Pilbeam: Mechanical Ventilation, 4th Edition

Test Bank

Chapter 1: Oxygenation and Acid-Base Evaluation
		
MULTIPLE CHOICE

	1.	The diffusion of carbon dioxide across the alveolar capillary membrane is ____.
A.	equal to oxygen	
B.	less than oxygen	
C.	10 times greater than oxygen	
D.	20 times greater than oxygen	

ANS:	D

	2.	When the blood PCO decreases, the oxygen dissociation curve shifts to the ____.
A.	right and the P50 decreases	
B.	left and the P50 increases	
C.	right and the P50 increases	
D.	left and the P50 decreases	

ANS:	D

	3.	Which of the following would be inconsistent with respiratory alkalosis?
A.	pH = 7.57	
B.	PaCO = 30 mm Hg	
C.	pH = 7.63	
D.	PaCO = 42 mm Hg	

ANS:	D

	4.	The oxyhemoglobin dissociation curve depicts the relationship ____.
A.	between percentage saturation of oxygen and partial pressure of oxygen in arterial blood	
B.	between percentage saturation of oxygen and fraction of inspired oxygen in venous blood	
C.	hemoglobin levels in the blood and oxygen saturation	
D.	hemoglobin levels in the blood and oxygen tension	

ANS:	A

	5.	After taking an arterial blood sample and mean exhaled air sample, the PCO values were found to be 40 mm Hg and 27 mm Hg, respectively. The ratio of ventilation to dead space is ____.
A.	0.20	
B.	0.25	
C.	0.33	
D.	0.41	

ANS:	C

	6.	While breathing room air, a patient has a P50 of 39 mm Hg. This situation could be the result of ____.
I. decrease in hydrogen ion concentration
II. an elevated temperature
III. an elevated 2,3-diphosphoglycerate
A.	I only	
B.	II and III	
C.	II only	
D.	I and III	

ANS:	B

	7.	Mixed venous blood entering the pulmonary capillaries normally has a PO of 47 mm Hg; the saturation of hemoglobin is approximately ____.
A.	50%	
B.	75%	
C.	65%	
D.	85%	

ANS:	B

	8.	Oxygen that is carried in the dissolved form is expressed as ____.
I. SaO
II. V
III. PAO
IV. PaO
A.	II and IV	
B.	I and II	
C.	III only	
D.	IV only	

ANS:	D

Please refer to this data: pH = 7.33; PaCO = 34 mm Hg; PaO = 80 mm Hg; SaO = 92%; Hb = 8 gm%.

	9.	This patient’s hemoglobin concentration most likely represents ____.
A.	erythrocytopenia	
B.	secondary polycythemia	
C.	primary hysteria	
D.	anemia	

ANS:	D

	10.	Calculate this person’s dissolved arterial oxygen content.
A.	0.102 vol %	
B.	0.24 vol %	
C.	0.34 vol%	
D.	0.28 vol%	

ANS:	B

	11.	Calculate this person’s combined arterial oxygen.
A.	8.84 vol%	
B.	10.24 vol%	
C.	13.56 vol%	
D.	23.56 vol%	

ANS:	B

	12.	Calculate the amount of oxygen combined to hemoglobin in a patient having 13 gm% Hb, a PaO of 60 mm Hg, and an arterial oxygen saturation of 85%.
A.	20.10 vol%	
B.	7.2 vol%	
C.	15.2 vol%	
D.	14.81 vol%	

ANS:	C

	13.	Which measurement best assesses the presence or absence of ventilatory failure?
A.	PaCO	
B.	PaO	
C.	pH	
D.	HCO	

ANS:	A

	14.	Interpret the following ABG data: pH = 7.17; PaCO = 42 mm Hg; PaO = 100 mm Hg; HCO = 16 mmol/L.
A.	Acute respiratory alkalosis	
B.	Acute metabolic acidosis	
C.	Partially compensated respiratory alkalosis	
D.	Compensated respiratory alkalosis	

