Transition block Flashcards by Samadhi Fernando

Where is resp rhythm generated?

Medulla

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Where are peripheral chemoreceptors found?

Carotid body and aortic arch

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Where are central chemoreceptors found?

Surface of the medulla

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Function of central chemoreceptors

Respond to H+ of the CSF

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Function of peripheral chemoreceptors?

Sense tension of O2, CO2 and H+ in the blood

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What is permeable and impermeable to CSF?

Impermeable- H+ and HCO3
Permeable- CO2 diffuses readily

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What is the most potent stimulant of respiration in normal people?

Arterial PCO2 (H+ in CSF) acting on central chemoreceptors

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When does the hypoxic drive of respiration kick in?

Stimulated when PO2 falls low
Important in patients with chronic CO2 retention eg COPD
Important at high altitudes

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Result of increased PCO2/H+

Hyperventilation to to eliminate CO2 (CO2 can generate H+ so reduces load on body)

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What is the transmural pressure gradient?

Difference between intrathoracic and intra alveolar pressure

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What happens to intrapleural pressure during inspiration?

Falls

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What happens to intrapleural pressure during expiration?

Rises

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What is cardiac ouput?

Volume of blood pumped by each ventricle per minute

CO= SV x HR

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What is the stroke volume?

Volume of blood ejected by each ventricle per heart beat

EDV-ESV

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What is the Frank-Starling curve?

The more the ventricle is filled with blood during diastole (EDV) the greater the volume of ejected blood in the next systolic contraction (stroke vol)

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Tidal Volume?

Volume of air entering or leaving lungs during a single breath

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Inspiratory Reserve Volume?

Extra volume of air that can be maximally inspired over and above the typical resting tidal volume

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Inspiratory capacity?

Maximum volume of air that can be inspired at the end of a normal quiet expiration (IC =IRV + TV)

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Expiratory reserve volume?

Extra volume of air that can be actively expired by maximal contraction beyond the normal volume of air after a resting tidal volume

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Residual Volume?

Minimum volume of air remaining in the lungs even after a maximal expiration

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Functional Residual Capacity?

Volume of air in lungs at end of normal passive expiration (FRC = ERV + RV)

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Vital capacity (VC)

Maximum volume of air that can be moved out during a single breath following a maximal inspiration (VC = IRV + TV + ERV)

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Total lung capacity (TLC)

Maximum volume of air that the lungs can hold (TLC = VC + RV)

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What is atrial fibrilliation?

Chaotic and disorganised atrial activity leading to an irregular heartbeat

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Classifications of atrial fibrillation

Paroxysmal, persistent or permanent

What is paroxysmal atrial fibrillation?

Lasts less than 48 hours Recurrent

What is persistent AF?

Episode lasting greater than 48 hours, can be cardioverted into NSR Unlikely to spontaneously reverse

What is permanent AF?

Inability to convert to NSR

What does an ECG for AF show?

Atrial rate >300bpm Irregularly irregular Absent P waves

What medication can be used for rate control during AF?

Digoxin, beta blockers, verapamil

What medication can be used for rhythm control during AF

Anti-arrthymic eg amiadarone Direct current cardioversion Catheter ablation

What are class 1 antiarrhythmic drugs?

Lignocaine Flecainide Quinidine Propafenone

What are class 2 antiarrhythmic drugs?

Propanolol

What are class 3 antiarrhythmic drugs?

Amidaraone, sotalol, dronedarone

What are class 4 antiarrhythmic drugs? - Ca channel antagonists

Verapamil

What is atrial flutter?

Rapid and regular form of atrial tachycardia- paroxysmal or persistent Re-entrant circuit usually right atrium

Treatment for atrial flutter?

RF ablation Pharmacological Cardioversion DOAC for stroke prevention

What is a granuloma?

A non-specific organised collection of activated macrophages and T lymphocytes

Function of natural killer cells

Kill cells that lack MHC molecules on the surface- no antigen specificity

How is there innate recognisation of receptors?

PAMPS expressed on phagocytes and dendrites

What does TNF alpha do?

Releases proinflammatory cytokines in response to stressors eg microbes, stress, chemicals

What do TNF biologics do?

Have TNF blocking antibodies to reduce immune response

What does vaccination do?

Produces memory in B and T cells

MMR is an example of what kind of vaccine?

Live attenuated

What are common URT colonisers?

Gram +ve: strep pneumoniae, strep pyogenes, staph aureus Gram-ve: Haemophilus influenzae, moraxella

Common bacteria in acute otitis media?

H.influenzae, strep pneumoniae, strep pyogenes

First line treatment of middle ear infection if non resolving and likely bacterial?

Amoxicillin or erythromycin

Bacteria in conjunctivitis?

Staph aureus Strep pneumoniae H.influenzae

Tx of bacterial conjunctivitis?

Chloramphenicol- treats most bacteria apart from pseudomonas

A panic attack/hyperventiliation leads to what blood gas abnormality?

Respiratory alkalosis due to blowing off more CO2 so carbonic anhydrase equation shifts to become more alkalotic

What blood gas abnormality would COPD show?

respiratory acidosis due to the retention of carbon dioxide

What muscles are involved in quiet inspiration?

Contraction of the diaphragm and external intercostal muscles

What happens to to FVC/FEV1 ratio in obstructive lung disease?

Reduced <0.7

What are the spirometry patterns in obstructive lung disease?

Reduced FEV1 (<80% of the predicted normal) Reduced FVC (but to a lesser extent than FEV1) FEV1/FVC ratio reduced (<0.7)

What are the spirometry patterns in restrictive lung disease?

Reduced FEV1 (<80% of the predicted normal) Reduced FVC (<80% of the predicted normal) FEV1/FVC ratio normal (>0.7)

What does the dorsal respiratory group do?

Inspiratory centre that generates the frequency of inspiration and the basic rhythm for respiration

What does the pneumotaxic centre do?

Pneumotaxic centre inhibits inspiration, reduces tidal volume and regulates respiratory rate

What is a cross sectional study?

Collection of data from a population in a specific time point- good for detecing prevelance of disease

What is a randomised control trial?

Those with or without an intervention, are compared and randomly assigned to the group this reduces selection bias. Does not look at outcomes

What is a cohort study?

A group of people with a common characteristic is followed over time to find how many reach a certain health outcome of interest

What is sensitivity?

The ability of a test to correctly identify patients with a disease

What is specificity?

The ability of a test to correctly identify people without the disease.

A more specific test will have a greater ___ value?

Positive predictive value as less likely an individual with a positive test will be free from disease

A more sensitive test will have a greater ___ value?

Negative predictive value