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Unit 13 > Spirometry practical > Flashcards

Spirometry practical Flashcards

1
Q

How do you calculate pressure?

A

Pressure (Pa) = Force in N/Area in m^2

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2
Q

What is boyles law?

A

Gives a simple inverse relationship between pressure and volume at a fixed temperature
P is proportional to 1/v
Therefore if volumes doubles, pressure halves.

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3
Q

What is compliance in physics?
How do we calculate it?

A

Compliance - the influence of pressure on a containers volume
How much pressure is required to produce a certain change in volume.
Calculate by the gradeint of a pressure-volume curve.
C - change in vol/ change in pressure.

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4
Q

What is meant by the resting state in the respiratory system?

A

When pressure within the lungs is equal to that of the atmosphere.
No air moves in or out.

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5
Q

The pressure of what anatomical compartment alters during breathing?

A

The intrathoracic compartment relative to atmospheric pressure.

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6
Q

What is amontons law in physics?

A

The relationship between temperature and pressure are directly proportional.
Inc temp molecules to move faster and collide more often and with more force.

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7
Q

What is Charles Law in physics?

A

Simple relationship between temp and volume when pressure is held constant
Directly proportional
Volume increases, temp increases at constant pressure.

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8
Q

What are the different components of water vapour that need to be considered in lung function testing?

A

PH2O - water vapour pressure - contributes to total gas pressure, reduced ‘available for other gases’
Temperature - temp of water vapour influence the pressure (hotter more pressure)

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9
Q

What are the three different common conditions used to compare results in respiratory physiology?

A

BTPS - body temp and pressure, saturated
ATPS - ambient temp and pressure, saturated
STPD - standard temp and pressure, dry.

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10
Q

What are the conditions in respiratory physiology in BTPS?

A

Body temp and pressure, saturated
Inspired air is fully saturated with water vapour at body temp.
This contributes 47mmHg to pressure
So the air is a body temp, atmosphere pressure and fully saturated

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11
Q

What are the conditions in respiratory physiology in ATPS?

A

Ambient temp and pressure, saturated
Expired air collected for analysis
Ambient temp, atmopshereic pressure and fully saturated.

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12
Q

What are the conditions in respiratory physiology in STPD?

A

Standard conditions used to compare O2 consumption nad CO2 production under different conditions.
Use standard temp (273 kelvin, 760mmHg and completely dry air)

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13
Q

How can we convert between different standard conditions in respiratory physiology?

A

use kelvins
correct total pressures for water vapour pressures.

(-47mmHg from BTPS pressure to account for water vapour)
+273 to degrees to get to kelvin.

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14
Q

What are the key components of spirometry?

A

Spirometer - record changes in lung volume
Spirogram - resulting graph of lung volume over time is produced (inspiration is an upwards waveform deflection)

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15
Q

What is a pneumotachometer?

A

An example of a spirometer
Uses flow rate to measure volume
Air is breathed through a fine mesh to create a pressure difference across the mesh
The pressure difference is proportional to flow rate
Volume is then calculated as an integral of flow
V = flow x change in time
Often a non rebreath mask is attached this ensures all inspired air comes from the ambient air and all expired air passes through the flow head for measurement.

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16
Q

What stage of ventilation does the pneumotachometer with a non rebreath mask measure?

A

Airflow in expiration only.

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17
Q

What is inspiratory reserve volume?
What is its normal value?

A

Maximum volume above tidal volume that can be inspired into our lungs
Approx 3 L

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18
Q

What is tidal volume?
What is its norm value?

A

The volume we inspire and expire during restful breathing.
Rate 10-12 bpm and 0.5L

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19
Q

What is expiratory reserve volume?

A

The maximum volume below the tidal volume that we can expire from out lungs
Approx 1.5L

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20
Q

What is residual volume?
What is its norm value?

A

The volume of air remaining in the lungs after a full expiration
Approx 1.2 L
We can never empty the lungs completely.

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21
Q

What is a lung capacity?

A

Measure of lung function
Made from at least two lung volumes

22
Q

What is inspiratory capacity?

A

IRV and TV
all air breathed in until maximal from end of norm expiration

23
Q

What is expiratory capacity?

A

All the air breathed out in maximal expiration after a normal inspiration
Vt plus ERV

24
Q

What is functional residual capacity?

A

The volume of air remaining in the lungs ar the end of normal expiration
ERV + RV.

25
Q

What is vital lung capacity?

A

All the air that can be expired from a maximal inspiration
Calculated by IRV + VT + ERV

26
Q

What is total lung capcacity?

A

All the air that it is possible for the lungs to contain
IRV + VT + ERC +RV

27
Q

What is the average total lung capacity in a healthy young adult?

A

6 litres.

28
Q

What are the different dynamic lung parameters?

A

Forced Vital Capacity
Forced Expiratory volume in one second.

29
Q

What is forced vital capacity?

