Anatomy
Outline the path by which oxygenated blood travels to get to the right atrium.
maternal capillaries -> diffuse into placental capillaries -> travel via umbilical vein through liver shunt (ductus venosus) or small fraction through liver itself to IVC -> RA
Provide 3 non-respiratory causes for dysnopea
Anaemia, deconditioning, ascites, pleural effusion, HF, pulmonary oedema, PE, PH, infection, sepsis, pain, anxiety (not exhaustive)
Provide 3 respiratory causes of abnormal blood gases
VQ mismatch, shunt, alveolar dead space, diffusion limitations, hypoventilation
What are 3 non-pharmacological interventions for stepwise management of COPD?
support smoking cessation, recommend annual influenza/pneumococcal vaccine, encourage PA, develop management plan and COPD action plan
What is coronary collateral circulation, and why does it develop?
Coronary collateral circulation is the formation of new blood vessels in response to chronic obstruction in coronary arteries. It develops to create alternate pathways for blood flow, bypassing areas of reduced blood supply and helping to maintain oxygen delivery to the heart muscle. Not always able to occur in disease states.
Common bacteria (especially strep pneumoniae, H. influenzae) with high fever and chills, sudden onset, pleuritic chest pain, productive cough v bacteria like mycoplasma pneumoniae, chlam. pneumoniae, legionella with gradual onset of low-grade fever, less prominent respiratory symptoms.
What is the likely alteration in FRC, RV and TLC in patients with COPD?
All likely increase (gas trapping, lung hyperinflation)
Why is it that in some patients, inhaled corticosteroids are not particularly useful (or even detrimental) for the management of COPD?
Increased risk of infection (immunosuppressant)
In left dominant hearts, where does the posterior interventricular branch arise from?
Enlarged circumflex branch that supplies the posterior wall of the LV
A 25-year-old female presents to ED with the following ABG results:
pH = 7.50, PaCO2 = 22mmHg, PaO2 = 100mmHg, HCO3- = 20mmol/L
Is the primary disturbance metabolic or respiratory?
Respiratory alkalosis (high pH, low PaCO2)
note: partial compensation as HCO3- levels <22 mmol/L but not yet restored pH within normal levels. Patient likely hyperventilating.
Explain paradoxical motion and an injury that may bring rise to the condition
Injury below C3,4,5 (innervation of diaphragm present but intercostal nerves impacted, lose intercostal muscle tone, don't resist decreased intrathoracic pressure and collapse)
Provide 3 examples of contraindications for the administration of thrombolysis medications (e.g. tPA) for high risk PE patients.
Anything that suggests high bleeding risk (hemorrhagic stroke, recent surgery or head trauma, active bleeding, pregnancy, age, dementia etc.)
When does the filling of aortic sinuses take place?
Early diastole - as blood recoils post ventricular contraction, fills the aortic sinuses, filling the coronary arteries which originate in the left and right aortic sinuses respectively.
What does Pulmonary Capillary Wedge Pressure (PCWP) measure and what does an elevated result (>18mm Hg) indicate?
PCWP is pressure within the pulmonary arterial system when catheter tip ‘wedged’ in the tapering branch of one of the pulmonary arteries - indirect measure for LA pressure (LVEDP and also LVEDV aka preload). High result indicates LHF (indicative of increase fluid backup in pulmonary circulation due to a failing ventricle).
Excluding hyperinflation, what are 3 features of a CXR you are likely to observe in patient with emphysema?
Any of the following: flattened diaphragm, loss of lung markings (air trapping), blebs, wide costophrenic angle, tear drop heart
In relatively mild cases of asthma and COPD, why is it preferable to initiate patients on short acting drugs?
Fast onset of action and immediate symptom relief
Why does the foramen ovale close after birth?
After birth, the baby's lungs begin functioning, increasing oxygen levels in the blood and dilating the pulmonary capillaries, decrease PVR. This increases blood flood to the pulmonary artery, lungs, pulmonary vein and LA. Loss of pressure differential (LA>RA) prompts the foramen ovale to close.
Describe the interdependent effects of increased afterload (e.g. increase aortic pressure) on SV, ESV, EDV and force of ventricular contraction.
Decrease in SV, increase in ESV (end systolic volume) resulting in secondary increase in EDV (end diastolic volume) because more blood is left inside ventricle post ejection. Secondary increase in preload results in greater force of ventricular contraction (Frank-Starling mechanism) - ultimately offsetting much of the loss in SV. See (https://cvphysiology.com/cardiac-function/cf026)
Describe how to calculate the anion gap and the significance of an elevated result.
Anion gap = (Na+ + K+) - (HCO3- + Cl-)
Increase in the anion gap (>16) indicates acidosis (most commonly caused by accumulation of acidic substances like lactic acid, ketoacids (e.g. diabetic ketoacidosis) or toxins (e.g. methanol).
Describe the pathway and mechanism of action for the three primary pharmacological treatments available to manage PH?
Prostacyclin agonists, NO pathway potentiators (e.g. inhibit PDE5 which degrades cGMP), endothelin antagonists.