Critical Care Nursing Theory
- 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
- 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
- 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%.
Dr Abdul-Monim Batiha - Assistant Professor Of Critical Care Nursing
Critical Care Nursing Theory
- 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
Etiology of HAP
- Enteric gram- negative bacilli predominate in HAP. The enteric gramnegative 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.
Dr Abdul-Monim Batiha - Assistant Professor Of Critical Care Nursing
Critical Care Nursing Theory
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.
- 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
- 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.
Dr Abdul-Monim Batiha - Assistant Professor Of Critical Care Nursing
Critical Care Nursing Theory
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
- 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
- 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.)
Dr Abdul-Monim Batiha - Assistant Professor Of Critical Care Nursing
Critical Care Nursing Theory
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
- 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
Dr Abdul-Monim Batiha - Assistant Professor Of Critical Care Nursing
Critical Care Nursing Theory
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
Dr Abdul-Monim Batiha - Assistant Professor Of Critical Care Nursing
Critical Care Nursing Theory
13- Supine position
C- Infection Control–Related Factors
1- Poor handwashing
2- Changing ventilator tubing less than every 48 hours
- 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
Dr Abdul-Monim Batiha - Assistant Professor Of Critical Care Nursing
Critical Care Nursing Theory
is “typical” in a younger person
Clinical manifestation in the older patient
- The usual symptoms (fever, chills, increased white blood count) may be
- 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.
Dr Abdul-Monim Batiha - Assistant Professor Of Critical Care Nursing
Critical Care Nursing Theory
- 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 deepcough 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
- 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
5- Conditions that require lung biopsy.
Dr Abdul-Monim Batiha - Assistant Professor Of Critical Care Nursing
Critical Care Nursing Theory
Antibiotic Therapy
- Patients should initially be treated empirically, based on the severity of
disease and the likely pathogens. Initial therapy should be instituted
- 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
Dr Abdul-Monim Batiha - Assistant Professor Of Critical Care Nursing
Critical Care Nursing Theory
- 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
- 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.
Dr Abdul-Monim Batiha - Assistant Professor Of Critical Care Nursing
Critical Care Nursing Theory
- Comprehensive guidelines on the prevention of HAP
World Wide Web access to the CDC guidelines is available at
Dr Abdul-Monim Batiha - Assistant Professor Of Critical Care Nursing