Pneumonia - Philadelphia University



Pneumonia

- Pneumonia is an acute infection of the pulmonary parenchyma

- Pneumonia is a common infection encountered by critical care nurses when

it complicates the course of a serious illness or leads to acute respiratory

distress.

- The mortality rate climbs to 40% in those requiring admission to the

intensive care unit (ICU) and elderly patients (older than 65 years of age)

died of pneumonia at a significantly higher rate

- Patients with severe community acquired pneumonia( CAP) require

admission to the ICU.

- Hospital-acquired (nosocomial) pneumonia (HAP) is defined as pneumonia

occurring more than 48 hours after admission, which excludes infection

that is incubating at the time of admission.

- Types of hospital acquired pneumonia

- Early-onset HAP occurs within 2 to 5 days of hospitalization,

- Late-onset HAP occurs after 5 days of hospitalization.

- Severe HAP may occur in the ICU, with patients receiving mechanical

ventilation being at the greatest risk, or it may precipitate admission to the

ICU.

- The incidence of HAP is increased by 6- to 20-fold in patients receiving

mechanical ventilation.

- HAP independently contributes to mortality in critically ill patients; the

attributable mortality rate is 11% to 33%.

Etiology

- Bacteria, viruses, mycoplasmas, other infectious agents such as fungi, and

foreign material can all cause pneumonia.

Etiology of CAP

- Gram-positive organisms predominate in CAP, Streptococcus pneumoniae

(pneumococcus) is the most common cause of CAP and also the most

frequent cause of mortality in CAP.

- Drug-resistant S. pneumoniae is frequently seen in individuals older than

65 years of age.

- Other pathogens that should be considered in severe CAP requiring

admission to the ICU include Haemophilus influenzae, Staphylococcus

aureus, Mycobacterium tuberculosis, respiratory viruses, and endemic

fungi.

Etiology of HAP

- Enteric gram- negative bacilli predominate in HAP. The enteric gram-

negative bacilli and S. aureus (grampositive) are the most frequently

identified organisms in HAP.

- More than one organism may be identified in over 30% of patients with

HAP, and HAP is frequently polymicrobial.

- Polymicrobial HAP is particularly common (>50%) in patients receiving

mechanical ventilation (ventilator-associated pneumonia).

- Highly resistant gramnegative organisms (e.g., Pseudomonas aeruginosa,

Acinetobacter species) and methicillin-resistant S. aureus are frequently

seen in late-onset HAP but may occur in early-onset HAP in patients with

risk factors for these pathogens.

The spectrum of potential pathogens can be defined by assessment of a variety of factors, including :-

1- The severity of the pneumonia,

2- Presence of comorbidities,

3- Prior therapy (including antibiotics),

4- Length of hospitalization.

Pathophysiology

- Pneumonia is an inflammatory response to inhaled or aspirated foreign

material or the uncontrolled multiplication of microorganisms invading the

lower respiratory tract.

- This response results in the accumulation of neutrophils and other effector

cells in the peripheral bronchi and alveolar spaces.

- The pathogenesis of bacterial HAP is depicted in the theoretical model

postulated by the Centers for Disease Control and Prevention

- The body’s defense system, which includes anatomical, mechanical,

humoral, and cellular defenses, is designed to repel and remove organisms

entering the respiratory tract.

- Many systemic diseases increase the patient’s risk of pneumonia by

altering the respiratory defense mechanism.

- Pneumonia develops when normal pulmonary defense mechanisms are

either impaired or overwhelmed, allowing microorganisms to multiply

rapidly.

- Pathogens may enter the lower respiratory tract and cause pneumonia in

four ways:

1- Aspiration,

2- Inhalation,

3- Hematogenous spread from a distant site,

4- Translocation.

1- Aspiration of microorganisms from the oropharynx.

- Aspiration occurs frequently (>45% of the time) in healthy individuals

while they sleep.

- The risk of clinically significant aspiration is increased in:-

- Patients with a depressed level of consciousness or dysphagia;

- Those who have endotracheal or enteral tubes;

- Those receiving enteral feedings.

- For example, aspiration occurs more often (>70% of the time) and more

extensively in patients with a depressed level of consciousness.

2- Inhalation of bacteria-laden aerosols from contaminated respiratory

equipment.

- Inhalation is an effective entry mechanism for Legionella species, M.

tuberculosis, certain viruses, and fungi.

3- Hematogenous spread may be an effective mechanism;

- The pulmonary circulation provides a potential portal of entry for

microbes.

- The pulmonary capillaries form a dense network in the walls of the alveoli

that is ideal for gas exchange.