ANS:	B

	15.	A patient has a PCO of 21 mm Hg. Based on this information you may correctly conclude that ____.
A.	the patient’s CO production is higher than normal	
B.	the patient is hypoventilating	
C.	the patient is hyperventilating	
D.	the patient’s tidal volume is less than normal	

ANS:	C

	16.	Which of the following best represent the partial pressure of all gases in the normally ventilated and perfused alveolus when breathing room air at sea level?
A.	PO = 100 mm Hg; PCO = 40 mm Hg; PN = 713 mm Hg; PHO = 47 mm Hg	
B.	PO = 149 mm Hg; PCO = 40 mm Hg; PN = 573 mm Hg; PHO = 47 mm Hg	
C.	PO = 100 mm Hg; PCO = 40 mm Hg; PN = 573 mm Hg; PHO = 37 mm Hg	
D.	PO = 100 mm Hg; PCO = 40 mm Hg; PN = 573 mm Hg; PHO = 47 mm Hg	

ANS:	D

	17.	The physical process whereby gas molecules move from an area of high partial pressure to an area of low partial pressure is called ____.
A.	ventilation	
B.	membrane exchange	
C.	diffusion	
D.	active transport	

ANS:	C

	18.	At a PaO of 30 mm Hg, what is the approximate SaO?
A.	53%	
B.	97%	
C.	72%	
D.	94%	

ANS:	A

	19.	What is the highest PAO one could expect to observe in an individual breathing room air at sea level?
A.	120 to 130 mm Hg	
B.	710 to 760 mm Hg	
C.	640 to 670 mm Hg	
D.	90 to 100 mm Hg	

ANS:	A

	20.	The largest percentage of CO is transported in the blood as ____.
A.	bicarbonate (HCO)	
B.	carbonic acid (HCO)	
C.	carbonic anhydrase	
D.	dissolved CO	

ANS:	A

	21.	In the red blood cell, the rate of the hydrolysis of CO is increased by ____.
A.	carboxyhemoglobin	
B.	2,3,diphosphoglycerate	
C.	carbonic anhydrase	
D.	cholinesterase	

ANS:	C

	22.	During the hydrolysis reaction of CO within the red blood cell, many of the HCO ions produced diffuse out of the erythrocyte into the plasma. How does the red blood cell maintain electrolytic equilibrium under these circumstances?
A.	By shifting positive ions out of the red blood cell	
B.	By shifting chloride ions into the red blood cell	
C.	By shifting chloride ions out of the red blood cell	
D.	By shifting positive ions into the red blood cell	

ANS:	B

	23.	Calculate a patient’s arterial oxygen content if Hb = 11 gm%, PaO = 90 mm Hg, and SaO = 80%.
A.	11.8 vol%	
B.	12.2 vol%	
C.	18.4 vol%	
D.	20.1 vol%	

ANS:	B

	24.	Prior to treatment, Patient B’s arterial blood gases were as follows: pH = 7.37, PaO = 50 mm Hg, and PaCO = 75 mm Hg. The physician ordered high-flow oxygen via non-rebreathing O mask. Over the next 4 hours the patient became somewhat confused and lethargic, and his breathing became shallow and slow. This would be consistent with ____.
A.	increased levels of 2,3diphosphoglycerate	
B.	early signs of O toxicity	
C.	loss of hypoxic drive	
D.	early signs of hypoxemia	

ANS:	C

	25.	A patient has a P value of 32 mm Hg. Which of the following is not true?
A.	A decreased affinity of hemoglobin for O	
B.	A shift in the oxyhemoglobin curve to the right	
C.	Improved delivery of oxygen to the tissues	
D.	A lower than normal Hb saturation for a given PO	

ANS:	B

	26.	A state of acidemia exists when ____.
A.	the HCO is >24 mEq/L	
B.	the blood pH is <7.35	
C.	the blood pH is 7.45	
D.	the HCO is <24 mEq/L	

