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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_2683_Библиотеки_им_академика_М_И_Перельмана.pdf
Respiratory system
• Dyspnoea.
• Haemoptysis.
• Crepitations: involved areas.
• Wheeze: partial bronchial obstruction.
Extrapulmonary
This is dependent on the organ system affected. Common
manifestations include:
tuberculomas: meningism, photophobia, reduced
conscious level, focal neurological signs;
• lymphadenopathy;
• abscesses;
• genitourinary: dysuria, frequency, epididymitis,
salpingitis;
• musculoskeletal: Pott disease—vertebral TB;
• cardiovascular: pericardial TB.
Investigations
A high index of suspicion for TB, especially in at-risk
groups, is necessary. TB should be included in the differential diagnosis in patients with febrile illnesses, cervical
lymphadenopathy or focal infiltrates on CXR.
The CXR may show the typical picture of upper lobe infiltrates, with or without cavitation. The diagnosis is based
on the finding of AAFB by microscopy of a diagnostic specimen such as sputum or tissue (e.g. lymph node biopsy) using either auramine staining and fluorescence microscopy
or the more traditional light microscopy of specimens using
the Ziehl–Neelsen stain.
Patients with suspected pulmonary TB normally require
three sputum specimens (including one early morning sample) for AAFB smear and mycobacterial culture and sensitivity testing. ‘Smear-positive’ patients (confirmed AAFB on
sputum smear) should be considered infectious and should
be isolated. Those without AAFB on sputum smear (‘smearnegative’) are not infectious and do not need isolation, even
if the sputum subsequently grows M. tuberculosis. Specimens
are inoculated onto Löwenstein–Jensen medium. Most species of mycobacterium, including M. tuberculosis, are slow
growing, so 4–8 weeks may be required before growth is
detected and antibiotic sensitivity can be assessed. Newer
molecular biological techniques, such as the rapid diagnostic
nucleic acid amplification test, can confirm the presence of
M. tuberculosis more quickly and give drug sensitivities.
Other diagnostic tests for pulmonary TB include:
• induced sputum by ultrasonic nebulization of
hypertonic saline for patients unable to produce a
sputum specimen spontaneously;
• fibre-optic bronchoscopy with bronchoalveolar lavage
or transbronchial biopsy (especially with miliary TB).
When extrapulmonary TB is suspected, specimens of involved sites may include:
• cerebrospinal fluid: tuberculous meningitis;
• pleural fluid and pleural biopsy samples: pleural disease;
• bone marrow and liver biopsy culture: good diagnostic
yield in disseminated (miliary) TB;
• early morning urine: renal TB.
In all cases specimens are sent for AAFB microscopy,
stain and culture.
Positive tuberculin testing indicates exposure to mycobacteria or vaccination and not active disease and is best
used in contact tracing and public health screening. The
Mantoux and Heaf tests are the two most common methods. They involve intradermal injection of purified protein derivative and then observation of the response. The
Mantoux test results may be falsely positive in bacillus
Calmette–Guérin (BCG)-vaccinated individuals (clinical notes: TB vaccination). In those patients, because of
the questionable reliability of the Mantoux test, interferon
gamma testing (interferon gamma release assay) is recommended as a first-line test.
False negatives are possible in active TB, especially in
miliary TB or if the patient is immunosuppressed, for example HIV infection (a defect in cell-mediated immunity).
Management
TB is a notifiable disease in the United Kingdom. Public
health authorities should be informed for contact tracing.
Uncomplicated TB is treated in the initial phase with a
four-drug regimen (rifampicin, isoniazid, pyrazinamide and
ethambutol) for 2months, then a continuation phase using
two drugs (rifampicin and isoniazid) for another 4months.
Central nervous system TB requires at least 12months of
therapy supplemented with high-dose dexamethasone or
prednisolone, weaned down over a period of 4–8weeks.
Treatment of extrapulmonary and drug-resistant TB
requires specialist involvement. Pyridoxine therapy is usually started to minimize the neurological side effects of
isoniazid.
Second-line drugs available for infections caused by
resistant organisms, or when first-line drugs are contraindicated, include amikacin, capreomycin, cycloserine,
newer macrolides (e.g. clarithromycin) and quinolones (e.g.
ciprofloxacin and ofloxacin).
