Respiratory Flashcards
What is the most significant cause of lung cancer?
Smoking
What is the most common type of lung cancer?
Non-small-cell lung cancer (80%):
Adenocarcinoma (40%)
Squamous cell carcinoma (20%)
Large-cell carcinoma (10%)
Other types (10%)
Small-cell lung cancer (SCLC) (20%)
What is mesothelioma?
Lung malignancy affecting mesothelial cells of pleura
Strongly linked to asbestos
Can take up to 45y to develop
What is the prognosis of mesothelioma?
Very poor
Chemo can improve survival, but is essentially palliative
Outline small-cell lung cancer
Contains neurosecretory granules that release neuroendocrine hormones
May be responsible for various paraneoplastic syndromes
Outline presentation of lung cancer
SOB
Cough
Haemoptysis
Finger clubbing
Recurrent pneumonia
Weight loss
Lymphadenopathy (often supraclavicular nodes 1st to be found)
List extrapulmonary manifestations of lung cancer
Recurrent laryngeal nerve palsy
Phrenic nerve palsy
SVC obstruction
Horner’s syndrome
Syndrome of inappropriate ADH (SIADH)
Cushing’s syndrome
Hypercalcaemia
Limbic encephalitis
Lambert-Eaton myasthenic syndrome
What is the association between lung cancer and recurrent laryngeal nerve palsy?
Presents with hoarse voice
Caused by tumour pressing on or affecting recurrent laryngeal nerve as passes through mediastinum
What is the association between lung cancer and phrenic nerve palsy?
Due to nerve compression
Causes diaphragm weakness and presents with SOB
What is the association between lung cancer and SVC obstruction?
Caused by direct tumour compression on SVC
Presents with facial swelling, difficulty breathing, distended neck and upper chest veins
Pemberton’s sign
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What is Pemberton’s sign?
Raising hands over head causes facial congestion and cyanosis
What is the association between lung cancer and Horner’s syndrome?
Triad of partial ptosis, anhidrosis and miosis
Caused by Pancoast tumour (in pulmonary apex) pressing on sympathetic ganglion
What is the association between lung cancer and SIADH?
Caused by ectopic ADH secreted by SCLC
Presents with hyponatremia
What is the association between lung cancer and Cushing’s syndrome?
Caused by ectopic ACTH secretion by SCLC
What is the association between lung cancer and Hypercalcaemia?
Caused by ectopic PTH secreted by squamous cell carcinoma
What is the association between lung cancer and Limbic encephalitis?
Paraneoplastic syndrome
SCLC causes immune system to make antibodies to tissues in brain (limbic system), causing inflammation
Associated with anti-Hu antibodies
List the symptoms of limbic encephalitis
Short-term memory impairment
Hallucinations
Confusion
Seizures
What is the association between lung cancer and Lambert-Eaton Myasthenic Syndrome?
Caused by antibodies against SCLC
Antibodies target and damage voltage-gated calcium channels on presynaptic terminals in motor neurones
List the symptoms of Lambert-Eaton Myasthenic Syndrome
Weakness in proximal muscles
Affect intraocular muscles causing diplopia (double vision)
Levator muscles in eyelid, causing ptosis
Pharyngeal muscles, causing slurred speech and dysphagia (difficulty swallowing)
Dry mouth, blurred vision, impotence, dizziness due to autonomic dysfunction
Outline the referral criteria for lung cancer
Suspected cancer- Recommend chest xray within 2wks to patients over 40y with signs of:
Clubbing
Lymphadenopathy (supraclavicular/persistent abnormal cervical nodes)
Recurrent/persistent chest infections
Raised platelet count (thrombocytosis)
Chest signs of lung cancer
Offer chest xray to patients over 40y with:
2+ unexplained symptoms in patients that have never smoked
1+ unexplained symptoms in patients that have smoked/had asbestos exposure
What are unexplained lung cancer guidelines as NICE guidelines suggest
Cough
SOB
Chest pain
Fatigue
Weight loss
Loss of appetite
What are the 2 key examination findings that automatically indicate an urgent chest xray for lung cancer?
