General Respiratory stuff Flashcards
Does a V/Q mismatch respond to 100% oxygen?
Does shunting respond to oxygen? Why?
YES
NO, because the alveoli are not adequately ventilated. Need to be careful with chronic COPD - too much oxygen dampens hypoxic respiratory drive.
What is a shunt?
Occurs when there is good perfusion but inadequate ventilation.
A pulmonary shunt is a pathological condition which results when the alveoli of the lungs are perfused with blood as normal, but ventilation (the supply of air) fails to supply the perfused region.
What is V/Q mismatch?
Some alveoli have high V/Q, some alveoli have low V/Q.
Problem: no shunting; all capillaries receive same ventilation (but lower in this case). capillaries that have more perfusion but are poorly ventilated will average a lower O2 sats.
What does the O2Sats value need to be, to warrant ABG measurement?
< 94%
Does oxygen help with V/ Q mismatch?
Yes because the underventilated alveoli ( with good perfusion) receives more oxygen and that combines with alveoli with a good V/Q to give a better average SatO2.
What happens to Functional Residual Capacity with emphysema?
Increased because
REDUCED elastic recoil, and therefore less resistance to the elastic recoil of the chest.
why don’t you get infarction of lung parenchyma following a PE?
Because of bronchial blood supply
What is the definitive examination for a PE?
CT pulmonary angiogram (CTPA) computed tomography using a contrast dye to obtain an image of the pulmonary arteries.
What is mesothelioma?
Mesothelioma is a type of cancer that develops from the thin layer of tissue that covers many of the internal organs (known as the mesothelium).
The most common area affected is the lining of the lungs and chest wall
What is hypoxic constriction?
capillaries to underventilated alveoli constrict to allow better perfusion to alveoli that are better ventilated.
If >>O2 supplemented then danger of reduced vasoconstriction to underventilated alveoli, and exacerbation of symptoms when oxygen reduced.
What are the four main infections of the lung?
- pneumonia
- TB
- Influenza
- HIV-related lung disease
What is the Wells score used for?
Objectives risks for PE
Diagram of Lung Volumes
What are the clinical features of a PE?
- sudden and unexplained dyspnoea. This maybe the only symptom, especially in the elderly.
- IMP> pleuritic chest pain and haemoptyosis are present only when infarction has occured. PE can be silent!
What’s the normal range for HCO3- ions?
22 - 26 mmol/L
What are the normal values for PaCO2 and PzO2?
PaCO2 = 4.5 - 6.0 kPa
Pa O2 = 11.5 - 13.5 kPa
What is LDH?
Tissue breakdown releases LDH, and therefore LDH can be measured as a surrogate for tissue breakdown.
(Lactate dehydrogenase)
Three big causes of secondary pulmonary hypertension
LHF
COPD and cystic fibrosis
thromboembolic disease (persistent blockage of arteries)
What is a muscarinic receptor antagonist?
A is a type of anticholinergic agent that blocks the activity of the muscarinic acetylcholine receptor.
what is a cardinal feature of bronchitis?
a productive cough.
(usually self resolving and viral)
- an infection of the main airways (bronchi)
Chronic bronchitis features in COPD
What three volumes result in the vital capacity?
Tidal volume + residual inspiratory volume + residual expiratory volume
(what remains is the residual volume)
What are the adenoids?
What is IRV? (lung volumes)
Inspiratory reserve volume
At the end of quiet inspiration, the person could breathe in more and this is termed the inspiratory reserve volume.
Why is cancer on Wells score a related risk with PE?
People with cancer often have a higher number of platelets and clotting factors in their blood.
This may be because cancer cells produce and release chemicals that stimulate the body to make more platelets.
Definititon of asbestosis
Progressive disease characterised by breathlessness and accompanied by finger clubbing and bilateral basa end-inspiratory crackles
What is Polycythemia?
A disease state in which the haematocrit is above 55%
(Haematocrit = volume percentage of RBC in the blood)
Can be due to an increase in the number of RBC (absolute polycythemia), or a decrease in the volume of plasma (relative polycythemia)
What are anticholinergic agents?
A substance that blocks the neurotransmitter acetylcholine in the cns and pns.
These agents inhibit parasympathetic nerve impulses
The nerve fibers of the parasympathetic system are responsible for the involuntary movement of smooth muscles present in the gastrointestinal tract, urinary tract, lungs, etc.
The inspiratory capacity consists of which two volumes?
The volume of a quiet breathe (Vt) plus the inspiratory residual volume.
What is ‘antigenic shift’?
Antigenic shift is the process by which two or more different strains of a virus combine to form a new subtype. Contains mixture of the surface antigens of the two or more original strains. The term is often applied specifically to influenza.
What is cor pulmonale?
Pulmonary heart disease.
Occurs in 25% of patients with COPD.
Caused by pulmonary hypertension causing enlargement of the right ventricle.
Why could you get pain and sob with pleural effusion?
pain due to swelling.
(Parietal membrane is pain sensitive.)
sob due to reduced lung volume
What is the most common cause of hypoxema, and why?