PATIENT SAFETY
Adherence to treatment is a serious issue in
tuberculosis. Successful drug therapy relies on
compliance with treatment. Supervised therapy in
at-risk groups (e.g. the homeless population) may
improve outcomes. Directly observed therapy,
short course in which medications are taken three
times per week under supervision can also be
helpful.
218
Pneumothorax
2828
CLINICAL NOTES
ANTITUBERCULOSIS MEDICATION—SIDE
EFFECTS
• Isoniazid: liver toxicity, peripheral neuropathy.
• Rifampicin: stains body secretions and urine
pink, liver toxicity, hepatic enzyme inducer,
thrombocytopenia.
• Pyrazinamide: liver toxicity, high uric acid levels,
gout, arthralgia.
• Ethambutol: visual disturbances such as altered
visual acuity, visual field defects, optic neuritis
leading to colour blindness.
Check liver function test results and urea and
electrolyte levels before commencement of
treatment. Visual acuity should be tested before
ethambutol is used.
CLINICAL NOTES
TB VACCINATION
Bacillus Calmette–Guérin (BCG) was derived from
an attenuated strain of Mycobacterium bovis and
was first administered to humans in 1921. Many
BCG vaccines are now available worldwide; all are
derived from the original strain, but the vaccines
differ in efficacy. The vaccine is safe and rarely
causes serious complications. It should not be
given to HIV-positive patients.
BCG vaccination induces purified protein derivative
(PPD) reactivity, but the magnitude of PPD skin test
reactions after vaccination does not predict the
degree of protection afforded. The UK Department
of Health and Social Care recommends vaccination
of all infants and children younger than 16years
at high risk of TB. Routine BCG vaccination is no
longer offered to all PPD-negative children at the
age of 12years.
underlying lung disease. The following distinctions are
made between the different types of pneumothorax:
• Spontaneous pneumothorax: occurs without trauma to
the thorax.
• Primary spontaneous pneumothorax: occurs in the
absence of lung disease.
• Secondary spontaneous pneumothorax: occurs
in the presence of preexisting lung disease (e.g.
COPD).
• Traumatic pneumothorax: penetrating or
nonpenetrating chest injuries.
• Tension pneumothorax: the pressure in the
pleural space is positive throughout the respiratory
cycle.
• Iatrogenic pneumothorax: occurs following
medical treatment (e.g. central venous catheter
insertion, mechanical ventilation, thoracic needle
aspiration).
• Catamenial pneumothorax: secondary to thoracic
endometriosis; occurs during menstruation.
Primary spontaneous pneumothorax is usually due to the
rupture of an apical pleural bleb that lies within or immediately under the visceral pleura. Approximately 25% of patients with an initial primary spontaneous pneumothorax
will have a recurrence.
Clinical features
The patient may be in extremis if a large tension pneumothorax is present or it may be seen on a CXR in a patient
with mild chest pain.
Clinical features of pneumothorax include:
• pleuritic chest pain on the affected side
• shortness of breath
• tachycardia
• decreased chest expansion, hyperresonance on
percussion and diminished breath sounds
A CXR will confirm the diagnosis by demonstrating a line
of visceral pleura with absent lung markings beyond the
line. Pneumothoraces as classified as large or small, on the
basis of the presence of a visible rim of air less than 2 cm or
more than 2 cm between the lung and chest wall at the level
of the hilum on a plain CXR.
PNEUMOTHORAX
General overview
A pneumothorax is the presence of air in the pleural space
(i.e. between the visceral pleura covering the lung and the
parietal pleura covering the inside of the chest wall) leading
to lung collapse. Risk factors for pneumothorax include
smoking, increased height, male sex, increasing age and
Management
The initial treatment for primary spontaneous pneumothorax is aspiration. If the lung does not expand with aspiration, or if the patient has a recurrent pneumothorax, chest
drain insertion with underwater seal drainage is indicated.
Small-diameter Seldinger chest drains are preferred for
nontraumatic pneumothorax. Pleurodesis or surgery by
thoracoscopy or thoracotomy plus pleural abrasion is very
successful in preventing recurrence. Treatment algorithms
are shown in Figs28.1 and 28.2.
219
Respiratory system
Primary pneumothorax
Yes
Needle aspiration
Successful?
No
Further aspiration?
No
Chest drain insertion
Successful?
