Pneumonia

1. Pneumonia and Chest infection

A. Chest infection
a. non-specific term which doesn't refer to sites of infection, cen be over whole whole respiratory tract, from URT to alveoli
b. examples:
1. upper respiratory tract infection
2. airway infection e.g. bronchitis
3. lung parenchyma e.g. pneumonia
B. Pneumonia: refers to a specific site and inflames the air sacs i.e. lung parenchyma
2. Classifications of pneumonia
A. Classification I: Infection or not
a. Infectious: caused by fungi, bacteria, virus i.e. the organism can spread
b. Non-infectious: example is aspiration pneumonia
B. Classification II: Places the patient acquires pneumonia

C. Classification III: Affected site

a. Bronchopneumonia:
1. A descending infection: from bronchi/bronchioles to distal part of lung (alveoli)
b. Lobar pneumonia:
1. Acute exudative inflammation of the entire lobe
c. Interstitial pneumonia:
1. Inflammation in the structural spaces between the alveoli
3. Sources of pneumonia: bacteria and virus
A. Viruses
B. Pneumococcus: 肺炎鏈球菌
a. Can be found in upper respiratory tract of most people because they have a special chemical which can attach to
epithelial cells in in URT.
b. Implication: 既然佢喺⼤部分⼈⾝體入⾯都有，姐係話infected ppl⼀定有某啲特點令到隻菌可以invade到patients
c. Example: children and elderly with poor immune response, adult with HIV, patients with virus
d. Epidemiology: 就係因為好多⼈都有，所以⼈⼝密集嘅地⽅特別容易有呢隻菌堆積
C. Staphylococcus: 葡萄球菌
a. 基本上⼈體周圍都有葡萄球菌，even成⽇聽到話致病嘅⾦⿈葡萄球菌喺⽪膚/upper respiratory tract上⾯都係周圍都有。但點
解我地唔會咁容易比佢感染同佢嘅致病性有關。葡萄球菌嘅致病性源⾃於菌表⾯⼀層叫coagulase(中⽂叫凝固酶)嘅東⻄，呢
 層嘢會喺菌表⾯形成保護膜（mechanism係凝固啲serum令到macrophage食佢唔到），令到佢地可以繁殖然後致病
b. Implication: 即係話如果patient嘅immune response唔夠強嘅話就殺啲菌唔死，因為佢嘅特點係prevent being killed by
immune cells 嘛
D. Mycoplasma pneumoniae: 肺炎⽀原體
a. 正常bacteria要cell wall黎protect⾃⼰，同埋攞黎痴住唔同嘅surface/object黎傳播出去。⽽⽀原體特別嘅地⽅在於佢係冇cell
wall嘅，所以⼀黎佢spread唔到好遠（因為冇得⽤cell wall黎痴住唔同嘅嘢），⼆黎喺醫院呢個成⽇消毒嘅地⽅好容易
destroy左佢。
b. Implication: Crowded community settings 容易spread
E. Haemophilus influenzae
a. Same as pneumococcus, infection happens when patients are weak
b. Especially when patients (children) have bronchiolitis
F. Pseudomonas aeruginosa: 綠膿桿菌
a. Opportunistic nature: patients in hospital can have weakened immune system
b. 醫院有好多so-called⼈造物放落個patient 度。由於Pseudomonas aeruginosa係會整⼀層保護膜（biofilm）黎包住⾃⼰令到
⾃⼰唔好比⼈清走，所以好容易會喺ventilator/catheter之類嘅地⽅⾒到佢（多左surface比佢⽣長）
G. MRSA
a. often use of antibiotics
H. Enteric gram-negative e.g. E-coli, klebsiella (gram-negative is a type of bacteria)
a. cuz patients receiving intensive care can't go to toilet so they have to handle feces near bed
I. Chlamydia：衣原體
a. 我發現衣原體基本上係咩情況下都⾒得到... really can't tell, but most commonly is sexual transmission
J. Fungi: related to water pollution
K. Anaerobic bacteria: hospital can have anaerobic environment, easy to understand
4. Places people can get pneumonia

Regarding the risk factors, there is one thing common:

