Respiratory Flashcards
Newly-diagnosed asthma
NICE do not follow the stepwise approach of the previous BTS guidelines. However, to try to make the guidelines easier to follow we’ve added our own steps:
Step
Notes
1
Newly-diagnosed asthma
Short-acting beta agonist (SABA)
2
Not controlled on previous step
OR
Newly-diagnosed asthma with symptoms >= 3 / week or night-time waking
SABA + low-dose inhaled corticosteroid (ICS)
3
SABA + low-dose ICS + leukotriene receptor antagonist (LTRA)
4
SABA + low-dose ICS + long-acting beta agonist (LABA)
Continue LTRA depending on patient’s response to LTRA
5
SABA +/- LTRA
Switch ICS/LABA for a maintenance and reliever therapy (MART), that includes a low-dose ICS
6
SABA +/- LTRA + medium-dose ICS MART
OR consider changing back to a fixed-dose of a moderate-dose ICS and a separate LABA
7
SABA +/- LTRA + one of the following options:
increase ICS to high-dose (only as part of a fixed-dose regime, not as a MART)
a trial of an additional drug (for example, a long-acting muscarinic receptor antagonist or theophylline)
seeking advice from a healthcare professional with expertise in asthma
Maintenance and reliever therapy (MART)
a form of combined ICS and LABA treatment in which a single inhaler, containing both ICS and a fast-acting LABA, is used for both daily maintenance therapy and the relief of symptoms as required
MART is only available for ICS and LABA combinations in which the LABA has a fast-acting component (for example, formoterol)
It should be noted that NICE does not advocate changing treatment in patients who have well-controlled asthma simply to adhere to the latest guidance.
Table showing examples of inhaled corticosteroid doses
Frustratingly, the definitions of what constitutes a low, moderate or high-dose ICS have also changed. For adults:
<= 400 micrograms budesonide or equivalent = low dose
400 micrograms - 800 micrograms budesonide or equivalent = moderate dose
> 800 micrograms budesonide or equivalent= high dose.
Asthma: diagnosis
NICE released guidance on the management of asthma in 2017. These followed on quickly from the 2016 British Thoracic Society (BTS) guidelines. Given previous precedents where specialist societies or Royal colleges eventually default/contribute to NICE, we have followed the NICE guidance for the notes and questions.
NICE guidance has radically changed how asthma should be diagnosed. It advocates moving anyway from subjective/clinical judgements are more towards objective tests.
There is particular emphasis on the use of fractional exhaled nitric oxide (FeNO). Nitric oxide is produced by 3 types of nitric oxide synthases (NOS). One of the types is inducible (iNOS) and levels tend to rise in inflammatory cells, particularly eosinophils. Levels of NO therefore typically correlate with levels of inflammation.
Other more established objective tests such as spirometry and peak flow variability are still important.
All patients >= 5 years should have objective tests. Once a child with suspected asthma reaches the age of 5 years objective tests should be performed to confirm the diagnosis.
Diagnostic testing
Patients >= 17 years
patients should be asked if their symptoms are better on days away from work/during holidays. If so, patients should be referred to a specialist as possible occupational asthma
all patients should have spirometry with a bronchodilator reversibility (BDR) test
all patients should have a FeNO test
Patients 5-16 years
all patients should have spirometry with a bronchodilator reversibility (BDR) test
a FeNO test should be requested if there is normal spirometry or obstructive spirometry with a negative bronchodilator reversibility (BDR) test
Patients < 5 years
- diagnosis should be made on clinical judgement
Specific points about the tests
FeNO
in adults level of >= 40 parts per billion (ppb) is considered positive
in children a level of >= 35 parts per billion (ppb) is considered positive
Spirometry
FEV1/FVC ratio less than 70% (or below the lower limit of normal if this value is available) is considered obstructive
Reversibility testing
in adults, a positive test is indicated by an improvement in FEV1 of 12% or more and increase in volume of 200 ml or more
in children, a positive test is indicated by an improvement in FEV1 of 12% or more
ABG
ROME
Respiratory = Opposite
low pH + high PaCO2 i.e. acidosis, or
high pH + low PaCO2 i.e. alkalosis
Metabolic = Equal
low pH + low bicarbonate i.e. acidosis, or
high pH + high bicarbonate i.e. akalosis
ABG triad for chronic CO2 retention:
Normal pH
High pCO2
High HCO3
Important for meLess important
The only option which would fit with a chronic picture of CO2 retention would be number 5 as this has the raised bicarbonate which is a result of chronic renal compensation of the acidosis. The pH is also within the normal range as this acidosis is fully compensated and the pO2 is low in keeping with the low saturations of 91%.
