Study Guide 3 cardiopulmonary Flashcards
What is the vasomotor center that sends sympathetic impulses to the blood?
Medulla Oblongota
Where are the baroreceptors located?
Carotid sinus and aortic arch (in the aorta)
What is the function of the baroreceptors?
Regulate arterial blood pressure.
Describe the baroreceptors reflex
BP drops: baroreceptors decrease impulse to medulla. Medulla increases signals which cause vasoconstriction, which cause heart rate to go up and BP to increase
Normal systolic/diastolic
Systemic
Pulmonary
Systemic: 120/80
Pulmonary: 25/8
Calculate driving pressure if given the mean pressure of various heart and blood vessel structures
Subtract from one another
Ex: 100-4=96
What is stroke volume
Volume of blood ejected from the ventricle during each contraction.
Normal is 40-80ml
What is cardiac output?
How do you calculate it?
Total volume of blood ejected from the ventricles per minute
CO=SV x HR
What happens to the blood pressure if the heart rate or stroke volume increases?
BP increases
What is the blood volume in an adult?
systemic, pulmonary, heart, veins, arteries, capillary beds
5L. systemic-75% pulmonary- 10% heart 15% veins 60% arteries 10% capillary 75ml
Where is perfusion better when the patient is in the following: supine, prone, side, upside down
supine-posterior
side- lateral
prone- anterior
upside down- upper lobes
Stroke volume is determined by 3 things. Name them:
ventricular preload
ventricular afterload
myocardial contractility
What is the ventricular preload
How much the myocardial is stretched prior to contraction
What is ventricular afterload and what is it determined by?
force against which the ventricles must work to pump blood.
Determined by viscosity (how thick the blood is. How open the blood vessels are)
What is myocardial contractility
force generated by the myocardium when the heart contracts
an increase in myocardial contractility is known as
positive inotropism
a decrease in myocardial contractility is known as
negative inotropism
what is vascular resistance
resistance to flow that has to be overcome to push blood through the circulatory system
what happens when vascular resistance increases? Decreases?
BP increases (goes up) BP decreases (goes down)
what are active mechanisms that change vascular resistance
pharmacological stimulation (drugs)-epi, dopamine (constriction) O2 (dilates) pathological conditions- different diseases Abnormal ABG- decrease PaO2, increase PaCO2= Increase PVR
What are passive mechanisms that change vascular resistance?
pulmonary arterial pressure changes left arterial pressure changes alveolar vessel resistance extra alveolar vessels blood volume changes blood viscosity changes
What are the causes of increased pulmonary vascular resistance?
Acute, chronic
Acute: hypoxia, acidosis, drugs, hypercapnia
Chronic: pathological conditions
What are normal arterial blood gas values?
pH 7.35-7.45
PCO2 35-45mmHg
PO2 80-100mHg
HCO3- 22-26mEq/l
Which blood gas values are actual determined by blood gas machines? Which are calculated?
PaO2, pH, PaCO2
SaO2, HCO3-
Oxygen is carried in 2 forms. Name them
dissolved O2 in plasma
chemically bound to Hb
Determine the amount of O2 carried in the plasma (dissolved O2)
PaO2 x 0.003
Determine the amount of O2 chemically bound the Hb (combined O2)
Hb x 1.34 x SaO2
Hb saturation is normally 97% due to:
Anatomical shunts
A decrease in affinity of Hb for O2 causes
increase unload of O2
What is p50?
What is the normal p50?
normal: 27mmHg
partial pressure at which the Hb is 50% saturated with O2
What are the factors that cause a right shift of O2 dissociation curve?
decrease pH
increase PaCO2
increase temperature
increase DPG (2,3)
What does a shift to the right of the O2 dissociation curve result in?
decrease Hb affinity for O2
decrease pH
increase unloading of O2
Hb saturation for a given PO2 falls
What are the factors that cause a left shift of the O2 dissociation curve?
increase pH decrease PaCO2 decrease temperature decrease DPG (2,3) COhb,MetHb, HbF
What does a shift to the left of the O2 dissociation curve result in?
increase Hb affinity of O2
decrease unloading of O2
Hb saturation for given PO2 rises
The effect of pH on the Hb affinity for O2 is known as
Bohr effect
O2 transport studies are indicators of
cardiac output and ventilation
What is total O2 delivery? What must you take into account when determining it?
Total amount of O2 delivered or transported to the peripheral tissue
cardiac output and O2 content
how do you determine the arterial-venous O2. content difference
CaO2-CvO2=
What is the normal CaO2? Which is the normal CvO2?
