Respiratory II (OSA; Asthma; Resp support) Flashcards
What is the difference between apnoea and hypopnoea? [2]
Apnoea – a complete cessation of airflow for
at least 10 seconds
Hypopnoea – a reduction in airflow to under
50% or by 30% for at least 10 seconds with a desaturation of at least 4%
What is Apnoea and Hypopnoea Index? [1]
What are normal, mild, moderate and severe scores? [4]
AHI – number of apnoeas and hypopnoeas
per hour of the study
- 0 to 5 Within normal limits
- 5 to 15 Mild OSA
- 15 to 30 Moderate OSA
- 30 plus Severe OSA
What is the name for the sleep score used for measuring sleep apnoea?
What score is abnormal?
What is the total score
Epworth sleepiness scale
10 / 24 is abnormal
What is this? [1]
When is it indicated? [1]
Mandibular splint
If CPAP not tolerated
What severity of sleep apnoea is CPAP indicated in? [2]
Continuous Positive Airway Pressure (CPAP):
Causes continous air passage to be open
Used for patients with moderate or severe sleep apnoea
Name three conditions that cause macroglossia and therefore sleep apnoea [3]
acromegaly, hypothyroidism, amyloidosis
What is the most common surgery for sleep apnoea? [1]
Surgery is an option but involves significant surgical reconstruction of the soft palate and jaw. The most common procedure is called uvulopalatopharyngoplasty (UPPP).
A 61-year-old male snores at night, and his wife reports it is so loud that he often wakes her up. She notes that her husband sometimes appears not to take a breath for a long time and then gasps for air before continuing to snore. He suffers from daytime headaches and sleepiness. He has a body mass index (BMI) of 40 kg/m2.
What would the most likely arterial blood gas result be if it was measured in this patient?
Compensated respiratory acidosis
Compensated respiratory alkalosis
Compensated metabolic acidosis
Uncompensated respiratory acidosis
Uncompensated metabolic acidosis
Compensated respiratory acidosis
Describe what hypoglossal nerve stimulation is [1]
How does it work? [1]
Hypoglossal nerve stimulation aims to treat obstructive sleep apnoea by preventing the tongue prolapsing backwards and causing upper airway obstruction during sleep. It works by delivering an electrical current to the hypoglossal nerve
What trio of crtieria make a diagnosis of obesity hypoventilation syndrome? [3]
- Daytime hypercapnia PaCO2 ≥ 45 mmHg
- Obesity (BMI > 30)
- Sleep disordered breathing (which can include OSA)
How do you determine obesity hypoventilation syndrome vs OSA? [1]
Daytime hypercapnia in OHS
What is the treatment for OHS? [1]
First line:
- CPAP
Second line:
- NIV
Desribe a key difference in OSA and OHS [1]
Patients with OHS often experience daytime hypoventilation, which leads to chronic hypercapnia and hypoxemia, resulting in symptoms such as dyspnea, exercise intolerance, morning headaches, and cognitive dysfunction.
In summary, OHS is a more complex disorder involving chronic hypoventilation, obesity, and sleep-disordered breathing, whereas OSA is specifically characterized by upper airway obstruction during sleep
Which type of hypersensitivty is asthma? [1]
Type 1
Describe the pathophysiology of asthma
Airway inflammation:
- Immune cells activated by TH2, mast cells and eosinophils
- Causes pro-inflam mediators (cytokines, chemokines, histamines, leukotrines) to cause airway oedema, mucus production, and bronchoconstriction
Bronchoconstriction
- narrowing of the airways and obstruction of airflow.
Airway hyperresponsiveness
- airways exhibit excessive narrowing in response to various stimuli, such as allergens, irritants, and cold air
- mediated by several factors, including the release of inflammatory mediators, increased airway smooth muscle contractility, and impaired bronchodilator mechanisms
Mucus production and airway remodeling:
* Chronic inflammation causes airway remodeling
* Subepithelial fibrosis, increased smooth muscle mass, mucus gland hypertrophy, and angiogenesis.
A number of patients with asthma are sensitive to which drug? [1]
Patients who are most sensitive to asthma often suffer from []? [1]
A number of patients with asthma are sensitive to aspirin.
Patients who are most sensitive to asthma often suffer from nasal polyps. Remember the nose is part of the respiratory tract from a histological point of view.
Describe the pathway that causes asthma [5]
i. Allergen picked up by dendritic cells and presented by MHC Class II molecules
ii. CD4 cells activate the TH-2 lymphocytes through the release of IL4, IL5, IL13.
iII. IL 4 leads to the production of IgE antibodies: coat mast cells and stimulate degranulation and the release histamines, leukotrienes and prostaglandins
iv. IL-5 activates eosinophils: causes more cytokine & leukotrienes release
v IL-9 = mast cell proliferation
What are the classical features of asthma? [4]
What helps to create a clinical picture regarding features and treatment? [1]
episodic symptoms; typically worse at night:
* widespread, polyphonic expiratory wheeze (occurs from turbulent airflow in narrow airways)
* breathlessness
* chest tightness: airway obstruction and increasde work of breathing
* cough: dry or productive; worse at night or early in morning.
Symptoms should improve with bronchodilators. No response to bronchodilators reduces the likelihood of asthma.
TOM TIP: A localised monophonic wheeze is not asthma.
Give the top differentials of a localised wheeze [3]
Inhaled foreign body
tumour
a thick sticky mucus plug obstructing an airway (pneumonia)
pulmonary oedema
A chest x-ray is the next step.
