Lower respiratory tract infections Flashcards
what are the lower respiratory tract infections
pneumonia
acute bronchitis
acute COPD exacerbation
what makes up the lower respiratory tract
what are the symptoms of of LRTI vs URTI
airway below the pharynx:
larynx –> trachea –> bronchi –> lungs
what is pneumonia
inflammatory condition of the alveoli
pathogen travel into alveoli –> triggers inflammaory response –> alveoli fill with fluid –> lung consolidation –> reduced gas exchange
what is the presentation of lower respiratory tract infections
(flu like)
cough
sputum production
chest pain/discomfort (muscle aches)
wheezing
breathlessness
fever
fatigue
what are the most common causes of pneumonia
most common cause is bacterial:
community acquired - streptococcus pneumonia (80% of overall pneumonia cases)
hospital acquired - staphylococcus aureus
(viral + fungal exist but are much less common)
what cause of pneumonia is associated with COPD
haemophilus infleunza
what cause of pneumonia is associated after an influenza infection
staphylococcus aureus
what are the causes of atypical pneumonia
the causative agent is different from typical pneumonia and therefore the presentation is diffferent
mycoplasma pneumoniae
legionella pneumophilia
chlamydia pneumoniae
Klebsiella pneumoniae
Pneumocystis jiroveci
what is the definition of hospital acquired pneumonia
lower respiratory tract infection which develops more than 48 hours after hospital admission
what is the presentation of typical pneumonia
fever
productive cough with purulent sputm
dyspnoea
pleuritic chest pain
malaise
rigors
what are the examination findings in typical pneumonia
tachypnoea
tachycardia
pyrexia
reduced O2 sats - cyanosis
on auscultation - coarse crackles (low pitch) and bronchial breath sounds (higher pitched than normal and gap between inspiration + expiration)
on percussion - dull + increased vocal resonance (due to consolidation)
reduced chest expansion
what are the investigaitons in suspected pneumonia
what would they show
chest x ray:
consolidation - alveoli filled with fluid (pus), can be lobar or multilobar
air bronchogram - dark lines of the larger air filled airways through the pus filled alveoli (sign which confirms consolidation)
bloods:
FBC - neutrophilia (in bacterial infection)
U&E - urea could be above 7 depending on severity
CRP - elevated (low CRP makes bacterial pneumonia very unlikely)
LFTS - patients with underlying liver disease more likely to have lung complications
Blood culture + sputum culture ideally before starting antibiotics in patients with Moderate/High CAP who come to hospital
pulse ox - O2 saturation <94% is bad sign –> urgent to go to hospital
NOTE: these investigations are done when patients come to hospital or when they have hospital acquired pneumonia not when they are just being managed in community
how is community acquired pneumonia severity measured
according to CURB 65
1 point for each parameter
C – confusion: An abbreviated mental test of ≤8
U – urea: >7mmol/L
R - Respiratory rate: ≥30/ min
B - blood pressure <90 systolic and/ or <60mmHg diastolic
65 - age: >65year old
how is pneumonia managed
if managed in the community give oral antibiotics
if severe + managed in hospital give IV antibiotics
follow up CXR in 6 weeks to check consolidation has resolved
which antibiotic class is associated with treating atypical pneumonia
macrolides e.g.clarithromycin, erythromycin, azithromycin
what are general features associated with atypical pneumonias
dry cough
abdominal pain, headache, myalgia
respiratory findings are less prominent - no productive cough or chest pain, normal breath sounds
generally milder symptoms + patients appear less unwell - low grade fever
gradual rather than sudden onset of symptoms
CXR - patchy infiltrates rather than lobar consolidaiton
