clinical relevance / extra pbl 2

Question 1

what spirometry values are abnormal in emphysema and why

Answer 1

IRV i increased due to loss of elasticity meaning that air can’t be expelled properly; total lung capacity (TLC) is also increased due to gas trapping

Question 2

brief overview of TH2 pathway response to allergens

Answer 2

1. dendritic cells pick up allergen -> become APC
2. APC present to CD4 cells 3. TH2 response initiated -> cytokine release (IL4,5,13)
3. IL5 attracts eosinophils to the area
4. IL4 + 13 work in partnership to cause IgE release from B cells

Question 3

5 investigations useful in asthma diagnosis

Answer 3

1. PEF variability
2. spirometry with reversibiltiy
3. FeNO
4. blood eosinophils
5. allergy tests

Question 4

what do steroids aim to treat in asthmatic patients

Answer 4

airway inflammation

Question 5

give 5 clinical features of acute severe asthma

Answer 5

1. PEF 33-50% best
2. respiratory rate >25/min
3. HR >110 bmp
4. inability to complete sentences in one breath
5. wheeze (progressive, worsening)

Question 6

7 signs of life-threatening asthma

Answer 6

1. altered conciousness
2. exhaution
3. arrythmia
4. hypotension
5. cyanosis
6. silent chest
7. poor respiratory effort

Question 7

how is acute asthma treated

Answer 7

ABCDE
treat with bronchodilators (SABA), oxygen, corticosteroids (oral pred if poss)

Question 8

what could cause COPD in a young patient

Answer 8

cannabis use

Question 9

what are 3 key elements to look for in an asthma review

Answer 9

inhaler technique; are they taking all the inhalers; triggers (pets, dust etc.)

Question 10

what is a rescue pack (asthma/COPD)

Answer 10

antibiotics and oral steroids for patients with pre-existing condition for use as part of an acute exacerbation plan

Question 11

3 clinical findings in emphysema

Answer 11

reduces cricosternal distance; quiet breathsounds; obstructive pattern (FEV1/FVC)

Question 12

what is the MRC dyspnoea scale

Answer 12

1. not troubled by breathlessness except on stenuous exercise
2. short of breath when hurrying
3. walks slower than contemporaries on level ground due to SOB/ has to stop
4. stops for breath after 100m/few mins on level ground
5. too breathless to leave the house/undressing

Question 13

3 investigations to help confirm a diagnosis of COPD

Answer 13

1. post bronchodilator spirometry (to check its not asthma)
2. a1 antitrypsin levels
3. elevatd Hb in FBC (polycythemia)

Question 14

what is hypoxic drive

Answer 14

a form of respiratory drive in which the body uses oxygen chemoreceptors instead of carbon dioxide receptors to regulate the respiratory cycle

Question 15

what is the O2 target range in a COPD patient

Answer 15

86-92%

Question 16

what are some examples of cardiac causes of acute breathlessness (9)

Answer 16

HF; AS; congenital heart disorders; MI; HCM; pericarditis; myocarditis; arrythmias; MS

Question 17

what are some resp causes of acute breathlessness (10)

Answer 17

COPD exacerbation; acute asthma; pneumonia; croup; pneumothroax/haemothorax; ARDS; acute bronchitis; PE; pleural effusion; pulmonary oedema

Question 18

signs that acute SOB has a resp cause (4)

Answer 18

cough, wheeze, stridor, hemoptysis

Question 19

signs acute SOB has a cardiac cause (4)

Answer 19

nausea; chest pain; sweating; palpitations

Question 20

what 3 things are key to ask when taking a SOB history

Answer 20

1. Speed of onset of breathlessness (dinural variation, episodic)
2. progression and variablity (cant do hobbies now etc.)
3. exacerbating and relieving factors

Question 21

what type of hypersensitivity reaction is atopy

Answer 21

type 1 - exaggerated IgE mediated immune response

Question 22

what immune cell is usually hyper-responsive in atopic people

Answer 22

T cells

Question 23

describe second exposure to triggering substances in asthmatics (immunologically)

Answer 23

1. Asthmatics have a naturally high level of IgE antibodies which are bound to receptors on mast cells;
2. On second exposure, the allergen binds to the IgE and activates these mast cells to degranulate;
   3.This binding causes the release of histamine, heparin, prostaglandins and leukotrienes which causes the contraction of the smooth muscle in the airways and inflammation - occurs through both late and early phase;
3. early phase histamine release causes : a) Smooth muscle contraction which causes a subsequent difficulty breathing,
   b) Blood vessel dilation causing increased permeability of the blood vessel wall which causes fluid to leak out into the interstitial spaces;
4. late phase: eosinophils, basophils, Th2 cells and leukotrienes are recruited to the site of the reaction as a result of interleukins –> leukotrienes (LTB4 and LTc4) cause smooth muscle contraction and damage to the epithelium and attract neutrophils, mast cells and eosinophils to their location even after the allergen is gone

Question 24

what is the atopic triad

Answer 24

1. Allergic rhinitis Inflammation of the mucosal membrane lining the nose;
2. Asthma Inflammation of the lung airways which is usually reversible;
3. Atopic dematitis Inflammation, redness and swelling of the skin

Question 25

how is the majority of O2 carried in the body

Answer 25

the majority of it is bound to respiratory pigments - haemoglobin and myoglobin (mostly all in haemoglobin, the very little bound to myoglobin is stored in the muscles for use during a sudden increase in O2 demand).