Finger clubbing
Supraclavicular lymphadenopathy
Outline investigations for lung cancer
Chest xray 1st line
Staging CT scan- Chest, abdomen, and pelvis- Should be contrast-enhanced
PET-CT- Inject radioactive tracer- Identify metastases by highlighting areas of increased metabolic activity
Bronchoscopy with endobronchial US (EBUS)- Detailed assessment of tumour and US-guided biopsy
Histological diagnosis (biopsy)
List some potential findings of lung cancer on xray
Hilar enlargement
Peripheral opacity (visible lesion in lung field)
Pleural effusion (usually unilateral in cancer)
Collapse
Outline management options in non-SCLC
Surgery 1st line if disease isolated to single area
Radiotherapy
Chemotherapy (adjuvant (to improve outcomes) or palliative)
Outline management of SCLC
Chemo and radiotherapy
Prognosis generally worse for SCLC than non-SCLC
When is endobronchial treatment used in lung cancer?
Stents or debulking as part of palliative treatment to relieve bronchial obstruction
Outline surgical options for removing lung tumour
Segmentectomy or wedge resection
Lobectomy (remove lung lobe)- Most commonly used
Pneumonectomy (remove entire lung)
What are the types of surgery that can be used to remove a lung tumour?
Thoracotomy
Video-assisted thoracoscopic surgery (VATS)- Minimally invasive ‘keyhole’ surgery
Robotic surgery
What is pneumonia?
Infection of lung tissue, causing inflammation in alveolar space
Seen as consolidation on chest xray
LRTI
What is acute bronchitis?
Infection and inflammation in bronchi and bronchioles
LRTI
Outline classification of pneumonia
Community-acquired pneumonia (CAP)
Hospital-acquired pneumonia (HAP)- Develops after >48h in hospital
Ventilator-acquired pneumonia (VAP)- Develops in intubated patients in ICU
Aspiration pneumonia
Outline aspiration pneumonia
Infection due to aspiration of food or fluids
Usually in patients with impaired swallowing (eg: Following a stroke or advanced dementia)
Associated with anaerobic bacteria
Outline presentation of pneumonia
Cough
Sputum production
SOB
Fever
Feeling generally unwell
Haemoptysis (coughing up blood)
Pleuritic chest pain (sharp chest pain, worse on inspiration)
Delirium (acute confusion)
What are the characteristic chest signs of pneumonia?
Bronchial breath sounds- Harsh inspiratory and expiratory breath sounds- Due to consolidation around the airway
Focal coarse crackles- Caused by air passing through sputum in airways
Dullness to percussion- Due to lung tissue filled with sputum/colapse
Outline indications of sepsis associated with pneumonia
Tachypnoea
Tachycardia
Hypoxia
Hypotension
Fever
Confusion
Outline the severity assessment scale of pneumonia
C- Confusion
U- Urea >7mmol/L
R- RR >30
B- BP <90 systolic or <60 diastolic
65- Age >65y
0-1= Consider treatment at home
>2= Consider hospital admission
>3= Consider intensive care
What is the most common cause of typical bacterial pneumonia?
Streptococcus pneumoniae (most common)
Haemophilus influenzae
When is Moraxella catarrhalis more likely to be a cause of pneumonia?
Immunocompromised patients
Chronic pulmonary disease
When is Pseudomonas aeruginosa more likely to be a cause of pneumonia?
Patients with cystic fibrosis or bronchiectasis
When is Staphylococcus aureus more likely to be a cause of pneumonia?
Cystic fibrosis
When is Methicillin-resistant Staphylococcus aureus (MRSA) more likely to be a cause of pneumonia?
Hospital-acquired infections
What is atypical pneumonia?
Caused by organisms that can’t be cultured in the normal way or detected using a gram stain
How is atypical pneumonia treated?
Penicillin is ineffective
Treat with macrolides (eg: Clarithromycin), fluoroquinolones (eg: Levofloxacin) and tetracyclines (eg: Doxycycline)
When is Legionella pneumophilia more likely to be a cause of pneumonia?
