Transition block Flashcards
Where is resp rhythm generated?
Medulla
Where are peripheral chemoreceptors found?
Carotid body and aortic arch
Where are central chemoreceptors found?
Surface of the medulla
Function of central chemoreceptors
Respond to H+ of the CSF
Function of peripheral chemoreceptors?
Sense tension of O2, CO2 and H+ in the blood
What is permeable and impermeable to CSF?
Impermeable- H+ and HCO3
Permeable- CO2 diffuses readily
What is the most potent stimulant of respiration in normal people?
Arterial PCO2 (H+ in CSF) acting on central chemoreceptors
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
Result of increased PCO2/H+
Hyperventilation to to eliminate CO2 (CO2 can generate H+ so reduces load on body)
What is the transmural pressure gradient?
Difference between intrathoracic and intra alveolar pressure
What happens to intrapleural pressure during inspiration?
Falls
What happens to intrapleural pressure during expiration?
Rises
What is cardiac ouput?
Volume of blood pumped by each ventricle per minute
CO= SV x HR
What is the stroke volume?
Volume of blood ejected by each ventricle per heart beat
EDV-ESV
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)
Tidal Volume?
Volume of air entering or leaving lungs during a single breath
Inspiratory Reserve Volume?
Extra volume of air that can be maximally inspired over and above the typical resting tidal volume
Inspiratory capacity?
Maximum volume of air that can be inspired at the end of a normal quiet expiration (IC =IRV + TV)
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
Residual Volume?
Minimum volume of air remaining in the lungs even after a maximal expiration
Functional Residual Capacity?
Volume of air in lungs at end of normal passive expiration (FRC = ERV + RV)
Vital capacity (VC)
Maximum volume of air that can be moved out during a single breath following a maximal inspiration (VC = IRV + TV + ERV)
Total lung capacity (TLC)
Maximum volume of air that the lungs can hold (TLC = VC + RV)
What is atrial fibrilliation?
Chaotic and disorganised atrial activity leading to an irregular heartbeat
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