No
Referral to chest physician
within 48 h for consideration
of suction
Referral to thoracic surgeon
after 5 days
Breathless and/or rim of air
>2 cm on CXR
Yes
Yes
No
Yes
Successful?
Yes
No
Discharge with
follow up
Remove after 24 h
Fully expanded on CXR
with no apparent leak
from drain site
Fig.28.1 Algorithm for treatment of primary pneumothorax. CXR, Chest X-ray. (After British Thoracic Society.)
Secondary pneumothorax
No
Aspiration
Successful?
Yes
Admit to ward
for 24 h
Discharge with
follow up
Referral to
chest physician
Suction on drain
Breathless rim of air >2 cm
on CXR and age >50 years
Chest drain
insertion
No
Successful?
Remove after 24 h
full expansion on CXR
and cessation of air leak
Successful?
Cardiothoracic
surgical review
after 3 days
Yes
No
Yes
Yes
No
Fig.28.2 Algorithm for treatment of secondary pneumothorax. CXR, Chest X-ray. (After British Thoracic Society.)
220
Pleural effusion
2828
CLINICAL NOTES
TENSION PNEUMOTHORAX
Tension pneumothorax is a medical emergency.
It is a well-recognized cause of a cardiac arrest.
Patients are acutely short of breath, tachypnoeic
and tachycardic. Breath sounds are absent on
the affected side, and the trachea is deviated
away from the side of the lesion. Treatment
includes oxygen and emergency thoracocentesis
(usually just above the rib margin to avoid the
neurovascular bundle, into the second intercostal
space in the midclavicular line, on the side of the
pneumothorax).
PLEURAL EFFUSION
General overview
Pleural effusion is an accumulation of excess fluid in the
pleural space. This can be caused by pulmonary, pleural or
extrapulmonary disease. The fluid is often described as being an exudate or transudate, depending on its composition.
The Light criteria are classically used to distinguish between
the two (see later).
If the fluid is blood, this is called ‘haemothorax’, if it
is puss, it is called ‘empyema’ and if it is chyle, it is called
‘chylothorax’.
Exudative effusions are due to increased capillary permeability with or without diminished fluid resorption; they
are most commonly unilateral:
• infection (parapneumonic effusion: ‘simple’ if pH >7.2
and ‘complicated’ if pH <7.2; empyema if frank pus on
aspiration);
• malignancy;
• pulmonary emboli;
• connective tissue disease (e.g. rheumatoid
arthritis);
• pancreatitis.
Transudative effusions tend to be bilateral and are due to
decreased oncotic pressure or elevated hydrostatic pressure
across the pleural membranes:
• heart failure.
• cirrhotic liver disease.
• hypoalbuminaemia (e.g. liver disease, nephrotic
syndrome).
• constrictive pericarditis.
• hypothyroidism.
• Meigs syndrome – in conjunction with ovarian
fibroma.
Clinical features
The accumulation of fluid within the pleural space will be
asymptomatic until it is large enough to cause respiratory
compromise. Symptoms include breathlessness, particularly on exertion, and sometimes chest pain or cough. The
examination findings include decreased breath sounds,
stony dull percussion note and decreased expansion on the
affected side. History taking should cover:
• Evidence of cardiac failure and ischaemic heart disease.
• Evidence of recent pneumonia: empyema and a reactive
effusion may develop, especially if symptoms of
infection persist.
• Evidence of malignancy: lung primary, metastatic
disease and mesothelioma (asbestos exposure).
Investigations
• CXR will confirm the presence of an effusion and
whether it is bilateral or unilateral. However, effusions
smaller than 200 mL will not usually show up on a
CXR. It may show underlying malignancy, pleural
plaques/thickening or heart failure. A repeat CXR
should be performed after aspiration or chest drain
insertion.
• Ultrasound scanning can visualize even small pleural
effusions. Direct ultrasound vision is recommended for
chest drain insertion.
• CT scanning may be required to further evaluate the
underlying cause.
A sample of the effusion should be obtained by pleural aspiration. Its gross appearance should be noted and then sent
for the following tests:
• pH: pH less than 7.2 in conjunction with pneumonia
implies an infected pleural space.
• Protein and lactate dehydrogenase (LDH): this should
be done with paired serum samples. Traditionally,
effusions are divided into:
• Exudative: protein level greater than 30 g/dL.
