Week One - Acute Breathlessness Flashcards
what are the signs and symptoms of allergies
urticarial (raised, itchy rash (hives)) or eczematous rash (dry, itchy and inflamed skin)
Asthma
Rhinitis
Conjunctivitis
Diarrhoea and vomiting
Anaphylaxis
how are allergies diagnosed
- a careful, good history
- family history
- skin prick test
what is involved in a skin prick test
exposure to standardised allergen solution through forearm skin prick
a wheal >2mm larger than the negative (saline) control is a positive result
what is the treatment for allergies
avoidance
Topical treatments:
sodium cromoglicate (nasal spray/eye drops)
Topical steroids;
Emollient cream;
Bronchodilators
oral antihistamines or steroids
Desensitisation therapy
what does sodium cromoglicate do
stabilises mast cells to prevent degranulation
what do topical steroids do
reduce vessel permeability and cytokine synthesis
what does emollient cream do
reduces itching and water loss through damaged skin
when is desensitisation therapy used
in upper airway allergies if symptoms are not controlled on maximal medical therapy
what is the antibody in type I allergic reaction
IgE
fixed on mast cells and basophils via FceR
what is the antibody in type II allergic reaction
IgG/IgM
free
what is the antibody in type III allergic reaction
IgG/IgM
free
what is the antibody in type IV allergic reaction
T-helper cells
Th1
what is the other cell influence in type I,II, III allergic reactions
B cells stimulated by Th2 (CD4 cells)
what is the other cell influence in type IV allergic reactions
as there is no production of antibodies, Th1 cells are activated - effect on macrophages
what is the antigen in type I
always free and foreign
what Is the antigen in type II
always fixed and intrinsic to tissue on which reaction occurs
what is the antigen in type III
always free and can be exogenous or endogenous
what is the antigen in type IV
present by antigen presenting cells (MHCII)
what is the effector in type I
mast cells and basophils
what is the effector in Type II,III
complement
what is the effector in type IV
T cytotoxic cells or macrophages
where is site of reaction of Type I
surface of mast cells and basophils
where is the site of reaction in type II
surface of target tissues
where is the site of reaction in type III
circulation or tissue fluid
where is the site of reaction in type IV
site of intruder
what are
- hay fever
- allergic rhinitis
- angioedema
- hives
- anaphylactic shock
examples of
type I allergic reactions
what are
- autoimmune diseases
e.g actue glomerulonephritis
examples of
type III allergic reactions
what are
- type I diabetes mellitus
- Crohn’s disease
- MS
examples of
type IV allergic reactions
what are
- blood transfusion
- glomerulonephritis
- Grave’s disease
- penicillin allergy
examples of
type II allergic reactions
what is the term used for acute allergic reactions producing life threatening features
anaphylaxis
what are these life threatening features
Hypotension and shock
Severe bronchospasm which might cause wheeze and stridor
Laryngeal oedema
Angioedema
Pruritus
Urticaria
Tachycardia
what are clinical signs of anaphylaxis
increased respiratory rate (e.g >30)
Increased pulse (e.g >120)
Decreased BP
what kind of diagnosis is it and why
it is a clinical diagnosis because there is no time for investigations
what increases the risk of anaphylaxis
increased risk of anaphylaxis in those with a family history of atopy, bronchial asthma and those on corticosteroid/ACEi/beta blocker therapy
what is the mechanism of anaphylaxis
exposure of susceptible individuals to allergen results in the production of IgE antibodies and the release of inflammatory mediators from mast cells
what does local histamine release cause
bronchoconstriction, vasodilation and increased vessel permeability
what does anaphylaxis require
previous exposure to the antigen
here is a sensitisation reaction that occurs on first exposure and it is only on subsequent exposure to the allergen, that anaphylaxis occurs
what is the difference between Anaphylactoid reactions and anaphylaxis reactions
are clinically distinguishable from anaphylaxis, however they are not IgE mediated, and do not require prior exposure
how do anaphylactoid reactions happen
occur via direct stimulation of mast cells and can be caused by agents such as NSAIDS, opioids, blood transfusion and even exercise
what is the treatment of anaphylactoid reactions
initial ABC approach - secure the airway and obtain IV access.
Give 100% oxygen. Lower the head of the bed to restore blood volume
Consider intubation
Adrenaline 0.5mg IM, repeated every 5 mins as required.
