Anatomy And Pattern Recognition Of Lower Respiratory System And Mediastinum Flashcards
What is the trachea?
The trachea is a tubular passageway connecting the upper respiratory tract to the lungs enabling gas exchange
What are anatomical landmarks for the trachea?
• Inferior margin of the cricoid cartilage (C6)
• Braches into the left and right main bronchi at the carina (T4) - the plane of Ludwig.
• Is in a midline position but can be slightly displaced to the right by the arch of the aorta.
• 10-1cm with a width of 1.5 - 2 cm (wider in men).
What does the trachea consist of?
• The fibro-elastic tissue is flexible and expands and contains “C” shaped cartilage rings which gives it rigidity. These are bridged by annular ligaments.
• Histology
Outer layer – connective tissue
Middle layer – tracheal cartilage, annular ligaments, connective tissue, trachealis muscle
Inner layer – respiratory mucous membrane
What is the carina?
The carina is a ridge of cartilage at the base of the trachea.
• It separates the openings of the right and left main bronchi
• Level of T4 / T5 but moves with breathing
• Lies to left of midline
Why is the carina important?
Important marker for tube position
-ET tubes should be 5cm above the carina to supply air to both lungs
-NG tubes should go straight through the carina
- SVC is to the right side of the carina for CVC (central venous catheter) position.
- Marker for CTPA scans
What can happen if the carina widened?
If widened (more than 100 degrees) can be a sign of:
o Left atrial enlargement
o Cardiomegaly
o Pericardial effusion
o A mass around the area
What is the bronchi?
respiratory epithelium (shorter than trachea) – lamina propria (denser than trachea) –
separated by a discontinuous layer of smooth muscle from the submucosa (cartilage are flat plates)
What are bronchioles?
no cartilage, airways must be kept open by radial traction. Prominent smooth muscle layer. Adjusting the tone of the muscle layer alters airway diameter so air flow can be controlled.
What are respiratory bronchioles?
no goblet cells, alveoli for gaseous exchange. Have alveolar ducts (rings of smooth muscle, collagen and elastic fibres) – leading to alveolar sacs – leading to alveoli - Provide the majority of the lung volume and surface area.
Can communicate between adjacent alveoli through pores of Kohn. Lined with pneumocytes
(provide structure and surfactant)
Fun fact of right main bronchus
Right main bronchus straighter so inhaled objects more likely to end up there
What are the lung lobes?
- superior lobe
- middle lobe
- inferior lobe
What are lung fissures?
• Lung fissures are a double fold of visceral pleura that either completely or incompletely invaginate (turned inside out) the lung parenchyma to form the lung lobes
• You will often see the horizontal fissure on a PA or AP CXR, and sometimes the oblique fissure on a lateral CXR.
What is the left lung fissure?
• Oblique fissure separating the upper lobe from the lower lobe
• T4/T5 posterior to the hemidiaphragm anteriorly
What is the right lung fissure?
• Oblique fissure separating the upper lobe from the lower lobe
• Horizontal fissure separates the upper lobe from the middle lobe
• 4th costal cartilage from the hilum to the anterior and lateral surfaces of the right lung.
Why are the fissures important for us?
For CT lung biopsy
• They help protect infections affecting nearby lobes – good way to differentiate between infection and possible malignancy
What do the lungs look like on CT?
Lung window’
• lungs W:1500 L:-600
Width is contrast and level is brightness - manipulate the grayscale in CT
• Axial slice
What is the pleura?
Covers the lung, chest wall and mediastinum with 2 continuous layers of epithelium
• Visceral – covers the lungs inner layer
• Parietal – covers the chest wall and is the outer later. Nerve supply is the phrenic nerve so inflamed pleura can cause ipsilateral shoulder tip pain
• Separated by a thin layer of liquid.
What is the pleura like on a X-ray?
You can only see the pleura and pleural spaces on plain film when they are abnormal.
• Lung markings should reach the thoracic wall on a CXR
• There should be no space between the pleura
What is the mediastinum?
