Respiratory Flashcards

Question

Factors Influencing Pulmonary Ventilation:

Answer 1

- The resistance of the airways - The surface tension of the alveoli - The compliance of the lung tissue

Answer 2

force that opposes flow of air

Answer 3

Resistance impedes airflow into lungs. Increased Resistance = increased energy needed to breathe in. Airways generate 80% of resistance. Diameter of airway is inversely proportional to the resistance it produces.

Answer 4

...is insignificant, as total diameter of airways is large. Large airway diameters in beginning of conducting zone Resistance disappears in terminal bronchiole → diffusion drives gas exchange

Answer 5

increased resistance to overcome in order to breathe

Answer 6

Smooth muscle of airway constricts (e.g., asthma) Mucous plugging of airways (e.g., COPD, bronchitis, cystic fibrosis) Obstruction of bronchioles and alveoli by infectious material (e.g., pneumonia)

Answer 7

Water molecules stick to other water molecules Resists any force that tends to increase surface area of liquid Occurs in alveoli due to the water molecules inside them If left unchecked, keeps alveoli from stretching during inspiration

Answer 8

Type II alveolar cells (pneumocytes) synthesize pulmonary surfactant Decreases alveolar surface tension by separating water molecules from each other Allows easier expansion during inspiration and prevents alveoli from collapsing during expiration

Answer 9

can cause pulmonary disease e.g. the lack of surfactant in premature infants leads to infant respiratory distress syndrome. e.g. chronic smokers produce less surfactant, leading to issues seen in COPD.

Answer 10

Measure of volume change with given change in transpulmonary pressure

Answer 11

tensile properties of lung tissue (how stiff the lungs are)

Answer 12

High compliance = increased lung stiffness = increased energy to stretch during inspiration Ventilation is more efficient in areas of lung with increased compliance. Areas with reduced compliance expand less.

Answer 13

o Apex is less compliant. o Base is more compliant.

Answer 14

 Distensibility of lung tissue  Reduced alveolar surface tension

Answer 15

 Fibrosis (e.g., acute respiratory surfactant distress syndrome, scarring after chemotherapy)  Reduced production of surfactant (e.g., premature lungs, COPD)  Reduced flexibility of thoracic cage (e.g., scoliosis, cerebral palsy)

Answer 16

 Pulmonary emphysema

Answer 17

Detect presence and severity of lung disease Determine the effects of intervention Assess preoperative risk

Answer 18

Haemoptysis (coughing up blood) Pneumothorax Unstable cardiovascular status Aneurysms - danger or rupture due to increased thoracic pressure Recent eye surgery (wait 4 weeks due to increased pressure at back of eye) Nausea/vomiting Recent thoracic or abdominal surgery Can worsen Angina due to blood pressure changes

Answer 19

Smoking 24hrs – has impact on gas transfer Alcohol for at least 4hrs – reduces gas exchange A large meal for 2hrs Bronchodilators – stop taking inhaler if possible Vigorous exercise for at least 30mins Wearing tight clothing or surgical appliances

Answer 20

ensure accuracy

Answer 21

specific volumes of air contained by different portions of lungs at specific points in the respiratory cycle

Answer 22

volume of air inhaled or exhaled with each breath under resting conditions (during the respiratory cycle)

Answer 23

volume of air left in lungs after forced exhalation

Answer 24

volume of air that can be forcefully exhaled after normal tidal volume exhalation

Answer 25

maximum volume of air that can be forcefully inhaled after normal tidal volume inhalation

Answer 26

a combination of 2 or more volumes

Answer 27

Maximum volume of air contained in lungs after maximum inspiration tidal volume + residual volume + expiratory reserve volume + inspiratory reserve volume

Answer 28

Maximum volume of air that a person can move in or out of lungs (air expelled by a full expiration after full inspiration) tidal volume + expiratory reserve volume + inspiratory reserve volume

Answer 29

Volume of air remaining in lungs after tidal (normal) expiration expiratory reserve volume + residual volume

Answer 30

Maximum volume of air that can be inspired after normal expiration (from the position of functional residual capacity) tidal volume + inspiratory reserve volume

Answer 31

Absolute volume of gas in the thorax at any point in time and at any alveolar pressure (FRC-pleth)

Answer 32

air that enters and exits lungs but does not make it to areas where gas exchange can occur Total dead space = alveolar dead space + anatomical dead space

Answer 33

air in airways that does not reach alveoli or respiratory bronchioles

Answer 34

air in alveoli that cannot be absorbed into bloodstream due to lung disease or blood flow limitations

Answer 35

Volume of air moved in and out of lungs per minute breathing frequency expressed in breaths/minute × tidal volume

Answer 36

Volume of air reaching alveoli per minute and is available for gas exchange breathing frequency expressed in breaths/minute - total dead space

Answer 37

the amount of energy a person needs to breathe Elastic work: done to overcome elastic recoil of chest wall and pulmonary parenchyma and surface tension of alveoli Resistive work: done to overcome resistance of airways and tissues

Answer 38

the use of helium dilution or plethysmography.

Answer 39

a gas of known helium concentration is breathed through a closed circuit and the volume of gas in the lungs is calculated from a measure of the dilution of the helium (helium is an inert gas that is not absorbed or metabolised)

Answer 40

a large airtight box that allows pressure-volume relationships in the thorax to be determined. When the plethysmograph is sealed, changes in lung volume are by a change in pressure within the box

Answer 41

A method of assessing the size of the lungs. Used to determine the elastic properties and the compliance of the lung and identify pathophysiology. Provides information on the functional status of the lungs, assessment of disease severity, course of disease and response to treatment. Identify hyperinflation and gas trapping.

Answer 42

Static lung volumes cannot be measured directly (there is always some air in the lungs). We calculate them from indirect measurements made using static lung volume techniques. There are 3 techniques: whole body plethysmography, nitrogen washout and helium dilution (the differences between these could be an exam question) Whole body plethysmography is the gold standard.

