Respiratory Medicine Flashcards
Small cell lung cancer paraneoplastic syndromes
ADH
ACTH - not typical, hypertension, hyperglycaemia, hypokalaemia, alkalosis and muscle weakness are more common than buffalo hump etc
Lambert-Eaton syndrome
Squamous cell lung cancer paraneoplastic syndromes
parathyroid hormone-related protein (PTH-rp) secretion causing hypercalcaemia
clubbing
hypertrophic pulmonary osteoarthropathy (HPOA)
hyperthyroidism due to ectopic TSH
Adenocarcinoma
lung cancer paraneoplastic syndromes
gynaecomastia
hypertrophic pulmonary osteoarthropathy (HPOA)
oxygen dissociation curve
Shifts to Left = Lower oxygen delivery
HbF, methaemoglobin, carboxyhaemoglobin Low [H+] (alkali) Low pCO2 Low 2,3-DPG Low temperature
oxygen dissociation curve
Shifts to Left = Lower oxygen delivery
What is the L rule
Low [H+] (alkali)
Low pCO2
Low 2,3-DPG
Low temperature
Shifts to L → Lower oxygen delivery, caused by
oxygen dissociation curve
Shifts to Right = Raised oxygen delivery
Raised [H+] (acidic)
Raised pCO2
Raised 2,3-DPG*
Raised temperature
‘CADET, face Right!’ for CO2, Acid, 2,3-DPG, Exercise and Temperature
What is transfer factor?
transfer factor describes the rate at which a gas will diffuse from alveoli into blood. Carbon monoxide is used to test the rate of diffusion. Results may be given as the total gas transfer (TLCO) or that corrected for lung volume (transfer coefficient, KCO)
Causes of a raised TLCO
asthma pulmonary haemorrhage (Wegener's, Goodpasture's) left-to-right cardiac shunts polycythaemia hyperkinetic states male gender, exercise
Causes of a lower TLCO
pulmonary fibrosis pneumonia pulmonary emboli pulmonary oedema emphysema anaemia low cardiac output
conditions may cause an increased KCO with a normal or reduced TLCO
pneumonectomy/lobectomy
scoliosis/kyphosis
neuromuscular weakness
ankylosis of costovertebral joints e.g. ankylosing spondylitis
Eosinophilic granulomatosis with polyangiitis (Churg-Strauss syndrome)
Eosinophilic granulomatosis with polyangiitis (EGPA) is now the preferred term for Churg-Strauss syndrome. It is an ANCA associated small-medium vessel vasculitis.
Features of Eosinophilic granulomatosis with polyangiitis (Churg-Strauss syndrome)
asthma blood eosinophilia (e.g. > 10%) paranasal sinusitis mononeuritis multiplex pANCA positive in 60%
Tidal volume
volume inspired or expired with each breath at rest
500ml in males, 350ml in females
Inspiratory reserve volume (IRV) = 2-3 L
maximum volume of air that can be inspired at the end of a normal tidal inspiration
inspiratory capacity = TV + IRV
Expiratory reserve volume (ERV) = 750ml
maximum volume of air that can be expired at the end of a normal tidal expiration
Residual volume (RV) = 1.2L
volume of air remaining after maximal expiration
increases with age
RV = FRC - ERV
Functional residual capacity (FRC)
the volume in the lungs at the end-expiratory position
FRC = ERV + RV
Vital capacity (VC) = 5L
maximum volume of air that can be expired after a maximal inspiration
4,500ml in males, 3,500 mls in females
decreases with age
VC = inspiratory capacity + ERV
Total lung capacity (TLC)
sum of the vital capacity + residual volume
Features of Cystic fibrosis
short stature diabetes mellitus delayed puberty rectal prolapse (due to bulky stools) nasal polyps male infertility, female subfertility
Causes of respiratory alkalosis
anxiety leading to hyperventilation pulmonary embolism salicylate poisoning* CNS disorders: stroke, subarachnoid haemorrhage, encephalitis altitude pregnancy
Features of allergic bronchopulmonary aspergillosis
bronchoconstriction: wheeze, cough, dyspnoea. Patients may have a previous label of asthma
bronchiectasis (proximal)
features of allergic bronchopulmonary aspergillosis
eosinophilia
flitting CXR changes
positive radioallergosorbent (RAST) test to Aspergillus
positive IgG precipitins (not as positive as in aspergilloma)
raised IgE
Management of allergic bronchopulmonary aspergillosis
oral glucocorticoids
itraconazole is sometimes introduced as a second-line agent
Features of moderate asthma
PEFR 50-75% best or predicted
Speech normal
RR < 25 / min
Pulse < 110 bpm
Features of severe asthma
PEFR 33 - 50% best or predicted
Can’t complete sentences
RR > 25/min
Pulse > 110 bpm
Features of life threatening asthma
PEFR < 33% best or predicted Oxygen sats < 92% Silent chest, cyanosis or feeble respiratory effort Bradycardia, dysrhythmia or hypotension Exhaustion, confusion or coma
Epidemiology of bronchiolitis
most common cause of a serious lower respiratory tract infection in < 1yr olds (90% are 1-9 months, with a peak incidence of 3-6 months). Maternal IgG provides protection to newborns against RSV
higher incidence in winter
Respiratory syncytial virus (RSV) is the pathogen in 75-80% of cases.
