Respiratory Flashcards
What is Pemberton’s sign?
Pemberton’s sign” is where raising the hands over the head causes facial congestion and cyanosis. This is a medical emergency.
SIADH and lung cancer cause
Syndrome of inappropriate ADH (SIADH) caused by ectopic ADH secretion by a small cell lung cancer and presents with hyponatraemia.
Cushing’s syndrome and lung cancer cause
Ectopic ACTH release from small cell lung cancer
SCC on histology
Malignant epithelial tumour showing keratinisation and/or intercellular bridges or squamous cell marker expression
Hypercalcaemia and lung cancer cause
Ectopic PTH
What is Limbic encephalitis?
This is a paraneoplastic syndrome where the small cell lung cancer causes the immune system to make antibodies to tissues in the brain, specifically the limbic system, causing inflammation in these areas. This causes symptoms such as short term memory impairment, hallucinations, confusion and seizures. It is associated with anti-Hu antibodies.
What is Lambert-Eaton Myasthenic Syndrome?
Lambert-Eaton myasthenic syndrome is a result of antibodies produced by the immune system against small cell lung cancer cells. These antibodies also target and damage voltage-gated calcium channels sited on the presynaptic terminals in motor neurones.
This leads to weakness, particularly in the proximal muscles but can also affect intraocular muscles causing diplopia (double vision), levator muscles in the eyelid causing ptosis and pharyngeal muscles causing slurred speech and dysphagia (difficulty swallowing). Patients may also experience dry mouth, blurred vision, impotence and dizziness due to autonomic dysfunction.
Signs and symptoms of Lambert-Eaton?
Weakness, particularly in the proximal muscles but can also affect intraocular muscles causing diplopia (double vision), levator muscles in the eyelid causing ptosis and pharyngeal muscles causing slurred speech and dysphagia (difficulty swallowing).
Dry mouth, blurred vision, impotence and dizziness due to autonomic dysfunction.
Reduced tendon reflexes. A notable finding is that these reflexes become temporarily normal for a short period following a period of strong muscle contraction. For example, the patient can maximally contract the quadriceps muscle for a period, then have their reflexes tested immediately afterwards, and display an improvement in the response. This is called post-tetanic potentiation.
In older smokers with symptoms of Lambert-Eaton syndrome consider
Small cell lung cancer
Mesothelioma is strongly linked to
Asbestos inhalation
Characteristic chest signs of pneumonia
Bronchial breath sounds. These are harsh breath sounds equally loud on inspiration and expiration. These are caused by consolidation of the lung tissue around the airway.
Focal coarse crackles. These are air passing through sputum in the airways similar to using a straw to blow in to a drink.
Dullness to percussion due to lung tissue collapse and/or consolidation.
CURB65
C – Confusion (new disorientation in person, place or time)
U – Urea > 7
R – Respiratory rate ≥ 30
B – Blood pressure < 90 systolic or ≤ 60 diastolic.
65 – Age ≥ 65
Common causes of pneumonia
Streptococcus pneumoniae (50%)
Haemophilus influenzae (20%)
Definition of atypical pneumonia
Pneumonia caused by an organism that cannot be cultured in the normal way or detected using a gram stain.
Atypical bacteria antibiotics
They don’t respond to penicillins and can be treated with macrolides (e.g. clarithomycin), fluoroquinolones (e.g. levofloxacin) or tetracyclines (e.g. doxycycline).
Legionella pneumophila (Legionnaires’ disease) caused by and causes
This is typically caused by infected water supplies or air conditioning units. It can cause hyponatraemia (low sodium) by causing an SIADH. The typical exam patient has recently had a cheap hotel holiday and presents with hyponatraemia.
Mycoplasma pneumoniae presentation
This causes a milder pneumonia and can cause a rash called erythema multiforme characterised by varying sized “target lesions” formed by pink rings with pale centres. It can also cause neurological symptoms in young patient in the exams.
Coxiella burnetii AKA “Q fever” presentation
This is linked to exposure to animals and their bodily fluids. The MCQ patient is a farmer with a flu like illness.
Chlamydia psittaci presentation
This is typically contracted from contact with infected birds. The MCQ patient is a from parrot owner.
Treatment for pneumocystis jirovecii
Treatment is with co-trimoxazole (trimethoprim/sulfamethoxazole) known by the brand name “Septrin”. Patients with low CD4 counts are prescribed prophylactic oral co-trimoxazole to protect against PCP.
Obstructive lung disease can be diagnosed when
FEV1 is less than 75% of FVC (FEV1:FVC ratio < 75%).
Restrictive lung disease can be diagnosed when
FEV1 and FVC are equally reduced and FEV1:FVC ratio > 75%
Asthma diagnosis
Fractional exhaled nitric oxide
Spirometry with bronchodilator reversibility
If there is diagnostic uncertainty after first line investigations these can be followed up with further testing:
Peak flow variability measured by keeping a diary of peak flow measurements several times per day for 2 to 4 weeks
Direct bronchial challenge test with histamine or methacholine
Inhaled corticosteroid example
Beclomethasone
Long-acting beta 2 agonists (LABA) example
Salmeterol
Asthma NICE guidelines - stepwise process
Add short-acting beta 2 agonist inhaler (e.g. salbutamol) as required for infrequent wheezy episodes.
Add a regular low dose inhaled corticosteroid.
Add an oral leukotriene receptor antagonist (i.e. montelukast).
Add LABA inhaler (e.g. salmeterol). Continue the LABA only if the patient has a good response.
Consider changing to a maintenance and reliever therapy (MART) regime.
Increase the inhaled corticosteroid to a “moderate dose”.
Consider increasing the inhaled corticosteroid dose to “high dose” or oral theophylline or an inhaled LAMA (e.g. tiotropium).
Refer to a specialist.
Types of acute asthma
Moderate
PEFR 50 – 75% predicted
Severe
PEFR 33-50% predicted
Resp rate >25
Heart rate >110
Unable to complete sentences
Life-threatening
PEFR <33%
Sats <92%
Becoming tired
No wheeze. This occurs when the airways are so tight that there is no air entry at all. This is ominously described as a “silent chest”.
Haemodynamic instability (i.e. shock)