LECTURE 5 RESPIRATORY Flashcards
what does the bony thorax consist of?
sternum, 12 thoracic vertebrae, 12 pairs of ribs
what overlays the thorax?
2 clavicles & 2 scapulae (forming shoulder girdles that attach to upper limbs)
what does the middle of thorax correspond to?
T7
what is the level of T1?
uppermost margin of apex of lungs
where is the centre of thorax?
18cm below vertebra prominens in females, 20 cm in males
what does PA projection use as anatomy landmark?
vertebra prominens C7
what does AP projection use as anatomy landmark?
jugular notch
how many cm is t7 below jugular notch?
t7 is 8 to 10cm below jugular notch
what is the paranasal sinuses lined with?
by mucous membrane continuous with nasal cavity
what are the paranasal sinuses?
maxillary, frontal, ethmoid, sphenoid
what is the height of maxillary sinuses?
3-4cm vertical height- roots of molar teeth project onto floor of sinus (possible root for infection)
where are the frontal sinuses?
above orbits- generally paired but not symmetric
how do the sinuses appear on radiographs?
all sinuses overlap & superimpose so they dont have clear borders
what is the larynx suspended from?
hyoid bone
what is the larynx made of?
3 unpaired cartilages- epiglottis, thyroid cartilage, cricoid cartilage & 3 paired cartilages
what is the epiglottis?
seals larynx to prevent foreign bodies entering trachea
what is the thyroid cartilage?
“Adam’s apple” – largest and least mobile cartilage
what is the cricoid cartilage?
ring forming inferior and posterior wall of larynx – attached to first tracheal ring.
what is provides further protection to the trachea?
provided by vocal cords (known as vocal folds)
how long & wide is trachea in adults?
12cm long, 2.1-2.5 cm wide
how does the trachea appear in radiograph?
slightly to right side of thorax- gives right paratracheal stripe, but should be close to midline in PA view- anterior to oesophagus
what is the trachea made of?
15-20 posteriorly incomplete cartilagenous rings that prevent collapse & overexpansion- stacked structure prevents occlusion of trachea during head movement
what does the mucosa of trachea & bronchi comprise of?
ciliated cells, goblet (mucous producing) cells, sero-mucous glands in sub mucosa
what do upper airway radiographs visualise?
larynx & trachea
what level does the trachea divide at?
T5 into 2 primary bronchi (right is larger)
how big is right bronchi?
2.5cm long, 1.2cm wide- affected by foreign bodies more
how big is left bronchi?
5cm long & 1.1 cm wide
what do primary bronchi divide into?
secondary bronchi made of cartilage plates
how many lobes does right & left lung have?
r= 3 lobes, l= 2 lobes
what does the secondary bronchi divide to form?
tertiary bronchi- right lung (10) left lung (8-10)
what do tertiary bronchi divide into?
divide to form bronchioles- no cartilage in wall, have smooth muscle
how do bronchi appear in radiograph?
very thin walled, contain air & surrounded by air
what are the outpouching connected to bronchioles?
alveoli where gas exchange occur - they terminate in alveolar sacs
how many airway divisions are between the larynx & alveoli?
23
what are larger airways held open by?
cartilage
what are respiratory bronchioles held open by?
elastic tissue- susceptible to collapse
what is the outer surface of lungs covered in?
visceral pleura
what is the inner surface of thoracic all covered in?
parietal pleura
what do pleural membrane produce?
fluid that acts as lubricant
how does pleura appear in radiographs?
not normally visible on plain radiograph, except when they fold to form fissures
what does the mediastinum contain?
central cardiovascular & tracheobronchial structures, oesophagus, fat, thymus & lymph nodes
what effect can mediastinal masses have on radiograph?
can obliterate or displace mediastinal contours- wider when patient is supine due to increased venous return
what does the base of each lung rest on?
diaphragm- right is higher due to presence of lover on right
what is the costophrenic angle?
