Session 5 - Hypoxia, Chemical Control Of Breathing + LRTI Flashcards
Define Hypoxia
A fall in alveolar, thus arterial pO2
Define Hypoventilation
When ventilation falls with no change in metabolism
What effects does Hyperventilation have on pCO2 and pH
- pCO2 decreases
- pH rises
How is a respiratory acidosis compensated for?
Kidneys reduce excretion of Hydrogen Carbonate, hence more is in the plasma, more hydrogen ions are buffered and pH rises to normal levels
Why can a severe Metabolic Alkalosis not be fully compensated for?
To compensate the lungs reduce ventilation rate. However RR must be kept at a minimum level to ensure that hypoxia doesn’t occur.
Where are the peripheral chemoreceptors located?
Carotid and Aortic bodies
What does stimulation of central chemoreceptors cause?
- Increase in tidal volume and RR
- More blood directed to brain and kidneys
- Increased pumping of heart
Which out of central or peripheral chemoreceptors detect more acute changes in gas concentrations?
Central
By which cells is the CSF’s Hydrogen carbonate concentration controlled by?
Choroid Plexus Cells
How do Type 1 and 2 respiratory failure differ?
Type 1 - Normal or low pCO2
Type 2 - Raised pCO2
How is living at altitude a risk factor for respiratory failure?
Lower pO2 of inspired air means hypoxia can result
Which type of respiratory failure is Hypoventilation linked with?
Type 2 only
Which type of respiratory failure is diffusion impairment always associated with and why?
Type 1
Because carbon dioxide diffuses much more easily than oxygen it is rarely effected by diffusion difficulties
Give some examples of when there may be a ventilation perfusion mismatch.
- Lobar Pneumonia
- Pulmonary embolism
Give some of the most common normal flora in the respiratory tract.
- Viridans Strep
- Neisseria Strep
- Anaerobes
- Candida Strep
What are some of the natural defences our respiratory tract has against infections?
- Cough and sneeze reflex
- Muco-ciliary clearance mechanisms (cilia and nasal hairs)
- Resp mucosal immune system (macrophages, IgA, IgG)
Give the names of some of the viruses which cause the most common URT infections
- Rhinovirus
- Coronavirus
- Influenza / Parainfluenza
Define Pneumonia
A general term donating inflammation of the gas-exchanging regions of the lung, usually due to infection
What is the difference between bronchiole and Lobar Pneumonia?
Lobar pneumonia is localised to a particular lobe of the lungs whereas bronchiole starts in a bronchiole and spreads to all regions that the bronchiole branches into
What are the most common organisms which cause community acquired pneumonias?
- Strep pneumoniae
- Haemophilus influenza
- Klebisiella pneumoniae
Name some organisms which commonly cause hospital acquired pneumonias.
- Staph aureus
- MRSA
- Pseodomonas
What are some of the most common symptoms of pneumonia?
- fever, chills, sweats, cough
- sputum (clear, rusty or heavily stained with blood)
- Dyspnoea, pleuritic chest pain, malaise, vomiting
- diarrhoea, headache, myalgia
What are the four criteria that make up the CURB 65 score and what are there values which would class them as a positive result for pneumonia?
- C - New mental confusion
- U - Urea >7mmol/L
- R - RR >30 per minute
- B - BP systolic < 90 or diastolic <60mmHg
If have two or more of above then this is an indication for hospital treatment
What samples may be taken for investigations of pneumonias?
- Sputum
- Nose + throat swabs
- Endotracheal aspirates
- Open lung biopsy
- Blood Culture
- Urine
What microbiological investigation may be undertaken to try and confirm or rule out pneumonia?
- Macroscopic investigation of sputum (colour)
- G - staining, acid fast
- Culture
- PCR
- Antigen and Antibody detection
How may pneumonias be managed in general?
- Fluids; oral or IV if severe
- Anti-pyretic drugs
- Analgesics
- Oxygen - if cyanosed
- Antiobtiotics
What is the usual antibiotic treatment for community acquired pneumonias?
Target is usually pneumococcus, which is sensitive to Penicillin or related antibiotics
What is the usual antibiotic treatment for hospital acquired pneumonias?
Usually G -ve so IV Co-Amoxiclav is used
What are the major complications of a pneumonias?
- Lung abscess
- Bronchiectasis
- Empyema
How can we prevent pneumonias from occurring?
- Flu vaccine
- Pneumococcal vaccine
- Chemoprophylaxis: Oral penicillin to patients with high risk of LRTI