Answer 43

1) Patient sits in box, box volume is corrected for patient weight, nose clip and mouthpiece attached. 2) door is sealed and the subject is asked to sit for 1 minute, allowing temperature to settle. Patient is asked to breathe normally. 3) Shutter is closed at end of normal tidal expiration and patient is asked to pant softly against the shutter at a frequency of 1 breath per second 4) Panting graph generated shows changes in box pressure and mouth pressure 5) Shutter is reopened, patient asked to breathe in fully to maximal inspiration and then breath out fully to empty (like a sigh) 6) The test finishes with a big breath back in to full 7) steps are repeated until 3 technically acceptable traces are obtained

Answer 44

a method of assessing lung function by measuring the volume of air that the patient is able to expel from the lungs after a maximal inspiration (also measures speed/flow). The results of the test are represented graphically as a plot of volume against time = forced expiratory spirogram. It is a reliable method of differentiating between obstructive and restrictive diseases. It can also help to monitor disease severity.

Answer 45

chronic obstructive pulmonary disease asthma

Answer 46

fibrotic lung disease

Answer 47

FEV1 = forced expiratory volume in 1 second FVC = forced vital capacity FEV1/FVC ratio

Answer 48

forced expiratory volume in 1 second maximum volume of air forcefully expired in the first second after maximal inspiration

Answer 49

forced vital capacity maximum volume of air forcefully expired after maximal inspiration = the total volume of air that the patient can forcibly exhale in one breath.

Answer 50

the ratio of FEV1 to FVC expressed as a percentage

Answer 51

a percentage of the predicted normal for a person of the same sex, age and height

Answer 52

Patient is asked to take big breath in and blow out normally. Then do another big breath in before blasting it out as hard as can until empty.

Answer 53

The expiratory volume-time graph

Answer 54

be smooth and free from abnormalities caused by: Coughing during expiration, extra breath during expiration, slow start to forced expiration, sub-maximal effort.

Answer 55

Slow Start Mouth Leak – weakness in face muscles = cannot get lips tight around mouth piece Coughing in first second Variable effort Glottis Closure (opening between the vocal folds)

Answer 56

Free from common errors Reproducible A minimum of 3 technically acceptable manoeuvres are required, of which the best two curves should be within 5% of each other The chosen values for FVC and FEV1 should not differ from the next best values for FVC and FEV1 by more than 150mL.

Answer 57

FVC can be reduced in any condition that limits the lungs ability to achieve a ‘full’ inspiration... - Reduced lung compliance (lung fibrosis, loss of lung volume) - Chest deformity - Muscle weakness (myopathy, myasthenia gravis) When lung volume is restricted FEV1 also reduces in proportion = FEV1:FVC ratio is normal

Answer 58

FEV1 is reduced in any condition that reduces vital capacity, but it is particularly reduced when there is diffuse airway obstruction = FEV1:FVC ratio is reduced - most commonly seen in asthma and COPD.

Answer 59

maximum rate of airflow that can be achieved during a sudden forced expiration after full inspiration It gives an indication of diffuse airway obstruction.

Answer 60

The patient takes a full inspiration, applies their lips to the mouthpiece and makes a sudden maximal expiratory blast. A piston is pushed down the inside the cylinder, progressively exposing a slot in the top, until a position of rest is reached. The position of the piston is indicated by a marker and PEF is read from a scale. The best of 3 attempts is accepted as the peak flow rate. It is somewhat dependent on patient effort.

Answer 61

measuring peak expiratory flow or plotting flow against volume on a flow volume loop (provide same information)

Answer 62

Airflow is represented on the vertical axis and lung volume is on the horizontal axis Expiratory flow appears above the line, inspiratory flow below the line At TLC airways are stretched (dilated) and airway resistance is minimised, so maximum (peak) expiratory flow is reached quickly after the start of forced expiration. As expiration continues, lung volume progressively diminishes, airway resistance increases and maximum flow achievable (at each lung volume) declines. In a healthy patient this declining portion of the expiratory limb is quite straight. When no further air can be exhaled, flow is zero and the loop reaches the horizontal axis. The inspiratory manoeuvre can then begin.

Answer 63

narrowing of the airways

Answer 64

1) take a full inspiration 2) maximal forced expiration 3)maximal forced inspiration

Answer 65

* PEF = peak expiratory flow * RV = residual volume * PIF = peak inspiratory flow * FEF = forced expiratory flow

Answer 66

...the flow of gas. The flow signal is integrated to derive volume.

Answer 67

concave expiratory part of loop (sudden drop in flow early in expiration due to collapse of airways) normal inspiratory part of loop Reduced FEV1 (<80%) FVC reduced to a lesser extent Reduced FEV1/FVC Ratio (<0.7)

Answer 68

Curve reaches top of expected but drops faster Proportional reduction in FEV1 and FVC (<80%) FEV1/FVC Ratio remains normal (>0.7) Flow volume loop cannot tell you what restrictive ventilatory defect they have

Answer 69

describes the rate of transfer of a gas between alveoli and the erythrocytes in the alveolar capillaries pressure difference between two sites (how good lungs are at passing O2 from alveoli to bloodstream)

Answer 70

Carbon monoxide is used as O2 is difficult to measure o similar properties to oxygen o technically easier to use o safe at low concentrations

Answer 71

Transfer Coefficient (KCO) = Rate of disappearance of CO from alveolar gas during 10s breath hold. Alveolar Volume (VA) = Lung Volume ‘seen’ by inhaled CO during the measurement

Answer 72

Carbon Monoxide Transfer Factor (TLCO) = Total ability of lungs to transfer gas across into bloodstream Calculated by multiplying the Transfer Coefficient (KCO) X VA

Answer 73

transfer of oxygen into the blood quickly becomes limited by the saturation of haemoglobin = carbon monoxide used to measure gas transfer instead

Answer 74

The amount of carbon monoxide (CO) transferred per minute The pressure gradient across the alveolar membrane (alveolar partial pressure)

Answer 75

the patient inspires a gas mixture of helium and carbon monoxide, hold their breath for 10 sec and then breathes out. A sample of expired gas is collected and analysed for alveolar concentrations of helium and carbon monoxide. The change in concentration of helium (which is an inert gas and not absorbed or metabolised) between the inspired and alveolar samples is the results of gas dilution and gives a measurement of alveolar gas volume.