outermost lowest portion of pleural cavity where diaphragm meets ribs
where does the apex of lung project to?
points superiorly & posterior to clavicle
what is the costal surface of lungs in contact with?
ribs
what enters & leaves through the hilus?
bronchi, pulmonary & lymphatic vessels, nerves
what is the hilus?
junction of lung & mediastinum- best investigated using MRI
what are the 3 lobes in right lung?
superior, middle, inferior
what seperates superior lobe from middle?
horizontal (transverse) fissue- runs from hilus to 4th rib
what seperates the middle lobe from inferior in right lung?
oblique fissue
what sperates the superior & inferior lobe in left lung?
seperated by oblique (major) fissure
how do lung fissures appear in lateral film?
visible as fine, white lines
what is the course for major lung fissures?
course obliquely, roughly from level of 5th thoracic vertebra to diaphragmatic surface of pleura a few cm behind sternum
what are each lobes divided into?
bronchopulmonary segment
what is each lobe supplied by?
tertiary bronchus, pulmonary artery branch, bronchial artery branch & drained by pulmonary vein - surrounded by CT
what are lungs supplied by?
both pulmonary & systemic circulation
what is pulmonary circulation?
low pressure, originates in right ventricle & terminates in left atrium- carries deoxygenated blood into lungs for gas exchange
what does systemic circulation supply?
bronchi & bronchioles
what is the bronchial artery a branch of?
thoracic artery
what does the bronchial vein drain in to?
azygos vein
what is the highest point that right dome reaches?
6th intercostal space
when supine, what is diaphragm doing?
it is elevated, lower lobes compressed
on full inspiration, how many ribs should be visible?
10 ribs above diaphragm
when is exposure made of inspiratory images?
exposure is made on second inspiration
what does contraction of diaphragm do to domes?
lowers done- predominated when supine, lifts & flares ribs- parasternal & scalenes are also active
what happens to diaphragm on standing?
diaphragm shortens, parasternals and scalene more activated
what happens to diaphragm in respiratory disease?
additional recruitment of other rib cage muscles and neck inspiratory muscles if there are high lung volumes and/or high resistance
what are the forces that act on lungs?
alveolar pressure, negative intrapleural pressure, intrapleural surface tension, elastic forces
what is the role of alveolar pressure?
pressure tends to keep the lungs inflated
what is the role of negative intrapleural pressure?
the pressure in the space between the two pleural layers is subatmospheric: this tends to suck the lungs outwards
what is the role of intrapleural surface tension?
the pleural space is filled with fluid. Surface tension makes the outer layer of the lungs loosely adhere to the inner wall of the chest
what are the elastic forces acting on the lung?
elastic tissue in the lung opposes inflation and facilitates deflation
what happens when gas enters the intrapleural space?
the negative intrapleural pressure (a force keeping the lungs inflated) is lost- elastic forces (collapsing the lung) dominate, and the lung deflates
what are radiographic signs of a pneumothorax?
Visceral pleura becomes visible – parallel to chest wall – especially on expiratory films- CT is often more useful- both inspiratory & expiratory images are needed- mediastinal shift to contralateral lung
what is the vital capacity?
total amount of air that can be moved through the airways by a maximal inspiration which is followed by a maximal expiration
what is tidal volume?
amount of air moved through airways during normal breathing
what is inspiratory reserve capacity?
extra air that can be added to the lungs after a tidal inspiration
what is expiratory reserve capacity?
extra air that can be removed from the lungs after a tidal expiration
what is the residual volume?
amount of air left in lungs are a tidal expiration
how do we transport oxygen?
as oxygen (gas) has low water solubility and carbon dioxide is higher, a carrier is required, haemoglobin (Hb)
how much oxygen can each Hb molecule carry?