A

The maximaum volume of air that a person can forcibly expire after a maximal inspiration

30
Q

What is FEV1?
What is is expected value?

A

The total volume of air a person can expire from their lungs in one second after a maximal inspiration.
In healthy young adult should be at least 80% FVC or higher.

31
Q

What are the key difference between how obstructive and restrictive lung disease present on spirometry?

A

Obstructive - reduced FEV1/FVC but FVC remains only slighly or not reduced

Resitrice - FVC reduced but FEV1/FVC is norm as no limitation on outwards airflow only lung volume.

32
Q

What is a flow volume loop?

A

Produces a cyclical shaped graph, plots flow on Y against volume on X
Records the airflow seen in expiration (above X) and inspiration (below X) can be used to test lung function/volumes and identify disease pathophysiology.

33
Q

Identify the start of expiration and inspiration on the flow volume loop?

A

Expiration - point closets to left, follow line above X until retouches X

Inspiration - point furthest to right, follow line below X until retouches X

34
Q

What is PEFR?

A

Peak expiratory flow rate
The maximal rate of flow during expiration, rate tends to peak early in expiration then decrease linearly.

35
Q

Identify PEFR and FEF volumes of a flow volume loop.

A

Left - PEFR
FEF 75%
FEF 50%
FEF 25%

??.??.

36
Q

What is forced expiratory flow?

A

Flow rate normally expressed as a percentage of forced expiratory flow
FEF75%, 50% and 25%

37
Q

What are the missing labels on this flow-volume loop?

A

Left - PIFR
Right - residual volume

38
Q

What do the two dashed lines and the arrow on the flow-volume loop represent?

A

Inner dash - tifal breathting
Outer dash - exercise breathing
Arrow - Functional residual capacity volume on X axis.

39
Q

How does a flow volume loop change in an obstructive lung condition?

A

The vital lung capacity remains the same
However the flow rates decreases giving a shortened but same width curve
Has greater effect on higher flow rates giving a wave like or scooped out appearance to the expiration curve.

40
Q

How does restrictive lung disease appear on the flow volume loop?

A

Reduced total volume
Slightly reduced flow but not at much
Gives a narrowed, shift to right loop.
Lung compliance is reduced for more force is required to expand lungs to the same degree, therefore same force less expansion, Smaller loop but of normal shape.

41
Q

Why do asthmatics tend to find exhalation worse than inhalation?

A

Exhalation - volume of lung and airways narrow slightly anyway, exacerbated in asthma
inspiration - volume of lungs and airways increase slightly, affect dampened by asthma
Overall greater narrowing in exhalation results in worse effect
Struggle in inspiration is often due to high respiratory rate decrease timing available rather than the narrowed airway itself.

42
Q

Why do we perform spirometry?

A

Measure lung function to help make a definitive diagnosis
Confirm presence/absence of airway obstruction
Assess severity of airflow obstruction in COPD and asthma
Detect airflow obstruction in smokers who may have few or no symptoms
Monitor disease progression
Assess response to therapy
Perform pre-operative assessment.
Pre-employement screening or pre-dive assessment
Distingush between obstruction and restriction
Assess severity of respiratory condition.

43
Q

What are the two different types of spirometer?

A

Desktop electronic spirometers
Small hand-held spirometers (portable)

44
Q

What medication should be withheld before spirometry?

A

SABA for 6 hrs
LABA for 12 hrs
Otimally no caffeine or cigarette smoking for 30mins before spirometry.

45
Q

Clinical skill
How should you prepare yourself and the patient for the examination?

A
  1. Explain the purpose of the test - demonstrate the procedure
  2. Record the patient age, height and gender and enter on the spirometer
  3. Note when bronchodilator was last used
  4. Have the patient sitting comfortably
  5. Loosen any tight clothing
  6. Empty the bladder beforehand if needed
46
Q

What instruction should be given to the patient when performing spirometry?

A

Breath in until the lungs are full
Hold the breath and seal the lips around clean mouthpiece (ensure nose clip is used)
Blast the air out forcibly and fast as possible - provide lots of encouragement
Continue blowing until the lungs feel empty.
Repeat procedure until at least 3 reading within 100ml or 5% of each other are obtained.

47
Q

What are the different phases of breathing?

A

Phase 1 - at rest - no air movement Pair = P lung
Phase 2 - inspiration
Phase 3 - expiration

48
Q

Do central or peripheral chemoreceptors have the greatest effect over the rate of respiration>

A

Central - mediates 70% of effect
Peripheral - mediates 30% of effect.

49
Q

What is body plethysmography?

A

Measures thoracic volume and airways resistance
Non invasive pulmonary function test
Able to detect changes in pressure and volume in an airtight container as you breath
Can indicate flow and volume during expiration and inspiration

50
Q

What are some of the aims of adminstering oxygen to a patient?

A

Given when blood PO2 levels are extremely low
Alleviate work of breathing
Reduce stress on heart
Help prevent hypoxemia.

Unit 13 (22 decks)

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