Patients that do not respond to adrenaline should be quickly intubated - reduces need for cricothyroidotomy.
antihistamine e.g 10mg
chlorphenamine and corticosteroid e.g 200mg
hydrocortisone IV
Could give IV saline as appropriate for BP management
For asthmatic wheeze - typically given inhaled B2 agonists
what are the possible conditions associated with breathlessness
pneumothorax
Pneumonia
Pericarditis
PE
Pulmonary oedema / heart failure
Diabetic ketoacidosis
Acute coronary syndromes
Panic attack
Asthma
COPD
what are the possible conditions associated with chest pain
GORD
Acute coronary syndrome
Boney chest pain
Myocarditis
Hypertrophic cardiomyopathy
Pneumothorax
Pneumonia
Panic attack
Pericarditis
Stable angina
Musculoskeletal chest pain
Sickle cell crisis
PE
what is circumoral cyanosis
is when only your mouth or lips turn blue
often occurs when blood vessels shrink
what is peripheral cyanosis
when only your hands, fingers, feet and or toes turn blue
cold weather and rarely life threatening
what is central cyanosis
when other parts of the body are affected in addition to your hands and feet
what are the possible conditions associated with cyanosis
asthma
Respiratory tract infection
PE
COPD
Pulmonary hypertension
Pneumonia
Congestive heart failure
Cardiac arrest
Raynaud’s
what are the possible conditions associated with pain on inspiration
pneumonia
Pleurisy
Costochondritis
Pneumothorax
Pericarditis
Chest injuries
what is stridor
Is a variable high pitched, turbulent respiratory sound that can be assessed during breathing
what is the most common cause of stridor
viral infection called croup
what can respiratory arrest be casued by
airway obstruction
decreased respiratory effort
respiratory muscle weakness
what is decreased respiratory effort
DRE reflects CNS impairment due to one of the following:
- CNS disorder (stroke etc)
- adverse medication
- metabolic disorder
when may hypoventilation develop
if the brain stem is compressed
what are examples of drugs that decrease respiratory effort
opioids and sedative-hypnotics (barbiturates and alcohol)
gabapentin and pregabalin may causes serious breathing difficulties in which patients
patients using opioids or other drugs that depress the CNS, older patients or patients who have underlying respiratory impairment, such as COPD
when can respiratory muscle fatigue occur
If patients breathe for extended periods at a minute ventilation exceeding about 70% of their maximum voluntary ventilation
what are neuromuscular causes of respiratory muscle weakness
Neuromuscular causes include spinal cord injury, neuromuscular diseases (eg, myasthenia gravis, botulism, poliomyelitis, Guillain-Barré syndrome), and neuromuscular blocking drugs (eg. succinylcholine, rocuronium, vecuronium).
how is respiratory arrest diagnosed
clinical evaluation
when does treatment for Respiratory arrest begin
simultaneously with diagnosis
the first consideration Is to exclude a foreign body obstructing the airway; if a foreign body is present, resistance to ventilation is marked during mouth to mask ventilation.
what is the treatment for respiratory arrest
clearing the airway
mechanical ventilation
what is respiratory failure
when the blood doesn’t have enough oxygen or too much C02
what is Type 1 respiratory failure
occurs when the respiratory system cannot adequately provide oxygen to the body, leading to hypoxemia
what is type 2 respiratory failure
occurs when the respiratory system cannot sufficiently remove carbon dioxide from the body, leading to hypercapnia
what are some common causes of respiratory failure
acute MI related
acute respiratory failure due to acute respiratory distress syndrome
acute respiratory failure related to COVID19
acute exacerbation of COPD
what is the distinguishing characteristic of type 1 respiratory failure
is a partial pressure of oxygen <60mmHg with a normal or decreased partial pressure of carbon dioxide.
what could happen to the A-a gradient (alveolar-arterial gradient)
may be normal or increased
what is the formula for the A-a gradient
A-a gradient = PAO2 - PaO2,
where;
PAO2 = Alveolar partial pressure of oxygen
PaO2 = Arterial partial pressure of oxygen
what is type 2 respiratory failure
defined as an increase in arterial carbon dioxide >45mmHg with a pH <7.35 due to respiratory pump failure and/or increased CO production
what is the respiratory pump comprised of
comprised of the chest wall, the pulmonary parenchyma, the muscles of respiration, as well as the central and peripheral nervous systems
what do patients present with
dyspnea, cough, hemoptysis, sputum production and wheezing
what is the gold standard for diagnosing respiratory failure
an ABG
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