• Transudative: protein level less than 30 g/dL. If the
serum protein level is low, then this is a less useful
cut-off and the Light criteria are more sensitive and
specific. These state that if one of the following is
true, then the fluid is exudative:
• pleural fluid protein/serum protein ratio greater
than 0.5;
• pleural fluid LDH/serum LDH ratio greater
than 0.6;
• pleural fluid LDH level more than two-thirds of
the upper serum LDH reference level.
• Gram stain, culture and sensitivities: for bacterial
infection. If there is suspicion of TB, then stain and
culture for Mycobacterium spp. should be requested.
• Cytology: for malignancy and differential
cell count.
221
Respiratory system
Further investigations may include pleural biopsy, thoracoscopy and bronchoscopy and are likely to need specialist
involvement.
Management
The underlying diagnosis should be sought and then treated.
Many effusions will resolve with this alone, particularly if
they are due to cardiac failure. If the history and fluid analysis suggest either empyema or complicated parapneumonic
effusion, then it should be drained in addition to antibiotic
therapy. Drainage is usually achieved by insertion of a chest
drain (Seldinger technique) in the safe triangle (formed anteriorly by the lateral border of the pectoralis major, inferiorly by the fifth intercostal space and laterally by the anterior
border of the latissimus dorsi). Fluid should be drained at
a rate no faster than 2 L in 24 hours. If malignancy is confirmed and the effusion is causing symptoms, then drainage
and pleurodesis with a sclerosing agent such as talc should
obliterate the pleural space, preventing reaccumulation.
INTERSTITIAL LUNG DISEASE
General overview
‘Interstitial lung disease’ (ILD) is an umbrella term for a
heterogeneous group of disorders that affect the lung parenchyma. Prolonged damage to the cells leads to cellular
proliferation and scarring with chronic loss of lung function
(pulmonary fibrosis). Pulmonary fibrosis for which no obvious cause can be identified is termed ‘idiopathic pulmonary fibrosis’ (IPF).
Clinical features
Most patients present with nonproductive cough, slowly
progressive dyspnoea, fatigue, weight loss and occasionally haemoptysis. CXR may show reticulonodular shadowing and loss of lung volume. Careful history taking
including occupational and environmental risks, travel,
medications, past illness, smoking and family history is
important to find a cause. Examination may show cyanosis, finger clubbing and bilateral fine end inspiratory
crackles. As the disease progresses, cor pulmonale may
develop.
Investigations
• FBC, erythrocyte sedimentation rate, U&Es, calcium,
liver function tests, serum angiotensin-converting
cause.
• CXR is often the first modality of imaging. In
sarcoidosis the stages of the disease are classified
according to the appearance on the CXR
(Table28.12). Beyond this, HRCT provides more
detailed diagnostic and prognostic information.
‘Ground glass’ changes on HRCT usually indicate
mild ILD, whereas ‘honeycomb’ changes signify
marked fibrosis and poor prognosis.
• Other tests include pulmonary function tests
(usually restrictive pattern), bronchoalveolar
lavage or lung biopsy. Lung biopsy should be
considered to differentiate between the various
subtypes of interstitial pneumonia. Only usual
interstitial pneumonia can be accurately
diagnosed by HRCT.
Aetiology
ILD can be classified into conditions with and without a
known cause.
Known cause:
• environmental agents: asbestosis, silicosis,
pneumoconiosis;
• drugs: sulfasalazine, gold, amiodarone, methotrexate,
oxygen, nitrofurantoin;
• Systemic disease: connective tissue disorders (systemic
lupus erythematosus, rheumatoid arthritis, systemic
sclerosis), neoplasia, vasculitides (granulomatosis
with polyangiitis (previously known as ‘Wegener
granulomatosis’), Churg–Strauss syndrome,
microscopic polyangiitis), sarcoidosis, inflammatory
bowel disease.
Unknown cause:
• IPF;
• usual interstitial pneumonia;
• cryptogenic organizing pneumonia.
222
Management
Therapy depends on the origin and the underlying cause
of the disease. For instance, if ILD is thought to be a result
of a certain drug, use of that medication should be discontinued. In connective tissue disease-related ILD, immunosuppression is indicated. Management of complications is
as they develop. In end-stage disease, referral for transplantation may be indicated.
