Pneumonia (Community-Acquired) Flashcards
(40 cards)
What is pneumonia?
Pneumonia is an infection of the lung tissue in which the air sacs in the lungs become filled with microorganisms, fluid and inflammatory cells, affecting the function of the lungs.
What is community acquired pneumonia (CAP)?
If the pneumonia developed outside of hospital it is labeled labelled “community acquired pneumonia”.
What organisms cause community-acquired pneumonia?
- Streptococcus pneumoniae* is the main causative pathogen of community-acquired pneumonia worldwide, independent of age.
- Haemophilus influenzae*, Staphylococcus aureus (including MRSA), group A streptococci, and Moxarella catarrhalis.
What is atypical pneumonia?
Pneumonia caused by an organism that cannot be cultured in the normal way or detected using a gram stain.
They don’t respond to penicillins and can be treated with macrolides (e.g. clarithomycin), fluoroquinolones (e.g. levofloxacin) or tetracyclines (e.g. doxycycline).
Give examples of organisms that cause atypical pneumonia
- Legionella pneumophila
- Mycoplasma pneumoniae
- Chlamydophila pneumoniae
What risk factors are associated with CAP?
- Age >65
- Residing in nursing home
- Contact with children
- Respiratory chronic conditions (e.g. COPD, asthma and bronchitis)
- Other chronic comorbidities (e.g. chronic heart disease, diabetes)
- Alcohol use
- Smoking
- Medications (e.g. PPI and H2 antagonists)
What are the signs of CAP?
- Abnormal ausculatory findings
- Tachypnoea
- Tachycardia
- Hypoxia
- Pyrexia
- Cyanosis
- Confusion (esp. in the elderly)
- Pleural rub
What abnormal ausculatory findings can be found on examination?
Crackles, decreased breath sounds, dullness to percussion, wheeze and vocal fremitus.
What are the symptoms of CAP?
- Cough with increasing sputum production
- Dyspnoea
- Haemoptysis
- Pleuritic chest pain
- Rigors or night sweats
- Fevers
- Confusion
- Myalgia
- Fatigue
- Anorexia
How can the sputum present in CAP?
The presence of mucopurulent sputum is associated with bacterial pneumonia.
Scant or watery sputum is associated with an atypical pathogen.
What criteria is used to assess pneumonia?
Determine disease severity (and therefore mortality risk) in patients with a working diagnosis of pneumonia using the CURB-65 score in hospital or the CRB-65 score in the community together with your clinical judgement.
The score allows initiation of appropriate antibiotic therapy and confirms whether the patient can be managed in the community or needs to be admitted to hospital.
How does the CURB-65 and CRB-65 differ?
CURB-65 score used in hospital or the CRB-65 score used in the community together with your clinical judgement.
CRB-65 does not assess urea in the community.
What is the CURB-65 scoring system?
Recommended by the British Thoracic Society (BTS) and the National Institute for Health and Care Excellence (NICE) in the UK for use in the hospital setting, CURB-65 stratifies patients according to the presence or absence of five prognostic features. Mortality at 30 days increases with the number of criteria that are met.
Prognostic factors:
- Confusion: 1 point
- Urea >7 mmol/L: 1 point
- Respiratory rate ≥30 breaths/minute: 1 point
- Blood pressure <90 mmHg systolic or <60 mmHg diastolic: 1 point
- Age ≥65 years: 1 point
Score:
- Score 3-5: high-risk
- Score of 3 or more: discuss with senior colleague at the earliest opportunity and manage as high-severity pneumonia.
- Score of 4-5: arrange emergency assessment by a critical care specialist.
- Score 2: moderate-risk
- Consider for short-stay inpatient treatment or hospital-supervised outpatient treatment
- Score 0-1: low-risk
- Consider for outpatient treatment
What is the CRB-65 scoring system?
Recommended by the BTS and NICE in the UK to be used in the community setting, CRB-65 stratifies patients according to the presence or absence of four prognostic features.
Prognostic factors:
- Confusion: 1 point
- Respiratory rate ≥30 breaths/minute: 1 point
- Blood pressure <90 mmHg systolic or <60 mmHg diastolic: 1 point
- Age ≥65 years: 1 point
Score:
- Score 3-4: high-risk
- Admit to hospital immediately
- Score 1-2: moderate-risk
- Consider hospital referral and assessment (particularly in those with a score of 2)
- Score 0: low-risk
- Consider for treatment at home
What investigations should be ordered for CAP?
- CXR
- Pulse oximetry
- ABG
- Urea and electrolytes
- FBC
- CRP
- LFTs
- Sputum culture
Why investigate using CXR?
A definitive diagnosis of CAP requires evidence of consolidation on chest x-ray. Perform a chest x-ray in all patients presenting in hospital as soon as possible and within 4 hours of admission.
Should show new shadowing (consolidation).
Also: lobar or multilobar infiltrates, cavitation and pleural effusion.
Briefly describe what can be seen on this CXR
Posterior-anterior chest radiograph showing right upper lobe consolidation in a patient with community-acquired pneumonia.
Why investigate using pulse oximetry?
Use pulse oximetry (preferably while breathing air) to assess oxygen saturation in hospital to inform supportive treatment.
May reveal low arterial oxygen saturation. Oxygen saturation <94% in a patient with CAP is an adverse prognostic factor and may be an indication for oxygen therapy and/or urgent referral to hospital.
Why investigate using ABG?
Measure ABG in patients with CAP receiving oxygen therapy with an SpO2 <94%, those with a risk of hypercapnic ventilatory failure (CO2 retention), and all patients with high-severity CAP.
Why investigate urea and electrolytes?
Request urea and electrolytes to inform disease severity and renal function in patients being investigated in hospital.
Usually normal; elevated in patients with severe CAP
. Urea >7 mmol/L counts for 1 point in the CURB-65 score to assess severity.
Why investigate using FBC?
Leukocytosis is often seen in people with CAP.
WBC count > 15 x109/L indicates a bacterial aetiology (particularly pneumococcal,) although lower counts do not exclude a bacterial cause.
Why investigate using CRP?
Order CRP as a baseline measurement and to help rule out other acute respiratory illnesses in patients being investigated in hospital.
Elevated in pneumonia:
- A level >100 mg/L makes pneumonia likely
- A level <20 mg/L with symptoms for more than 24 hours makes the presence of pneumonia highly unlikely
Why investigate using LFTs?
Take blood for a baseline measurement. Provides information about liver function.
Usually normal; abnormal in patients with underlying liver disease or legionella infection.
Why investigate using sputum culture?
Do not routinely recommend microbiological tests for people with low-severity community-acquired pneumonia.
Request a sputum culture for a person with moderate severity community-acquired pneumonia for whom community management is appropriate.