It is the space in the midline of the chest between the pleura of each lung and extends from the sternum to the vertebral column.
• Contains all the thoracic viscera except the lungs
• Which are Heart
• Great vessels
• Oesophagus
• Trachea
• Phrenic nerve
• Cardiac nerve
• Thoracic duct
• Thymus
• Mediastinal lymph nodes
What is the mediastinum divided into?
Can be divided into parts based on their relationship to the pericardium.
• Superior mediastinum – above the level of the pericardium and plane of Ludwig
• Inferior mediastinum – below the plane of Ludwig:
• Anterior mediastinum – anterior to pericardium
• Middle mediastinum – within the pericardium
• Posterior mediastinum – posterior to the pericardium
What is the hila/hilum?
May be at the same level but commonly the left is higher than the right
• Should look similar in appearance
• Anatomical landmark – anteriorly 3-4th costal cartilage, posteriorly T5-T7
Hila = 2 and hilum = 1
Why do we have the sternum?
- Protect your heart and mediastinum
What is the diaphragm?
C shape structure
Separates chest from abdomen
Main muscle of respiration - how we breathe
What is chilaiditi sign?
It is a condition in which a segment of the intestine is interposed between the liver and diaphragm
. Is the anterior interposition of the colon to the liver reaching the under surface of the right hemi- diaphragm
• One of the cause of pseudopneumoperitonuem
• Can have Chilaiditi syndrome where patients experience pain
What is dextrocardia
Dextrocardia means the heart is on the right side
What is hiatus hernia
Occurs when there is herniation of the abdominal contents through the oesophageal hiatus of the diaphragm
Where the causes and symptoms of hiatus hernia
Causes = increases with age and slight female predilection
Symptoms = chest/abdominal pain
Nausea and vomitting
Sometimes GORD gastro-oesophageal reflux disease
What is the diagnosis of hiatus hernia
Plain film – retrocardiac opacity with air fluid level
CT – fat collection in middle mediastinum, may see hernia or widened oesophageal hiatus
What treatments are used for hiatus hernia
Surgery in severe cases
What is pulmonary embolic disease
Most commonly a blood clot (which often starts in the leg), which travels through the circulatory system and then causes a blockage in the pulmonary artery – can be partial or complete
What are the causes and symptoms of pulmonary embolic disease
Causes
o Recent surgery
o Immobility
o Diseases with a risk of thrombus formation e.g. lupus, HIV, Covid
o Drugs such as the contraceptive pill,
o Pregnancy
o Malignancy
Symptoms
o History fitting any of the causes above
o Tachycardia, dyspnea (breathing difficulty), chest pain, hemoptysis
o Signs of a DVT
What are the treatments of pulmonary embolic disease
o Anticoagulation
o CPR if necessary
What are complications of pulmonary embolic disease
o PEA in the case of a cardiac arrest
o Right ventricular strain
o Pulmonary infarction
o Pulmonary hypertension
Damage heart
Part of the lung can die off
Stops blood getting to lungs
Which imaging is used for pulmonary embolic disease
CXR
•Nonspecific, not suggested
CT
CTPA immediately if possible depending on
Wells score.
• If wells is <4 D-dimer – if high = CTP (how likely it is a patient has PED)
MRI
Magnetic resonance imaging findings in acute pulmonary embolism - PMC (nih.gov)
VQ
• Looks for that mismatch from ventilation and perfusion
• Have to have a CXR first
What is pulmonary oedema
• Accumulation of fluid in the interstitial and alveolar spaces – very broad term! it manifests in 2 types –
alveolar and interstitial
What are the causes of pulmonary oedema
Cardiogenic
o Congestive heart failure
o Cardiomyopathy
o Arrythmias
o Mitral regurgitation
Non cardiogenic
o Near drowning
o O2 (post intubation)
o Trauma
o CNS
o Alveolitis (hypersensitivity pneumonitis)
o Renalfailure
o Drugs
o Inhaled toxins
o Altitude
o Contusion
What are the symptoms and diagnosis of pulmonary oedema
Symptoms = breathlessness and distress and increased heart rate due to fluid in lungs
Diagnosis =
• CXR – increased cardio/thoracic ratio, upper lobe pulmonary venous diversion, alveolar signs (batwing
shadowing, airspace shadowing, consolidation), interstitial signs (Kerley B lines, thickening of the
fissures), pleural effusion.