Table28.12 Chest X-ray stages of sarcoidosis
Stage 1 Bihilar lymphadenopathy
Stage 2 Bihilar lymphadenopathy
and pulmonary infiltrates
(reticulonodular shadowing)
Stage 3 Bilateral pulmonary infiltrates
Stage 4 Fibrocystic sarcoidosis typically
with upward hilar retraction, cystic
and bullous changes
Interstitial lung disease
2828
Idiopathic pulmonary fibrosis
IPF is a progressive disorder of unknown origin. It is associated with high morbidity and mortality (median survival
from the time of diagnosis is 3years). It is the most common of the ILDs.
There is currently no curative therapy for IPF, and
treatment is supportive. This includes thalidomide (for
persistent cough, unlicensed use), orally administered N-
acetylcysteine (unlicensed use) and, in selected patients,
immunosuppression. Patients with forced vital capacity
between 50% and 80% can be considered for treatment
with pirfenidone or nintedanib (immunosuppressants
with antifibrotic actions). Nintedanib is a tyrosine kinase
inhibitor.
Sarcoidosis
Sarcoidosis is a multisystem chronic inflammatory disorder of unknown origin. The most commonly affected
sites include the lungs, skin and eyes. Pathophysiology
involves formation of noncaseating granulomas. Almost
half of individuals with sarcoidosis are asymptomatic,
and the disease is an incidental discovery. Symptoms can
be nonspecific, and include fever, fatigue, malaise and
weight loss. Pulmonary disease can present with dyspnoea and nonproductive cough. Heerfordt syndrome
is a manifestation of sarcoidosis and includes uveitis,
facial nerve palsy and parotid gland swelling. Löfgren
syndrome is bilateral hilar lymphadenopathy with arthralgia and erythema nodosum. Serum ACE levels are
elevated in most patients with sarcoidosis, but sensitivity and specificity are limited. Management includes
systemically acting corticosteroids as initial treatment.
Antimetabolites (e.g. methotrexate) or biological agents
(e.g. anti-tumour necrosis factor inhibitors) can be used
as second- and third-line agents respectively.
Occupational lung disease
Many acute and chronic lung diseases are directly related
to occupational exposure to inorganic and organic dusts.
A number of different clinical syndromes may result, and
these are listed in Table28.13. They are important as they
are largely preventable through increased awareness and
improved workplace conditions.
Aspergillus and the lung
Aspergillus is a genus of fungi consisting of several hundred species. Organisms belonging to this group are mainly
found in soil and other organic materials. Aspergillus fumi-
gatus and Aspergillus niger are pathogens most commonly
implicated in human disease. Normally, Aspergillus spp.-associated disorders occur in patients with a compromised
immune system.
Pulmonary aspergillosis is a respiratory disease caused
by Aspergillus spp. Many clinical syndromes have been
described:
• Allergic bronchopulmonary aspergillosis: a combined
type I and type III hypersensitivity disorder. It
occurs in patients with asthma, cystic fibrosis and
Table28.13 Common occupational lung diseases
Disease Causes Lung injury
Chronic fibrotic lung disease Coal workers’ pneumoconiosis
Silicosis
Asbestosis
Hypersensitivity pneumonitis Mouldy hay (farmer’s lung)
Avian proteins (bird fancier’s lung)
Obstructive airway disorders Grain dust
Wood dust
Tobacco
Pollen
Synthetic dyes
Formaldehyde
Toxic lung injury Irritant gases Pulmonary oedema
Lung cancer Asbestos Mesothelioma
Arsenic All lung cancer types
Chromium All lung cancer types
Hydrocarbons All lung cancer types
Pleural diseases Asbestos May cause benign effusions and plaques
Talc May cause benign effusions and plaques
Diffuse nodular infiltrates on chest X-ray
Restrictive pulmonary dysfunction
Occupational asthma
Bronchiolitis obliterans
223
Respiratory system
bronchiectasis. It is characterized by bronchospasm,
peripheral blood eosinophilia, Aspergillus precipitins
and raised IgE levels with pulmonary infiltrates. It can
lead to bronchiectasis. Treatment is with corticosteroids
and antifungals.
• Severe asthma with fungal sensitization: A. fumigatus
and Candida albicans are the most common offenders.
Treatment is as for asthma with antifungals.
• Aspergilloma: presence of a cluster of mould in a
body cavity secondary to Aspergillus spp. colonization.
