What is the partial pressure of oxygen in atmospheric air?
159 mm Hg
What is the partial pressure of carbon dioxide in atmospheric air?
0.228mm Hg
What is the partial pressure of water vapor at 37� C and 100% relative humidity (RH)?
47 mm Hg
What is the partial pressure of oxygen in the lung's airways?
149 mm Hg
VE is the product of which of the following parameters?
VT x f
What is the amount of CO2 produced under normal resting conditions?
200 mL [O2 consumed 250 mL/min]
Oxygen consumption:
1,2,4: increases with exercise, is the amount of oxygen used by the body, is about 250 mL/min in the resting adult
A sample of blood has been taken from a patient's pulmonary artery. What mixed venous oxygen saturation value (SvO2) would indicate that the patient is normal?
75%
Your patient has a chronic respiratory disorder and vasoconstriction of her pulmonary vascular system. What is the chief control over this vasoconstriction?
Low PAO2
A condition that will cause hypoxic hypoxia is:
hypoventilation from an overdose of a sedative medication
A condition that will cause anemic hypoxia is:
carbon monoxide poisoning [anemic=blood]
A pulmonary artery (Swan-Ganz) catheter can be used for all of the following EXCEPT:
arterial blood sampling [can be used for measuring cardiac output, measuring left atrial pressure, measuring pulmonary artery pressure]
Which of the following statements are true of the bronchial vasculature?
I II III: Bronchial system venous blood drains directly into the pulmonary veins, oxygen-poor blood mixes with freshly oxygenated pulmonary venous blood on its way to the left ventricle, bronchial blood flow is only 1% to 2% of the cardiac output
Which of the following statements are true of the pulmonary circulation?
I II IV: It is a low-resistance system compared with the systemic circulation, its pressures are lower even though it receives the same cardiac output as the systemic circulation, the resistance to blood flow in the pulmonary circulation is approximately
Which pressure is commonly used as a clinical indicator of the left ventricular function?
Wedge pressure
Which of the following techniques is useful in evaluating cardiac output?
Thermodilution
What is the normal value for PVR?
96 dynes
sec
What is the normal value for systemic vascular resistance (SVR)?
156 dynes
sec
cm-5
In which of the following groups of patients has NO been especially beneficial in treating pulmonary hypertension?
Infants
Which of the following is the most important chemical factor causing pulmonary vasoconstriction?
Alveolar hypoxia
Which of the following will inhibit HPV?
I II III IV: Alkalemia, Nitric oxide and prostacycling, alpha-adrenergic blockers, Beta-adrenergic stimulants
The HPV response is often diminished in patients with the following conditions, except:
Emphysema [HPV diminished in: smoke inhalation, ARDS, Sepsis]
All of the following are some fo the alternatives to inhaled NO for lowering PVR, except:
Captopri [alternatives include: Prostacycling (PGI2), Sildenafil (Viagra), Nitroprusside]
What is the name of the force tending to move fluid into the capillary?
Oncotic pressure
Which of the following are causes of pulmonary edema?
I II III IV: Increased hydrostatic pressure, increased capillary permeability, decreased plasma oncotic pressure, insufficient lymphatic drainage
Which of the following is a good example of edema associated with high PCWP?
Cardiogenic pulmonary edema [wedge pressure]
All of the following conditions are associated with noncardiac pulmonary edema, except:
Mitral stenosis [associated noncardiac edema pneumonia, sepsis, oxygen toxicity {think of ARD}]
Which of the following are true of the respiratory exchange ration?
I II IV: It is the ratio of alveolar CO2 excretion to blood oxygen uptake, R=VCO2/VO2, Its value is normally approximately 0.8
What is the PAO2 of a person breathing air at sea level, with a PaCO2 equal to 40 mm Hg and an R equal to 0.8?
Approximately 100 mm Hg
Which of the following statements apply to Fick's law?
I III IV gas diffusion increases with increased membrane surface area, Gas diffusion increases with increased pressure gradient, Gas diffusion decreases if membrane thickness increases
When combining Graham's law and Henry's law, how many times faster does carbon dioxide diffuse across the alveolar capillary membrane than oxygen?