Option 2 reflects a normal blood gas result. The normal values of arterial blood gases are shown in the table below:
pH 7.35 - 7.45
pO2 10.0 - 14.0 kPa
pCO2 4.5 - 6.0 kPa
HCO3- 22 - 26 mmol/l
Arterial blood gas interpretation
The Resuscitation Council (UK) advocate a 5 step approach to arterial blood gas interpretation.
- How is the patient?
- Is the patient hypoxaemic?
the Pa02 on air should be >10 kPa
- Is the patient acidaemic (pH <7.35) or alkalaemic (pH >7.45)
- Respiratory component: What has happened to the PaCO2?
PaCO2 > 6.0 kPa suggests a respiratory acidosis (or respiratory compensation for a metabolic alkalosis)
PaCO2 < 4.7 kPa suggests a respiratory alkalosis (or respiratory compensation for a metabolic acidosis)
- Metabolic component: What is the bicarbonate level/base excess?
bicarbonate < 22 mmol/l (or a base excess < - 2mmol/l) suggests a metabolic acidosis (or renal compensation for a respiratory alkalosis)
bicarbonate > 26 mmol/l (or a base excess > + 2mmol/l) suggests a metabolic alkalosis (or renal compensation for a respiratory acidosis)
COPD stable management
NICE updated its guidelines on the management of chronic obstructive pulmonary disease (COPD) in 2018.
General management
>smoking cessation advice: including offering nicotine replacement therapy, varenicline or bupropion
annual influenza vaccination
one-off pneumococcal vaccination
pulmonary rehabilitation to all people who view themselves as functionally disabled by COPD (usually Medical Research Council [MRC] grade 3 and above)
Bronchodilator therapy
a short-acting beta2-agonist (SABA) or short-acting muscarinic antagonist (SAMA) is first-line treatment
for patients who remain breathless or have exacerbations despite using short-acting bronchodilators the next step is determined by whether the patient has ‘asthmatic features/features suggesting steroid responsiveness’
There are a number of criteria NICE suggest to determine whether a patient has asthmatic/steroid responsive features:
any previous, secure diagnosis of asthma or of atopy
a higher blood eosinophil count - note that NICE recommend a full blood count for all patients as part of the work-up
substantial variation in FEV1 over time (at least 400 ml)
substantial diurnal variation in peak expiratory flow (at least 20%)
Interestingly NICE do not recommend formal reversibility testing as one of the criteria. In the guidelines they state that ‘routine spirometric reversibility testing is not necessary as part of the diagnostic process or to plan initial therapy with bronchodilators or corticosteroids. It may be unhelpful or misleading…’. They then go on to discuss why they have reached this conclusion. Please see the guidelines for more details.
