all the equation tell you
How much O2 is dissolved in the plasma
Hb F is
Normal fetal hemoglobin (has two alpha chanins and two gamma chains)
shunt like effect respond well to
O2 treatment
the O2 extraction ratio equation is
O2ER= CaO2-CvO2/CaO2
the amount of O2 extracted by the peripheral tissues during the period of 1 minute is called
Oxygen Comsuption
a shunt between 10-20% is indicative of
intrapulmonary abnormality but seldom of clinical significance
carbonic acid is
ionized into HCO3- H+
in the center of each of the 4 heme there is a
iron -containing non protein portion
In terms of total O2 transport is the dissolved O2 a high or low percentage of O2 transport
low percentage
volume percent can be also be written as
mL O2/ 100 ml of blood
when various drugs and chemicals such as nitrites change the iron molecule in the heme from the ferrous state to the ferric state eliminating the ability of hemoglobin to transport oxygen this type of hemoglobin is called
methemoglobin
Hb A is
normal adult hemoglobin
pulmonary shunting below 10% indicates
normal lung status
to determine the total amount of O2 in 100 ml of blood the dissolved o2 and the O2 to hemoglobin must be
added
globin portion that has 141 amino acids chains is called
alpha
capillary is commonly caused by
alveolar collapse or atelectasis alveolar fluid accumulation alveolar consolidation
in a normal person your vol% of CaO2 should be
around 20.1 vol% but because of normal physiologic shunt it is 19.5 vol%
name diffusion limited problems (defects)
atelectasis alveolar fibrosis emphysema pneumonia interstitial edema pulmonary edema (APE PIA)
At a normal Pa O2 of 100 torr the hemoglobin saturation is only about 97% why
because of the normal physiologic shunts
Why can high altitude cause hypoxic hypoxia
because the barometric pressure decreases as altitude increases causing the PAO2 to decrease as well
globin portion that has 146 amino acids is called
beta
circulatory hypoxia or stangant
blood flow to the tissue cell is inadequate
O2 delivery decrease when there is a decrease in
blood oxygenation (CaO2) Hb concentration Qt
The total amount of O2 delivered or transported to the peripheral tissues is dependent on the
body's ability to oxygenate blood the Hb concentration Qt
three common abnormalities that cause anatomic shunting
congenital heart disease intrapulmonary fistula vascular lung tumors
Common cause of anemic hypoxia
decreased Hb anemia hemorrhage abnormal Hb (carboxyhemoglobin and methemoglobin)
an increased SvO2 indicates that the C(a-v)O2, VO2, and O2ER are
decreasing
hemoglobin not bound with O2 is called
deoxyhemoglobin
Hb is encased in the
erythrocytes or red blood cells
First part of all the equation tell you
how much O2 is combine to Hb
CO2 combines with water in a process called
hydrolysis
the bulk of dissolved CO2 that enters the RBC undergoes
hydrolysis(it is much faster in the RBC because of an enzyme called carbonic anhydrase.)
common causes of relative shunt is
hypoventilation diffusion defects V/Q mismatches (Chronic emphysema, bronchitis, asthma,and excessive airway secretions
refers to a condition which there is inadequate O2 at the tissue cells casued by an abnormally low arterial oxygen tension
hypoxemia
refers to low or inadequate O2 for aerobic cellular metabolism
hypoxia
P(A-a)O2 tell you
if there is a diffusion defect
histotoxic hypoxia
impaired ability of the tissue cells to metabolize O2
hemoglobin bound with O2 is called
oxyhemoglobin
If the ratio of HCO3- to H2CO3 increase it does what to pH and if it decrease it does what to pH
pH is more alkaline with increase pH is more acid with decrease
absolute shunting respond how to O2 therapy
poorly (refractory Hypoxemia)
an increase in your (c-v) difference will do what to your consumption
increase
the reduced level of O2 in the arterial blood may be offset by an
increased cardiac output
a decreased Svo2 indicates that the C(a-v)O2, VO2, and O2ER are
increasing
is the portion of the cardiac output that moves from the right side to the left side of the heart without being exposed to the alveolar O2
pulmonary shunting
Calculating the degree of pulmonary shunting is not reliable in Pt who demonstrate
questionable perfusion status a decreased myocardial output an unstable O2 consumption demand(this effect the CaO2 and CvO2 two major components of the shunt equation)
Hb is
reduced hemoglobin (uncombined or deoxygenated hemoglobin)
a shunt between 20-30% denote
significant intrapulmonary disease ( may be life threatening to Pt with CHF)
there are how many ways to transport CO2
six three in the plasma three in the RBC
common causes of circulatory hypoxia
slow or stagnant pooling peripheral blood flow arterial venous shunts
hypoxia is characterized by
tachycardia hypertension peripheral vasoconstriction dizziness mental confusion
use for venous blood samples
the dissolved carbon dioxide in the plasma
the H+ is buffered by
the plasma proteins
O2 ER provides what information
the pt O2 transport status
when hydrolysis take place in the RBC two things happen
the reduced Hb picks up the H+ ions( in other words buffered) the left over HCO3- is diffused out of the RBC
name the normal physiologic shunts
thebesian venous drainage into the left atrium bronchial venous drainage into the pulmonary veins alveoli that are under ventilated relative to pulmonary blood flow
the sum of the anatomic shunt and capillary shunt is referred to as the
true shunt or absolute shunt
the end result of pulmonary shunting is
venous admixture (drops PaO2)
Pulmonary artery is the truest place to get what type of sample
venous blood sample
in a normal person your vol% of CvO2 should be
around 15 vol%
a decrease in your (c-v) difference will do what to your consumption
decrease
at normal body temperature about how much O2 will dissolve in 100ml of plasma for every 1 torr of Pressure
0.003ml
in the healthy individual with an PaO2 of 100 torr what is the dissolved vol%
0.3 vol% (0.003 x 100 torr = 0.3 ml ) ( this is equal to about 5 L )
each g% of hb is capable of carrying approximately how much O2
1.34 ml of O2
cyanosis may appear whenever the blood contains at least
1/3 reduction in Hb g% (ex. 15g% for male Pt is normal if Pt Hb g% is 10g% you know there would present with cyanosis)
5 ml are extracted from 100 ml of blood but total O2 delivery is 1000 ml O2/Min how many ml O2/L is available ?