ANS:	B

	27.	Which of the following would be common findings in “chronic” or compensated respiratory acidosis?
I. An elevated HCO
II. A pH well below 7.35
III. A pH above 7.45
IV. A decreased PCO
A.	I, III, and IV	
B.	I only	
C.	I, II, and IV	
D.	III and IV	

ANS:	B

	28.	In regard to hypoxemia and peripheral chemoreceptors, stimulation to increase ventilation does not occur until the PaO falls below ____.
A.	80 mm Hg	
B.	60 mm Hg	
C.	70 mm Hg	
D.	90 mm Hg	

ANS:	B

	29.	What percentage of saturation would you expect to find with PaO of 63 mm Hg?
A.	53%	
B.	92%	
C.	62%	
D.	97%	

ANS:	B

	30.	Both anemia and carbon monoxide poisoning can cause severe hypoxia. Yet, neither condition results in a major stimulation of breathing. This is because ____.
A.	the peripheral chemoreceptors are responsive mainly to a decreased PaO, not a decreased CaO	
B.	anemia and carbon monoxide poisoning depress the peripheral chemoreceptors	
C.	anemia and carbon monoxide poisoning depress the central chemoreceptors	
D.	anemia and carbon monoxide poisoning cause stagnant hypoxia, not hypoxemia	

ANS:	A

	31.	Calculate the PO breathing ambient air at an Indian village in the Peruvian Andes, barometric pressure = 400 mm Hg.
A.	149 mm Hg	
B.	65 mm Hg	
C.	84 mm Hg	
D.	74 mm Hg	

ANS:	D

	32.	What is the alveolar PO for the situation in question 31 if the PaCO is 30 mm Hg?
A.	50 mm Hg	
B.	70 mm Hg	
C.	62 mm Hg	
D.	37 mm Hg	

ANS:	D

	33.	What type of hypoxia, if any, would an individual suffer at this altitude?
A.	Hypoxemic	
B.	Anemic	
C.	Histotoxic	
D.	Stagnant	

ANS:	A

Calculate the following based upon this patient environment and the following arterial blood gases: FO = 0.21, PaO = 68 mm Hg, SaO = 88%; Hb = 15 g/dL, PaCO = 40 mm Hg, PvO = 39 mm Hg, SvO = 70%, PB = 760 mm Hg.

	34.	The CaO is ____.
A.	16.5 mL/dL	
B.	17.9 mL/dL	
C.	17.7 mL/dL	
D.	19.8 mL/dL	

ANS:	C

	35.	The P(A-a)O in this patient is approximately ____.
A.	10 mm Hg	
B.	20 mm Hg	
C.	30 mm Hg	
D.	40 mm Hg	

ANS:	C

	36.	A hypotensive patient is spontaneously breathing room air when an arterial blood gas sample is taken for analysis. The following values are found: PaO = 105 mm Hg, PaCO = 25 mm Hg, pH = 7.27, bicarbonate = 11 mEq/L. Based on this information, what best describes the patient’s condition?
A.	Partially compensated respiratory acidosis	
B.	Uncompensated hyperventilation	
C.	Combined respiratory and metabolic acidosis	
D.	Completely compensated metabolic acidosis	

ANS:	A

	37.	The following arterial blood gas results are from a patient who is spontaneously breathing room air: PaO = 55 mm Hg, PaCO = 58 mm Hg, pH = 7.36, bicarbonate = 32 mEq/L. Which of the following best describes this patient’s condition?
A.	Compensated respiratory alkalosis	
B.	Uncompensated metabolic acidosis	
C.	Uncompensated metabolic alkalosis	
D.	Compensated respiratory acidosis	

ANS:	D

	38.	What is the pH if the H+ concentration is 56 and the PaCO is normal?
A.	7.29	
B.	7.36	
C.	7.40	
D.	7.56	

ANS:	D

	39.	If your PCO is 36 and the HCO is 24, what should the pH be?
A.	7.40	
B.	7.50	
C.	7.42	
D.	7.56	

ANS:	C