Answer 76

because CO (carbon monoxide) and CH4 (methane) have to have time to get to alveoli where gas exchange takes place

Answer 77

Inert gas, almost insoluble (doesn’t react or diffuse through membranes) Chemically stable, almost inactive and have negligible leakage into the blood Provides estimate of alveolar volume Dilution effect on CO Can use Helium, Argon, Neon, Methane

Answer 78

CO and O2 bind to same sites(behaves like O2 – attaches to haemoglobin) COHb levels are negligible in non-smokers Readily measure CO in low concentrations COHb and O2Hb dissociation curves same shape and affected in same manner Even when large amounts of CO combine with Hb, the PCO remains low

Answer 79

A minimum of two technically acceptable gas transfer manoeuvres should be performed with a maximum of five. Five gas transfer manoeuvres will increase carboxyhaemoglobin (COHb) by approximately 3.5%, which will ultimately decrease measured transfer factor by 3.5%). TLco results should be within the repeatability criterion of 0.67 mmol/min/kPa. Kco within 0.10 mmol/min/kPa/L VA within 5%. The mean of two technically acceptable manoeuvres should be reported.

Answer 80

COPD, Pulmonary fibrosis, Pulmonary vascular disease, Renal failure, Cardiac failure, Mitral valve disease, Cirrhosis, Collagen diseases.

Answer 81

Asthma – increase in gas exchange. Often get increase in blood supply around lungs Pneumonectomy – DLCO reduces because less lung but KCO increases Extrapulmonary restriction - type of restrictive lung disease, indicated by decreased alveolar ventilation with accompanying hypercapnia (buildup of carbon dioxide in your bloodstream)

Answer 82

alveoli destruction and distention TLCO ↓ KCO ↓ Diffusion distance ↑ SA for gas exchange ↓ = gas exchange reduces

Answer 83

TLCO ↓ (but can be ↑) KCO tends to be ↑ Reason not known Hyperaemia of airways Greater perfusion of lung apices in asthma

Answer 84

e.g. Fibrosis fibrotic tissue makes it hard for gas exchange = TLCO ↓ KCO ↓

Answer 85

e.g. Muscle weakness, scoliosis, pleural disease underinflated lungs = less air into them = TLCO ↓ KCO ↑

Answer 86

At a constant temperature, the volume (V) of a given mass of an ideal gas is inversely proportional to its pressure (P), that is, PV=K. The constant (K) is proportional to the mass of the gas (the number of moles) and its absolute temperature. Assuming that temperature remains constant (isothermal conditions of measurement): P1 × V1=P2 × V2. I.e. if the volume of a closed container is doubled, the pressure will fall by half

Answer 87

1. Determination of transfer gas volume (FRC-pleth) is possible if the lungs are treated as a closed compartment and alveolar pressure can be measured at the same time as changes in volume. 2. At the end of tidal expiration (at FRC) the alveolar pressure approximates mouth pressure and thus can be measured at the mouthpiece 3. When the airway is occluded at the end of the mouthpiece, the lungs can then be treated as a closed compartment, this prevents airflow and holds the lung at a constant volume (FRC) 4. The patient is asked to pant gently against the shutter, causing pressure changes within the thoracic cavity, resulting in rarefaction (inspiratory efforts) and compression (expiratory efforts) of the air within the cavity (lungs) 5. Changes in the thoracic volume are recorded by changes in box pressure, these changes can be used to calculate TGV (FRC-pleth) 6. By relating changes in alveolar pressure (reflected by changes in mouth pressure), to changes in thoracic gas alveolar volume (reciprocal to changes in the box pressure during panting). TGV (FRC-pleth) can be calculated at the moment of occlusion (at the end of a normal breath- FRC)

Answer 88

a known volume is injected into the box resulting in an increase in box pressure, therefore, box pressure changes during the manoeuvre can be converted to volume changes own volume is injected into the box resulting in an increase in box pressure, therefore, box pressure changes during the manoeuvre can be converted to volume changes

Answer 89

FRC measured during the test. When FRC has been calculated, we calculate the other subdivisions of the lungs by asking the patient to fully inhale and exhale: ERV and VC measured at the end of the test

Answer 90

the line should be straight errors can be caused by excessive force leading to hysteresis, excessive panting or box leakage

Answer 91

At least three FRCpleth values that are technically acceptable and agree within 5% (ie, the difference between the highest and lowest values divided by the mean is ≤5%) should be obtained and the mean value reported. If there is a larger deviation, additional values should be obtained until three values agree within 5% of their mean, and the mean value should be reported

Answer 92

Calculating Lung Compliance = change in volume ÷ change in pressure

Answer 93

a measure of the lungs ability to stretch and expand. It is a measure of the dispensability of the elastic tissue. the measurement of lung compliance can be useful in determining the effects of a disease on the structure of the lung.

Answer 94

stiff lungs (restrictive defect- pulmonary fibrosis)

Answer 95

floppy lungs (obstructive - emphysema)

Answer 96

lungs are bigger = more air in lungs than there should be increased total lung capacity (TLC) but airways tighter = cannot expel air Increased functional residual capacity (FRC) - due to air trapping increased residual volume (RV) due to air trapping Reduced vital capacity (VC) - less air moved in and out of lungs lungs become floppy = increased compliance

Answer 97

smaller lungs due to... intrinsic = stiff lungs that do not expand/contract properly extrinsic = crushing lungs due to overweight or scoliosis Reduced TLC, FRC, RV, VC Z score is lower than expected for all (-)

Answer 98

In patients with obstructive pulmonary disease, who may have gas trapping and hyperinflation, FRC measured by body plethysmography is usually higher than when measured using dilution or washout techniques. Gas trapping and hyperinflation in obstructive disease involves areas of the lung being unventilated, due to airway collapse. – gas isn’t going to disperse into areas that are collapsed = underestimated volumes Body plethysmography measures all gas in the thorax and will incorporate unventilated areas of the lung, whereas dilution and washout techniques can only measure areas of ventilated lung due to the measurement technique.