• CT – ground glass opacification, septal thickening
• US – B lines
What are the treatments of pulmonary oedema
Depends on the underlying cause
What is aortic dissection (type a)
Separation in the aortic wall intima (tear), allowing blood to flow between the layers of the aortic wall (inner and outer walls of the media). Type A – ascending aorta with or without the aortic arch and descending aorta. Type B – mainly descending aorta and / or abdominal aorta.
What are the causes and symptoms of aortic dissection
o Causes
• Risk factors include:
▪ Hypertension
▪ Marfan syndrome - connective tissue disorder
▪ Ehlors-Danlos syndrome - connective tissue disorder
o Symptoms
• Acute severe chest pain
• Left right blood pressure differential
• Pulse deficit
• Dyspnoea
. Struggling to breathe
. Low pulse in wrist
Treatment of aortic dissection
. Aggressive blood pressure control with beta blockers to reduce blood pressure and heart rate
•Immediate surgical repair
What is pneumonia
• Broad term to describe acute infection on the lung parenchyma (functional tissue e.g. alveoli
Causes + symptoms of pneumonia
Causes
• Infection e.g. COVID 19, bacteria, viral or fungal
Symptoms
• Productive cough / breathlessness / chest pain
• High temperature (pyrexia), sometimes associated with tachycardia
• Malaise
Diagnosis of pneumonia
• CXR – air space opacification
• CT – not generally used as the initial diagnostic tool, but useful in cases with complications or for follow up
Treatment of pneumonia
Antibiotics
Potentially follow up imaging - ecg
primary lung cancer:
o Broad term referring to primary lung malignancy. You may also see the term bronchogenic
Causes + symptoms of PLC
Causes
o Tobacco smoking
o Asbestos
o COPD
Symptoms
o Patients may be asymptomatic in up to 50% of cases
o Hemoptysis
o Cough and dyspnoea
o Pleural effusion
o pneumonia
Diagnosis for plc
CXR
CT
PET CT
MRI
Treatments for plc
Surgery chemotherapy radiotherapy depending on tumour
Molecular testing can help with targeted treatments
What is pleural effusion
Is any accumulation of fluid in the pleural cavity – this could be simple fluid, blood, pus etc. Results from many pathological processes which overwhelm the pleura’s ability to reabsorb fluid
Causes and symptoms of pleural effusion
Causes
. Most common are cardiac failure and malignancy
Symptoms
•Small amount may have no symptoms
•As volume increases symptoms include breathlessness especially when active
•Causes are generally split into transudate and exudate
Diagnosis of pleural effusion
US - allows detection of small amounts
CT - excellent in detecting small amounts
CXR - most commonly used imaging method
Complications and treatment of pleural effusions
Complications = lung collapse, scarring (fibrotic changes)
Treatment = may drain if it large
What is transudate fluid
Lower protein content (<30g/L)
o Occurs when there is an increase in hydrostatic pressure
o Cardiac failure
o Cirrhosis
o Trauma
o Post coronary surgery
What is exudate fluid
Exudate
o Higher protein content (>30 g/L)
o Occurs due to an alteration in the pleural space drainage to lymph nodes
o Bronchial cancer o Lung metastases o PE
o Pneumonia
o TB
o Mesothelioma
Pleural effusion – AP / Pa erect
Erect films are insensitive to small amounts of fluid
• May see blunting of the costophrenic angle
• Blunting of the cardiophrenic angle
• Fluid within the horizontal or oblique fissure
• Eventually a meniscus will be seen, (not with a hydropneumothorax)
• Lateral images can identify a smaller amount of fluid
Pleural effusion - supine
Large amounts fluid can be present on supine image with minimal imaging changes as the fluid is dependent and collects posteriorly
There is no meniscus and only a veil like increased density of the hemithorax may be visible
Can be very diffuse to identify bilateral effusions as the density will be similar