Surgical resection remains the most effective
treatment.
• Invasive aspergillosis: disseminated infection in
immunocompromised patients. Treatment is with
antifungal therapy.
• Chronic necrotizing pulmonary aspergillosis.
• Aspergillus clavatus causes a type of extrinsic allergic
alveolitis also referred to as ‘malt worker's lung’.
Treatment is with oral steroids; if it is left untreated,
pulmonary fibrosis may develop.
HYPOVENTILATION SYNDROMES AND SLEEP-RELATED RESPIRATORY DISORDERS
General overview
Apnoea is defined as an intermittent cessation of respiratory airflow especially during sleep. The most common
cause of sleep-disordered breathing is obstructive sleep apnoea (OSA); other hypoventilatory disorders are much less
common.
Sleep apnoea is divided into three types:
• Central sleep apnoea: apnoea with a patent upper
airway. The cause is central in origin and usually
involves dysregulation in the functioning of the
respiratory centres in the brainstem.
• OSA: apnoea despite continuing respiratory
effort because of complete or partial upper airway
occlusion.
• Mixed apnoea.
Obstructive sleep apnoea syndrome
This is OSA resulting in irregular night-time ventilation
and excessive daytime sleepiness. The symptoms include
snoring, poor concentration, unrefreshing restless sleep,
daytime somnolence, morning headaches, poor libido and
reduced cognitive function. Risk factors include increasing
age, male sex, obesity, neck circumference, sedative drugs
and alcohol.
COMMUNICATION
The history of patients with suspected OSA
is best obtained with their partner present.
Patients may be untroubled by their own snoring.
Partners may be affected more than patients;
you can gauge the impact of the problem on their
combined life. They also often describe apnoeas
with great accuracy!
Management of OSA includes weight reduction,
avoidance of alcohol at night, smoking cessation,
intraoral devices (e.g. mandibular advancement
device) and avoidance of sleeping supine. Sleep
hygiene advice should be given. Nasal continuous
positive airway pressure remains the gold standard
treatment to splint open the upper airway during
sleep. Rarely surgical intervention may be
recommended.
Obesity hypoventilation syndrome
Also known as ‘Pickwickian syndrome’, this condition is
characterized by hypoventilation associated with obesity
and daytime hypercapnia. Night-time hypoventilation is
more profound here than OSA. This may cause poor nighttime sleep and, in chronic untreated cases, lead to congestive cardiac failure and cor pulmonale.
Congenital hypoventilation syndrome
Congenital hypoventilation syndrome, or Ondine's curse,
is a fatal respiratory condition if left untreated. It can be
congenital or a result of significant neurological injury. The
condition is characterized by episodes of central apnoea secondary to autonomic failure at the level of the brainstem. It
is a rare condition that may be associated with Hirschsprung
disease and neuroblastoma. Treatment used to involve tracheostomy and lifelong mechanical ventilation. More recently biphasic cuirass ventilation and phrenic nerve pacing
have been successfully used to manage the condition.
ACUTE RESPIRATORY DISTRESS SYNDROME
General overview
ARDS is a life-threatening condition characterized by severe
respiratory failure secondary to noncardiogenic pulmonary
224
Cystic fibrosis
2828
oedema on a background of acute alveolar injury. The
pathogenesis is complex, but involves capillary leak, marked
lung inflammatory response, surfactant dysfunction, coagulopathy and atelectasis.
ARDS can develop as a result of sepsis, pneumonia,
trauma, severe burns, pancreatitis, disseminated intravascular coagulopathy, blood transfusions, drug reactions and
near drowning. Hypoxaemia results from noncardiogenic
pulmonary oedema. Prognosis in ARDS is poor. Mortality
of severe ARDS is close to 50%. Most survivors have residual impairment of lung function.
ARDS is defined by:
• acute onset lung injury (within 1week of exposure to a
well-recognized risk factor);
• new bilateral infiltrates on CXR (Fig.28.3);
• noncardiogenic origin of pulmonary oedema;
• refractory hypoxaemia: Pa2/Fi2 of 39.9 kPa or less.
Management
ARDS should be managed in an intensive care unit. The
mainstay of therapy is the use of lung protective strategies
and treatment of the underlying cause. Most patients require mechanical ventilation.