Answer 99

Weakness of the respiratory muscles causes a restrictive ventilatory defect, with reduced TLC and VC. Comparison of VC when sitting upright and in a supine position allows assessment of the diaphragm strength – pressure of the abdominal contents on a weak diaphragm causes a fall of VC in the supine position by ~30%. Global respiratory muscle function can be assessed by measuring mouth pressures.

Answer 100

pulmonary disorders defined by restrictive patterns on spirometry Characterised by a reduced distensibility of the lungs, compromising lung expansion and thus reduced lung volumes, particularly with reduced total lung capacity.

Answer 101

Intrinsic = lung parenchymal involvement – e.g. interstitial lung disease Extrinsic = outside pressure reducing lung volume – obesity, neuromuscular disorders, chest wall deformities (scoliosis, kyphosis)

Answer 102

decreased lung volumes increased work of breathing inadequate ventilation Inadequate oxygenation. Spirometry shows a decrease in the forced vital capacity (FVC).

Answer 103

conditions affecting the lung interstitium (space between an alveolus and its surrounding capillaries). there is inflammation and fibrosis (scarring) in the lung interstitium.

Answer 104

unknown cause - Idiopathic pulmonary fibrosis - Interstitial pneumonia

Answer 105

known cause - Connective tissue and autoimmune disease: Sarcoidosis, Rheumatoid arthritis - Infective: Mycoplasma pneumonia, Pneumocystis pneumonia - Environmental: Asbestosis, Silicosis - Drugs: Methotrexate, Amiodarone, Bleomycin

Answer 106

- Male sex - Cigarette smoking - Regular dust exposure (could be occupational)

Answer 107

idiopathic pulmonary fibrosis

Answer 108

Type of ILD characterised by fibrosis in the lung interstitium, which is irreversible.

Answer 109

Fibrosis is triggered by repeated injury to the lung tissue (e.g. from inhaled toxins). Usually, fibroblasts respond to this lung injury by secreting extracellular matrix, which repairs the injuries. In ILD, genetic mutations lead to excess secretion of extracellular matrix, which accumulates in the lung interstitium, leading to fibrosis. The lung interstitium becomes thicker, increasing the diffusion distance for oxygen to travel from the air in the alveoli to the blood in the surrounding capillaries. Hence, gas exchange in the lungs is compromised.

Answer 110

- Progressive exertional dyspnoea (usually presents slowly, over many weeks and months) - Dry cough - Connective tissue disease symptoms, such as arthralgia, difficulty swallowing and dry eyes - General malaise and fatigue (due to underlying connective tissue disease or vasculitis)

Answer 111

Lung function tests: typically show a restrictive pattern (reduced FVC, reduced FEV1, normal ratio)

Answer 112

- Idiopathic pulmonary fibrosis: antifibrotics - Connective tissue disease: corticosteroids

Answer 113

Indications for long-term oxygen therapy: o Resting PaO2 ≤ 7.3kPa o Resting PaO2 ≤ 8.0kPa with peripheral oedema/polycythaemia/pulmonary hypertension

Answer 114

- Respiratory failure: due to failure of gas exchange in the lungs. - Pulmonary hypertension: due to chronic hypoxic pulmonary vasoconstriction (constriction of blood vessels supplying fibrotic areas of the lung, to direct blood to healthier areas of the lung).

Answer 115

disease characterised by progressive, largely irreversible airflow obstruction = chronic bronchitis + emphysema

Answer 116

Occurs when the respiratory system fails to maintain gas exchange. Respiratory failure is classified according to blood gas abnormalities type 1 = low oxygen level type 2 = high carbon dioxide level

Answer 117

hypoxemic = low oxygen level in blood paO2 <60mmHg with normal/below normal paCO2 Gas exchange is impaired at level of alveolo-capillary membrane Caused by lung damage that prevents adequate oxygenation of the blood (hypoxaemia), but remaining lung is still sufficient to excrete the carbon dioxide produced by tissue metabolism

Answer 118

Ventilation (V) = air that reaches alveoli Prefusion (Q) = blood that reaches the alveoli mismatch causes hypoxemia

Answer 119

hypercapnic – too much CO2 in blood o PaCO2 >50mmHg o Low pO2 = Hypoxemia is common due to respiratory pump failure Alveolar ventilation is insufficient to excrete carbon dioxide produced = CO2 retention in lungs As lungs become less efficient, CO2 increases = chemoreceptors act to increase drive to breathe. Overtime, CO2 becomes too high.

Answer 120

The most common cause is COPD Airway obstruction (e.g. blockage of trachea by choking = underventilation) Respiratory muscle weakness (e.g. Guillain-Barre syndrome)) Central loss of drive (e.g. opiates – lead to loss of drive to breathe) Chronic lung disease (re-setting of central drive)

Answer 121

Occurs due to damage to lung tissue pulmonary oedema severe pneumonia COVID-19 acute respiratory distress syndrome (ARDS) emphysema

Answer 122

damage to vital organs due to hypoxaemia central nervous system depression due to increased carbon dioxide levels respiratory acidosis (carbon dioxide retention) ultimately fatal unless treated

Answer 123

- Arterial blood gases- measures oxygen and carbon dioxide levels in the blood - Pulmonary function tests - identifies obstruction, restriction, and gas diffusion abnormalities.

