Rcp 107 exam 3 Flashcards
List the normal pressures of O2 and CO2 in air, lung, venous, and arterial blood.
-O2 in Air: 159mmHg
-O2 in Lung (PAO2): 100mmHg
-O2 in Arterial Blood (PaO2): 80-100mmHg
-O2 in Venous Blood (PvO2): 35-45mmHg
-CO2 in Arterial Blood (PaCO2): 35-45mmHg
-CO2 in Venous Blood (PvCO2): 42-48mmHg
Alveolar Gas Equation
-(Pb-PH2O) x FiO2 - (PaCO2 x 1.25)
-Normal: 97-100mmHg
-Used to calculate A-aDO2
A-aDO2 - also P(A-a)O2
-PAO2-PaO2
-Normal: 5-10mmHg
-Determines hypoxia, diffusion issues, V/Qmm, R to L shunt
-Difference between the alveolar and arterial
CaO2
-(Hb x 1.34 x SaO2) + (PaO2 x .003)
-Is total arterial oxygen content
-Normal: 20vol%
CvO2
-(Hb x 1.34 x SvO2) + (PvO2 x .003)
-Is total venous oxygen content
-Normal: 15vol%
-Lower than CaO2 because this is deoxygenated blood taken from pulmonary artery
CcO2
-(Hb x 1.34) + (PaO2 x 0.003)
-is total capillary oxygen content
VO2
-CO (cardiac output) [C(a-v)O2 x 10]
-is oxygen uptake
-amount of oxygen extracted by the peripheral tissues during the period of one minute
-normal: 250mL/min
C(a-v)O2
-CaO2-CvO2
-total arterial oxygen content minus the total venous oxygen content
-normal: 5vol%
DO2
-CO x (CaO2 x 10)
-normal 1,000mL/min
-total amount of oxygen delivered/transported to peripheral tissues
Normal value of CaO2
20vol%
Normal value of Hb (hemoglobin) levels
-male: 14-16g%
-female:12-15g%
Normal value for PaO2
80-100 mmHg
normal value of SaO2
97-100%
normal value of PvO2
35-45mmHg
normal value of SvO2
60-80%
normal value of PvO2
24-48
normal value of PaCO2
35-45 mmHg
normal value of VO2 (oxygen consumption)
35-40 mL/min
what factors will increase the A-aDO2 [P(A-a)O2]
-diffusion block
-V/Qmm
-shunt
-high altitude
-(these things impair our gas exchange and less O2 is diffusing from alveoli to blood)
what factors will decrease the A-aDO2 [P(A-a)O2]
-Normal lung function
-High FiO2
-Low altitude
-Improved V/Q matching
-Increased Hb affinity for oxygen (anything that would increase PaO2 or decrease PAO2 - based on the equation)
Briefly describe O2 transport
-At tissue level, O2 leaves the blood & enters the cells (internal respiration)
-CO2 is formed as a byproduct of tissue metabolism
-CO2 diffuses from the tissue into the blood
-CO2 is carried in the blood by RBC’s & plasma
-Most of the CO2 is carried to the lungs in the form of Bicarb in the RBC
Examples of Abnormal Types of Hb
-carboxyhemoglobin
-Met Hb
-Fetal Hb
mild hypoxemia
60-80mmHg
moderate hypoxemia
40-60 mmHg
severe hypoxemia
less than 40 mmHg
pulmonary dead space
-normal alveolar ventilation, poor blood perfusion
- anatomical and alveolar
shunt
-normal blood perfusion, poor alveolar ventilation
-anatomical and capillary
v/q ratio
-ventilation to perfusion ratio
- normal is 0.8 mL (4mL/5mL)
shunt causes
pneumonia, pulmonary edema, tissue trauma, atelectasis, mucus plugging
pulmonary dead space causes
cardiovascular shock, emphysema
alveolar ventilation (va)
VA=(VT-VD) x F
room air
21% oxygen
examples of ischemic/circulatory hypoxia
-shock
-coronary artery disease
-peripheral vascular disease
-heart attack
ischemic/circulatory hypoxia
-low blood flow
-low CO
-low preload
-low contractility
-increased afterload
histotoxic hypoxia (cellular hypoxia)
-dysoxia: inadequate tissue oxygenated
-normal PaO2 and hemoglobin
-inability of mitochondria to metabolize O2
-severe acidema (low pH)
-severe alkalemia (high pH)
examples of histotoxic hypoxia
-cyanide poisoning
-carbon monoxide (CO) poisoning
examples of anemic hypoxia
-carbon monoxide (CO) poisoning
-trauma (bleeding)
-malnutrition
-iron deficiency
-B12 deficiency bone marrow problems
anemic hypoxia
-normal PaO2
-reduced Hb to carry oxygen to tissues
-blood loss (and therefore oxygen loss)
-reduced blood content of arterial blood (CaO2)
-CaO2=(hb x 1.34)(SaO2/100)+(PaO2x0.003)
hypoxic hypoxia
-low arterial PO2 (PaO2)
-low atmospheric O2
-inadequate alveolar ventilation
-insufficient O2 diffusion through capillaries
-less hemoglobin (Hb) is converted to oxy-hemoglobin
-low A-aDO2
causes of hypoxic hypoxia
-high altitude
-fluid in lungs (pulmonary edema)
-airway obstruction
-lung disease (COPD, pulmonary fibrosis,etc)
How does low PAO2 cause hypoxemia
With low PAO2, O2 will not adequately enter the blood & therefore not enough oxygen will be delivered to the tissues/body
How does hypoventilation cause hypoxemia
When hypoventilating, there is a high level of CO2 & low level of O2 in the blood. Therefore, not enough O2 is available for delivery.