Basics of bronchiolitis
respiratory syncytial virus (RSV) is the pathogen in 75-80% of cases
other causes: mycoplasma, adenoviruses
may be secondary bacterial infection
more serious if bronchopulmonary dysplasia (e.g. Premature), congenital heart disease or cystic fibrosis
Features of bronchiolitis
coryzal symptoms (including mild fever) precede:
dry cough
increasing breathlessness
wheezing, fine inspiratory crackles (not always present)
feeding difficulties associated with increasing dyspnoea are often the reason for hospital admission
Bronchiolitis - referral to hospital
apnoea (observed or reported)
child looks seriously unwell to a healthcare professional
severe respiratory distress, for example grunting, marked chest recession, or a respiratory rate of over 70 breaths/minute
central cyanosis
persistent oxygen saturation of less than 92% when breathing air.
Bronchiolitis
consider referral to hospital
a respiratory rate of over 60 breaths/minute
difficulty with breastfeeding or inadequate oral fluid intake (50-75% of usual volume ‘taking account of risk factors and using clinical judgement’)
clinical dehydration.
Management of bronchiolitis
humidified oxygen is given via a head box and is typically recommended if the oxygen saturations are persistently < 92%
nasogastric feeding may be needed if children cannot take enough fluid/feed by mouth
suction is sometimes used for excessive upper airway secretions
Features of sarcoidosis
acute: erythema nodosum, bilateral hilar lymphadenopathy, swinging fever, polyarthralgia
insidious: dyspnoea, non-productive cough, malaise, weight loss
skin: lupus pernio
hypercalcaemia: macrophages inside the granulomas cause an increased conversion of vitamin D to its active form (1,25-dihydroxycholecalciferol)
Lofgren’s syndrome
Sarcoidosis
an acute form of the disease characterised by bilateral hilar lymphadenopathy (BHL), erythema nodosum, fever and polyarthralgia. It usually carries an excellent prognosis
Mikulicz syndrome
there is enlargement of the parotid and lacrimal glands due to sarcoidosis, tuberculosis or lymphoma
Heerfordt’s syndrome
(uveoparotid fever) there is parotid enlargement, fever and uveitis secondary to sarcoidosis
What is anti-alpha 1 trypsin deficiency
(A1AT) deficiency is a common inherited condition caused by a lack of a protease inhibitor (Pi) normally produced by the liver. The role of A1AT is to protect cells from enzymes such as neutrophil elastase. It classically causes emphysema (i.e. chronic obstructive pulmonary disease) in patients who are young and non-smokers.
Genetics of alpha 1 anti-trypsin deficiency
located on chromosome 14 inherited in an autosomal recessive / co-dominant fashion* alleles classified by their electrophoretic mobility - M for normal, S for slow, and Z for very slow normal = PiMM homozygous PiSS (50% normal A1AT levels) homozygous PiZZ (10% normal A1AT levels)