20
Diffusion of which of the following gases will be limited by a defective alveolar capillary membrane?
O2
When are patients with thickened alveolar capillary membranes most likely to show evidence of oxygen diffusion impairment?
During exercise
If oxygen equilibrium between the alveolus and capillary never occurs because of thickened membranes, oxygen transfer is then truly:
Diffusion limited
Why is CO the ideal gas for measuring the extent to which the alveolar capillary membrane itself impedes the diffusion rate?
Blood can absorb CO at a greater rate than CO can diffuse across the alveolar
What is the most common cause of resting hypoxemia?
A mismatch between ventilation and blood flow [V/Q ventilation/perfusion mismatch]
What is the standard accepted normal DLCO range for healthy adults in an upright position?
20 to 30 mL/Min/mm Hg
How do you obtain the diffusion capacity for oxygen?
It is obtained by multiplying DLCO by 1.23
The DLCO is useful in differentiating emphysema from what other obstructive diseases?
Asthma
Regional factors affecting the distribution of gas in the normal lung result in which of the following?
More ventilation goes to the bases and the lung periphery
What is gas that is wasted during normal ventilation called?
Dead space ventilation
A patient has a VT of 625 ml and a physiological dead space of 275 ml and is breathing at a frequency of 16 per minute. What is the alveolar ventilation (VA)
5600 ml/min [(625 - 2750) * 16 = 5,600]
Blockage of the pulmonary arterial circulation to a portion of the lung would cause which of the following?
Increase in alveolar dead space
Given a constant carbon dioxide production, how will changing the level of VA affect the PaCO2?
An increase in VA will decrease PaCO2
On what does the movement of gases between the lungs and the body tissues mainly depend?
Gaseous diffusion
The highest PCO2 levels are found in what location?
Cells [approximately 60 mm Hg]
Which of the following are true regarding the PACO2?
I, II and III or all of the above: directly proportional to whole-body carbon dioxide production, inversely proportional to alveolar ventilation (VA), and normally maintained at about 35 to 45 mm Hg
Calculate the approximate PAO2 given the following conditions (assume R = o.8): FIO2 = .40, PB = 77 mm Hg, PACO2 = 31 mm Hg
250 mm Hg [PAO2 = ( FiO2
(PB - PH2O)) - (PaCO2 / RQ). PAO2 = (.40 (770 - 47)) - (31/0.8) = (.40
723)- 38.75 = 289.2 - 38.75 = 250.45 PAO2 = approx. 250mm Hg]
A normal person breathing 100% oxygen at sea level would have a PAO2 of about what level?
670 mm Hg
Which of the following best represents the partial pressures of all gases in the normally ventilated and perfused alveolus when breathing room air t sea level?
PO2 = 100 mm Hg: PCO2 = 40 mm Hg; PN2 = 573 mm H; PH2O = 47 mm Hg
In a person breathing room air, and will all else being normal, if the alveolar PCO2 rises from 40 to 70 mm Hg, what would you expect?
PAO2 to fall by about 30 mm HG
Assuming a constant FIO2 and carbon dioxide production, which of the following statements are correct?
Increases in VA decrease the PACO2 and increase the PAO2
What is the highest PAO2 one could expect to observe in an individual breathing room air at sea level?
110 to 120 mm Hg
Which of the following conditions must exist for gas to move between the alveolus an pulmonary capillary?
Difference in partial pressures (pressure gradient)
Which of th following values corresponds most closely to the normal PO2 and PCO in the mixed venous blood returning to the lungs form the right side of the heart?
PO2 = 40 mm Hg; PCO2 = 46 mm HG
Which of the following gases would diffuse fastest across the alveolar-capillary membrane? Air , carbon dioxide, oxygen, nitrogen
carbon dioxide
The time available for diffusion in the lung is mainly a function of which of the following? Functional residual capacity (FRC), inspired oxygen concentration, level of VA, rate of pulmonary blood flow
Rate of pulmonary blood flow
What is the minimum amount of time that the blood must take for pulmonary capillary transit for equilibration of oxygen to occur across the alveolar-capillary membrane?