Answer 124

Correction of Hypoxemia - The goal is to maintain adequate tissue oxygenation, generally achieved with an arterial oxygen tension (PaO2) of 60 mmHg or arterial oxygen saturation (SaO2) at about 90%. Un-controlled oxygen supplementation can result in oxygen toxicity and CO2 narcosis. Inspired oxygen concentration should be adjusted at the lowest level, which is sufficient for tissue oxygenation. Oxygen can be delivered by several routes depending on the clinical situations in which we may use a nasal cannula, simple face mask nonrebreathing mask, or high flow nasal cannula.

Answer 125

Too high levels of oxygen, too quickly, results in death by hypercarbia – the drive to breathe has been taken away (peripheral chemoreceptors need time to adjust) = low levels (controlled oxygen) is required

Answer 126

A type of obstructive lung disease. It is a chronic respiratory disease characterised by permanent bronchial dilation, due to irreversible damage to the bronchial wall.

Answer 127

An initial insult to the bronchi (e.g. infection) results in immune cells being recruited. These immune cells secrete cytokines and proteases, leading to inflammation in the bronchi. Inflammation damages the muscle and elastin found in the bronchial walls, leading to bronchial dilation.

Answer 128

impaired muco-ciliary clearance and dysregulated immunity

Answer 129

Dilated bronchi are predisposed to persistent microbial colonisation, as mucus traps in the dilated bronchi. Blockage of the airways – if airway is occluded air cannot get down = alveoli are not going to be perfused = whole areas of lung cannot function.

Answer 130

increases airway resistance in airways due to narrowing = increased work of breathing + patients are unable to fully expel air during exhalation

Answer 131

asthma, chronic bronchitis, emphysema, obstructive sleep apnoea, bronchiectasis

Answer 132

decrease in compliance of lungs = increasing amount of work needed to expand and contract lungs = Patients are unable to completely stretch the lungs to breathe in sufficient air = increased work of breathing

Answer 133

Restrictive diseases effect all of lung parenchyma = cause reduced oxygen saturation unless obstruction is widespread, patients can continue to have normal or near-normal oxygen saturation

Answer 134

pulmonary fibrosis neonatal respiratory distress syndrome sarcoidosis Pneumoconiosis

Answer 135

Lung diseases often have elements of both restrictive and obstructive pathologies. The most common example of mixed lung disease is cystic fibrosis, where airways are narrowed and the lung parenchyma is stiffened.

Answer 136

Reduced FEV1 (<80% of the predicted normal) Reduced FVC (but to a lesser extent than FEV1) FEV1/FVC ratio reduced (<0.7)

Answer 137

Skeletal abnormalities (e.g. kyphoscoliosis), Neuromuscular diseases (e.g. motor neuron disease, myasthenia gravis, Guillan-Barre syndrome), Connective tissue diseases, Obesity or pregnancy.

Answer 138

Reduced FEV1 (<80% of the predicted normal) Reduced FVC (<80% of the predicted normal) FEV1/FVC ratio normal (>0.7)

Answer 139

assess reversibility with a bronchodilator administer 400 micrograms of salbutamol and repeat spirometry after 15 minutes presence of reversibility is suggestive of a diagnosis of asthma absence of reversibility suggests COPD Partial reversibility may suggest a coexisting diagnosis of asthma and COPD

Answer 140

= obstructive FEV1 >80% = mild obstruction FEV1 50-80% = moderate obstruction FEV1 30-50% = severe obstruction FEV1 <30% = very severe obstruction

Answer 141

= normal or restrictive VC >85% = within normal limits VC 75-85% = borderline restriction VC <75% = probable restriction

Answer 142

lung expandability (stretch)

Answer 143

elasticity from elastin surface tension which is decreased by surfactant

Answer 144

more resistance = difficult to stretch + readily recoils stiff lung due to high elastic recoil thick balloon

Answer 145

less resistance = easily stretched + doesn't easily recoil plastic bag

Answer 146

change in volume / change in pressure

Answer 147

Restrictive lung diseases (compromised lung expansion) * Intrinsic - Interstitial Lung Disease (ILD) - e.g. pulmonary fibrosis (scarring of lung tissue) * extrinsic - poor muscular effort (muscular dystrophy, Myasthenia Gravis, Guillain-Barre Syndrome) or structural limitation (scoliosis/obesity) Reduced surfactant = increased surface tension (e.g. neonatal/acute respiratory distress syndrome where fluid builds up in alveoli)

Answer 148

degeneration of parenchyma = loss of alveoli elastic recoil harder for lungs to expand extra work required to exhale increased lung compliance

Answer 149

scarring/hardening of lung tissue elastin replaced by collagen decreased stretch (stiff) decreased lung compliance increased work of breathing

Answer 150

reduced compliance

Answer 151

functional residual capacity volume of air in lungs at rest

Answer 152

all lung volumes except residual volume FEV1 = forced expiratory volume in 1 sec FVC = forced vital capacity = volume of air forcibly exhaled after full inspiration VC = vital capacity = max air exhaled when blowing out as fast as possible PEF = peak expiratory flow = max flow exhaled when blowing out at steady rate

Answer 153

allows identification of obstructive or restrictive ventilatory defects

Answer 154

FEV1/FVC <70% FEV1 is reduced more than FVC

Answer 155

FEV1/FVC >70% FVC reduced more than FVC

Answer 156

Too much carbon dioxide (CO2) in the blood caused by hypoventilation of the body can eventually cause hypoxaemia due to reduced respiratory drive can conversely be caused by long term hypoxaemia = body tries to compensate = increased CO2 in the blood. This is known as type 2 respiratory failure.