Atypical pneumonia
Caused by inhaling infected water from infected water systems, such as air conditioning
Causes a syndrome of SIADH, resulting in hyponatremia
Typical patient- Cheap hotel holiday, presents with pneumonia and hyponatremia
Diagnosis- Urine antigen test
When is Mycoplasma pneumoniae more likely to be a cause of pneumonia?
Atypical pneumonia
Milder pneumonia
Rash- Erythema multiforme- Target lesions
Neurological symptoms in young patients
When is Chlamydophilia pneumoniae more likely to be a cause of pneumonia?
Atypical pneumonia
Mild to moderate chronic pneumonia and wheezing in school-age children
When is Coxiella burnetii more likely to be a cause of pneumonia?
Atypical pneumonia
Q fever
Linked to exposure to bodily fluids of animals
Patient- Farmer with flu-like illness
When is Chlamydia psittaci more likely to be a cause of pneumonia?
Contracted from contact with infected birds
Patient example- Parrot owner
Outline pneumocystis jirovecii pneumonia (PCP)
Fungal pneumonia
Occurs in immunocompromised patients
Poorly controlled HIV and low CD4 count at particular risk
How does PCP present?
Subtle
Dry cough
SOB on exertion
Night sweats
Outline management of PCP
Co-trimoxazole (trimethoprim/sulfamethoxazole)
Low CD4 count prescribed prophylactic co-trimoxazole to protect against PCP
List complications of pneumonia
Sepsis
ARDS
Pleural effusion
Empyema
Lung abscess
Death
How is mild community-acquired pneumonia typically managed?
5 days oral ABs:
Amoxicillin or doxycycline or clarithromycin
How is moderate/severe pneumonia managed?
IV ABs
Respiratory support (eg: Oxygen/intubation/ventilation)
Outline investigations of pneumonia
Point-of-care test for CRP level
Chest xray
FBC- Raised WCC
Renal profile- Urea level for CURB-65 and AKI
CRP- Raised in inflammation and infection
Sputum cultures
Blood cultures
Pneumococcal and Legionella urinary antigen tests
What is PaO2 a marker of on an ABG
Partial pressure of oxygen
Amount of oxygen dissolved in blood
Low PaO2- Indicates hypoxia and respiratory failure
What is FiO2 a marker of?
Fraction of inhaled oxygen
Room air= FiO2 of 21%
Venturi masks control FiO2
How can you distinguish the type of respiratory failure?
Normal PaCO2 with low PaO2- Type 1 respiratory failure (only one affected)
Raised PaCO2 with low PaO2- Indicates Type 2 respiratory failure (2 affected)
Outline respiratory acidosis
CO2 makes blood acidotic by breaking down into carbonic acid (H2CO3)
Low pH (acidosis) with raised PaCO2- Respiratory acidosis
Suggests patient is retaining CO2
What is the role of bicarbonate in the body?
Kidneys produce bicarbonate
Bicarbonate acts as buffer to neutralise acid in blood and maintain normal pH
In acute resp acidosis- Bicarbonate not produced fast enough to compensate rising CO2
What does a raised bicarbonate suggest?
Patient chronically retains CO2
Kidneys respond to CO2 by producing additional bicarbonate
Seen in COPD
Outline respiratory alkalosis
Occurs when patient has raised respiratory rate and ‘blows off’ too much CO2
Hyperventilation syndrome
High pH and low PaCO2
Outline metabolic acidosis
Low pH, low bicarbonate
List causes of metabolic acidosis
Raised lactate- Lactate released during anaerobic respiration (indicating tissue hypoxia)
Raised ketones- DKA
Increased hydrogen ions- Due to renal failure, type 1 renal tubular acidosis or rhabdomyolysis
Reduced bicarbonate- Due to diarrhoea, renal failure or type 2 renal tubular acidosis
Outline metabolic alkalosis
Raised pH, raised bicarbonate
What are the causes of metabolic alkalosis?
