L15 Flashcards by Hayley 1234

Lung compliance is increased in emphysema

BECAUSE

chronic emphysema increases airway resistance.

Both statements are true but are not causally related

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what does Spirometry measure

Lung volumes – How much?

Air flow rates – How fast?

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what do you use to mesure lung function

Pulmonary Function tests, Lung Function tests

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define tidal volume (VT or TV)

Volume of air moved in and out during normal quiet

breath

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what is the approx value of tidal volume

~ 500 ml

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define Inspiratory reserve volume (IRV)

Extra volume that can
be inspired with
maximal inhalation - external intercostal
muscles.

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define Expiratory reserve

volume

Extra volume that can
be exhaled with
maximal effort - internal intercostal and
abdominal muscles.

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define residual volume (RV).

Volume remaining
in lungs after maximal
exhalation.

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when exercising what lung volumes will increase

When you are exercising you need to breath in more O2 (inspiratory reserve) and breathe out CO2 (expiratory reserve)

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define Inspiratory capacity

maximal breath in

Vt + IRV

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define Vital capacity

Maximal breath into out
Volume of air can shift
in/out of lungs (IC +ERV)

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define functional residual capacity

• Lung volume at the end of a normal
expiration when there is no inspiratory
or expiratory muscle contractions (ERV +RV)

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define total lung capacity

Total volume in lungs
when maximally full =
(VC + RV)

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which of the lung capacities is not clinically relevant

inspiratory capacity

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which of the lung capacities is the most clinically relevant

vital capacity

because it is vital

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what is the “resting equilibrium” position for the lungs + thorax (in “elastic” combination)

functional residual capacity

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what are the normal values for functional residual capacity

Normal large FRC ~2.4 L (~40% of TLC),
“Topped up” each breath by the smaller
resting Vt ~500 ml (only ~20% top up!)

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what is the importance of large FRC

At all times during the breath cycle O2 and CO2 exchange can occur between alveolar gas and the pulmonary capillaries.

Prevents large fluctuations in the composition of alveolar gas

eg you don’t want to go from 0% O2 - 100% O2 or from 0% CO2 to 100% CO2

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when you have a restrictive lung disease what does that do to your breathing

breathe more shallowly and rapidly

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what happens in terms of lung volumes in restrictive lung disease

decrease in compliance means that you need to do a lot of work to get air in

Therefore people with this breath more shallow

The whole spirometry trace has gone down

This is because the lung is not expanding

VC ↓
IRV ↓
ERV ↓
RV↓
FRC ↓
TLC↓

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what happens to the way someone breathes in OBstructive lung disease

Increased work due to increased airway resistance,“narrow pipes”, breathe more slowly and deeply

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what happens to the spirometry trace in obstructive lung disease

why

Bronchi constricted, air
obstructed in alveoli, more air remaining in the lung therefore the trace gets shifted up

VC 
IRV 
ERV 
RV ↑
FRC ↑
TLC ↑

Forced measurements give info about what

air flow rates

Air flow rates – how fast?

what is Forced Vital Capacity FVC

– maximum breath into maximum breath out

(VC) - forced out as hard as possible

Variant of vital capacities (VC) are useful for what

useful diagnostic tool for the diagnosis of | lung diseases – indicator of airway resistance

in healthy lungs what % of your total forced expiratory volume is breathed out in 1 sec

80%

in obstructive lung disease FEV1 & FVC decrease. what effect would this have on the ratio of volume expired in 1 second what does that mean

Ratio of less than 70%, indicative of increased airway resistance.

Restrictive lung disease: FEV1/FVC ratio doesn’t change (or increased) what does this mean for airway resistance

no change in airway resistance

why is there no change in airway resistance/FEV1 for restrictive lung disease

Fibrotic lungs are quite stiff therefore it is hard to get air in but they are going to recoil very quickly

FEV1/FVC ratio does not decrease below 70% in restrictive lung disease BECAUSE restrictive lung disease does not affect the airway resistance

both are true and causal

define Ventilation

process by which air moves in and out of the lungs It is ONE process of respiration however Ventilation ≠ Respiration. processes are interdependent Ventilation determines Respiration and vice versa

what is the symbol for volume and time venterlation

a V with a dot on top a dot over anything means per minute

what is Dalton's law of partial pressures

In a gas mixture (air), each gas exerts its own individual pressure, called a partial pressure (P), in direct proportion to its fractional concentration in the mixture.

