Where is breathing controlled?
The medulla oblongata
What is the atmospheric pressure at sea level and why is this important?
760mmHG.
If alveolar pressure = < then air moves in
If alveolar pressure = > then air moves out
What effects lung compliance?
Elasticity- Thickening due to disease = reduced elasticity
Surface tension- reduced by surfactant
What cells produce surfactant?
Type II pneumocytes
What is most CO2 carried in the blood as?
HCO3- –> when it enters the pulmonary capillaries it –> CO2 + H2O
What is the pp of O2 and CO2 in oxygenated blood?
O2= ~100mmHg CO2= ~ 40mmHG
What is the PP of O2 and CO2 in deoxygenated blood?
O2= ~40mmHg CO2 = ~ $%mmHg
What is the alveolar pp of O2?
105mmHg
What is the chloride shift?
HCO3- and Cl- exchange in RBCd to allow more CO2 to diffuse in whilst maintaining neutrality
What is a shunt and a dead zone?
Shunt= No ventilation Deadzone= No bloodflow
What nerves stimulate breathing?
Voluntary = Cerebral cortex Autonomic = Medulla oblongata --> Phrenic nerve (C3, 4 & 5)
What does a low V/Q= ?
Impaired pulmonary gas exchange = decreased O2 & ^ CO2.
What is the haldane effect?
Deoxygenation of blood ^ CO2 carrying capacity
Oxygenation of blood decreases CO2 carrying capacity
What is the Bohr effect?
Haemoglobins O2 binding affinity is inversely related to acidity and Conc. of CO2
What is COPD?
Umbrella term for: Chronic bronchitis, emphysema and small airways disease.
What is the main immune cell in chronic bronchitis?
Neutrophil, the leukocyte infiltration is CD8+
What is the normal epithelial lining of the bronchioles and what does it change to in chronic bronchtis?
Pseudostratified, cilliated, columnar epithelium that metaplases to squamou epithelium –> loss of cilia
What is emphysema?
Destruction of lung tissue. –> terminal bronchiole and alveoli = loss of elasticity.
Collagen and elastin broken down –> airways “snap shut” trapping air = hyperinflation
What are the types of respiratory failure?
Type 1- ‘pink puffers’ = low O2 normal Co2
Type 2- ‘blue bloaters’ low o2, high co2
How is COPD diagnosed?
FEV1/FVC <80% predicted
What pressure is the pleural space kept at?
Atmospheric pressure
What is the 1st line treatment for COPD exacerbations?
Amoxicillin
What is transudative pleural effusion and what can cause it?
Clear, low protein fluid, can be caused by:
Heart failure,
Liver failure
Renal failure
What is exudative pleural effusion and what can it be caused by?
Empyema- pus and is from inflammation. Can be caused by: Malignancy, Trauma Infection TB P.E.
What is asbestosis?
Long-term exposure to asbestos –> ‘holly leaf’ plaques. Inflammation and fibrosis caused by macrophages attempting to phagocytose asbestos fibres
What is the pathophysiology in the early response to an asthma attack?
IgE mediated Type 1 hypersensitivity. It’s reversible with B2 agonists and subsides w/in 2 hrs.
What are the treatment options for asthma?
B-agonists - Salbutamol Inhaled corticosteroids - Beclamethasone LABAs - Salmeterol Leukotriene receptor agonists - Montelukast Xanthines - Theophylline
What is pneumonia?
Acute, lower respiratory tract infection usually with fever symptoms, chest signs and an abnormal CXR
What are the criteria in the CURB-65 score and what is it used for?
Confusion, Urea >7mmol/L, Resp rate >30, BP 65y.o.
Score >2 = IV ABx and higher = worse prognosis
What investigations are performed to diagnose pneumonia?
SUBEX: Sputum- AFB, culture, gram stain Urine- Output is reduced in sepsis Blood- cultures, WBC, urea, serology ECG X-ray
What is the most common cause of pneumonia and what are its symptoms?
Strep pneumoniae-
Abrupt onset, rust coloured sputum, lobar, pleural rub –> rapid, shallow breathing.
-Medical emergency
What is the treatment for uncomplicated pneumonia?
Oral amoxycilin and oral clarithromycin
What are the ABx used to treat aspiration pneumonias?
IV cefuroxime and UV metronidazole
What is acute respiratory distress syndrome?
PaO2 <20mmHg
Bilateral infiltrates on CXR
Massive inflammatory response
High mortality
What is the ABx treatment in complicated pneumonia?
IV cefuroxime and oral clarithryomysin
What type of pneumonia is more common in COPD patients?
Haemophillus influenza
What 2 types of pneumonia are associated with aspiration?
Klebsiella and E.coli
What type of pneumonia is most common in the immunocompromised?
Pseudomonas aeroginoas
What is the treatment for TB?
RIPE: Rifampicin- orange secretions Isoniazid- N&V, hepatitis, neuropathy Pyrazinamide- hepatotoxicity Ethambutol- colourblindness
What caused TB and where is it most common?
Mycobacterium tuberculosis and most commonly affects the upper lobes
How do inhaled corticosteroid work in asthma?
Anti-inflammatory –> reduce TH2 cytokines & vasodilators PGe2 and PGE1 by inhibiting COX-2 –> lowers eosinophils
What are some side effects of B2-agonists?
Tremor
Tachycardia
Oral candidiasis
Tolerance