- Hematogenous microbes from distant sites of infection can migrate through

this network and cause pneumonia.

- (Pneumonia can also cause bacteremia. Secondary bacteremia after

pneumonia has been reported in 6% to 20% of pneumonia cases.)

4- Translocation of bacterial toxins from the gut lumen to the

mesenteric lymph nodes and eventually to the lungs

- It may possibly cause bacterial pneumonia. However, translocation has not

yet been confirmed as a pathophysiological mechanism.

- Colonization of the oropharynx and the stomach plays an important role in

the pathophysiology of bacterial pneumonia.(Colonization is the presence

of microorganisms other than the normal flora in the absence of clinical

evidence of infection.)

- Gram-positive bacteria and anaerobic bacteria normally live in the

oropharynx, and it is hypothesized that they occupy bacterial binding sites

in the oropharyngeal mucosa. When normal oropharyngeal flora are

destroyed, these binding sites are susceptible to colonization by pathogenic

bacteria.

- The gram-negative or pathogenic gram-positive organisms that have

colonized the oropharynx are readily available for aspiration into the

tracheobronchial tree.

Risk factors associated with oropharyngeal colonization include

- Previous antibiotic therapy,

- Increased age,

- Depressed level of consciousness,

- Dental plaque,

- Smoking,

- Chronic diseases, such as chronic obstructive pulmonary disease (COPD),

- Alcoholism,

- Diabetes mellitus,

- Malnutrition.

- The stomach can serve as a reservoir for bacteria. This organ is normally

sterile because of the bactericidal activity of hydrochloric acid. However,

when gastric pH increases above normal (pH >4), microorganisms are able

to multiply.

- Gastric colonization increases retrograde colonization of the oropharynx

and increases the risk of pneumonia.

Individuals at risk for gastric colonization include

1- The elderly;

2- Achlorhydria,

3- Ileus,

4- Upper gastrointestinal disease;

5- Antacids,

6- Histamine-2 antagonists,

7- Enteral feedings.

Risk factors for HAP :-

A- Host-Related Risk Factors

1- Increased age

2- Altered level of consciousness

3- Chronic obstructive pulmonary disease (COPD)

4- Severe illness

5- Malnutrition

6- Shock

7- Blunt trauma

8- Severe head trauma

9- Chest trauma

10- Smoking

11- Dental plaque

B- Treatment-Related Risk Factors

1- Mechanical ventilation

2- Reintubation or self-extubation

3- Bronchoscopy

4- Nasogastric tube

5- Presence of intracranial pressure (ICP) monitor

6- Prior antibiotic therapy

7- Elevated gastric pH

8- Histamine type 2 receptor blockers

9- Antacid therapy

10- Enteral feedings

11- Head surgery

12- Upper abdominal or thoracic surgery

13- Supine position

C- Infection Control–Related Factors

1- Poor handwashing

2- Changing ventilator tubing less than every 48 hours

Assessment

History

- Hemoptysis implies tissue necrosis and is more common with

- pyogenic streptococcal pneumonia,

- anaerobic lung abscesses,

- S. aureus,

- necrotizing gram-negative organisms,

- invasive Aspergillus.

- Extrapulmonary symptoms may indicate specific pathogens;

(Diarrhea & abdominal discomfort indicate Legionella species, )

(Otitis media & pharyngitis indicate Mycoplasma pneumoniae )

- Historical information may also be extremely helpful in diagnosis of CAP

and HAP. It is necessary to include information about contact with animals,

especially birds, bats, rats, and rabbits, which can assist with the diagnosis

of histoplasmosis, psittacosis, tularemia, and plague.

- In addition, a complete history may assist in the differential diagnosis.

Diseases that may mimic pneumonia include:-

- Congestive heart failure,

- Atelectasis, pulmonary

- Thromboembolism,

- Drug reactions,

- Pulmonary hemorrhage,

- Acute respiratory distress syndrome.

- The clinical presentation in the older adult may vary somewhat from what

is “typical” in a younger person

Clinical manifestation in the older patient

- The usual symptoms (fever, chills, increased white blood count) may be

absent.

- Confusion and tachypnea are common presenting symptoms in older

patients with pneumonia.

- Other symptoms in the older patient include weakness, lethargy, failure to

thrive, anorexia, abdominal pain, episodes of falling, incontinence,

headache, delirium, and nonspecific deterioration.

Physical Findings

- Patients present with new-onset respiratory symptoms (e.g., cough, sputum

production, dyspnea) that are usually accompanied by fever and chills.

- A comprehensive cardiovascular and pulmonary assessment should be

completed, with a focus on the major and minor criteria of pneumonia .

