Respiratory Quiz #2

Question 1

What is alveolar ventilation?

Answer 1

the volume of air that ventilates all the perfused alveoli, equal to total ventilation minus dead space ventilation. The normal average is between 4 and 5 L/min.

The last part of each inspiration that remains in the conducting airways(the anatomic dead space)

Question 2

What do you call the condition of alveoli that are ventilated by not perfused?

Answer 2

Alveolar dead space

Question 3

What is the definition of physiologic dead space?

Answer 3

the sum of anatomic dead space and alveolar dead space

Question 4

At constant carbon dioxide production, alveolar pCo2 is approximately _____ proportional to _____ ventilation; Alveolar pO2 must be calculated with the……?

Answer 4

inversely, alveolar, alveolar air equation

Question 5

At or near the fictional residual capacity, alveoli in the lower regions of the upright lung are…..

Answer 5

relatively better ventilated than those in the upper regions of the lung.

Question 6

What are the 3 determinants of volume in the lungs?

Answer 6

1. lung mechanics and compliance 2. chest wall mechanics and compliance 3. pathology of lungs or chest wall

Question 7

Define residual volume and its normal value.

Answer 7

-Residual volume is the volume of gas left in the lungs after a MAXIMAL FORCED EXPIRATION -RV usually about 1.5 L -determined by the force generated by the muscles of exp and the inward elastic recoil of the lungs -prevents lungs from collapsing at low lung volumes

Question 8

Define expiratory reserve volume and its normal value.

Answer 8

-Expiratory reserve volume is the volume of gas that is expelled during a maximal forced expiration that begins at the end of a normal Vt. -ERV usually ~1.5 L -determined by the difference between the FRC and RV

Question 9

Define inspiratory reserve volume and its normal value.

Answer 9

-volume of gas inhaled during a maximal forced inspiration beginning at the end of a normal Vt. -IRV is usually ~ 2.5 L -determined by the strength of contraction of the inspiratory muscles and inward elastic recoil of the lungs

Question 10

Identify the lung volumes which comprise the vital capacity.

Answer 10

-comprised of the IRV, tidal volume and the ERV -usually about 4.5L in a 70 kg adult -comprised amount of air expelled after a maximal forced inspiration

Question 11

Identify lung volumes which comprise the functional residual capacity.

Answer 11

-comprised of the ERV and the residual volume

Question 12

Identify the lung volumes which comprise the inspiratory capacity.

Answer 12

-the amount of air that can be MAXIMALLY INHALED at the end of a NORMAL EXHALATION(ERV + Vt) -IC is usually 3 L in a 70 kg adult

Question 13

Identify lung volumes which comprise the total lung capacity.

Answer 13

-the amount of air in the lungs after a maximal inspiratory effort(IRV + Vt + ERV + RV) -usually 6L in a 70 kg adult -determined by strength of contraction of inspiratory muscle and the inward elastic recoil of the lungs and chest wall

Question 14

List 7 factors in our practice that may affect lung volumes.

Answer 14

1. height 2. position(e.g., supine, trendelenberg….) 3. age(decreased closing volume with age) 4. anesthesia(decreased FRC, VC) 5. obesity 6. disease(e.g., asthma, COPD) 7. surgery(decreased FRC, VC)

Question 15

Identify the effects of surgical positions on FRC and IRC.

Answer 15

trendelenberg-FRC=~2 L

supine -FRC=~2.1-2.2 L

reverse trendelenberg- FRC=~2.5 L

semi fowlers-FRC=~2.7 L standing-FRC=~3.0 L

sitting-FRC=~2.8 L

Question 16

Identify the effect of residual muscle relaxation and thoracic surgery on VC and IC.

Answer 16

VC and IC DECREASES with residual NDMR and thoracic surgery(affects ability to cough, deep breath)

Question 17

Identify the effects of restrictive and obstructive lung disease on TLC, FRC, IC and RV.

Answer 17

RESTRICTIVE: TLC-decreased FRC-decreased IC-decreased RV-decreased Obstructive: TLC-increased FRC-increased IC-increased RV-increased

Question 18

List 5 methods for measuring lung volumes.

Answer 18

1. spirometery 2. nitrogen washout 3. helium dilution technique 4. body plethysmography 5. Fowler’s method-for determine anatomic dead space uses a nitrogen meter to analyze the expo nitrogen {} after a single insp of 100% oxygen

Question 19

Compare and contrast FVC, FEV1 and FVC/FEV1 in obstructive and restrictive lung disease.