No asthmatic features/features suggesting steroid responsiveness
add a long-acting beta2-agonist (LABA) + long-acting muscarinic antagonist (LAMA)
if already taking a SAMA, discontinue and switch to a SABA
Asthmatic features/features suggesting steroid responsiveness
LABA + inhaled corticosteroid (ICS)
if patients remain breathless or have exacerbations offer triple therapy i.e. LAMA + LABA + ICS
if already taking a SAMA, discontinue and switch to a SABA
NICE recommend the use of combined inhalers where possible
Oral theophylline
NICE only recommends theophylline after trials of short and long-acting bronchodilators or to people who cannot used inhaled therapy
the dose should be reduced if macrolide or fluoroquinolone antibiotics are co-prescribed
Oral prophylactic antibiotic therapy
azithromycin prophylaxis is recommended in select patients
patients should not smoke, have optimised standard treatments and continue to have exacerbations
other prerequisites include a CT thorax (to exclude bronchiectasis) and sputum culture (to exclude atypical infections and tuberculosis)
LFTs and an ECG to exclude QT prolongation should also be done as azithromycin can prolong the QT interval
Mucolytics
should be ‘considered’ in patients with a chronic productive cough and continued if symptoms improve
Cor pulmonale
features include peripheral oedema, raised jugular venous pressure, systolic parasternal heave, loud P2
use a loop diuretic for oedema, consider long-term oxygen therapy
ACE-inhibitors, calcium channel blockers and alpha blockers are not recommended by NICE
Factors which may improve survival in patients with stable COPD
smoking cessation - the single most important intervention in patients who are still smoking
long term oxygen therapy in patients who fit criteria
lung volume reduction surgery in selected patients
COPD Azithromycin
According to NICE 2018, consider azithromycin (usually 250 mg 3 times a week) for people with COPD if they:
do not smoke and
have optimised non-pharmacological management and inhaled therapies, relevant vaccinations and (if appropriate) have been referred for pulmonary rehabilitation and continue to have 1 or more of the following, particularly if they have significant daily sputum production:
frequent (typically 4 or more per year) exacerbations with sputum production
prolonged exacerbations with sputum production
exacerbations resulting in hospitalisation.
Carbocisteine is an example of a mucolytic agent. The routine usage of mucolytic drugs to prevent exacerbations in people with stable COPD is not recommended. [NICE 2010]
Oral codeine phosphate is an example of an anti-tussive agent. Anti-tussive therapy should not be used in the management of stable COPD. [NICE 2004]
Alpha-tocopherol and beta-carotene supplements are both examples of an anti-oxidant agent. Oral anti-oxidant therapy, alone or in combination, is not recommended in managing patients with stable COPD. [NICE 2004]
Haemoptysis
The table below lists the main characteristics of the most important causes of haemoptysis:
Diagnosis
Notes
Lung cancer
History of smoking
Symptoms of malignancy: weight loss, anorexia
Pulmonary oedema
Dyspnoea
Bibasal crackles and S3 are the most reliable signs
Tuberculosis
Fever, night sweats, anorexia, weight loss
Pulmonary embolism
Pleuritic chest pain
Tachycardia, tachypnoea
Lower respiratory tract infection
Usually acute history of purulent cough
Bronchiectasis
Usually long history of cough and daily purulent sputum production
Mitral stenosis
Dyspnoea
Atrial fibrillation
Malar flush on cheeks
Mid-diastolic murmur
Aspergilloma
Often past history of tuberculosis.
Haemoptysis may be severe
Chest x-ray shows rounded opacity
Granulomatosis with polyangiitis
Upper respiratory tract: epistaxis, sinusitis, nasal crusting
Lower respiratory tract: dyspnoea, haemoptysis
Glomerulonephritis
Saddle-shape nose deformity
Goodpasture’s syndrome
Haemoptysis
Systemically unwell: fever, nausea
Glomerulonephritis
Oxygen therapy
The British Thoracic Society updated its guidelines on emergency oxygen therapy in 2017. The following selected points are taken from the guidelines. Please see the link provided for the full guideline.
In patients who are critically ill (anaphylaxis, shock etc) oxygen should initially be given via a reservoir mask at 15 l/min. Hypoxia kills. The BTS guidelines specifically exclude certain conditions where the patient is acutely unwell (e.g. myocardial infarction) but stable.
Oxygen saturation targets
acutely ill patients: 94-98%
patients at risk of hypercapnia (e.g. COPD patients): 88-92% (see below)
oxygen should be reduced in stable patients with satisfactory oxygen saturation
Management of COPD patients
prior to availability of blood gases, use a 28% Venturi mask at 4 l/min and aim for an oxygen saturation of 88-92% for patients with risk factors for hypercapnia but no prior history of respiratory acidosis
adjust target range to 94-98% if the pCO2 is normal
Situations where oxygen therapy should not be used routinely if there is no evidence of hypoxia:
myocardial infarction and acute coronary syndromes
stroke
obstetric emergencies
anxiety-related hyperventilation
Obstructive lung disease
Obstructive lung disease
FEV1 - significantly reduced
FVC - reduced or normal
FEV1% (FEV1/FVC) - reduced
Asthma
COPD
Bronchiectasis
Bronchiolitis obliterans
Restrictive lung disease
FEV1 - reduced
FVC - significantly reduced
FEV1% (FEV1/FVC) - normal or increased
Pulmonary fibrosis
Asbestosis
Sarcoidosis
Acute respiratory distress syndrome
Infant respiratory distress syndrome
Kyphoscoliosis e.g. ankylosing spondylitis
Neuromuscular disorders
Severe obesity
Pleural effusion investigation and management
The British Thoracic Society (BTS) produced guidelines in 2010 covering the investigation of patients with a pleural effusion.