V/Q mismatch becauses the causes are so common.
eg. pneumonia
COPD
embolism
What can be the only symptom of a PE?
sudden onset of unexplained dyspnoea
Pathophysiology of pleural effusion due to LVF
back up of fluids increases pulmonary pressure resulting in pulmonary oedema in the alveoli, fluid in the interstitial fluid, and finally into the pleural cavity.
What’s the cause of primary pulmonary hypertension?
hereditary or idiopathic
Smokers/ COPD. What’s the risk problem following acute bronchitis?
bacterial infections; maybe step. pneumoniae, or H influenzae
What are the two groups of acetylcholine receptors?
- muscarinic, which respond to muscarine
- nicotinic, which respond to nicotine
What symptoms occur after infarction of a PE?
Pleuritic chest pain
haemoptysis
(also unexplained dyspnea)
* many pulmonary emboli occur silently *
(Lung volumes)
What is FRC?
Functional Residual Capacity
The volume of air left in the lungs at the END of a normal breathe. (Includes residual volume)
At this point the respiratory muscles are relaxed and volume is determined by the elastic properties of the lungs and chest wall.
Whats the target O2 sats with COPD?
88-92%
What happens to Functional Residual Capacity with cystic fibrosis?
FRC occurs at a small volume because the lungs are STIFF and have increased elastic recoil.
What do you get a V/Q mismatch with a PE?
No blood beyond the embolism. Blood is shunted to other parts of the lung. V/Q
Perfusion increases, and this reduces V/Q ratio, resulting in << PaO2
Nebulisers; what would you combine this with for asthma and COPD respectively?
Asthma: high driven oxygen
COPD: medical air
What kind of things affect lung compliance?
Fibrotic tissue - eg. lung fibrosis
Loss of elastic recoil - eg. emphysema
atelectasis - greater density of tissue
What is the most common cause of bronchiectasis?
CF
Definition of bronchiectasis
abnormal and permanent dilation of proximal (>2mm) bronchi due to inflammation and subsequent destruction of the elastic and muscular components of their walls.
- associated with < mucociliary clearance
- persistent respiratory infections
Name two key symptoms of bronchiectasis
- persistent productive cough
- large quantities of purulent odorous sputum
Can lymphatic blockage cause pulmonary oedema?
YES
What is the most common cause of pulmonary oedema?
cardiogenic - LHF
back pressure increases hydrostatic pressure; increases fluid leakage in interstitial tissue and then aleovli.
What are the causes of non-cardiogenic pulmonary oedema?
Increased permeability of othe pulmonary capillaries following:
Sepsis
bacterial pneumonia
trauma
What’s the most common type of lung cancer?
non-small-cell lung cancer
Squamous cell carcinoma
Squamous (42% of NSCLCs)
(slow growth and late metastasis)
(Adenocarcinoma is 39%)
Which type of lung cancer spreads quickly?
Small cell carcinoma ; spreads quickly and highly malignant.
approx 15% of cases
What are the three divisions of non-small cell carcinoma?
- squamous cell carcinoma (most common) 42%
- adenocarcinoma (39%)
- large cell carcinoma (8%)
Which lung cancer is more common in non-smokers?
adenocarcinoma
(NSCLC)
associated with asbestos and more common in non-smokers.
What are the characteristics of adenocarcinoma?
More common in non-smokers, associated with asbestos.
Invasion of the pleura and mediastinal lymph nodes is common.
Often metasises to the brain and bones.
Staging classification
Stage 1: localised with no lymph node involvement
Stage 2: 2A, 2B lymph node involvement
Stage 3: spread into mediastinal nodes/ mediastinum
Stage 4: distant spread
Which type of cancer is most often associated with finger clubbing?
squamous carcinoma
What are the risk factors for lung cancer?
Active or passive cigarette smoking is the main one.
Increasing age.
People with COPD
Previous history, exposure to environmental irritants
Red flags for referral if CA lung is suspected:
CXR suggestive of lung cancer
Age >40 which unexplained haemoptysis
Is RhA and Interstitial Lung Disease related?
Yes, over active immune system attacks the lungs.
History of RhA is a risk factor for ILD
Can you get gastric reflux with Interstitial Lung Disease? Why?
Yes
Lung fibrosis can pull oesophagus apart and cause acid reflux.
Some presenting symptoms of Interstitial Lung Disease
- >> dyspnoea
- dry cough
- patients over 60 yrs old, and incidence higher with males.
- finger clubbing (except asbestosis)
- fine crackles on auscultation
- Right ventricular heart strain
What is the definition of pneumoconiosis?
lung fibrosis secondary to inhaled organic dust
Why do you get CXR consolidation around the hilum with Interstitial Lung Disease?
maybe because dust particles phagocyted and collect in the lymphatics around the hilum.
Possible causes of pneumoconiosis…
- coal dust
- silica (found in stone and sand)
- asbestos (brake linings)
What is allergic interstitial lung disease?
inhalation of organic matter with hypersensitive patients.
eg bird faeces (bird fancier’s lung), cotton fibres, farmer’s lung (caused by a fungus in mouldy hay)
NB> acute dysnpoea and cough a few hours after inhalation.
