Hospital-Acquired and Ventilator-Associated Pneumonias (Clinical)

Clinical Presentation and Diagnosis

Clinical presentation

Signs and symptoms may include:^[1]

• Respiratory:
  • Dyspnea Dyspnea Dyspnea is the subjective sensation of breathing discomfort. Dyspnea is a normal manifestation of heavy physical or psychological exertion, but also may be caused by underlying conditions (both pulmonary and extrapulmonary). Dyspnea
  • Cough
  • ↑ Sputum production
• Vitals:
  • New fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever
  • Tachypnea Tachypnea Increased respiratory rate. Pulmonary Examination
  • Tachycardia Tachycardia Abnormally rapid heartbeat, usually with a heart rate above 100 beats per minute for adults. Tachycardia accompanied by disturbance in the cardiac depolarization (cardiac arrhythmia) is called tachyarrhythmia. Sepsis in Children
  • Hypoxemia Hypoxemia Neonatal Respiratory Distress Syndrome
• Physical examination findings:
  • Use of accessory muscles
  • ↑ Tactile fremitus Tactile Fremitus Pulmonary Examination and dull percussion Percussion Act of striking a part with short, sharp blows as an aid in diagnosing the condition beneath the sound obtained. Pulmonary Examination → consolidation Consolidation Pulmonary Function Tests
  • ↓ Tactile fremitus Tactile Fremitus Pulmonary Examination and flat/dull percussion Percussion Act of striking a part with short, sharp blows as an aid in diagnosing the condition beneath the sound obtained. Pulmonary Examination → pleural effusion Pleural Effusion Pleural effusion refers to the accumulation of fluid between the layers of the parietal and visceral pleura. Common causes of this condition include infection, malignancy, autoimmune disorders, or volume overload. Clinical manifestations include chest pain, cough, and dyspnea. Pleural Effusion
  • Auscultation findings can include:
    • Crackles
    • Bronchial sounds in the periphery
    • Pleural friction rub
• Signs of sepsis Sepsis Systemic inflammatory response syndrome with a proven or suspected infectious etiology. When sepsis is associated with organ dysfunction distant from the site of infection, it is called severe sepsis. When sepsis is accompanied by hypotension despite adequate fluid infusion, it is called septic shock. Sepsis and Septic Shock, shock Shock Shock is a life-threatening condition associated with impaired circulation that results in tissue hypoxia. The different types of shock are based on the underlying cause: distributive (↑ cardiac output (CO), ↓ systemic vascular resistance (SVR)), cardiogenic (↓ CO, ↑ SVR), hypovolemic (↓ CO, ↑ SVR), obstructive (↓ CO), and mixed. Types of Shock, or multiorgan failure

With mechanical ventilation Ventilation The total volume of gas inspired or expired per unit of time, usually measured in liters per minute. Ventilation: Mechanics of Breathing, suggestive findings may include:^[22]

• ↓ Tidal volume Tidal volume The volume of air inspired or expired during each normal, quiet respiratory cycle. Common abbreviations are tv or V with subscript t. Ventilation: Mechanics of Breathing
• ↑ Inspiratory pressures
• ↑ Minute ventilation Minute ventilation Ventilation: Mechanics of Breathing
• ↑ Fraction of inspired oxygen (FiO₂) requirement

Diagnostic considerations^[1,17]