Which drugs can worsen asthma? [3]
Non-selective beta blockers: propranolol
- blocking the beta receptors in the lungs, which leads to bronchoconstriction and breathing difficulties.
Non-steroidal anti-inflammatory drugs: aspirin, ibuprofen or naproxen
- This reaction is known as aspirin-exacerbated respiratory disease (AERD) or aspirin-induced asthma.
Which cells are responsible for the acute phase of asthma? [1]
Which cells are responsible for the late phase of asthma? [3]
Early: mast cells
Late: Th2 helper cells –> B cells –> IgE & Eiosinophils
Describe the features that would make you suspicious that a patient has asthma [6]
More than one of the following in episodes:
wheeze
breathlessness
chest tightness
cough
diurnal variability
Triggered by allergen, exercise, cold air, aspirin or β-blocker
Atopic features
Eczema
Hayfever
Fx
Low PEFR or FEV (note: both decrease with age)
Describe the diagnostic pathway for diagnosis of asthma
- Clinical suspicion based off clinical assessment (history, exam, previous medical records)
- IF high probabilty of asthma:
Code as suspected asthma and start treatment
Assess response to treatment:
Good response = asthma;
poor response then intermediate probability of asthma. - Next: Test for airway obstruction using spirometry and bronchodilator reversibility:
-
Test for variability by investigating:
Reversibility
PEF charting
Challenge tests -
Test for eosinophilic inflammation:
FeNO
Blood eosinophs
Skin prick test, IgEIf good response: asthma
If poor response: investigate other more likely diagnosis
BTS pathway
What does FeNO test? [1]
What level of FeNO would be considered positive for asthma in adults? [1]
What level of FeNO would warrent further consideration for asthma positive for asthma in adults? [1]
What level of FeNO would you consider a different diagnosis than asthma in adults? [1]
fractional exhaled nitric oxide (FeNO):
FeNO tests the amount of NO produced by iNOS, which is raised in eisinophils (which are raised in asthma)
- in adults a level of >= 40 parts per billion (ppb) is considered positive
- 25-39 ppb would warrant further investigations
- < 25 ppb would be a different diagnosis
What level of FeNO would be considered positive for asthma in children? [1]
- in children a level of >= 35 parts per billion (ppb) is considered positive
What would indicate positive reversibility testing in adults [2] and children [1]?
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
Describe what is meant by direct bronchial challenge testing [1]
What results would indicate a positive result for asthma? [1]
Direct bronchial challenge testing is the opposite of reversibility testing.
Inhaled histamine or methacholine is used to stimulate bronchoconstriction, reducing the FEV1 in patients with asthma.
NICE say a PC20 (provocation concentration of methacholine causing a 20% reduction in FEV1) of 8 mg/ml or less is a positive test result.
How long would you ask a patient to keep a peak flow diary for when investigating asthma? [1]
What results would indicate a positive result for asthma? [1]
Peak flow variability is measured by keeping a peak flow diary with readings at least twice daily over 2 to 4 weeks.
NICE says a peak flow variability of more than 20% is a positive test result, supporting a diagnosis.
PEF: 20%
FEV1: 12% or 200ml
Label A-E [5]
A: FEV1/FVC< 70%
B: >12% or 200ml improvement in FEV1
C: >40 ppb
D: concentration required to cause 20% fall in FEV1 (PC20) OF 8mg/ml or less
E: 20% variability
What five steps should you educate / make on self management plans for patietns? [5]
How to use treatment
Self monitoring/assessment skills
Action plan with regard to goals
Recognition and management of exacerbations
Allergen/trigger avoidance
State the treatment algorithm for asthma
- Newly-diagnosed asthma:
SABA; (salbutamol) - Inhaled corticosteroid (low dose) taken regularly
- BTS: Long-acting beta-2 agonists (e.g., salmeterol) or maintenance and reliever therapy (MART)
OR
NICE: Leukotriene receptor antagonist (e.g., montelukast) taken regularly - BTS: Increase the inhaled corticosteroid or add a leukotriene receptor antagonist (e.g., montelukast)
OR
NICE: Long-acting beta-2 agonists (e.g., salmeterol) taken regularly - BTS: Specialist management(e.g., oral corticosteroids)
OR
NICE: Consider changing to a maintenance and reliever therapy (MART) regime - NICE: Increase the inhaled corticosteroid to a moderate dose
- NICE: Consider high-dose inhaled corticosteroid or additional drugs (e.g., LAMA or theophylline)
Explain how CPAP works (when providing oxygen therapy) [1]
CPAP supplies constant fixed positive pressure throughout inspiration AND expiration. It, therefore, is not a form of ventilation, but splints the airways open
What are the different colours of venturi mask colours? [6]
What are the oxygen flow rate (L/min) for these different colours of venturi mask? [6]
What are the FiO2 (approx. oxygen) delivered for these different colours of venturi mask? [6]
Label A-F
A: Blue
B: White
C: Orange
D: Yellow
E: Red
F: Green
Label A-F
A: 24%
B: 28%
C: 31%
D: 35%
E: 40%
F: 60%
How does a high-flow nasal cannula work? [3]
Reduces the amount of room air that the patient inhales alongside the supplementary oxygen, increasing the concentration of oxygen inhaled with each breath.
It also adds some positive end-expiratory pressure to help prevent the airways from collapsing at the end of exhalation (although this effect is reduced if the patient opens their mouth).
Also, provides dead space washout: normally, dead space is ar that remains in airwaays and oropharnyx, not undergoing respiration. High-flow oxygen effectively clears this and replaces it with oxygen, improving patient oxygenation.