If patients has dry high pitched cough with Interstitial Lung Disease, little can be done except…
codeine/ morphine dampens cough reflex.
With Interstitial Lung Disease, apart from fibrosis, what else can cause restriction in breathing?
reduction in costal muscle strength
Where is there consolidation with Interstitial Lung Disease?
How does it present?
more prevalent at bottom of lungs.
could be reticular or nodular.
Interstitial Lung Disease and ausculation - what would you find?
Fibrotic crackles
A really important symptom Interstitial Lung Disease is….
unexplained chronic exertional dyspnoea
and
dry cough
(and finger clubbing)
What would you find on auscultation with Interstitial Lung Disease?
Fine ‘velco-like’ inspiratory crackles.
What might you find on a CXR with Interstitial Lung Disease?
Kerley B Lines
Reticular lines
Nodular
reticulonodular
What is pivotal when case history taking and suspecting Interstitial Lung Disease?
Hobbies, workplace, exposure to allergens.
What is a diagnostic sign of asbestosis?
asbestos plaques seen on CT scans
What happens to the lymph nodes in silicosis? (classic sign if present)
Eggshell calcification
refers to fine calcification seen at the periphery of a mass and usually relates to lymph node calcification
what are the surfactant cells in the lungs?
type II alveolar cells
How is TB spread?
+ organism
aerosolized droplets; mycobacterium tuberculosis
Cough reflex; efferent pathways travel where?
to the ‘cough centre’ in the medulla via the vagus nerve.
Common causes of ankle oedema
Impaired venous return;pregnancy, immobility
Obstruction; DVT, pelvic mass
Congestive cardiac failure (CCF)
Hypoalbuminaemia (liver disease, nephrotic syndome, malnutition)
Cellulitis
What four groups of drugs can lower respiratory drive centrally?
Alcohol
Opiates
Benzodiazepines
Anaesthetics
What drugs are used in the treatment of acute pulmonary oedema?
diruetics, nitrates, analgesics, and inotropes.
bronchodilators
How does furosemide IV reduce fluid overload in pulmonary oedema?
inhibits NaCl reabsorption in the ascending loop of of Henle to cause diuresis.
(ototoicity potential side effect)
What drug is often combined with furosemide for more aggressive diuresis?
Metolazone
(potent thiazide-related diuretic)
Name an aldosterone inhibiting drug
Spironolactone
Name three loop diuretic drugs
Furosemide
Bumetanide
Ethacrynic acid
What is sodium nitroprusside (SNP)?
Brand: Nitropress
Nitrate causes vasodilation of venous and arterial circulation.
Onset is immediate and effect can last up to 10 mins.
( on World Health Organization’s List of Essential Medicines)
What is GTN?
Glyceryl Trinitrate.
Onset of action of spray is 1-3 minutes, half life 5 mins.
Which drug can do the following; anxiolysis, analgesic, venedilator (and arterial dilator)
Morphine (eg. Oramorph, morphine sulphate)
What is Naloxone used for?
blocks the effects of opioids, especially in overdose.
Effects last 1/2 to 1 hour.
(opioid antagonist)
(It is on the World Health Organization’s List of Essential Medicines)
What is an inotrope?
An inotrope is an agent that alters the force or energy
of muscular contractions.
Name some inotropes
In patients with hypotension who present with CHF, the
principal inotropic agents are dopamine, dobutamine,
inamrinone, milrinone, dopexamine, and digoxin.
What are digoxin, dopamine, dobutamine examples of?
Inotropic agents
What are chronotropic drugs?
Chronotropic drugs change the heart rate and rhythm by affecting the electrical conduction system of the heart and the nerves that influence it, such as by changing the rhythm produced by the sinoatrial node.
Positive chronotropes increase heart rate; negative chronotropes decrease heart rate.
What are the signs and symptoms of hypoxemia?
sweating
tachycardia
poor peripheral perfusion
central cyanosis
restlessness
confusion
Management of Type I Respiratory failure
ABC
oxygen therapy
CPAP
Treat underlying cause
Sputum clearance
Assisted ventilation?
What are the signs and symptoms of type II respiratory failure? (hypercapnia)
breathlessness
cyanosis
confusion (parallels increading CO2 levels)
Flapping tremor
warm peripheries
bounding pulse
What are the risk factors for a pneumothorax?
Smoking is the most important factor. More common in men too.
Marfan’s syndrome
Management of primary pneumothorax
if the rim of air is < 2cm and the patient is NOT short of breath then discharge should be considered
otherwise aspiration should be attempted
if this FAILS (defined as > 2 cm or still short of breath) then a chest drain should be inserted
patients should be advised to avoid smoking to reduce the risk of further episodes
PE: What’s the treatment option if CTPA not feasible?
A V/Q scan is the preferred option if the patient has an allergy to contrast media or has renal impairment.