what is the equation for PP

Partial Pressure = fraction of individual gas x total gas pressure Pgas= Fgas x Ptotal

Need to know the % concentration of each gas and the atmospheric pressure

 O2 =20.93 % FIO2= 0.2093  CO2 =0.03 % FICO2 = 0.0003  N2 =79.04 % FIN2 = 0.7904 • Barometric pressure PB at sea level ~ 760mmHg. • The partial pressures are calculated as:  PO2 = 159 mmHg at sea level  PCO2 = 0.23 mmHg at sea level  PN2 = 601 mmHg at sea level

what is Water vapour pressure at body temperature

– 47mmHg

Air gets warmed | as it moves down the respiratory tract, therefore how would you calculate PP at the trachea

(Barometric pressure PB at sea level ~ 760 mmHg.) (Water vapour pressure at body temperature =-47mmHg) • The partial pressures at trachea are calculated as: Pgas= Fgas x (Ptotal - 47)

what is the respiratory quotient (RQ)

* The amount of CO2 produced in relation to the amount of O2 consumed by metabolism and is dependent on caloric intake. * Considered as a measure of cell metabolism

how do you calculate respiratory quotient (RQ)

𝑅Q =𝑉𝐶O2/𝑉𝑂2 V̇CO2 = amount of CO2 excreted/produced V̇O2 = amount of O2 taken up

what are the RQ values for exclusive FA metabolism, exclusive carbohydrate metabolism and normal conditions

RQFA= 0.7 RQC = 1 QRN = 0.8

what is total mouth venterlation = to

Total (mouth) ventilation (V̇ E ) = frequency (f) x tidal volume (VT) VT= 500mL frequency of breaths per minute = 10-12 therefore at rest approx 5L/min

when would VE ( total mouth ventilation) change

To match metabolic demands (involuntarily, e.g exercise) Voluntarily (changing breathing behavior) eg when you hold your breath

what is dead space

• Some of the inhaled air never gets to the alveoli so cannot gas exchange – known as dead space ventilation ( VD )

• There are two types of dead spaces contributing to VD. what are they

1. Anatomical dead space 2. Physiological dead space (also known as functional dead space) VD = anatomical dead space + functional dead space

what is anatomical dead space

1. Conducting airways (including mouth, trachea) Ventilated but no respiration (no gas exchange)

what is functional/physiological dead space

2. respiratory area (gas exchange) could exchange gases but not happening unused respiratory area (some alveoli that are not used all the time)

Knowing the dead space allows to determine alveolar ventilation (VA)

AV = ventilation - VD

what happens to the dead space in Pulmonary Fibrosis

increases dead space by transforming | respiratory tissue in fibrotic tissue (e.g. cystic fibrosis)

what happens to VD in Pulmonary Hypertension

increased dead space by impairing pulmonary | perfusion (pulmonary arteries not functioning properly)

what is Pulmonary Hypertension and fibrosis's effect on respiration and ventilation

In both cases respiration is impaired and this also | affects the ventilation

what is the effect of Fast Shallow Breathing

↓ alveolar ventilation – causing hypoxia (↓PAO2), hypercapnia (↑PACO2) and acidity • From a gas exchange point of view, wastes ventilation in the dead space • Is energetically costly for the respiratory muscles • No gas exchange (when the tidal volume (VT) is low)

what is the effect of Slow Deep Breathing

• alveolar ventilation – causing hyperoxia (↑PAO2), hypocapnia (↓PACO2) and alkalinity • ↑ Gas exchange • Is energetically costly for the respiratory muscles

The respiratory quotient (RQ) is: A. V̇O𝟐/V̇CO2 B. a measure of cell metabolism. C. V̇CO𝟐/V̇O2 D. A and B are both correct. E. B and C are both correct.

Lung disease -> ventilation impaired • Atelectasis (fibrosis) • Emphysema • Pulmonary oedema (fluid) Vascular disease -> perfusion impaired • Pulmonary hypertension • Heart failure • COPD

various reasons same consequences