How does diffusion impairment cause hypoxemia
Something impairing diffusion will impair gas exchange at the a-c membrane. Decreased O2 entering blood & decreased CO2 escaping blood and entering the alveoli
How does a V/Qmm cause hypoxemia
V/Qmm means either ventilation is too high or low or perfusion is too low. With this there is inadequate gas exchange.
How does shunting cause hypoxemia
Shunting is when the blood goes from the right to left heart without gas exchange at the a-c membrane. Therefore, deoxygenated blood is circulating.
Define P50
-P50 is the partial pressure in which the Hb is 50% saturated with oxygen.
-Normally P50 is about 27mmHg.
-Right Shift: P50 increases
-Left Shift: P50 decreases
Factors that will shift oxygen association curve to the Right
-low pH
-increased temp
-increased CO2
-increased 2-3BPG
Factors that will shift oxygen association curve to the Left
-high pH
-low temp
-increased CO2
-increased 2-3BPG
-Met Hb
-Fetal Hb
Significance of the Flat portion of the oxygen dissociation curve
Oxygen is loading onto the Hb. PaO2 can fall from 100-60mmHg & the Hb will still be 90% saturated.
Significance of the Steep portion of the oxygen dissociation curve
Oxygen is released to the tissues. Reduction of PaO2 below 60mmHg causes rapid decrease in amount of O2 bound to Hb
Given an SpO2 estimate PaO2
-Remember 60mmHg = 90%
-PaO2 of 50mmHg = 85%
-PaO2 of 100mmHg = 98-100%
What happens to SaO2 when the oxygen dissociation curve shifts
-Right Shift: SaO2 decreases (O2 unloading is enhanced)
Ex: PaO2 of 60mmHg = 75%
-Left Shift: SaO2 increases (O2 unloading is reduced)
Ex: PaO2 of 60mmHg = 95%
Primary Disorder of Metabolic Acidosis
-Loss of Bicarb (HCO3) or gain of fixed acids
-Anion Gap helps determine
Primary Disorder of Metabolic Alkalosis
-Hypokalemia (low potassium) & Hypochloremia (low chloride)
-Excessive ingestion of bases (antacids)
Primary Disorder of Respiratory Acidosis
Hypoventilation
Primary Disorder of Respiratory Alkalosis
Hyperventilation
Uncompensated
-pH out of range
-one component is out of range
-other component is within normal ranges
compensated
-pH is normal
-both components are out of range
partially compensated
-pH out of range
-both components out of range
-other components are pulling in opposite directions
Causes of Respiratory Acidosis
Hypoventilation can be caused by:
-CNS depression, neuromuscular disorders, and obstructive lung diseases, O2-induced hypoventilation, extreme V/Qmm, inadequate mechanical ventilation
Causes of Respiratory Alkalosis
Hyperventilation can be caused by:
-CNS hyperactivity, hypoxemia (early stages), fever, anxiety, excessive mechanical ventilation
Causes of Metabolic Alkalosis
-Excessive steroid use
-Excessive ingestion of bases (antacids)
-Hypokalemia (diuretics, excessive IV therapy)
-Gastric suctioning or vomiting
-Hypochloremia
Causes of Metabolic Acidosis
-Anion Gap helps differentiate types of metabolic acidosis.
-Loss of Bicarb = normal anion gap
-The loss of Bicarb is compensated by an increase in Cl- (hyperchloremia).