• Lung protective measures: low tidal volume
ventilation at lower pressures, negative fluid
balance.
• Permissive hypercapnia.
• Lung recruitment manoeuvres (e.g. proning, highfrequency oscillatory ventilation, corticosteroids),
higher positive end-expiratory pressure.
• Extracorporeal membrane oxygenation.
• Cardiovascular support: ARDS is often associated
with multiorgan distress or failure. Invasive
haemodynamic monitoring such as with arterial and
central venous lines is used to monitor fluid balance,
blood pressure and cardiac output (PiCCO line). If
blood pressure remains low despite adequate fluid
resuscitation, ionotropes such as noradrenaline may
be indicated.
• Sepsis: this is the most common cause of ARDS.
Remember that the source may be from sites other than
the lungs – a patient presenting with sepsis secondary
to an Escherichia coli urinary tract infection may
develop ARDS.
CYSTIC FIBROSIS
Fig.28.3 Chest X-ray showing bilateral infiltrates in acute
respiratory distress syndrome. (Reprinted from Su Y-J,
Kung C-T, Lee C-H, etal. An industrial worker hospitalized
with paralysis after an aerosolized chemical exposure.
American Journal of Kidney Diseases 2010; 56:A38–A41,
with permission from Elsevier.)
General overview
Cystic fibrosis is a multisystem autosomal recessive disorder that results from mutations in the cystic fibrosis
transmembrane conductance regulator gene (CFTR) located on chromosome 7. Its function involves regulation
of chloride and water movement across the cell membrane. Close to 2000 mutations have been identified but
the most common one in the Caucasian population, accounting for more than 70% of cases is the ΔF508 mutation. Cystic fibrosis occurs in 1 in 2500 live births; 1
person in 25 is a carrier.
Clinical features
Cystic fibrosis is characterized by:
• chronic airway infection and inflammation leading to
bronchiectasis and progressive airway obstruction
• exocrine and endocrine pancreatic insufficiency
• intestinal and hepatic dysfunction
• abnormal sweat gland function
• urogenital dysfunction (obstructive azoospermia
in males)
The signs and symptoms typically occur in childhood, but
cystic fibrosis is diagnosed in up to 5% of patients in adulthood. Because of neonatal screening programmes for cystic
fibrosis (at day 6 of life), clinical presentation of cystic fibrosis has become less frequent. Respiratory problems, such
225
Respiratory system
as recurrent infections or sputum overproduction, are the
most common initial concerns in newly presenting patients.
The diagnosis of cystic fibrosis rests on a combination of
clinical criteria, analysis of sweat chloride (the ‘sweat test’) and
increasingly genotyping. The faecal elastase test is a useful
screening test for exocrine pancreatic function impairment.
Management
A multidisciplinary approach leads to better patient outcomes. Improvements in supportive therapy mean that
the median survival is now 40years. Strategies aimed at
treating cystic fibrosis aim to promote clearance of secretions and reverse bronchoconstriction (physiotherapy,
mucolytics and bronchodilators), control infection in the
lung (prophylactic antibiotics) and ensure adequate nutrition (pancreatic enzyme and fat-soluble vitamin supplements). Pneumococcus and influenza vaccinations are
recommended. Patients should be monitored for signs of
diabetes and intestinal obstruction. As irreversible complications arise, heart–lung transplantation may be an option for some. Gene therapy remains elusive and far from
clinical use.
CLINICAL NOTES
PATHOGENS COLONIZING LUNGS OF PATIENTS
WITH CF
The pathogens that most commonly colonize
the lungs of patients with cystic fibrosis are
Staphylococcus aureus, Pseudomonas aeruginosa,
Escherichia coli, Klebsiella pneumonia and
Burkholderia cepacia.
COMMUNICATION
The transition from paediatric to adult care is
difficult for both patients and their parents.
Patients need to build relationships with a new
medical team at a time when they are becoming
independent adults. This may be hard for parents,
who have often spent most of their time caring for
their child and now may feel they have no clear
role. Offer support to both parties to help facilitate
this transition.
Chapter Summary
• Respiratory failure is a medical emergency. Type I is associated with hypoxia with normal
CO2 levels whereas type II is hypoxia with hypercapnia. Oxygen therapy is the mainstay
of emergency treatment.
