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Thoracic Anesthesia and Respirology > Respiratory Physiology MCQs > Flashcards

Respiratory Physiology MCQs Flashcards

1
Q

Which of the following cause a rightward shift in the oxygen-hemoglobin dissociation curve?

(a) Methemoglobinaema
(b) Acidosis
(c) Hypercarbia
(d) CO poisoning
(e) 2,3-BPG
(f) Hypothermia

A

(b) Acidosis
(c) Hypercarbia
(e) 2,3-BPG

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2
Q

What percentage of carbon dioxide in the blood is transported bound to hemoglobin?

(a) 90%
(b) 40%
(c) 20%
(d) 10%
(e) 5%
(f) 1%

A

(e) 5%

…and…
5% dissolved as CO2
90% dissolved as HCO3

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3
Q

Which of the following statements are true?

(a) Vital capacity is reduced in both restrictive and obstructive lung disease
(b) Residual volume is increased in restrictive lung disease
(c) Total lung capacity is increased in obstructive lung disease
(d) FVC is always decreased in obstructive lung disease

A

(a) Vital capacity is reduced in both restrictive and obstructive lung disease
(c) Total lung capacity is increased in obstructive lung disease

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4
Q

Which of the following statements are false?

(a) The length of capillary required for gas equilibrium is longer during exercise
(b) Anemia reduces diffusion capacity
(c) Hb-bound oxygen does not contribute to decreasing the diffusion gradient of oxygen across the alveolar capillary membrane
(d) At rest, equilibrium is usually reached at 50% of the capillary length

A

(d) At rest, equilibrium is usually reached at 50% of the capillary length

(25 to 30%)

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5
Q

Which of the following factors decrease diffusion across the capillary membrane?

(a) Increased mixed venous oxygen
(b) Increased capillary wall thickness
(c) Increased molecular weight of a gas
(d) Increased solubility in plasma

A

(c) Increased molecular weight of a gas

(d) Increased solubility in plasma

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6
Q

Which of the following are causes of increased CO2 retention in patients with COPD?

(a) Decreased diffusion capacity of CO2
(b) Increased dead space
(c) Decreased minute ventilation
(d) Decreased alveolar ventilation

A

(b) Increased dead space
(d) Decreased alveolar ventilation (i.e. in patients who cannot increase MV sufficiciently to offset increased dead space)

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7
Q

Which of the following statements are true about the induction of anesthesia?

(a) FRC is reduced with the induction of anesthesia
(b) FRC is reduced in the prone position in awake patients
(c) Muscle relaxants contribute to further reductions in FRC
(d) General anesthesia increases airway resistance and airway closure
(e) High inspired FIO2 can help to counter-act the effects of general anesthesia on airway closure
(f) Static compliance of the respiratory system is reduced during general anesthesia

A

(a) FRC is reduced with the induction of anesthesia
(b) FRC is reduced in the prone position in awake patients
(d) General anesthesia increases airway resistance and airway closure
(f) Static compliance of the respiratory system is reduced during general anesthesia

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8
Q

Which of the following statements are true about CO2?

(a) PaCO2 is determined by minute ventilation
(b) The difference between ET CO2 and alveolar CO2 is determined by diffusion capacity
(c) PaCO2 is set to a higher point in patients with COPD because of decreased minute ventilation
(d) The intercostal muscles are responsible for increases ventilation in response to increased PaCO2

A

(d) The intercostal muscles are responsible for increases ventilation in response to increased PaCO2

False:

(a) PaCO2 is determined by minute ventilation (F - alveolar vent)
(b) The difference between ET CO2 and alveolar CO2 is determined by diffusion capacity (F - dead space)
(c) PaCO2 is set to a higher point in patients with COPD because of decreased minute ventilation (F - increased dead space and decreased alveolar ventilation)

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9
Q

Which of the following statements are true?

(a) Impaired diffusion is not a significant contributor to hypoxaemia in patients with fibrotic lung disease
(b) Use of 100% FiO2 during anesthetic induction increases the risk of hypoxemia in the postoperative period
(c) HPV is impaired by the use of sevofluorane but not propofol to maintain general anesthesia
(d) Regional anesthesia does not affect FRC

A

(b) Use of 100% FiO2 during anesthetic induction increases the risk of hypoxemia in the postoperative period (d/t atelectasis)
(c) HPV is impaired by the use of sevofluorane but not propofol to maintain general anesthesia
(d) Regional anesthesia does not affect FRC

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10
Q

What is the most common cause of impaired oxygenation?