1000ml/100ml O2=10x5=50mL O2/L
normal Hb for male and female is and infant
14-16 g % 12-15 g % 14-20 g %
normal CvO2 is
15 vol %
normal adult hemoglobin contains
4 heme groups (non-protein) 4 globin or amino acid chains (a protein)
how many O2 molecule can be transported in each heme/iron groups
4 one per heme
normal RBC
4-6 million
normal hematocrit level is
50%
Since normal Qt is about 5L/min what would be the amount of O2 extracted from the blood?
50ml O2/L X 5L/min= 250 ml O2/Min
arterial venous O2 content difference equation
C(a-v)O2= CaO2-CvO2 Normal is 5 Vol%=20vol%-15vol%
content of the pulmonary capillary blood O2
Cco2:[( Hb x 1.34 )+ (PAo2 x 0 .003)]
Factor the Decrease the C(a-V)O2 ,ERO2,VO2 and increase the SvO2
Certain poison Hypothermia increased Qt(Qt in VO2 remain the same) peripheral shunting skeletal muscle relaxation (CHIPS) (For O2 ER increased Hb and Increased arterial O2)
when HCO3 diffuses out the what moves into the RBC
Cl- because the HCO3 combines with the Na+ found in out blood in the form of NaCl and Cl is now free and NaCHO3 is form and transported to lungs in the plasma venous blood.
inadequate O2 at the tissue cells caused by low arterial O2 tension
Hypoxic hypoxia or hypoxemic hypoxia
under normal circumstances an individual's hemoglobin returns to the alveoli approximately how saturated
SvO2 75%- 65%
the transport of O2 between the lungs and the cells of the body is a function of what organ
The heart and the blood
polycythemia is
abnormally high RBC
if the diffusion defect is severe enough to completely block gas exchange across the alveolar capillary membrane than the shunt would be referred to as an
absolute or true shunt
can be grouped under two major categories anatomic shunts and capillary shunts
absolute shunts or true shunt
exists when the blood flows form the right side of the heart to the left side without coming in contact with an alveolus for gas exchange
anatomic shunt
name the three transport for CO2 in the plasma
bound/protein -Carbamino Compound =1% HCO3- anion 5% or 10ml dissloved in plasma (PaCo2x0.03) 5% or 10ml
when hydrolysis occur this creates
carbonic acid (H2CO3)
common causes of histotoxic hypoxia
cyanide poisoning
are abnormal anatomic alteration of the lungs that result in an impedance of oxygen transfer across the alveolar capillary membrane
diffusion defects
hemoglobin molecules are
highly specialized to transport O2 and CO2
a nonvolatile acid and causes the pH to decrease
lactic acid
when hypoxia exist alternate anaerobic mechanism are activated in the tissues that produce dangerous metabolites such as
lactic acid
common causes of Hypoxic hypoxia
low PAO2 (Hypoventilation, High altitude) Diffusion impairment V/Q mismatch shunting
when pulmonary capillary perfusion is in excess of alveolar ventilation
relative shunt or shunt-like effect (caused by a diffusion defect)
as the venous blood enters the alveolar capillaries the chemical reaction occurring at the tissue level are
reversed and continue until equilibrium is reached in CO2
Hb S is
sickle cell hemoglobin (has a different amino acid substituted into the Beta chain)
also during the chloride shift what causes the RBC to slightly swell in the venous blood
some water that moves into the RBC
the term dissolve means
that when a gas like O2 enters the plasma it maintains it precise molecular structure and moves freely throughout the plasma in it normal gaseous state.
what are two major reason absolute shunting does not respond to O2 treatment
the alveoli are unable to accommodate any form of ventilation the blood that bypasses functional alveoli cannot carry more O2 once full saturated except for what is dissolved in the plasma .003
volume percent represent s the amount of
the amount of O2 in milliliter that is in 100 ml of blood
the exchange of HCO3- for Cl- is know as
the chloride shift or the hamburger phenomenon or the anionic shift to equilibrium