Imaging
posterioranterior (PA) chest x-rays should be performed in all patients
ultrasound is recommended: it increases the likelihood of successful pleural aspiration and is sensitive for detecting pleural fluid septations
contrast CT is now increasingly performed to investigate the underlying cause, particularly for exudative effusions
Pleural aspiration
as above, ultrasound is recommended to reduce the complication rate
a 21G needle and 50ml syringe should be used
fluid should be sent for pH, protein, lactate dehydrogenase (LDH), cytology and microbiology
Light’s criteria was developed in 1972 to help distinguish between a transudate and an exudate. The BTS recommend using the criteria for borderline cases:
exudates have a protein level of >30 g/L, transudates have a protein level of <30 g/L
if the protein level is between 25-35 g/L, Light’s criteria should be applied. An exudate is likely if at least one of the following criteria are met:
pleural fluid protein divided by serum protein >0.5
pleural fluid LDH divided by serum LDH >0.6
pleural fluid LDH more than two-thirds the upper limits of normal serum LDH
Other characteristic pleural fluid findings:
low glucose: rheumatoid arthritis, tuberculosis
raised amylase: pancreatitis, oesophageal perforation
heavy blood staining: mesothelioma, pulmonary embolism, tuberculosis
Pleural infection
All patients with a pleural effusion in association with sepsis or a pneumonic illness require diagnostic pleural fluid sampling
if the fluid is purulent or turbid/cloudy a chest tube should be placed to allow drainage
if the fluid is clear but the pH is less than 7.2 in patients with suspected pleural infection a chest tube should be placed
Management of recurrent pleural effusion
Options for managing patients with recurrent pleural effusions include:
recurrent aspiration
pleurodesis
indwelling pleural catheter
drug management to alleviate symptoms e.g. opioids to relieve dyspnoea
Shortness of breath chronic
The table below gives characteristic features for conditions causing chronic shortness of breath (SOB):
Chronic obstructive pulmonary disease
Seen invariably in smokers
Chronic productive cough is typical
Features of right heart failure may be seen
Heart failure
A history of ischaemic heart disease or hypertension may be present
Orthopnoea and paroxysmal nocturnal dyspnoea are characteristic
Bibasal crackles and a third heart sound (S3) are the most reliable features of left-sided failure
Right heart failure causes peripheral oedema and a raised JVP
Asthma
Cough, wheeze and shortness of breath are typical
Symptoms are often worse at night and may be precipitated by cold weather or exercise
Associated with hay fever and eczema
Aortic stenosis
Chest pain, SOB and syncope seen in symptomatic patients
An ejection systolic murmur radiating to the neck and narrow pulse pressure are found on examination
Recurrent pulmonary emboli
There may be a history of predisposing factors e.g. Malignancy
Pleuritic chest pain and haemoptysis may be seen but symptoms are often vague
Tachycardia and tachypnoea are common in the acute situation
Symptoms of right heart failure may develop in severe cases
Lung cancer
Normally seen in smokers
Haemoptysis, chronic cough or unresolving infection are common presentations
Systemic symptoms e.g. Weight loss and anorexia
Pulmonary fibrosis
Progressive shortness of breath may be the only symptom
Fine bibasal crackles are typical
Spirometry shows a restrictive pattern
Bronchiectasis
Affected patients may produce large amounts of purulent sputum
Patients may have a history of previous infections (e.g. Tuberculosis, measles), bronchial obstruction or ciliary dyskinetic syndromes e.g. Kartagener’s syndrome
Anaemia
There may be a history of gastrointestinal symptoms
Pallor may be seen on examination
Obesity
Obese patients tend to be more SOB due to the increased work of activity