4 oxygen molecules (4 binding sites)
what is saturation a measure of?
how many binding sites are occupied- if every Hb molecule is carrying 4 oxygen, saturation is 100%- the max is 95-98%
what does arterial oxygen content indicate?
how much oxygen the blood is carrying - content= saturation X (Hb)
when is o2 transport normal?
when person has normal (Hb) & normal saturation o2 transport
when is o2 transport low?
if person has low (HB) and normal saturation 02 transport
what is the relationship between oxygen pressure & saturation?
when PO2 is high, saturation is high- when PO2 is low, saturation is low
what happens if the partial pressure of carbon dioxide (PCO2) increases?
our pH will fall
how much is PCO2 allowed to change before respiration is altered?
change by +1 Torr
what happens if PaCO2 increases & decreases ?
ventilation increases or ventilation decreases- pao2 is allowed to fall much more severly before ventilation is stimulated, about 100 torr to 50 to 60 torr
what is a tension pneuomothorax?
injury to chest wall & injury is acting like a valve causing gas to fill the lung cavity & increasing pressure- stops heart getting back to blood
what can diseases of the lung tissue produce in radiographs?
opacity & lucency
what is the ratio of air to tissue?
11:1
what causes opacities in radiographs?
atelectasis, pulmonary oedema, pheumonia, haemorrhage, tumour
what are radiographic signs of aspiration?
unilateral hyperinflation (expiratory images show gas trapping), atelectasis, visualise foreighn body with CT)
what is atelectasis?
collapse/incomplete expansion of alveolia- can be obstructive (resorption to obstructed bronchus) & nonobstructive (pneumothorax, deficiency of surfactant, compression by transudate, exudate or tumours)
what are radiographic signs of atelectasis?
increased radiodensity, displacement of fissures & hilus + mediastinal shift
what is bronchiectasis?
Irreversible dilation of the bronchi caused by destruction of walls during infection- uncommon
what are symptoms of bronchiectasis?
chronic cough, purulent sputum (looks pussy due to infection), recurrent infections
what are radiographic signs of bronchiectasis?
peribronchial fibrosis (fibrous tissue around bronchi), increased pulmonary markings, atelectasis, dilate bronchi
what is chronic bronchitis (COPD)?
Increased mucus production and narrowing, cough- can be due to smoking & can be confused for pneumonia in radiographs
how is chronic bronchitis diagnosed?
chronic cough for 3 months for 2 years
what is emphysema?
destruction of alveolar walls causes dilated air spaces- causes empty space in lungs
what are the radiographic signs seen in emphysema?
hyperinflation of lungs (gas becomes traps), hyperlucency (less lung tissue & vascularity making dark lung fields), increased retrosternal air space, loss of vascularity, flattened diaphragm (due to lungs over-expanded), small heart, thickened bronchial walls
what is cystic fibrosis?
Abnormal exocrine function affecting several body systems (cannot secrete chloride ions so mucus is very sticky & remains in airways)- Causes cough, wheezing, recurrent pneumonia, dyspnoea (breathelessness)
what are radiographic signs of cystic fibrosis?
hyperinflation, peribronchial thickening, bronchiectasis (widening of airways)
what is epiglottitis?
Acute inflammation of pharynx due to bacterial or viral infection, drug abuse and other burns- causes breathing difficulties
what are the radiographic signs of epiglottitis?
swollen epiglottis- only radiograph patients with stable airways
what is neoplasia?
metaplasia of brochial cells- if epithelial cells transform you get large cell tumours (squamous cell carcinoma or adenocarcinoma e.g. cells of mucous glands)- if endocrine cells transform, get small cell tumours)
where can tumours appear in neoplasia?
centrally located (hilar- small cell tumours) or peripherally located (large cell tumours in lungs)
what are symptoms of neoplasia?
bronchial irritation, atelectasis & infections, nerve damage due to local growth, distant metastases
what are the common types of neoplasia?
