118 - Bronchial Sepsis Flashcards
Define pneumonia
Acute infection of portion of lung involved in gas exchange (Alveoli). High mortality/morbidity.
Incidence of pneumonia
5th leading cause of death - most common infectious cause of death. 1/4 ITU pts.
Aetiology of pneumonia
Anything that impairs lungs defences is a risk. Huge surface area so at risk from inhaled microbes.
4 classifications of pneumonia
Community acquired pneumonia
Hospital acquired pneumonia
Aspiration pneumonia
Pneumonia in immunocompromised patients
Presentation of pneumonia
SOB Pleuritic chest pain Cough Fever Sputum production Confusion
Patients with pneumonia are generally
Pyrexial Tachypnoeic Tachycardic Have reduced lung expansion Have signs of consolidation
Key complications of pneumonia
Respiratory failure Pneumonia induced pleural effusion Empyema Lung abscess Atrial fibrillation
Pneumonias to treat quickly
Streptococcus - Medical emergency. S. aureus - drain before abs M.tuberculosis - isolate if suspect. Pseudomonas - Penicillin doesn't work PCP - AIDS defining.
Streptococcus pneumonia
MEDICAL EMERGENCY Up to 75% UK cases. Infection in bloodstream so infects whole lobes. Healthy to dead in hours. Gram +ve diplococci - stay in pairs.
Staphylococcus aureus
Common in IV drug users.
Bunch of grapes appearance.
Upper lobe cavitation.
Forms capsule - need to drain first and then give antibiotics.
Mycobacterium tuberculosis
Great mimic - commonly seen in pts who are immunocompromised or who have a travel history. May have millet seed appearance on X-Ray
Pseudomonas aeriginosa
Gram -ve affects chronically ill. Pea soup coloured sputum.
Common in cystic fibrosis
Penicillins don’t work.
Haemophilis influenza
Bacterial URTI - only an issue in immunocompromised patients. Airborne so spreads along bronchus.
Klebsiella
Gram +ve Hospital acquired pneumonia. Mostly in patients with other co-morbidities.
Think alcoholic/COPD
Generally an aspiration pneumonia. Poor prognosis.
E.Coli
Not generally seen to cause pneumonia in healthy patients. Aspiration so most common in right lower lobe. Right bronchi shorter and more vertical
Legionella pneumonia
Gram -ve. Lives in water. Air conditioning units a risk. Immunocompromised most affected. Up to 30% mortality.
Deranged LFTs
Chlamydia psittaci
Transmitted by parrots. 1% mortality.
Pneumocystis jiroveni pneumonia
Shows ground glass shadowing on X-Ray. AIDS defining illness.
Fungal pneumonia
Only seen in immunocompromised.
What is bronchitis
Inflammation of bronchi.
What causes acute bronchitis and how to tell if it is viral or bacterial.
Infection - If bacterial, green sputum, if viral - yellow sputum.
What causes chronic bronchitis
Smoking - constant inflammation of the airway results in development of fibrous scar tissue over time that narrows the airway.
What is tracheaitis
Inflammation of trachea. Usually viral. Barking cough. Not usually treated.
What is pharyngitis
Sore throat. Generally minor unless prevents swallowing.
What is epiglottis
Acute ENT emergency - inflammation of epiglottis (flap to prevent food entering trachea).
How to treat epiglottis
Limit examinations (can make worse) and secure airway. Particular risk in children.
Investigations for Community Acquired Pneumonia
O2 SATS
Sputum sample - general culture, gram stain, acid fast bacilli (TB) - Don’t wait for results
Urine - check output and dipstick for legionella.
Bloods
ECG
CXR
ABG
What is CURB-65?
Method of assessing community acquired pneumonia after diagnosis. Can underscore younger patients - need to use with common sense.
CURB-65: 1 point given for
C - Confusion - More than normal
U - Urea - >7mm/l
R - Resp rate >30
B - BP - either
Management of CURB-65 score of 0-1
Manage in community. Amoxycillin.
Management of CURB-65 score 2
Consider as inpatient or supervised outpatient
Management of CURB-65 score 3 or higher
Severe pneumonia. Consider HDU.
IV augmentin/cefuroxine plus IV clarithromycin
Impact of poor prognostic features on CURB-65 score.
If 1 then needs IV abx. If 2 or more then treat as severe pneumonia.
What are the poor prognostic features that need to be considered with the CURB-65 score
Co-existing disease
Albumin
Define hospital acquired pneumonia
Occurs when antibiotics have been taken by the patient previously NOT just pneumonia caught in hospital. Increased risk of resistance so need to treat differently.
Investigations/Treatments for Hospital acquired pneumonia
Sputum sample, trachea aspirate and blood culture.
Give empirical antibiotics
If fails to respond - broncheoalveolar lavage with brushings taken. Sample used to determine predominant pathogen.
Follow up of patients with pneumonia
If no response to abx- review dx and cultures.