Answer 157

PaCO2 greater than 4.2kPa and PaO2 less than 8kPa caused by reduced respiratory drive common in advanced COPD patients due to: long term hypoxaemia or lack of gas exchange occurring in the alveoli thanks to poor tissue quality patient will present as drowsy and with low respiratory rate as a result of the increased CO2 in the brain

Answer 158

Abnormally low partial pressure of oxygen in the blood

Answer 159

tissue oxygen delivery is inadequate to support normal the aerobic metabolism of the tissues

Answer 160

emphysema + chronic bronchitis chronic inflammation from prolonged exposure to noxious particles or gases, most commonly cigarette smoke Chronic inflammation causes airway narrowing and decreased lung recoil

Answer 161

All except residual volume measured using spirometry Body plethysmography or helium dilution used to measure functional residual capacity (FRC) - this can be used to calculate residual volume (FRC-expiratory reserve volume)

Answer 162

used to measure lung volumes 1) fixed amount of helium mix in reservoir 2) normal tidal breathing 3) at the end of a normal expiration (at FRC) shutter closed 4) patient begins to breath in helium mixture 5) helium moves into lungs until equilibrium is reached and helium level in resiovoir levels off Helium not absorbed across alveoil-capillary membrane = initial amount of helium is equal to final amount can calculate FRC measures volume of air in upper airway only (doesn't measure air in emphysema bullae)

Answer 163

1) patient breathes in 100% oxygen 2) exhales nitrogen containing gas initially left in lungs 3) measured over course of several minutes until nitrogen reduces to 0 initial nitrogen in lungs = total nitrogen exhaled can calculate FRC disadvantage = can cause oxygen retention in patients with severe COPD due to 100% oxygen overcoming pulmonary hypoxic vasoconstriction = worsening VQ mismatch

Answer 164

respiratory system fails to maintain gas exchange classified by blood gas

Answer 165

hypoxemic (low oxygen in blood) paO2 <60mmHg normal paCO2 gas exchange is impaired at the level of the alveolar-capillary membrane Examples: pulmonary oedema, COVID, severe pneumonia

Answer 166

hypercapnic (high carbon dioxide in blood) paCO2 >50mmHg hypoxemia (tissue oxygen delivery is inadequate) caused by respiratory pump failure

Answer 167

low partial pressure of oxygen in blood

Answer 168

too much carbon dioxide in blood caused by co2 retention (failure to remove) can lead to hypoxemia due to reduced respiratory drive or can be caused by long-term hypoxemia (body compensates leading to increased co2 in blood

Answer 169

long term hypoxemia due to lack of gas exchange = retention of co2 = hypercapnia = type 2 respiratory failure

Answer 170

ventilation/perfusion ratio per min air reaching alveoli/blood reaching alveoli via capillaries

Answer 171

damage to lung tissue (pulmonary oedema, pneumonia, acute respiratory distress syndrome) damage prevents adequate oxygenation of blood = hypoxemia (<60mmHg) remaining lung is still sufficient to excrete carbon dioxide being produced by tissue metabolism = normal co2 level in blood

Answer 172

Pump failure = hypercapnia Decreased ventilatory effort or inability to overcome high resistance alveolar ventilation is insufficient to excrete co2 being produced = co2 retention lung is affected as a whole = co2 accumulates = respiratory acidosis

Answer 173

damage to organs due to hypoxemia CNS depression due to hypercapnia fatal if not treated

Answer 174

hypoxemia = dyspnea (SOB), confusion, cyanosis Body tries to accommodate = tachycardia, tachypnea

Answer 175

hypercapnia change in behaviour, headache, coma

Answer 176

arterial blood gases - measure o2 and co2 in blood renal (kidney) function liver function pulmonary function ECG chest radiography

Answer 177

correction of hypoxemia - controlled o2 supplementation (uncontrolled = oxygen toxicity/co2 narcosis) ventilatory support - e.g. non-invasive positive pressure ventilation

Answer 178

compromised lung expansion decreased lung volumes (reduced TLC) increased work of breathing inadequate ventilation/oxygenation reduced FVC

Answer 179

hypersomnia or insomnia

Answer 180

intrinsic = arising from within body (idiopathic insomnia, narcolepsy, OSA) extrinsic = secondary to environment (inadequate sleep hygiene, alcohol sleep disorder) circadian rhythm disruption (shift work, jet lag)

Answer 181

daily complaints of insufficient sleep or not feeling rested

Answer 182

excessive sleepiness daytime sleep episodes

Answer 183

sudden + uncontrolled sleep attacks

Answer 184

cataplexy = sudden bilateral loss of muscle tone usually after strong emotion sleep paralysis = aware of surroundings but unable to move hypnagogic hallucinations = sensations that feel real but are imagined automatic behaviour = doing things without thinking and not remembering

Answer 185

measured at end of normal expiration = functional residual capacity (FRC) body plethysmography used to measure (panting against closed shutter)

Answer 186

carbon monoxide transfer coefficient alveoli problem with reduced gas exchange COPD emphysema - destruction go alveoli Pulmonary fibrosis - scarring of alveoli

Answer 187

carbon monoxide transfer coefficient incomplete alveolar expansion with preserved gas exchange - extra-parenchymal restriction (scoliosis, chest wall deformity, neuromuscular) increased pulmonary blood floe from areas with low gas exchange to areas with better gas exchange (asthma)

Answer 188

1. Circadian rhythm (body clock) = 24 hour cycle, rhythmic, intrinsic process, Generated from the suprachiasmatic nucleus (SCN) of the hypothalamus- linked to retinol ganglion cells (responding to light entering the eye) 2. Homeostatic drive (sleep pressure) = Dependent on previous sleep quality/ duration, Pressure to sleep builds up the longer we are awake

Answer 189

Circadian pacemaker is linked to light exposure The longer you are awake and alert with neuronal activation, there is a build-up of adenosine which causes an increased sleep need (homeostatic drive)

Answer 190

= an environmental agent/event that provides the stimulus for a biological clock Most potent Zeitberger affecting sleep/wake is light. Without a Zeitberger (light) the clock runs at 25 hours naturally - can occur in blindness.