All factors are related to exposing to the risk of reduced immune response

1. Consider the community acquired one:

A. How ppl can get reduced immune response in community e.g.
smoking
2. Consider the hospital acquired one:
A. Basically in hospital patient get reduced immune response
because they have comorbidity e.g. surgery, chemotherapy
5. Pneumonia in different population
A. Children
a. Viruses, Pneumococcus, Staphylococcus, Mycoplasma pneumoniae, Haemophilus influenzae (can cause COPD later)
B. Adult
a. Viruses, Pneumococcus, Staphylococcus, Mycoplasma pneumoniae, Haemophilus influenzae
b. Chlamydia psittaci (birds/ farm animals), Legionella (contaminated water system), HIV (reduced immune response)
C. Elderly
a. Pneumococcus, Staphylococcus, Mycoplasma pneumoniae, Haemophilus influenzae
b. Legionella (contaminated water system), HIV (reduced immune response), Enteric gram-negative(klebsiella)
c. TB: logic same as staphylococcus, originally present in human body then become active when people get old with weak
immune response
d. Aspiration pneumonia: easily swallow something into trachea
D. Infants
a. Respiratory syncytial virus (RSV), Adenovirus, Bacterial
b. Already existing illness, weaken immune system and cause infection from:
1. Staphylococcus
2. E. coli and gram-negative bacteria
3. Viruses
6. Normal Pulmonary Defenses
A. Nostrils: ⿐孔/⿐⽑sometimes
B. Cough reflex
C. Commensal microbes(微⽣態平衡)
D. Mucociliary apparatus：globet cells secret mucous to engulf the foreign organism, removed by cilia
E. Alveolar macrophages
F. Innate immunity
7. Pathophysiology of Pneumonia
A. Bacterial pathogen has escaped the respiratory defenses and go down the airway
a. Because of weakened immune response/exposure to pathogens after surgery etc
B. Multiply within the alveoli and airways
C. Macrophages recognize pathogens and inflammatory response happens
D. Inflammatory cytokines, white blood cells and edema flood the alveoli and bronchi causing consolidation of the lung
E. V/Q mismatch causes hypoxemia
F. For severe cases, the bacteria may spread to other parts of body causing infection at multiple sites
8. Viral Pneumonia
A. Special things and symptoms presented
a. Frequent site of infection: ciliated cells of respiratory tract
1. Once there is infection, fever must be present because body needs to increase metabolic rate
b. Ciliated cells become paralyzed and degenerate and there is a area of necrosis and desquamation (the cells break down)
1. Breaking down of the cellular layers in airway irritate the airway, causing persistent cough (like COVID we feel ⼝乾）
 c. Inflammatory responses cause exudation of fluid and erythrocytes in both alveolar space and airways (exudation into
alveoli will form a membrane of fluid, called hyaline membrane)
1. The hyaline membrane reduce the effectiveness of gaseous exchange, causing dyspnoea
d. Dysfunction of ciliated cells can cause high risk of bacterial infection cuz the airway can't remove the bacteria
e. Because viral infection only causes destruction to ciliated cells, the damage caused by virus is relatively small
1. Less septum produced cuz only destruction to ciliated cells
2. Auscultation: cuz less septum production so normal breath sound throughout both lungs with some crackles
f. CXR behaviors
1. Again, because of less severe and less production, severe cases like consolidations and pleural effusion less frequent
2. Behaviors can range from minor infiltrates to bilateral involvement i.e. ground-glass appearance
B. Medical management
a. Vaccination
b. Supportive and Preventive Care
1. Symptoms management
c. Rest
d. High Fluid Intake
1. Helps thin mucus and get it out of airway (cuz the ciliated cells are damaged so mucus can't be removed easily)
9. Bacterial Pneumonia
A. Sources of the problem:
a. Primary infection: infection because contacting the virus e.g. pneumococcus
b. Secondary infection: infection because patients immune system is weak
B. Phases of infection: basically the same cuz inflammation, but it has wider affected area and more "attack" from pathogens
The first 3 stages are the
jobs of doctor
After the inflammation
subsides, we need to clean
the waste in lung

C. Symptoms: greater extend then viral one

a. Fever, same as viral infection which can happen in any type of infection
b. Dyspnea, basically the same as viral one, caused by something congested in alveoli. But bacterial one has a larger extend
so more blockage will happen, causing hypoxemia. So body will compensate by breathing faster so tachypnea and
tachycardia will happen
c. Secretion containing dead bacteria and macrophages so purulent sputum.
 d. Cuz the infection can spread to a larger area, it can spread to the pleura causing swelling of pleura and they will rub
against each other. Rubbing of pleura can cause pleuritic pain and there will be muscle splinting, decreasing expansion
e. Auscultation: we have to know that the infection will spread to a very large area first
1. Because it spread very widely, the whole affected area will have decreased sound, crackles or wheeze
2. Because there is many secretion, the lung may collapse/completely consolidate causing bronchial breath sound
D. Medical management
a. Antibiotics/medication
b. Increased fluid intake
c. Ultrasonic nebulization
d. Physiotherapy
e. If severe, supplementary oxygen therapy is indicated
10. Diagnosis