Mostly bronchogenic carcinoma – arises from bronchial or alveolar epithelium e.g. adenocarcinoma, small cell tumours, squamous cell carcinoma, non small cell tumours
what is adenocarcinoma?
33% of tumours, most common form in nonsmokers, 75% are peripheral
what are small cell tumours?
25% of tumours, most are central (hilar mass)
what are squamous cell carcinoma?
25% of tumours, most are central (hilar mass)- hard to detect
what are non small cell tumours?
15% of tumours- most are peripheral
what is atelectasis?
obstruction of airways
when are masses malignant or benign?
if mass is more 4cm+= malignant- if fully calcified, lesions are benign
what is doubling time?
time required to double tumour mass (increase diameter of sphere by 25%)
what is the average double time is malignent neoplasms?
180 days
what is the doubling time if lesion is benign?
if doubling time is <30 days or >2 years= lesion is benign
what are the nodules in young non smokers with no history of neoplasma?
usually inflammatory
what are common patterns of metastatic tumours?
miliary (rash with lesions- lots of small tumours in both sides of lungs), solitary nodules, cavitating, oedema if lymphatics obstructed
how do metastatic tumours are in lungs?
via blood stream, lymphatic or direct invasion
where is the main origin of metastatses?
breast, kidney, gut, gonads
what is a pleural effusion?
abnormal accumulation of fluid in pleural space- due to disease processes
what are the 2 types of pleural effusions?
transduate (oedema- affecting the heart) or exudate (inflammation, tumour)
what are the symptoms of pleural effusion?
pain, dyspnoea
what is the diagnoses of pleural effusion?
chest radiograph (increased radio opacity, giving ground glass appearance), CT, ultrasound- uni or bilateral
where does increase radio opacity show in pleural effusions?
between lower lobe & diaphragm
what is pneumonia?
Infection of alveoli, pulmonary interstitium or both- can be bacterial or viral
where does lobar pneumonia occur?
infectios begins in alveoli- gives of exudate in responce to inflammation- spread across lobe- air bronchograms due to patent larger aiways- usually begins in lower lobes
what is bronchopneumonia?
most common, initially inflammation in airways, causes patchy consolidation
what is atypical pneumonia?
inflammatory thickening of airways & interstitium
what are symptoms of pneumonia?
general sign of infection, coughing, chest pain, airway obstruction, sputum, haemoptysis
what are signs of pneumonia on plain radiographs?
localise infiltrates & assess extend of consolidation
what are pulmonary embolisms?
often misdiagnosed- a thrombus migrates to pulmonary vessels causing obstruction- stops blood flowing through it
what does obstruction of blood flow cause in pulmonary embolism?
pulmonary hypertension causing right heart failure- V/Q mismatch happens when part of your lung receives oxygen without blood flow or blood flow without oxygen (low po2)
what are symptoms of a pulmonary embolism?
dyspnoea at rest, chest pain, haemoptysis (cougling up blood)
what do plain radiograph show in pulmonary embolisms?
perfusion scanning shows area with low blood flow (using labelled albumin)- ventilation scanning shows good ventilation
what is acute respiratory disease syndrome (ARDS)?
Sign of acute lung injury causing damage to alveoli and pulmonary capillaries
what are radiographic signs show in ARDS? ·
Bilateral pulmonary infiltrates – symmetric or asymmetric
what is tuberculosis?
multi systemic bacterial infection
what are radiographic signs of tuberculosis?
patchy or nodular infiltrate, often in upper lobes- calcified inflitrates, cavity formation
what is pulmonary oedema?
initially fluid builds up in interstitium due to CVD, alveoli are flooded cause interstitial oedmea
how does interstitial oedema appear in radiographs?
loss of definition of structures, local ground glass opacity
how does alveolar flooding appear in radiographs?
bilateral symmetrical opacities
what do inspiratory & expiratory images show?
small pneumothorax, abnoral diapragm movement, foreign bodies, differentiate opacities in ribs & lungs