If consolidation in smokers. Need to check wasn’t hiding cancer.
Potential complications of pneumonia
Empyema Abscess Pulmonary embolism Pleural effusion Bronchiectasis ARDS - Acute respiratory distress syndrome
Impact of foetal hiatus hernia on lungs
Presence of GI tract in thorax can prevent lungs from developing correctly
Rusty sputum - think
Streptococcus pneumonia
Currant jelly sputum - think
Klebsiella
In respiratory embryology, Type 2 pneumocytes do what?
Produce surfactant
In respiratory embryology. What do Type 1 Pneumocytes do?
Increase surface area
What is infant respiratory distress syndrome? What to do about it?
Not enough surfactant produced. Immaturity of lungs - not enough type 2 pneumocytes. Can give steroids to help develop lungs if think at risk but may also increase risk of premature labour.
When do lung buds start to form?
Embryological week 4
Clinical week 6
When are lungs fully formed?
Lung development continues through last weeks of foetal period
Where do lung buds develop?
Bud out from ventral wall of foregut level with future oesophagus
What makes lung buds grow?
Increase in [Retinoic acid] produced by adjacent mesoderm. Upregulates transcription factor TBX4 which triggers lung formation and development.
What are lungs lined with?
Epithelium derived from endoderm like the gut tube. Internal external surface.
What happens in the embryonic stage of lung development.
3-5 weeks. Lung budding and branching.
What happens in the pseudo glandular stage of lung development?
6-16 weeks. Branching to form terminal bronchioles. No respiratory bronchioles or alveoli.
What happens in the Canalicular stage of lung development.
17-24 weeks. Terminal bronchioles divide into respiratory bronchioles which divide into alveolar ducts.
What happens in the Saccular stage of lung development
25 weeks-term. Primitive alveoli form and capillaries establish good blood supply.
What happens in the alveolar stage of lung development
More alveoli develop. Mature alveoli have developed epithelial-endothelial contacts
Treatment for oesophageal atresia
Surgery always required. Baby will not be able to feed otherwise and is at risk of aspiration pneumonia
What is oesophageal atresia?
Abnormalities in separation of oesophagus and trachea. Can occur with or without transoeophageal fissures - abnormal connection between oesophagus and trachea
Most common type of oesophageal atresia
90% cases - upper portion of oesophagus ends in line pouch and lower segment forms fistula with trachea.
Role of surfactant
Reduces surface membrane tension of alveoli - if not enough then risk of alveolar collapse on expiration.
How do pulse oximeters work? Are they the best option?
Blood changes colour when oxygenates. Pulse oximeter measures ratio of red:UV light absorption to determine ratios of oxygenated and unoxygenated blood.
Less accurate than ABG
How does haemoglobin bind oxygen?
Harm group - Fe2+ in centre of perforin ring - carries oxygen.
Globin - modifies haem to allow binding to be reversible
What determines the shape of the oxygen dissociation curve?
The 4 globes in haemoglobin. 2 alpha and 2 beta. Held together by salt bridges. As O2 bind then salt bridges broken and Haemoglobin relaxes.
This increases the affinity for another O2 molecule to bind to the same haemoglobin.
Why does random movement result in diffusion
More molecules in area of high concentration that can move to area of low concentration.
What is Henry’s Law?
Partial pressure = [dissolved gas]/solubility coefficent
What is a solubility co-efficent?
Some molecules more attracted to water than others. More attracted they are, more can be dissolved at a lowe partial pressure.
What is the major limiting factor in movement of gases through tissues?
Rate of gas diffusion through water
Factors affecting rate of diffusion through the respiratory membrane?
Membrane thickness
Surface area
Diffusion coefficient of gas
Partial pressure difference between the 2 sides of the membrane
What is the diffusing capacity of the respiratory membrane
Ability of respiratory membrane to exchange gas between alveoli and pulmonary blood
How to measure diffusing capacity of oxygen
Measure diffusing capacity of CO and then calculate.
What is the Bohr effect?
Increase in CO2 and H+ in blood shifts the Oxygen dissociation curve to the right resulting in release of O2 from blood into tissues where needed.
What is the Haldane effect?
When O2 brings to haemoglobin - displaces CO2. Opposite of Bohr effect.
3 different mechanisms of CO2 transport in the blood
Dissolved in blood
Bound to Haemoglobin as carboxyhaemoglobin
Transported as a bicarbonate ion
How is CO2 transported as a bicarbonate ion?
CO2 in blood reacts with H20 to form carbonic acid. Carbonic acid dissociates into H+ and bicarbonate. H+ combines with haemoglobin and bicarbonate ions are in the plasma. Catalysed by carbonicanhydrase in RBC.
What is sepsis and what can it lead to?
Sepsis - a systemic infection that causes vasodilation. Patient can then go into shock as not enough blood is being pushed around the body.
What does palmar erythema indicate
Septic shock. Blood has moved to surface due to vasodilation.