20% volume
15% volume
What is the normal difference
5% volume
What is O2 consumption? What is this related to? What is the average?
amount of O2 extracted by the peripheral tissue during the period of 1 minute
Patient’s body surface area
Average is 125-165
What is the O2 extraction ratio? What is normal O2 extraction ratio?
amount of O2 extracted by peripheral tissue divided by amount of O2 delivered in tissue
25% or 0.8
What is the normal SvO2?
What is acceptable
75%
65%
What does it mean when the SvO2 is decreased? What would you do to correct it?
tissue took out too much O2.
decreased cardiac output, periods of O2 consumption, exercise shivering, seizure hyperthermia
increase cardiac output with drugs
Describe true shunt
blood flows from right heart to left heart without gas exchange
An anatomical true shunt comprises __ of cardiac output
3-5%
Name the abnormalities that cause true anatomic shunt
congenital heart disease, intrapulmonary fistula, vascular lung tumors, capillary shunts
How do you usually correct a true shunt
surgery
Descrive a shunt like effect how is it corrected?
pulmonary capillary perfusion is in excess of alveolar ventilation.
O2 therapy
Name the causes of a shunt like effect
hypoventilation
V/Q mistmach
alveolar capillary diffusion
_____ is the end result of venous shunting
venous admixture
Ideal alveolar gas equation
[(Pb-47)FIO2] - (PaCO2 x 1.25)
What is the normal pulmonary shunting?
less than 10%
What percentage shows intrapulmonary abnormality
10-20%
what percentage shows significant pulmonary disease
20-30%
What percentage shows potentially life threatening condition
more than 30%
Name 4 types of hypoxia and describe them
hypoxic- lower PaO2
anemic- low blood Hb or abnormal Hb
circulatory- not enough blood, bad heart
hisotoxic- inability to utilize O2
types of hypoxic associated with
-overdose of nitric oxide therapy in NICU
hisotoxic, anemic
types of hypoxia associated with
-patient with cardiomyopathy?
circulatory
severe hemorrhage in MVA
circulatory/ anemic
types of hypoxia associated with
-rookie mountain climber at 7k ft elevation
hypoxic
What indicates a more life threatening condition, central or peripheral cyanosis? Why?
Central
Brain’s not getting enough air
at rest, metabolizing tissue cells consume at __ ml of O2 and produce at ___ ml of CO2
250
200
What is the end result of the adaptive mechanism to increase the O2 carrying capability of the blood in the patient with COPD
hypoxia -> polycythemia (makes more RBC) -> cor pulmonale (right heart failure)
What are 3 ways CO2 is transported in the plasma
delivered CO2
HCO3-
Carbamino compound
What are the 3 ways CO2 is transported in the RBC?
dissolved CO2
HCO3-
carbamino compound
the majority of CO2 is carried __ in the __
bicarbonate
RBC
The CO2 dissociation curve is ___
linear
This means that there is a direct relationship between the __ and ___
partial pressure of CO2
amount of CO in the blood
describe the Haldane effect
deoxygenated blood enhances the loading of CO2, oxygenated of blood enhances unloading of O2
What is the average ventilation/perfusion ratio?
4:5 or 0.8
in an increased V/Q ratio: the PAO2 __and the PaCO2__
rise
fall
in a decreased V/Q ratio, the PAO2__ and the PaCo2___
falls
rises
what is the respiratory quotient
internal respiration gas exchange between the systemic capillaries and cells
RQ= VCO2 / VO2
What is the respiratory exchange ratio? (RR)
external respiration gas exchange between the systemic capillaries and cells
if the V/Q ratio is increase what is happening?
perfusion decreasing
Name the respiratory disorders that cause an increase V/Q ratio
pulmonary emboli, partial/complete obstruction in pulmonary arteries/arterioles, decrease cardiac output, extrinsic pressure on pulmonary vessels, destruction of capillaries
if the V/Q is decreasing what is happening?
ventilation decreasing
name the respirator disorders that cause a decrease in V/Q ratio
obstructive (CBABE)
restrictive- pneumonia, silicosis, pulmonary fibrosis
emphysema does both
Be able to label ventilation/ perfusion sliding bar diagram
Top bar (Vs anatomical, ventilation) Bottom Bar (Q-perfusion, Qs anatomical)
Total O2 delivery (DO2)
total amount of O2 delivered to the peripheral tissues
