Respiratory Flashcards
What are the indications for daily preventative medication for asthma <5yo
The “three strikes” rule is a handy memory aid for determining if an asthmatic child should receive controller therapy. If a child has asthma symptoms or uses quick-relief medication > 3x per week, awakens at night due to symptoms >3x per month, requires a refill prescription for quick relief inhaler >3x per year then the patient should receive daily controller therapy
Bronchiolitis obliterans
Cause Clinical manifestations Exam signs Investment Management
Bronchiolitis obliterans occurs after an insult to the lower respiratory tract from infectious or non-infectious causes and leads to chronic obstructive lung disease from fibrosis of the small airways.
In children, bronchiolitis obliterans occurs after a respiratory viral infection, or due to another inflammatory disease (e.g. juvenile idiopathic arthritis, systemic lupus erythematosus) from inhalation of toxic fumes, or as a complication of graft vs. host disease or lung transplant.
Clinical manifestations include cough, fever, dyspnoea, cyanosis, chest pain and respiratory distress. Chronic symptoms include chronic cough, dyspnoea, sputum production and wheeze.
Physical examination findings are often wheeze, hypoxemia and crackles.
Chest X-ray findings can be variable and often show hyperlucency and patchy infiltrates. Pulmonary function tests show an obstructive pattern with variable response to inhaled bronchodilators.
Management is supportive with administration of antibiotics to treat secondary infection, supplemental oxygen if required, corticosteroids may provide benefit in some patients. Immunomodulatory agents, tacrolimus, sirolimus, aerolysed cyclosporine and macrolide antibiotics have been used in post-transplant patients with bronchiolitis obliterans with variable success.
Bronchiectasis
Cause
Typical signs
Bronchiectasis can be congenital or acquired. Acquired bronchiectasis arises from obstruction of the airways, caused by repeated infections, inflammation, impacted mucus and poor ciliary clearance, which then renders the airways susceptible to microbial colonisation.
A cycle of intense chronic inflammatory response is triggered and leads to bronchiole remodelling (dilation and increased wall thickness). The cycle of chronic infection, inflammation and difficulty clearing secretions, propagates airway injury and remodelling.
Typical clinical manifestations are chronic cough with copious purulent sputum, crackles wheezing, clubbing, anorexia and poor weight gain.
Rates of bronchiectasis are higher in children from remote Indigenous Australian communities
14.7/1000 in Indigenous Australian children under 15 years old
Bronchiectasis is rarely encountered in children in resource-rich societies, expect for in cystic fibrosis patients.
acidosis, fever, or increased adult haemoglobin shifts curve to?
shift the curve to the right.
As a result, at a given arterial PO2, there is increased oxygen delivery to the tissues resulting in a greater concentration of reduced haemoglobin, and cyanosis appears more readily.
Fetal vs adult haemoglobin O2 binding
Fetal hemoglobin
Binds oxygen more than adult haemoglobin.
The oxygen dissociation curve is shifted to the left, so that for a given level of oxygen tension the oxygen saturation is higher in the newborn than older infants or adults.
It also follows that for a given level of oxygen saturation, the pO2is lower in newborns.
As a result, cyanosis is detected at a lower pO2in newborns compared with older patients. Thus, in evaluating a cyanotic newborn, pO2should be measured in addition to SO2to provide more complete data.
Asthma
FEV1/FVC
Response to an inhaled β-agonist
Bronchoprovocation testing
Generally a FEV1/FVC ratio of <0.8 indicates significant obstruction.
Response to an inhaled β-agonist is expected to be ≥ 12% or >200mL to be consistent with asthma
Bronchoprovocation testing with either methacholine or histamine is useful when spirometry findings are normal or near normal, especially in patients with intermittent or exercise-induced asthma symptoms. Bronchoprovocation testing helps determine if airway hyperreactivity is present, and a negative test result usually excludes the diagnosis of asthma.
Interpretation of Mantoux Test:
An induration of 5mm or more is considered positive in:
A recent contact with a person with tuberculosis disease
HIV infected people
People with fibrotic changes on chest X-ray consistent with prior tuberculosis
Patients with organ transplants
People who are immunosuppressed for other reasons
Interpretation of Mantoux Test:
An induration of 10mm or more is considered positive in:
Recent immigrants (<5 years) from high prevalence countries
Children <4 years old
Infants, children and adolescents who are exposed to adults in high risk categories
People with clinical conditions that place them at high risk
Interpretation of Mantoux Test:
An induration of 15mm or more is considered positive in:
Any person, including people with no known risk factors for tuberculosis
The five phases of lung development
Embryonic (26 days to 6 weeks gestation)
Pseudoglandular (6 to 16 weeks gestation)
Canalicular (16-28 weeks gestation)
Saccular (28-36 weeks gestation)
Alveolar (36 weeks through to infancy)
Digoxin
Mechanism and action
Na/K/ATPase pump inhibitor, depresses the SA and AV nodes, prolongs refractiveness and slows conduction.
Sotalol
class 2/3 agent and beta blocker, has been shown to be effective in the maintenance of sinus rhythm in patients with atrial flutter.
Flecanide
sodium channel blocker and class 1c agent, slows conduction velocity in the accessory pathway in WPW and can be used to terminate supraventricular tachycardias in this condition. Flecanide should only be used in structurally normal hearts.
Propranolol
non-selective beta blocker, is the pharmacological treatment of choice for long QT syndrome and is effective in 70% of cases in preventing ventricular tachyarrhythmias.
Amiodarone
class III agent, inhibits nodal function as wells a cardiac conduction and prolongs the refractory period. It has been shown to suppress both supraventricular and ventricular arrhythmias in all forms of cardiomyopathy (dilated, hypertrophic and restrictive).