Results from loss of H+ ions: GI tract- Vomiting
Kidneys- Due to increased activity of aldosterone- Increased H+ ion excretion
List causes of increased aldosterone activity
Conn’s syndrome (primary hyperaldosteronism)
Liver cirrhosis
HF
Loop diuretics
Thiazide diuretics
List respiratory support options from least to most invasive
Oxygen therapy
High flow nasal cannula
Intubation and mechanical ventilation
ECMO
What is Acute Respiratory Distress Syndrome (ARDS)?
Occurs due to severe inflammatory reaction in lungs
Often secondary to sepsis or trauma
Outline features of ARDS
Collapse of alveoli and lung tissue (atelectasis)
Pulmonary oedema (not related to HF or fluid overload)
Decreased lung compliance (reduced lung inflation when ventilated)
Fibrosis of lung tissue (typically after 10+ days
List the clinical signs of ARDS
Acute respiratory distress
Hypoxia with inadequate response to oxygen therapy
Bilateral infiltrates on chest xray
Outline management of ARDS
Respiratory support
Prone position
Careful fluid management to avoid excess fluid collecting on lungs
PEEP
Why is PEEP used in ARDS?
In ARDS- Only small portion of total lung volume is aerated
During mechanical ventilation, low volumes and pressures used to avoid over-inflating small functional portion of lung
PEEP prevents lungs from collapsing further
List the benefits of prone positioning
Reduces compression of lungs by other organs
Improving blood flow to lungs, especially well-ventilated areas
Improves clearance of secretions
Improves overall oxygenation
Reduces required assistance from mechanical ventilation
Outline basic methods of oxygen therapy
FiO2 depends on oxygen flow rate
Nasal cannula: 24-44% oxygen
Simple face mask: 40-60% oxygen
Venturi mask: 24-60% oxygen
Face mask with reservoir (non-rebreather): 60-95% oxygen
What is the maximum oxygen flow rate of a nasal cannula?
4L/min
What is the function of a venturi mask?
Used to deliver exact conc. oxygen in COPD CO2 retainers
Blue- 2L, 24% FiO2
White- 4L, 28% FiO2
Orange- 6L, 31%
Yellow- 8L, 35%
Red- 10L, 40%
Green- 15L, 60%
What is end-expiratory pressure?
Pressure that remains in airways at end of exhalation
How can PEEP be delivered?
High-flow nasal cannula
Non-invasive ventilation (NIV)
Mechanical ventilation
What is PEEP?
Positive end-expiratory pressure
Additional pressure in airways at end of exhalation that keeps them inflated
Keeps airways from collapsing and improves ventilation
Reduces atelectasis
Decreases effort of breathing
Outline high-flow nasal cannulas
Allows controlled flow rates up to 60L/min of humidified and warmed oxygen
High flow rate reduces amount of room air patient inhales alongside O2, increasing conc. inspired O2
Adds PEEP
Provides dead space washout- Adds O2 to dead space
What is CPAP?
Continuous positive airway pressure
Constant pressure added to lungs to keep airways expanded
Used in OSA
Not technically NIV as ventilation is still dependant on respiratory muscles
Outline non-invasive ventilation (NIV)
Full face mask, hood or tight fitting nasal mask to blow air forcefully into lungs
BiPAP (Bilevel)
Involves a cycle of high and low pressure to correspond with inspiration and expiration
Outline NIV IPAP and EPAP
High and low pressure to correspond to inspiration and expiration
IPAP (inspiratory PAP)- Pressure during inspiration- Air forced into lungs
EPAP (expiratory PAP)- Pressure during expiration- Stops airways collapsing
Outline mechanical ventilation
Used when other forms of respiratory support (NIV and oxygen) inadequate or CI
Ventilator machine used to move air in and out of lungs
Patients generally require sedation whilst on ventilator
ETT or tracheostomy
Delivers controlled pressures and volumes into lungs
Outline Extracorporeal Membrane Oxygenation (ECMO)
Blood removed from body and oxygenated, CO2 removed, then pumped back into body
Only used short term in potentially reversible cause of respiratory failure
What is spirometry?
