Mechanics of ventilation 2

Question 1

tidal volume - TV

Answer 1

amount of air inhaled or exhaled during normal quiet breathing w/o effort

Question 2

inspiratory reserve volume - IRV

Answer 2

The maximum amount of air that can be inhaled after a quiet inhale

Question 3

expiratory reserve volume - ERV

Answer 3

the amount of air that can be exhaled with maximum effort after normal inhalation

Question 4

residual volume - RV

Answer 4

the amount of air remaining in the lungs after maximum exhalation

Question 5

inspiratory capacity

Answer 5

maximum amount of air that can be inhaled - IRV
after quiet inhalation - TV
TV + IRV

Question 6

Functional residual capacity

Answer 6

the amount of air remaining in the lungs - RV after quiet exhalation - ERV

Question 7

Total lung capacity

Answer 7

RV + ERV + TV + IRV

Question 8

Vital capacity

Answer 8

amount of air that can be exhaled w/ max effort - ERV after maximum inhalation - TV + IRV
cane be forced FVC or slow

Question 9

FEV1 - Forced Expiratory Volume

Answer 9

amount of air that is exhaled during 1st second of forced exhalation after full inhalation

Question 10

normal FEV1/FVC ratio

Answer 10

70-80%

Question 11

low FEV1/FVC ratio indicates

Answer 11

increased lung resistance

Question 12

how is inspiratory restrictive disease evident in spirometers

Answer 12

reduced lung compliance - limited lung expansion during inhalation
significant decrease in IRV and TV only

Question 13

example of restrictive inspiratory disease

Answer 13

fibrosis -

Question 14

how is expiratory restrictive disease evident in spirometers

Answer 14

weakness of accessory muscles in deep exhalation
decreased lung volumes - ERV,
and TLC

Question 15

Signs of obstruction in spirometer

Answer 15

increased lung resistance, making it harder and slower to breath out - causes increased residual lung volume
normal vital capacity
reduced FVC

Question 16

helium dilution technique

Answer 16

spirometer - V1 contains a measured conc of helium - C1
patient starts breathing in normal outside air in normal tidal volume
when the patient is at the functional residual capacity patient begins to inhale helium/air mixture until the air mixture has reached equilibrium with the tank and the patients lungs - FRC = V2 - V1
V2 = FRC + V1
volume of lungs - V2
Helium conc in lungs = C2

Question 17

Initial amount of helium calculation

Answer 17

conc of helium = C1
Volume of spirometer = V1
C1 X V1

Question 18

Final amount of helium calculation

Answer 18

C2 (V2 + FRC)

Question 19

FRC calculation using the helium dilution method

Answer 19

C1 x V1 = C2 x V2
V2 = V1 + FRC
C1 x V1 = C2 x (V1 + FRC)
FRC = (C1 x V1)/C2 – V1

Question 20

Process of body plethysmography

Answer 20

Patients sits in a “body box” (airtight chamber) and breathes through a mouthpiece
At FRC, the mouthpiece is closed
Patient tries to breathe in

Question 21

consequences of body plethysmography

Answer 21

• Chest and lungs expand, pressure in lungs drop as volume increases
  
  • Expanding chest compresses the air inside the chamber, air volume in chamber decreases, pressure in chamber increases

Question 22

key principle in body plethysmography

Answer 22

Boyles law

P1V1 = P2V2

Question 23

how can Boyle’s law to find ∆V

Answer 23

Change in lung volume: trying to find FRC and therefore ∆V
FRC = FRC + ∆V
Change of air volume in box:
V1 = V1 - ∆V
Change of pressure in box:
P1 = P1 + ∆P
P1 x V1 = (P1 + ∆P) x (V1 - ∆V) [Boyle’s Law]
- P1 x V1 = P1 V1 + ∆P V1 - ∆V P1 - ∆P ∆V
- ∆V = ∆P V1/ (P1+ ∆P)

Question 24

how can Boyles law be used to find FRC in body plethysmography

Answer 24

P1 x FRC = (P1 - ∆P) x (FRC + ∆V) [Boyle’s Law]

FRC = ∆V(P1- ∆P)/ ∆P

Question 25

lung volumes vary with

Answer 25

body size
age
sex
muscular training
posture
race
respiratory diseases

Question 26

dead space

Answer 26

the volume occupied by gas in the lungs which does not participate in gas exchange.

Question 27

3 types of dead space

Answer 27

anatomical dead space
physiological dead space
alveolar dead space

Question 28

calculating dead space volume

Answer 28

tidal volume - alveolar volume

Question 29

alveolar dead space

Answer 29

Air in alveoli that are surrounded by pulmonary capillaries without blood flow

Question 30

when can alveolar dead space increase

Answer 30

pulmonary embolism

Question 31

physiological dead space calculation

Answer 31

Anatomical Dead Space + Alveolar Dead Space

Question 32

fowlers method nitrogen washout

Answer 32

messures conc of nitrogen exhaled
inspiration - N2 decline rapidly
exhalation - inclines rapidly but not to the same - mixture of dead space and alveolar gas magnitude and plateau

Question 33

phase 1 of fowlers method

Answer 33

low N2 - end of inspiration
all of the dead space air - air in alveoli w/ no blood vessel to diffuse air into
only oxygen that has been exhaled

Question 34

phase 2 of fowlers method

Answer 34

mix of dead space air and alveolar space air

Question 35

Bohrs method

Answer 35

VT x PeCO2 = VA x PaCO2

tidal volume x expire partial pressure of CO2 = Alveolar space x partial pressure of CO2 in arterial blood of alveoli

Question 36

how can we use Bohrs method to find dead space

Answer 36

VT x PeCO2 = VA x PaCO2
VT = VA + VD -> VA = VT - VD
Replace VA with VT - VD
VT x PeCO2 = (VT - VD) x PaCO2 
VD = VT x [(PaCO2 - PeCO2)/PaCO2]

Question 37

Pul. Ventilation

Answer 37

VT x f = VT x RR
VT = Tidal volume [L]
f = RR = respiratory frequency, respiratory rate [min-1