How many people in hospital will develop HAP? How many in ITU? How many ventilated patients?
1/100 hospital patients.
1/4 ITU patients.
Almost certain to develop if ventilated for a long time.
How to differentiate between typical and atypical pneumonia?
No clinically reliable way
Highest risk groups for pneumonia
All age groups but elderly, children and the immunocompromised at higher risk
Typical pneumonia generally presents with
Abrupt onset, high fever, purulent sputum, focal consolidation
Atypical pneumonia generally presents with
Gradual onset, dry cough, myalgia, headache
Aspiration pneumonias mostly affect
Alcoholics
Patients with impaired consciousness
Patients with swallowing problems
What can cause pneumonias?
Bacteria
Viral
Fungal
(Rarely) helminth/protozoa
Aspiration pneumonias are generally caused by
Anaerobes
Gram negative enterobacteria
S. aureus
Hospital acquired pneumonias are generally caused by
S. aureus
Gram negative enterobacteria
Pseudomonas
Klebsiella
Common causes of community acquired pneumonias
Streptococcus pneumonia (60-75%)
Haemophilus influenzae
Mycoplasma pneumoniae
What pneumonia are penicillins ineffective against?
Pseudomonas
World’s leading cause of death from infectious disease
TB
Risk factors for TB
Close contact (>8hrs/day) with infected person Immunocomprimised Homeless - 150x national average Drug/alcohol abuse Smoking Healthcare workers
What causes TB?
Inhalation of causative organism.
M tuberculosis
M africanum
M bovis
Geography of TB infection
95% of cases in the developing world
Africa - most severe buren.
SE Asia/Western Pacific - most new cases occur here.
UK - mostly in ethnic minorities.
Presentation of primary TB
Usually asymptomatic, can be associated w. mild febrile illness.
Presentation of secondary TB
Classically: Cough Sputumn production Haemoptysis Fevers Night sweats Fatigue Weightloss
Can affect most organs. Elderly patients commonly have non-specific symptoms.
Why does TB have such an impact on developing countries?
Mostly affects adults during their most productive years
Appearance of TB skin
Erythema nodosum - Inflammation of the fat cells, resulting in red lumps. Generally on the shin.
What does TB spine cause?
Vertebral collapse
What does TB brain cause?
Chronic meningitis or space occupying lesions can develop
What does TB of the adrenal glands cause?
Addison’s disease. Now rare in the UK
What is primary TB
Initial lesion (1-2cm diameter) develops in middle or upper lobes of lung. Ghon complex - focus of primary infection. After few weeks, initial lesion becomes a tubercle which undergoes necrosis during 'caseation'. The caseous tissue can liquefy, empty into the airway or be transmitted to other parts of the lung allowing bacterial spread.
What is secondary TB?
Reactivation of the primary infection or reinfection occurs. More common in the immunocompromised. Usually bilateral caveatting lesions as the tubercle follicles develop and new tubercles form.
What is progressive TB?
Can happen after primary or secondary TB.
TB progresses to widespread cavitations, pneumonitis and lung fibrosis.
What is miliary TB?
Acute, diffuse dissemination of tubercle bacilli through the bloodstream, Characteristic millet seed appearance on CXR.
Latent TB
Roughly 1/3 of worlds population. Infected but not yet sick. Cannot transmit the disease. 10% lifetime risk of becoming ill in the future. Higher if malnourished, smoker or immunocomprimised.
Investigations for TB
- Sputum test - Acid fast bacilli, culture, PCR (resistance), Need to request TB specific culture.
- Blood - FBC, ESR, CRP
- ECG - Normal sinus rhythm?
- X-Ray
- Heaf/Mantoux-Tuberculin tests. Won’t work if immunocompromised or miliary TB
- Histology
Treatment for symptomatic TB
6 months quadruple therapy supervised by chest physician.
RIPE.
2 months - Rifampicin, isoniazid, pyrazinamide, ethambutol.
Then 4 months rifampicin and isoniazid only if TB fully sensitive.
Major problem with TB treatment is
Non-compliance. Side effects mean patients are likely to stop taking.
Rifampicin side effects
Orange body secretions
Hepatitis
Thrombocytopenia
Flu-like symptoms
Isoniazid side effects
Peripheral neuropathy
Hepatitis
Seizures
Psychoses
Pyrazinamide side effects
Hyperuricaemis
Hepatitis
Rash
Gout
Ethambutol side effects
Optic neuritis - can cause blindness
Rashes
What is a DOTS strategy?
Directly Observed Treatment, Short-course.
Drugs given by healthcare workers who observe them being taken. Greatly increases compliance.
Problems with TB and resistance
TB - adapts very quickly to develop resistance.
If poor drug availability, poor compliance, inappropriate treatment then resistance likely to develop.
MDR (multi drug resistant) and XDR (Extremely drug resistant) TB now exists.
XDR - worst in Eastern Europe due to partial treatment. No treatments available.