Establishes objective measures of lung function
Involves different breathing exercises into machine and measures volume of air and flow rates
What is reversibility testing?
Give bronchodilator (eg: Salbutamol) before repeating spirometry
What is FEV1?
Air a person can forcefully exhale in 1s
Measures how easily air moves out of lungs
Reduced with airflow obstruction
What is FVC?
Total air a person can forcefully exhale in 1s
Measures total volume of air a person can take into their lungs
Reduced with restricted lung capacity
How is obstructive lung disease diagnosed?
FEV1:FVC ratio <70%
Suggests obstruction is slowing air passage out of lungs
What is the difference between asthma and COPD?
Asthma- Obstruction is a narrowed airway due to bronchoconstriction
COPD- Chronic airway and lung damage causing obstruction
Test reversibility- Give bronchodilator- Typically reversible in asthma, less so in COPD
Outline restrictive lung disease
FEV1 and FVC equally reduced
FEV1:FVC ratio >70%
Limits ability of lungs to expand and sill with air
Leads to inadequate ventilation of alveoli and insufficient blood oxygenation
FEV1:FVC ratio normal/raised in restrictive without obstructive pathology affecting airflow- FVC reduced due to restriction of lung expansion and capacity
List conditions of restrictive lung disease
Interstitial lung disease- Idiopathic pulmonary fibrosis
Sarcoidosis
Obesity
Motor neurone disease
Scoliosis
What does a low FVC and normal FEV1:FVC ratio indicate?
Restrictive lung disease
What does a low FVC and low FEV1:FVC ratio indicate?
Combination of obstructive lung disease and restrictive lung disease
What does a low FEV1:FVC ratio indicate?
Obstructive lung disease
Outline peak flow
Measures fastest point of expiratory flow of air
Demonstrates how much obstruction to airflow is present in lungs
What is predicted peak flow based on?
Sex
Height
Age
Result can be recorded as percentage of the predicted
What is asthma?
Chronic inflammatory airway disease leading to variable airway obstruction
Smooth muscle in airways is hypersensitive and responds to stimuli by constricting and causing airflow obstruction
Bronchoconstriction reversible with bronchodilators
List the atopic conditions
Asthma
Eczema
Hay fever
Food allergies
Outline presentation of asthma
SOB
Chest tightness
Dry cough
Wheeze
Diurnal variability- Symptoms fluctuate at different times of day- Typically worse at night
Widespread ‘polyphonic’ wheeze
What are the top differentials of a localised monophonic wheeze?
Inhaled foreign body
Tumour
Thick sticky mucus plug obstructing an airway
Chest xray is next step
What are the typical triggers of asthma?
Infection
Night time/early morning
Exercise
Animals
Cold, damp, dusty air
Strong emotions
What are the meds that can worsen asthma?
Non-selective BBs- Propanolol
NSAIDs- Ibuprofen or naproxen
Outline investigations of asthma
Spirometry
Reversibility testing- >12% increase in FEV1 supports diagnosis of asthma
FeNO- Measures conc. NO exhaled- Marker of airway inflammation- >40ppb +ve test result- Smoking can lower FeNO making results unreliable
Peak flow variability- >20% supports diagnosis
Direct bronchial challenge
How is direct bronchial challenge testing done?
Tests for diagnosis of asthma
Opposite of reversibility testing
Inhaled histamine or metacholine stimulates bronchoconstriction, reducing FEV1 in patients with asthma
Outline beta-2 adrenergic receptor agonists
Bronchodilators (open airways)
Adrenalin acts on smooth muscle of airways to cause relaxation
Stimulating adrenalin receptors dilates bronchioles and reverses bronchoconstriction
SABA (salbutamol)- Work quickly, effects last a few hrs- Rescue/reliever medication
LABA (salmeterol)- Slower to act, last longer
Outline inhaled corticosteroids
Beclometasone
Reduce inflammation and reactivity of airways
Used as maintenance or preventer medications