11. Complications of pneumonia

A. Consolidation and atelectasis
a. Consolidation is easy to understand cuz there will be many secretion anyway
b. Atelectasis can have many causes, mainly compression or obstruction
1. Compression: tumors
2. Obstruction: less air enters the lung so the remaining air dissolves into blood, causing rapid reduction in volume
A. Airway obstructed by many many secretions
B. After surgery, the pain makes patient can't breath well
B. Lung fibrosis
a. After being infected the soft tissue make fibrosis
C. Cavitary lesion with lung abscess
a. In acute infection stage the lung tissue is destroyed and dead bacterial cells are left
D. Pleural effusion/Empyema
a. Inflammation spread to pleural space so sth left there
E. Septicemia / bacteremia
a. Inflammation spread to bloodstream
F. Respiratory failure, may require mechanical ventilation
What is Ventilator Associated Pneumonia?

 CDC’s (The Centers for Disease Control and Prevention)

National Healthcare Safety Network
- Pneumonia that occurs in a patient who was intubated and
ventilated at the time of, or within 48 hrs, “before” the onset
of the pneumonia

 ATS (American Thoracic Society) and the IDSA (Infectious

Diseases Society of America)

- Pneumonia that arises >48–72 hrs “after” intubation

CDC, 2008
ATS & IDSA. Am J Respir Crit Care Med 2005
Why VAP is important?

 Second most common nosocomial infection in the ICU and

most common in mechanically ventilated patients

 Leading cause of death among hospital-acquired infections.

 Hospital mortality with and without VAP is 46% vs 32%
 In recent data, the attributable mortality for VAP is around 9-
13%

 Increase in ICU stay of between 4.3 and 13 days

 Increase in costs. In US, VAP adds an estimated cost of

$40,000 per hospital admission

 VAP is preventable
Melson et al. Lancet Infect Dis 2013
 Risk Factors for Nosocomial
Pneumonia
 Major risk factor: improper handling by health care professionals

 Factors that enhance colonization of the oropharynx &/or stomach:

- mechanical intubation

- administration of antibiotics

- underlying chronic lung disease

 Conditions favoring aspiration into the respiratory tract or reflux from GI tract

- Supine position

- Nasogastric tube placement

- Immobilization

- Surgery of head/neck/thorax/ upper abdomen

- Coma
VAP Prevention Bundles
what dept do
1. Elevation of the Head of the Bed 30°-45°
2. Daily sedative interruption and daily assessment of
readiness to extubate
3. Peptic ulcer disease prophylaxis
4. Deep venous thrombosis prophylaxis
5. Daily oral care with Chlorhexidine
6. Maintain airway pressure
7. Promote early mobilization

By Institute for Healthcare Improvement (IHI)

So the thing is that both tubes are used to maintain patency of airway to support ventilation
As a result, they may be used together with mechanical ventilator (which is the case of close suction, px needs continuous O2 while
suctioning) so there are extra precautions

Maintenance of Airway Pressure

• Maintenance of PEEP during mechanical ventilation, avoid zero
PEEP Minimize airway disconnection as much as possible
(minimize MHI)

• Avoid frequent patient transport

Reason is to minimize disturbance to PEEP but can I only do subglottic suction to minimize risk of infection?
cuz PEEP 個邏輯就係唔好吸到個肺就得right？

• Avoid routine suction and keep lowest suction pressure and

shortest suction duration (follow strictly the suctioning
parameters)

Lau ACW et al. HKMJ, 2015

 Strategies to prevent VAP – PT perspective To reduce risk of infection
Ensure good oxygenation of px
⽤得ventilator嘅都係weak嘅px，while suctioning係吸走緊肺入⾯嘅
1. Stringent infection control measures air

2. Minimize the chance of disconnecting the ventilator (e.g perform

Manual Hyperinflation) does it mean that we shouldn't remove the ventilator at all?
3. Replaced by performing Ventilator Hyperinflation Minimize saline
instillation Using saline will push the secretion back
4. Keep suction pressure: should be appropriated enough that can clear
secretions and the pressure should be <200mmHg
5. Keep suction duration: <15 sec
6. Perform subglottic aspiration and oral suction before closed suction
* Procedure for subglottic aspiration is almost the same as nasopharyngeal
suctioning