What is a pneumothorax
Air in the pleural space
Causes and symptoms of pneumothorax
o Causes
o Many! Primary generally in younger patients, secondary in older/
• Primary spontaneous – no underlying lung disease
• Secondary spontaneous – underlying lung disease is present
• Iatrogenic / traumatic - caused by medical device
o Symptoms
• Pain and breathlessness
Diagnosis of pneumothorax
Plain film imaging
CT
Complications and treatment of pneumothorax
o Complications
• Tension pneumothorax
o Treatment
• Observation
• Aspiration
• Chest drain
• surgery
Pneumoperitoneum
. Gas within the peritoneal cavity
• Generally, from a perforated hollow viscus, post operative, from peritoneal dialysis, due to mechanical
ventilation, pneumothorax or pneumomediastinum, and many diseases
• Patient will often be very ill
• On CXR (most sensitive):
• Sub diaphragmatic free gas
• Continuous diaphragm sign
What is copd
Is a general term with 2 key disease features – chronic bronchitis and emphysema
Causes and symptoms of COPD
Causes
. Smoking – most common
•Cystic fibrosis
•Industrial exposure e.g. mining
Symptoms
Dyspnoea on extertion
•Wheezing
•Productive coughSymptoms
Diagnosis of COPD
CXR - hysema predominent
CT – may be as for CXR and also fibrotic changes and bronchial wall thickening for bronchitis and for emphysema
Complications and treatments of COPD
Treatments = Condition is irreversible, but can manage symptoms and delay progression
Complications = Exacerbation – infection, and acute breathlessness
•Pulmonary hypertensionComplications
What are rib fractures
Most commonly due to trauma. When rib is fractured twice it is termed a floating rib. When there are 3 or more, this is a flail chest which indicates severe chest trauma
Causes and symptoms of rib fractures
causes = Trauma
• Osteoporosis
• Pathological fracture
Symptoms = Relevant clinical history
• Pain on inspiration or movement
Diagnosis of rib fractures
CXR – fracture and displacement seen
• CT – better at diagnosing a flail chest
Complications and treatment of rib fractures
Complications = Fracture of 1st rib is an indicator for severe chest trauma as this is protected by the clavicle and scapula
Treatments = O2 therapy as infection is a common complication
• Surgery is rare
What is goitre
Enlargement of the thyroid gland. It can be caused by multiple conditions including – iodine deficiency,
thyroid cancer, Hasimotos
Causes and symptoms of goitre
Causes
It can be caused by multiple conditions including – iodine deficiency, thyroid cancer,
Symptoms
Visible swelling
•Tight feeling in throat
•Coughing
•Difficulty in swallowing or breathing
Diagnosis of goitre
US can give accurate measurements
•CXR – may see deviation of the trachea and a soft tissue mass in the upper mediastinum
•CT – as for chest. Also mixed density mass
Complications and treatments of goitre
Complications = •Difficulty in swallowing and breathing
•May need thyroid surgery
Treatment = may need it if it is large
What is Mesothelioma
o Rare malignancy that mostly arises from the pleura
Causes and symptoms of mesothelioma
Causes
Asbestos exposure
o Symptoms
o Vague
o Dyspnoea
o Back pain
o Pleural effusion
Diagnosis of mesothelioma
PET CT is often used for staging as metastases are common
o CXR – non specific. Will see pleural thickening with / without a pleural effusion. May see rib destruction.
o CT – most commonly used for diagnosis. Will see a pleural, nodular mass. May see invasion into chest wall lung or bones. May see metastases in lung and
lymphadenopathy
o MRI – not commonly used but may provide more accurate staging
Treatments and complications of mesothelioma
Complications
From metastases
o Pleural effusion
o Treatment
o Long term survival is poor. Surgery, chemotherapy and radiotherapy can be used