Answer 191

Hormone that causes sleepiness Produced by the Pineal gland Released/suppressed in response to light/dark = Important to seek light during the day and dim light in the evening Linked to photoreceptor in the eye that detect light intensity (Retinol ganglion cells) Blue light has the greatest power to switch off melatonin (high blue light levels in natural light and in LED light)

Answer 192

Pineal gland switched off and Melatonin release is suppressed

Answer 193

Pineal gland switched on and Melatonin is released

Answer 194

Each cycle lasts around 90 minutes: - Stage 1 sleep (5%) - Stage 2 sleep (50%) - Stage 3 (Delta) sleep = slow wave/deep sleep) (20%) - REM (rapid eye movement) sleep (25%)

Answer 195

Stage 1-3 = voluntary muscle paralysis

Answer 196

hypotonia of skeletal muscles only diaphragm working ensures we don’t act out our dreams

Answer 197

EEG during polysomnography investigations is used to stage sleep by monitoring electrical activity of the brain - Each stage of sleep exhibits different waveforms

Answer 198

survey to score the chance of dozing when completing certain tasks

Answer 199

Obstructive sleep apnoea will exacerbate all other sleep problems and may be the primary cause

Answer 200

Characterized by periodic narrowing and obstruction of the pharyngeal (upper) airway during sleep, despite ongoing effort to breathe Muscles relax during sleep- soft tissue at the back of the throat collapses and can block or partially obstruct the upper airway Leads to partial reductions (hypopnoea) and/or complete cessation (apnoea) of airflow that last at least 10 seconds Leads to reduction in blood oxygen levels and an increase in carbon dioxide levels The brain responds causing the patient to rouse = airway reopens There is an adrenaline response and a surge in heart rate as well as blood pressure surges

Answer 201

partial obstruction of airway

Answer 202

Familial history Epworth sleepiness score>10 Obesity (extra weight on throat) Snoring >40 years old Witnessed apnoea More common in males (due to deposition of fat) Restless sleep Crowded/narrow pharynx

Answer 203

The pharynx walls are susceptible to collapse Due to muscle relaxation during sleep, there is loss of the necessary contraction of the pharyngeal dilators leading to narrowing/collapse

Answer 204

sleep = relaxation of muscles apart from diaphragm With OSA = pharynx collapses Impaired alveolar ventilation = hypoxaemia + hypercapnia arousal threshold reached = adrenergic response = increase in catecholamines = increase heart rate, contraction of smooth muscle, blood pressure surges pharynx reopens = blood gas levels return to open patient goes back to sleep

Answer 205

Apnoea-hypopnoea index = >5 events per hour saw tooth dipping - following apnea spO2 slowly falls, then quickly returns to baseline as airflow restored Usually snore is observed Heart rate and blood pressure rises in response to each event Respiratory effort is maintained but there is a reduction in respiratory effort during events

Answer 206

loss of respiratory effort

Answer 207

activated inflammatory pathways, increasing risk of disease

Answer 208

puts pressure on blood vessels = can lead to sustained hypertension

Answer 209

systemic hypertension increased inflammation and oxidative stress metabolic dysfunction insulin resistance/glucose dysregulation - poorly controlled diabetic weight gain hyper coagulability - atherosclerosis/ stroke endothelial dysfunction congestive heart failure/arrythmias

Answer 210

Apnoea hypopnoea index within normal range (<5 events per hours) Oxygen levels stay steady Snoring observed Significant heart rate variability throughout Flow limitation observed on trace (but flow not reduced enough to be marked as a hypopnoea- >30%) Can have similar clinical issues as OSA

Answer 211

weight loss Continuous positive airway pressure (CPAP) therapy Mandibular Advancement Devices positional therapy tonsil reduction/tonsillectomy nasal surgery hypoglossal nerve stimulation

Answer 212

mouthguard that keeps airway open Mild-moderate OSA with a near to normal BMI Used for symptomatic snoring

Answer 213

Implanted in chest and connected to the nerve under the tongue - causes genioglossus muscle activation and decreases upper airway collapsibility Stimulation timed with breathing- during each inspiration the system delivers a signal to the hypoglossal nerve

Answer 214

Training of the upper airway dilator muscles using neuromuscular electrical stimulation Therapy consists of a series of pulse bursts

Answer 215

Gold standard in treating moderate/severe OSA – first line treatment Delivered pressurised air through a mask sealed over nose/mouth to splint the airway Works immediately, resolves apnoea's, desaturations and HR variability Side effects are minimal - dry mouth/nose, red marks on face, air leak = noise

Answer 216

combination of obesity (BMI> 30kg/m2) and daytime hypercapnia (PCO2 >45mmHg or >6kPa) Nocturnal alveolar hypoventilation Arises from a complex relationship between sleep disordered breathing, diminished respiratory drive and obesity-related respiratory impairment Increased risk of pulmonary hypertension and heart failure

Answer 217

Significantly obese Morning headaches Daytime sleepiness/morning grogginess May have peripheral oedema Polycythaemia (high red blood cells) Often have a degree of OSA sleep study = SpO2 staying low throughout the night- not returning to baseline An arterial blood gas will confirm type 2 respiratory failure

Answer 218

Blood gas changes can be metabolic or respiratory in origin ABG’s are used to identify the presence of type 1 and 2 respiratory failure In health, we are driven to our next breath by the PaCO2, which is linked to pH Additional receptor (the hypoxic centre) in the brainstem monitors PaO2- spends most of the time ‘asleep’, unconcerned about minor fluctuations in oxygenation level

Answer 219

hypercapnia = CO2 retention measurement of arterial blood gas (PaCO2)

Answer 220

NIV = Non-invasive ventilation Process of supporting ventilation with the aim to normalise blood gases Delivers two different pressures to assist or establish adequate ventilation

Answer 221

Drive to breath has been lost Apnoea’s occur with no respiratory effort O2 desaturation is slow No snoring (no narrowing at back of throat)