0.25
What is the normal range of PAO2 - PaO2 for healthy young adult's breathing room air?
5 to 10 mm Hg
An area of the lung has no blood flow but is normally ventilated. Which of the following statements are true about this area?
I ii iii The alveolar gas is like air (PO2 = 150; PCO2 =0), The area represents alveolar dead space, The V/Q is elevated
Regarding pulmonary blood flow in the upright lung, which of the following statements is true?
The bases receive about 20 times more blood flow than the apexes
How is the vast majority of oxygen carried in the blood?
Chemically combined with Hb
Under normal physiologic circumstances, how many milliliters of oxygen are capable of combining with 1 g of Hb?
1.340 ml [Hb * 1.34]
At PaO2 of 65 mm Hg, what is the approximate saturation of Hb with oxygen?
90%
Why is it necessary to keep the patient's PaO2 greater than 60 mm Hg?
A level of 60 mm Hg marks the beginning of the steep part of the dissociation curve
Given the following blood parameters, compute the total oxygen content (dissolved + HbO2) of the blood in ml/dl: Hb = 18; PO2 = 40 mm Hg; SO2 = 73%
17.7 ml/dl [(Hb
SO2)
1.34 -> (18
.73)
1.34 = 17.607 approximately 17.7 ml/dl]
Given the following blood parameters, compute the total oxygen content (dissolved + HbO2) of the blood in ml/dl: Hb = 16; PO2 = 625 Hg; SO2 = 100%
21.4 ml/dl 16
1.0
1.34= 21.44
What is the approximate normal CaO2 - CVO2 in a healthy adult at rest?
5 ml/dl
According to the Bohr effect, when the pH drops (blood becomes more acidic), what happens?
I and II only; the affinity of Hb for oxygen decreases, the Hb saturation for a given PO2 falls
Compared to normal levels, a shift in the HvO2 curve to the right has which of the following effects?
I and II The affinity of Hb for oxygen decreases, the Hb saturation for a given PO2 falls
What role does the Bohr effect play in oxygen play in oxygen transport?
Enhances oxygen delivery to tissues and oxygen pickup at lungs
In which of the following conditions will erythrocyte concentration of 2, 3-DPG be decreased?
Banked blood
The affinity of Hb for carbon monoxide (CO) is approximately how many times greater than its affinity for oxygen?
200 or greater
In which of the following forms is carbon dioxide transported by the blood?
All of the above, I ii iii, chemically combined with proteins, ionized as bicarbonate (HCO3-), simple physical solution
The target percentage of carbon dioxide transported in the blood occurs as which of the following?
HCO3-
Why is the presence of carbonic anhydrase in RBCs so crucial for carbon dioxide transport?
Drives the hydrolysis reaction that forms HCO3-
When a Hb molecule accumulates excessive amounts of HCO3-, it is expelled from the cell in exchange for Cl-. What is this called?
Hamburger phenomenon [named after Hartog Jakob Hamburger (1859-1924), Dutch physiologist) is a process which refers to the exchange of bicarbonate (HCO3-) and chloride (Cl-) across the membrane of red blood cells (RBCs)]
When Hb saturation with oxygen is high, less carbon dioxide is carried in the blood. What is this relationship called?
Haldane effect
Which of the following equations best describes oxygen delivery to the tissues?
Arterial oxygen content X cardiac output
Hypoxia is best defined as a condition in which what occurs?
Tissue oxygen delivery is inadequate to meet cellular needs [tissue = hypoxia, blood = hypoxemia]
An abnormal metabolic state in which the tissues are unable to utilize the oxygen made to available to them best describes which of the following?
Dysoxia
What is the most common cause of hypoxemia
V/Q mismatch
What is the most important component in the oxygen transport system?
Hb
What does V/Q mismatch have the biggest impact on?
oxygenation