Question 26

2 ways O2 can be carried in the body

Answer 26

bound to haemoglobin; dissolved in the blood plasma

Question 27

what 3 factors determine the rate of O2-haemoglobin dissociation

Answer 27

[H+], temperature, 2,3-Diphosphoglycerate (2,3-DPG)

Question 28

what is the Bohr effect

Answer 28

a shift to the right of the O2-haemoglobin dissociation curve due to a lower affinity for O2 in more acidic/CO2 rich conditions

Question 29

why is the O2-Haemoglobin curve sigmoidal?

Answer 29

It gets easier for the next oxygen to bind to haemoglobin with every O2 that binds prior to - when one O2 molecule bind there is a structural change in the whole haemoglobin molecule which allows for increased access to the Haemgroup in the other subunits of the protein

Question 30

3 ways CO2 is transported in the body

Answer 30

1. dissolved into the blood plasma/RBCs as bicarbonate (the majority); 2. in solution in the blood plasma or cytoplasm of RBCs; 3. bound to protein subunits of haemoglobin/ to other plasma proteins

Question 31

what is chloride shift

Answer 31

an exchange of ions that takes place in our red blood cells in order to ensure that no build up of electric change takes place during gas exchange - bicarb out and Cl- in

Question 32

why is chloride shift reversed in the lungs compared to the rest of the blood

Answer 32

to allow HCO3- to enter and be converted by carbonic anhydrase to CO2 and then diffuses into the alveolar air

Question 33

CO2 -> HCO3- reaction

Answer 33

CO2+H2O ⇌ H2CO3 ⇌ H+ +HCO3- initial step involves the use of carbonic anhydrase

Question 34

what is the Haldane effect

Answer 34

oxygenation of blood in the lungs displaces carbon dioxide from hemoglobin, increasing the removal of carbon dioxide

Question 35

what are the 4 types of respiratory acid-base disorders (and what is unbalanced in them)

Answer 35

1. respiratory acidosis (the blood pCO 2 rises and pH falls) 2. respiratory alkalosis (pCO 2 falls and pH rises, occurs during hyperventilation) 3. metabolic acidosis (excessive production of H+ or excessive excretion of CO3-) 4. metabolic alkalosis (excessive intake of bicarbonate or excessive loss of acidic fluid e.g. during vomiting)

Question 36

how does the paraympathetic system control the RT

Answer 36

Ach release causes bronchoconstriction - useful when there is a need to reduce the flow of air to the lungs, such as during an asthma attack

Question 37

what is the main NT involved with RT sympathetic control

Answer 37

adrenaline - relaxation of smooth muscle

Question 38

symp/parasymp control of mucous and blood vessels i the RT

Answer 38

sympathetic: decreases muscous secretion and BV constriction; parasympathetic: promotes mucus secretion and BV dilation

Question 39

what is the pulmonary plexus

Answer 39

Network of autonomic nerves and ganglia located at pulmonary hila of each lung

Question 40

role of the pulmonary plexus

Answer 40

Regulates bronchial smooth muscle tone, mucus secretion, vascular permeability, and blood flow

Question 41

pulmonary plexus nerve supply

Answer 41

sympathetic - indirectly from the cervical sympathetic ganglia via the cardiac plexus; directly from the sympathetic cardiac nerves from the paravertebral ganglia of T2 to T6 segments of the spinal cord parasympathetic - vagal trunks (cranial nerve X) via several cardiac nerves

Question 42

how to calculate alveolar ventilation

Answer 42

VCO2/FCO2 v - volume of CO2 produced f - fraction of alveolar ventilaiton that is CO2

Question 43

biochem make up of surfactant

Answer 43

Phospholipids make up around 75% - form a lattice structure called tubular myelin that forms film that spreads over entire surface of alveoli; main ion is Ca2+;

Question 44

5 funcitons of surfactant

Answer 44

1. Reduces surface tension in alveoli and prevents collapsing tendency of lungs; 2. stabilise the alveoli to withstand collapsing 3. play an important role in inflation of lungs after birth 4. Defense against infection and inflammation 5. Stops transudation of fluid from blood into alveoli

Question 45

what is cor pulmonale

Answer 45

right heart failure - most commonly due to COPD, occurs due to loss of vascular bed and chronic hypoxic pulmonary vasoconstriction (HPV) due to alveolar wall destruction

Question 46

common signs of cor pulmonale (6)

Answer 46

Fainting spells during activity; Chest discomfort/pain; Swelling of the feet or ankles; Symptoms of lung disorders, such as wheezing or coughing or phlegm production; Bluish lips and fingers (cyanosis)