(a) Decreased diffusion capacity
(b) Hypoventilation
(c) V/Q mismatch
(d) Shunting
(e) Low FiO2

A

(c) V/Q mismatch

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11
Q

What are the most important causes of hypoxemia in pulmonary embolism?

(a) Edema and impaired diffusion
(b) High V/Q ratio in areas surrounding the embolus
(c) Low V/Q ratio in areas distal to the embolus
(d) Increased shunt

A

(b) High V/Q ratio in areas surrounding the embolus
(c) Low V/Q ratio in areas distal to the embolus
(d) Increased shunt (because of generally increased PA pressures)

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12
Q

Atelectasis in the postoperative period is greatest after:

(a) Open abdominal surgery
(b) Laparoscopic abdominal surgery
(c) Thoracic surgery
(d) Cardiac surgery

A

(d) Cardiac surgery (T - often both lungs collapsed)

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13
Q

Which of the following statements are true about PEEP?

(a) PEEP improves V/Q mismatch in patients with atelectasis
(b) PEEP of 10 is sufficient to decrease and prevent further atelectasis in obese surgical patients
(c) PEEP increases ventilatory deadspace

A

(c) PEEP increases ventilatory dead space (alveolar pressure > cap pressure in upper regions)

False:

(a) PEEP improves V/Q mismatch in patients with atelectasis (usually worsens by increasing ventilation of poorly perfused areas and worsening perfusion, and decreasing ventilation of well-perfused bases)
(b) PEEP of 10 is sufficient to decrease and prevent further atelectasis in obese surgical patients (need VC breath + lower FiO2)

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14
Q

Which of the following statements are true of shunt?

(a) Healthy people have 5-8% shunt from return of Thebesian veins to the left atrium
(b) Shunt is not part of the disease process in asthma and COPD
(c) Hypoxemia from shunt is not corrected with supplemental FiO2
(d) Shunt can be worsened by application of PEEP

A

(b) Shunt is not part of the disease process in asthma and COPD
(c) Hypoxemia from shunt is not corrected with supplemental FiO2
(d) Shunt can be worsened by application of PEEP (T - increased flow through unventilated regions from highly vented regions)

False:
(a) Healthy people have 5-8% shunt from return of Thebesian veins to the left atrium (F - 2-3%)

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15
Q

Which of the following statements are true?

(a) Normal dead space accounts for one third of the tidal volume
(b) Normal volume of dead space is 150-200 cc per tidal breath
(c) Normal vital capacity is 6-8 L/min
(d) Normal PaO2 is 100 mmHg
(e) Normal PvO2 is 80mmHg
(f) Physiologic dead space is greatest at the lung apex (

A

(a) Normal dead space accounts for one third of the tidal volume
(b) Normal volume of dead space is 150-200 cc per tidal breath
(d) Normal PaO2 is 100 mmHg
(f) Physiologic dead space is greatest at the lung apex

False:

(e) Normal PvO2 is 80mmHg (F-40mmHg)
(c) Normal vital capacity is 6-8 L/min (F - 4-6)

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16
Q

Which of the following is true of lung measurements:

a) Fowlers method measures physiological dead space

b) TLC can be measured using a spirometer

c) the FRC in an average adult is 2.2litre

d) vital capacity is the volume of air expired from full inspiration to full expiration
e) helium dilution over estimates FRC in patients’ with bullous lung disease

A

c) the FRC in an average adult is 2.2 L
d) vital capacity is the volume of air expired from full inspiration to full expiration

Fowlers method measures anatomical dead space. TLC, RV and FRC are measured using either helium dilution or body plethysmography techniques. FRC is about 2.2 litres in an average adult. Vital capacity is the combination of inspiratory reserve volume, tidal volume and expiratory volume. Helium dilution will underestimate the FRC in patients with bullous lung disease

17
Q

The functional residual capacity:


a) is increased in the obese

b) is the residual volume plus the inspiratory reserve volume
c) falls with general anaesthesia

d) is not affected by posture

e) falls with increasing age

A

c) falls with general anaesthesia

e) falls with increasing age

18
Q

Surfactant:


a) is a mucopolypeptide

b) causes a decrease in surface tension

c) keeps alveoli dry

d) causes an increase in compliance
e) production is reduced after a prolonged reduction in pulmonary blood flow

A


b) causes a decrease in surface tension


c) keeps alveoli dry

d) causes an increase in compliance
e) production is reduced after a prolonged reduction in pulmonary blood flow