- The nurse should assess for signs of hypoxemia (duskiness or cyanosis)

and dyspnea (nasal flaring).

- Inspection of the chest includes assessing respiratory pattern and

respiratory rate, observing the patient’s posture and work of breathing, and

inspecting for the presence of intercostals retractions.

- Percussion of the chest frequently reveals dullness with lobar pneumonia.

- Auscultation of the chest reveals decreased breath sounds are heard fine

early crackles (formerly called rales) or bronchial breath sounds are heard

over the area of consolidation.

Diagnostic Studies

- The diagnostic evaluation must be performed rapidly to prevent delays in

initiation of antibiotic therapy.

- All patients should have a chest radiograph (posteroanterior and lateral

views) to identify both the presence and location of infiltrates. The chest

radiograph is helpful in differentiating pneumonia from other conditions

and identifying severe pneumonia, which is indicated by the presence of

multilobular, rapidly spreading or cavitary infiltrates.

- The value of examining lower respiratory secretions with Gram’s stain and

culturing sputum is controversial. it is not recommend routine

use of Gram’s stain and sputum culture and advises that results must be

interpreted cautiously.However, the Infectious Disease Society

of America (IDSA) recommends routine Gram’s stain and culture of deep-

cough specimens.

- Lower respiratory secretions can be easily obtained in intubated patients

using endotracheal aspiration.

- Nonquantitative endotracheal aspiration cultures may assist in excluding

certain pathogens and may be helpful in modifying initial empirical

treatment.

- Routine use of quantitative invasive diagnostic techniques (bronchoscopy

with protected specimen brush [PSB] or bronchoalveolar lavage [BAL]) in

severe pneumonia is not recommended

- Current guidelines suggest that BAL or PSB be used only in selected

circumstances, such as in nonresponse to:-

1- Antimicrobial therapy,

2- Immunosuppression,

3- Suspected tuberculosis in the absence of a

productive cough,

4- Pneumonia with suspected neoplasm or foreign

body,

5- Conditions that require lung biopsy.

Management

Antibiotic Therapy

- Patients should initially be treated empirically, based on the severity of

disease and the likely pathogens. Initial therapy should be instituted

rapidly.

- Initial therapy should not be changed within the first 48 to 72 hours unless

progressive deterioration is evident or initial microbiological (blood or

respiratory) cultures indicate a need to modify therapy.

Factors to consider when determining the duration of therapy include

1- Concurrent illness,

2- Bacteremia,

3- Severity of pneumonia at the onset of antibiotic therapy,

4- Infecting pathogen(s),

5- Rapidity of clinical response.

Recommended duration of therapy is

- 7 to 10 days for S. aureus or H. influenzae;

- 10 to 14 days for M. pneumoniae and C. pneumoniae;

- 14 to 21 days for P. aeruginosa and Acinetobacter, multilobar

involvement, malnutrition, or a necrotizing gram-negative bacillus.

Supportive Therapy

- Oxygen therapy is required to maintain adequate gas exchange.

- Mechanical ventilation to correct hypoxemia is frequently required in both

severe CAP and HAP .

- Humidified oxygen should be administered by mask or intubation to

promote ciliary movement

Prevention

- Primary measures to prevent CAP include the use of influenza and

pneumococcal vaccines.

- All immunocompetent patients 65 years of age or older should receive the

pneumococcal vaccine.

- People 65 years of age and older should receive both the pneumococcal

vaccine (a one-time vaccination) and yearly influenza vaccines.

- In addition, individuals 64 years of age or younger should be immunized if

they have chronic illnesses, such as cardiovascular disease, chronic

pulmonary disease (COPD, but not asthma), diabetes mellitus, alcoholism,

chronic liver disease, cerebrospinal fluid leaks, and functional or anatomic

asplenia; or live in special social settings, such as long-term care facilities.

- Influenza vaccine is recommends for three target groups:

- Persons at a high risk of influenza complications,

- Persons who may transmit influenza to high-risk patients (e.g.,

health care workers);

- Any person who wishes to decrease the chance of becoming

infected with influenza.

High-risk patients include

- Individuals older than 65 years of age,

- Residents of long-term care facilities,

- Patients with chronic cardiovascular or pulmonary disease,

- Patients who required regular medical care or hospitalization during

the preceding year,

- Pregnant women in the second or third trimester during influenza

season.

- Smoking cessation, particularly in patients who have previously had

pneumonia, because cigarette smoking is a risk factor for both HAP and

CAP pneumonia, education the cornerstone of an effective infection

control program and the prevention of HAP.

- Comprehensive guidelines on the prevention of HAP

World Wide Web access to the CDC guidelines is available at

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