Answer 222

Adaptive servo-ventilation (not safe in patients with HF) Treat the underlying cause of the condition: o Heroin/opioids o Heart failure o COPD o Brainstem dysfunction o Myotonic dystrophy o High altitude o Severe obesity

Answer 223

- OSA and COPD - Poorer outcomes - Pulmonary hypertension - CPAP needed

Answer 224

Respiratory Effort Related Arousals Increased upper airway resistance = Increased respiratory effort = Arousals occur results in excessive daytime sleepiness

Answer 225

Severe upper airway resistance Obstructive apnoea and hypopneas Sleep fragmentation Hypoxemic episodes – dips in O2 levels throughout night

Answer 226

Repetitive absent respiratory efforts during sleep – drive to breathe is effected Open airway Sleep fragmentation Hypoxemic episodes

Answer 227

o Cataphrenia o Night terrors o Sleep eating o Sleep walking

Answer 228

o REM behaviour disorder o Nightmares

Answer 229

Problems getting to sleep Difficulty staying asleep through the night Common causes = Stress, Irregular sleep schedule, Poor sleeping habits, Mental health issues, Physical illnesses, Medications, Neurological problems

Answer 230

Overwhelming urge to move the legs when they are at rest. These unpleasant sensations keep many people from falling asleep since they constantly want to move their legs.

Answer 231

Repetitive movements in sleep, most typically in the lower limbs. Brief muscle twitches, jerking movements or an upward flexing of the feet.

Answer 232

Cataplexy = Sudden loss of postural tone brought on by emotion e.g. Laughter Excessive sleepiness = not relieved by adequate sleep, persistent throughout day Sleep paralysis = Onset of sleep or on awakening Hypnagogic hallucinations = Dream imagery at onset or end of sleep

Answer 233

Respiratory Polygraphy = Pulse oximetry, Oronasal airflow, Chest and/or abdominal movements, Sound, Body position and movements Polysomnography = respiratory polygraphy + Sound, EEG, Tibial EMG

Answer 234

Cessation of airflow (Apnoea) = arterial blood passing through the lungs picks up less oxygen = Reduction in levels of saturation (desaturation) Airflow returns to normal = Oxygen saturation returns to the original level.

Answer 235

with any arousals from sleep - Periodic Limb Movement Disorder - Sleep Related Breathing Disorders

Answer 236

high and steady O2 levels low and steady heart rate

Answer 237

Dips in O2 levels throughout the night – airway collapses and then opens up again following arousal. blood pressure changes with pulse rate changes = increases risk of high blood pressure

Answer 238

Resistance of upper airway that doesn’t restrict airway enough to reduce amount of O2 in lungs but causes arousal due to increased effort. Pulse rate rises and falls = patients sleep is disturbed.

Answer 239

Good baseline of O2 saturation. Dips caused by muscle weakness – when patient goes into REM sleep (every 90min) muscles work at lower level making breathing harder.

Answer 240

reduced airflow

Answer 241

no airflow

Answer 242

upper airway collapses = portions of no airflow (slight dip in O2) but still effort throughout

Answer 243

central drive to breathe is interrupted = portions of no effort + no airflow

Answer 244

Essential for sleep staging, identifying arousal Non polarisable silver electrodes stuck to head

Answer 245

Rapid eye movement sleep The potential between two electrodes placed 1cm above and 1 cm below outer canthus of R and L eye

Answer 246

The potential between two electrodes placed 2cm apart on the skin of chin . The chin (submental) muscle: - High activty when awake - Low activity when sleep (paralysis of skeletal muscles during REM sleep)

Answer 247

alpha waves (regular pattern of 8-12Hz)

Answer 248

slow rolling eye movements positive occipital sharp transients of sleep central theta activity enhance beta activity attenuation of alpha rhythm

Answer 249

sleep spindles (short runs of rhythmical EEG waves of 12-16Hz) K complexes (duration 0.5s with well delineated sharp wave 12-14Hz)

Answer 250

delta waves (slow EEG waves 1-2Hz)

Answer 251

EEG looks like stage 1 rapid eye movement appears on EOG recording EMG = low amplitude (paralysis of skeletal muscles)

Answer 252

70% of volume change due to diaphragm 30% due to rib movements

Answer 253

Change in volume ÷ change in pressure

Answer 254

lung volume and lung recoil pressure

Answer 255

the difference between the pressure inside the lungs (the alveolar pressure) and the pressure outside the lungs (the pleural pressure).

Answer 256

An overproduction of collagen and scaring on the lungs = stiff small lungs = reduced compliance

Answer 257

The elastic recoil of the lungs is required to expire gases, thus even though floppy lungs will not be stiff and could indicate increased compliance, this lack of elasticity actually reduces compliance.

Answer 258

chemical control of breathing Central Chemoreceptors = main ones located in the brain stem Peripheral (arterial) chemoreceptors = reserve/back up located in carotid & aortic bodies

Answer 259

Respond to pH of cerebrospinal fluid CO2 diffuses across the blood-brain barrier and changes pF

Answer 260

Respond to low levels of oxygen Low levels of oxygen cause hypoxic drive to breath causing an increase in respiration. High levels of oxygen reduce hypoxic drive to breath so inspiration levels reduce.

Answer 261

predicted value+/- 1.645 SD This includes 90% of the normal population. Values outside this range statistically likely to be abnormal

Answer 262

R = (observed – predicted)/SD A positive z score indicates a value higher than predicted, a negative z score indicates a value lower than predicted.

Answer 263

higher than predicted

Answer 264

lower than predicted

Answer 265

reduced in obstructive reduced in restrictive

Answer 266

Normal (may be slightly reduced) in obstructive reduced in restrictive

Answer 267

reduced in obstructive Normal in restrictive

Answer 268

obstructive

Answer 269

restrictive

Answer 270

percent predicted can have the potential to over diagnose those older and underdiagnose those younger

Answer 271

Idiopathic pulmonary fibrosis (IPF)