19
Q

A pressure-volume curve can be used for measuring:

a) the work of breathing

b) functional residual capacity

c) anatomical dead space
d) compliance

e) respiratory quotient

A

a) the work of breathing


d) compliance


20
Q

The oxyhaemoglobin dissociation curve is shifted to the left by:

a) an increase in arterial PCO2

b) acidosis

c) a decrease in 2,3 DPG
d) carbon monoxide

e) a fall in temperature

A

c) a decrease in 2,3 DPG
d) carbon monoxide

e) a fall in temperature

21
Q

Anatomy of the respiratory tract
:

a) the alveoli humidify gas

b) generations 1- 18 are known as the conducting zone of the lungs
c) there are 25 bronchial generations

d) bifurication of the bronchi occurs at T4

e) the lungs are lined with transitional epithelium

A

d) bifurication of the bronchi occurs at T4

The nose and mouth act to filter and humidify gases as they flow into the lungs. There are 23 bronchial generations, 1-16 are the conducting zone and 17-23, the respiratory zone. The lungs are lined with columnar ciliated epithelium.

22
Q

Dead space:


a) is defined as the volume of gas which does take part in gas exchange
b) physiological dead space is the same as alveolar dead space

c) anatomical dead space is measured by the Bohr equation

d) dead space is usually about 45% of tidal volume

e) occurs with pneumonia

A

e) occurs with pneumonia

Dead space is the volume of gas which does not take part in gas exchange. It is classified into Anatomical, avelore and physiological which is a combination of both and can account for about 30% of tidal volume. Anatomical dead space is measured via Fowlers method and Physiological by the Bohr equation.

23
Q

Pulmonary vascular resistance

a) is high at high lung volumes

b) is low at low lung volumes

c) can cause heart failure 
d) is calculated using PCWP

e) is decreased by nitrous oxide
A

a) is high at high lung volumes
c) can cause heart failure
d) is calculated using PCWP


24
Q

Diffusion of gases
:
a) is increased with a decrease in surface area

b) is indirectly proportional to the concentration gradient
c) is not governed by Grahams law

d) is directly proportional to the thickness

e) is decreased according to Beers law

A

NONE

25
Q

Gas transport in the blood


a) there is about 15ml of oxygen per 100ml of oxygenated blood

b) oxygen CO2 is mainly tranported as carbamino compounds
c) CO2 is carried best by oxygenated haemoglobin

d) More oxygen is carried dissolved in blood than CO2
e) CO2 is transported in the blood by 3 main routes

A

NONE

There is 15ml of oxygen on venous blood and 20ml per 100ml in oxygenated blood.
O2 is carried mainly by haemoglobin whereas CO2 is transported as bicarbonate, caramino compounds or dissolved in blood.
The Haldane effect describes deoxygenated blood carrying CO2 better than oxygenated blood due to its effectiveness in forming carbamino compounds.

26
Q

If oxygen is added to inspired air to increase its partial pressure from 20 kPa (150 mmHg) to 60 kPa (450 mmHg):

a) dissolved oxygen will increase approximately three-fold
b) the oxygen content of the blood will increase approximately three-fold
c) the PaN2 will remain the same
d) the PaO2 will increase approximately three-fold
e) hypercarbia will be prevented

A

a) dissolved oxygen will increase approximately three-fold

d) the PaO2 will increase approximately three-fold

27
Q

Pulmonary vascular resistance is increased by:

a) serotonin
b) hypocarbia
c) hypoxia
d) a fall in pH
e) adrenaline

A

a) serotonin
c) hypoxia
d) a fall in pH

28
Q

The Hb-oxygen dissociation curve shifts to the right in:

a) acute hypoxia
b) stored blood
c) metabolic acidosis
d) respiratory alkalosis
e) hypothermia

A

c) metabolic acidosis

29
Q

In calculating the shunt fraction, the following need to be measured or estimated:


a) mixed venous oxygen content
b) pulmonary end-capillary oxygen content
c) arterial oxygen content
d) alveolar partial pressure of oxygen
e) haemoglobin concentration

A

ALL:

a) mixed venous oxygen content
b) pulmonary end-capillary oxygen content
c) arterial oxygen content
d) alveolar partial pressure of oxygen
e) haemoglobin concentration

30
Q
  1. Acute untreated haemorrhagic shock in a patient will lead to:

a) an increase in physiological dead-space
b) an increase in the arterio-venous PCO2 difference
c) a fall in the pulmonary vascular volume
d) an increase in antidiuretic hormone secretion
e) an increase in plasma bicarbonate concentration

A

a) an increase in physiological dead-space
c) a fall in the pulmonary vascular volume
d) an increase in antidiuretic hormone secretion

Thoracic Anesthesia and Respirology (4 decks)

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