• Severe or life-threatening asthma is a medical emergency. Management includes oxygen
therapy, salbutamol and ipratropium bromide nebulizers and steroids. Magnesium is
added if response to the initial treatment is poor. Intravenously administered
aminophylline or salbutamol can also be used.
• Chronic obstructive pulmonary disease (COPD) is a disease that is most commonly
associated with smoking. It tends to present with chronic dyspnoea and productive of
sputum cough. Emergency management is similar to that of asthma; however, one needs
to remember that the blood oxygen saturation target level in patients with COPD is 88%–
92% as opposed to more than 94% in asthma. Therefore fixed oxygen concentrations
with the use of venturi masks are used to treat hypoxaemia in these patients.
• Different organisms are implicated in different types of pneumonia. The most common
pathogens responsible for community-acquired pneumonia are pneumococcus,
Haemophilus influenzae and Staphylococcus aureus; atypical pneumonia is most
commonly caused by Mycoplasma, Legionella and Chlamydia species; hospital-acquired
pneumonia is most commonly caused by gram-negative species such as Pseudomonas
and Klebsiella. If aspiration pneumonia is suspected, antibiotic treatment should include
anaerobic organism cover.
• CURB65 is a useful tool that helps to assess the risk of death in patients presenting with
pneumonia.
• Venous thrombosis is the most common cause of pulmonary embolism. CT pulmonary
angiogram is the most useful diagnostic tool, but is contraindicated in kidney failure or
allergy to contrast media and is not desirable in pregnancy.
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Further reading
• Haemodynamically unstable patients with pulmonary embolism should be considered for
thrombolysis. In the event of a cardiac arrest, if a decision to treat the patient with
thrombolysis is made, it is recommended that CPR be continued for 60–90 min after
administration of the drug or until the return of spontaneous circulation.
• Lung cancer is the most deadly cancer worldwide. Different types have been described.
Adenocarcinoma is more common in nonsmokers, and is usually located in the
peripheries of the lung; squamous cell carcinoma tends to affect the large airway; small
cell carcinoma is the most aggressive type of lung cancer, and grows fast and spreads
early. Other types include large cell carcinoma and mesothelioma.
• Tuberculosis (TB) is a chronic granulomatous disease that can affect various organs in the
body. Treatment of pulmonary tuberculosis is with a 6-month therapy with four different
drugs for the first 2months (rifampicin, isoniazid, pyrazinamide and ethambutol) and two
drugs (rifampicin and isoniazid) for the remaining 4months. Central nervous system TB
treatment is continued for 12months.
• Tension pneumothorax is a medical emergency and should be managed with the ABCDE
approach. Immediate needle decompression is the life-saving treatment. This is achieved
by thoracocentesis with a large-bore cannula in the second intercostal space in the
midclavicular line.
• Pleural effusion can be exudative or transudative. Exudative pleural effusion is most
commonly unilateral and a result of infection or malignancy. Transudative pleural effusion
tends to be bilateral and a result of heart failure, hypoalbuminemia or liver disease.
• Idiopathic pulmonary fibrosis is the most common of the interstitial lung diseases. It is a
progressive disease of unknown cause. Treatment is supportive.
• Acute respiratory distress syndrome is a life-threatening complication of an acute lung
insult. The most common causes include sepsis, pancreatitis and trauma. It is managed
in an intensive care setting.
• Cystic fibrosis is an autosomal recessive disorder that affects the CFTR gene. This leads
to abnormalities in electrolyte transport across epithelial cell membranes in, mainly the
lung, pancreas, gastrointestinal tract, genitourinary tract and skin. The most common
mutation is ΔF508.
2828
FURTHER READING
BTS, 2016. BTS/SIGN British guideline on the management of
asthma.
BTS, 2018. BTS guideline for oxygen use in healthcare and emer-
gency setting.
NICE, 2010. Chronic obstructive pulmonary disease in over 16s:
diagnosis and management.
NICE, 2014. Pneumonia in adults: diagnosis and management.
NICE, 2015. Venous thromboembolic disease: diagnosis, manage-
ment and thrombophilia testing.
NICE, 2011. Lung cancer: diagnosis and management.
NICE, 2016. Tuberculosis.
NICE, 2013. Idiopathic pulmonary fibrosis in adults: diagnosis and
management.
NICE, 2017. Asthma: diagnosis, monitoring and chronic asthma
management.
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