-Normal Anion Gap: Renal tubular acidosis, hyperchloremia, hyperkalemia, severe diarrhea)
-Gain of fixed acids = high anion gap
-High Anion Gap: Lactic acid, ketoacidosis, late renal failure, acid ingestion (aspirin overdose)
Chronic Hyperventilation (chronic respiratory alkalosis)
-Normal pH
- low PaCO2
- low HCO3 (kidneys compensated for low PaCO2 by offloading more HCO3)
Chronic Hypoventilation (chronic respiratory acidosis):
-Normal pH
- high PaCO2
- high HCO3 (kidneys compensated for high pH by producing more HCO3)
Acute Hyperventilation (acute respiratory alkalosis):
-high pH
- low PaCO2
-normal HCO3 (kidneys have not yet compensated for low PaCO2)
Acute Hypoventilation (acute respiratory acidosis):
-low pH
- high PaCO2
- normal HCO3 (kidneys have not yet compensated for high PaCO2)
Respiratory Acidosis
hypoventilation
respiratory alkalosis
hyperventialation
metabolic alkalosis
-excessive use of steroids
-excessive ingestion of bases (antacids)
-hypokalemia (excessive iv therapy, diuretic therapy)
-gastric suctioning or vomiting
-hypochloremia
metabolic acidosis- normal anion gap
-renal tubular acidosis
-hyperchloremia
-hyperkalemia
-severe diarrhea
metabolic acidosis- high anion gap
-lactic acid
-ketoacidosis
-late renal failure
-acid ingestion (aspirin)
pH normal value
7.35-7.45
PaCO2 normal value
35-45 mmHg
HCO3-
22-26 mEq/L
PO2
80-100
O2 Sat
95-100%
PaCO2
respiratory
HCO3-
metabolic
Ideal body weight calculation
-Male IBW: 106 + (6 x inches over 5ft)
-Female IBW: 105 + (5 x inches over 5ft)
Minute ventilation (Ve)
Ve=Vt x f
major causes of tachypnea
-hypoxemia
-respiratory alkalosis
Areas of lung that have increased ventilation & perfusion, and lower V/Q ratios
-Apices of lungs have increased ventilation & decreased perfusion
-Bases of lungs have decreased ventilation & increased perfusion
-Apices/Above Heart have higher V/Q ratio
-Bases/Below Heart have lower V/Q ratio
State ways in which the V/Q ratios can be increased
-If ventilation is increased or perfusion is decreased, V/Q is increased
state ways in which the V/Q ratios can be decreased
-if ventilation is decreased V/Q is decreased
state the effect of a low V/Q ratio on blood gases
-PAO2 decreases and PaCO2 increases
-increased PaCO2 = low pH (acidosis)
State the effect of a high V/Q ratio on blood gases
-PAO2 increases & PaCO2 decreases
-Decreased PaCO2 = high pH (alkalosis)
Anatomic Shunt
-2-3% of unoxygenated blood from R side of heart flows directly into pulmonary veins without opportunity to participate in gas exchange (bronchial, pleural, thebesian veins).
Abnormalities causing Anatomic Shunts
-congenital heart disease
-intrapulmonary fistula
-vascular lung tumors
Capillary shunt
-causes are hypoventilation
- V/Q mm (emphysema, bronchitis, asthma, excessive airway secretions)
-a-c diffusion defects
Venous Admixture
-The mixing of shunted, non-reoxygenated blood with re-oxygenated blood distal to the alveoli
-Reduces the PaO2
Respiratory Quotient
-Ratio between O2 consumed (VO2) & volume of CO2 produced (VCO2) during internal respiration (at the cellular level)
-RQ = VCO2/VO2
- = 200ml/250ml = 0.8
Understand the relationship of volume and pressure and its effect on compliance
-Clt = change in volume/change in pressure
-Normal: 0.1L/cm H2O
-Rearrange: V = P x Clt
Understand the relationship between pressure and flow and its effect on Raw
-Raw = change in pressure/flow
-Normal: 0.5 to 2.5cm H2O/L/sec
Given Poiseuille’s Law, determine the relationship between flow, viscosity, pressure, length, and radius
-Flow: directly related to pressure
-Viscosity: directly related to pressure
-Pressure: inversely related to radius
-Length: directly related to pressure
-Radius: flow is extremely affected by radius (r to the 4th power) Decreased radius = decreased flow
BOHR Effect
-Right shifts cause a release of O2 to the tissues
-Mnemonic:
B:
O: oxygen
H- hydrogen
R - released to tissues