Answer 19

Obstructive: vT-normal VC-normal FRC-increased FVC-low(normal) FEV1-decreased FEV1/FVC-decreased FEF25-75%-decreased Restrictive: vT-decreased VC-decreased FRC-decreased FVC-decreased FEV1-decreased FEV1/FVC-normal FEF25-75%-normal

Question 20

List four examples of obstructive lung disease.

Answer 20

1. asthma 2. COPD 3. Emphysema 4. Chronic Bronchitis

Question 21

List four examples of restrictive lung disease.

Answer 21

1. Pulmonary Fibrosis 2. Morbid Obesity 3. Chest wall disease 4. Neuromuscular Disease

Question 22

List 5 effects of anesthesia on lung volumes.

Answer 22

1. increase in closing capacity 2. increase in shunt 3. increase in respiratory rate 4. decrease in tidal volume 5. decrease in FRC

Question 23

Define anatomic dead space as it relates to lung anatomy and ventilation/perfusion.

Answer 23

“conducting zone” becomes anatomic dead space VENTILATION WITHOUT PERFUSION

Question 24

Define alveolar ventilation as it relates to tidal volume and minute ventilation.

Answer 24

-alveolar ventilation is that portion of tidal volume that reaches the alveoli -always less than minute ventilation -alveolar ventilation participates in gas exchange

Question 25

Compare and contrast anatomic and alveolar dead space as they relate to physiologic dead space.

Answer 25

-Anatomic Dead Space: the portion of the breath that enters and leaves the conducting zones of the airways(nose—>terminal bronchioles) -Alveolar Dead Space: air that reaches the alveoli but do not participate in gas exchange. -Physiologic Dead Space: anatomic dead space + alveolar dead space

Question 26

Describe the Bohr equation and use it to calculate dead space.

Answer 26

-physiologic dead space= anatomic dead space + alveolar dead space -The Bohr equation is used to calculate physiologic dead space -VD/VT=PaC02-PeC02/PaCO2 If PaCO2 is 45 mmHg and ETCO2 is 30 mmHg and Vt is 600 ml then: VD/600=45-30/45 VD=200 ml

Question 27

Describe the normal anesthesia circuit dead space(including anatomic) and identify the delivery system with the most VD

Answer 27

-Normal dead space is approximately 30%(conducting airways) -ET tube and connector increases dead space to 51% -Upper airway, facemask and connector increased dead space to 68%(face mask/connector most dead space)

Question 28

Identify the effect of volatile agents on tidal volume and minute ventilation.

Answer 28

-VA depress ventilation in a dose-dependent fashion -VA depress ventilatory response to pCO2 and pO2 -VA depress tidal volume but RR increased so mV only moderately depressed -VA increase ratio of dead space to total ventilation -Substitution of N2O for = MAC fraction of anesthetic lessens the increase in pCO2

Question 29

Describe the effect of the anesthesia machine and circuit on airway resistance.

Answer 29

-while patient is connected to the circuit, SPONTANEOUS VENTILATION without assistance creates HYPERCARBIA(> 40 mmHg) as minute ventilation decreases -dead space and resistance increases due to circuit and airway caliber -conversion to positive pressure ventilation from negative pressure ventilation not as efficient and higher pressures required

Question 30

Calculate partial pressure of a gas based on its {} at sea level.

Answer 30

For any gas in a mixture(gas1), its partial pressure is: pGas1 = % total gas x pTotal -Oxygen constitutes 21% of dry atmospheric air(760 mmHg) such that: pO2 = 0.21 x 760 mmHg= 159 mmHg

Question 31

Calculate partial pressure of oxygen in the alveolus(PAO2) based on FiO2.

Answer 31

PAO2 in the alveolus is 104 mmHg PaO2 is 159 mmHg PAO2 = FIO2- PAO2/R + F F=small correction factor that is usually ignored so: PAO2=FIO2(Pb-PH20)-PAco2/R Alveolar Air Equation

Question 32

Estimate partial pressure of oxygen in the arterial system(PaO2) based on FiO2.

Answer 32

Multiple by 5’s: -FiO2 - 21%—> 21 x 5 = 105 mmHg -FiO2 - 50%—> 50 x 5 = 250 mmHg -FiO2 - 100%—> 100 x 5 = 500 mmHg

Question 33

Identify the region of the lung where most ventilation occurs.

Answer 33

Lower zone-90 vnt/unit vol Middle zone-70 vnt/unit vol Upper zone- 60 vnt/unit vol