• VAP and HAP should be suspected if:
  • Presence of new lung infiltrate, and
  • Evidence that the infiltrate is due to an infection 
• VAP is more difficult to diagnose:
  • Prior infiltrates are common with patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship requiring mechanical ventilation Ventilation The total volume of gas inspired or expired per unit of time, usually measured in liters per minute. Ventilation: Mechanics of Breathing.
  • Anteroposterior (AP) view on chest X-ray X-ray Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard x-rays are the higher energy, shorter wavelength x-rays. Soft x-rays or grenz rays are less energetic and longer in wavelength. The short wavelength end of the x-ray spectrum overlaps the gamma rays wavelength range. The distinction between gamma rays and x-rays is based on their radiation source. Pulmonary Function Tests is more difficult to interpret.
  • Signs and symptoms such as fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever and leukocytosis Leukocytosis A transient increase in the number of leukocytes in a body fluid. West Nile Virus could be due to a variety of other causes such as sepsis Sepsis Systemic inflammatory response syndrome with a proven or suspected infectious etiology. When sepsis is associated with organ dysfunction distant from the site of infection, it is called severe sepsis. When sepsis is accompanied by hypotension despite adequate fluid infusion, it is called septic shock. Sepsis and Septic Shock, other infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease, and medication.
• Other diagnoses to keep in mind:
  • ARDS
  • Pulmonary edema Pulmonary edema Pulmonary edema is a condition caused by excess fluid within the lung parenchyma and alveoli as a consequence of a disease process. Based on etiology, pulmonary edema is classified as cardiogenic or noncardiogenic. Patients may present with progressive dyspnea, orthopnea, cough, or respiratory failure. Pulmonary Edema
  • Pulmonary contusion Pulmonary Contusion Flail Chest
  • Alveolar hemorrhage
  • Hypersensitivity pneumonitis Pneumonitis Human Herpesvirus 6 and 7
  • Pulmonary embolism Pulmonary Embolism Pulmonary embolism (PE) is a potentially fatal condition that occurs as a result of intraluminal obstruction of the main pulmonary artery or its branches. The causative factors include thrombi, air, amniotic fluid, and fat. In PE, gas exchange is impaired due to the decreased return of deoxygenated blood to the lungs. Pulmonary Embolism

Imaging and procedures^[3]

• Chest X-ray X-ray Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard x-rays are the higher energy, shorter wavelength x-rays. Soft x-rays or grenz rays are less energetic and longer in wavelength. The short wavelength end of the x-ray spectrum overlaps the gamma rays wavelength range. The distinction between gamma rays and x-rays is based on their radiation source. Pulmonary Function Tests:
  • Often the initial test of choice
  • Findings may include:
    • Lobar consolidations
    • Interstitial infiltrates
    • Cavitations
    • Pleural effusion Pleural Effusion Pleural effusion refers to the accumulation of fluid between the layers of the parietal and visceral pleura. Common causes of this condition include infection, malignancy, autoimmune disorders, or volume overload. Clinical manifestations include chest pain, cough, and dyspnea. Pleural Effusion
• Chest CT: helpful when detection of inflammatory changes may not be apparent on X-ray X-ray Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard x-rays are the higher energy, shorter wavelength x-rays. Soft x-rays or grenz rays are less energetic and longer in wavelength. The short wavelength end of the x-ray spectrum overlaps the gamma rays wavelength range. The distinction between gamma rays and x-rays is based on their radiation source. Pulmonary Function Tests
• Bronchoscopy Bronchoscopy Endoscopic examination, therapy or surgery of the bronchi. Laryngomalacia and Tracheomalacia:
  • May be performed to obtain invasive sampling Invasive sampling Coccidioides/Coccidioidomycosis (e.g., bronchoalveolar lavage Bronchoalveolar lavage Washing out of the lungs with saline or mucolytic agents for diagnostic or therapeutic purposes. It is very useful in the diagnosis of diffuse pulmonary infiltrates in immunosuppressed patients. Pulmonary Fibrosis)
  • Usually reserved only for cases unresponsive to typical treatment, when the causative organism remains unknown, or there is concern for specific nosocomial organisms (e.g., invasive Aspergillus Aspergillus A genus of mitosporic fungi containing about 100 species and eleven different teleomorphs in the family trichocomaceae. Echinocandins).

Determining the etiology^[1,8,18,19]

• Cultures from tracheal aspirates or more distal bronchial aspirates are used for etiologic diagnosis.
  • Noninvasive sampling (endotracheal aspiration) with semiquantitative cultures
    • Recommended by IDSA/ATS over invasive sampling Invasive sampling Coccidioides/Coccidioidomycosis ( bronchoscopy Bronchoscopy Endoscopic examination, therapy or surgery of the bronchi. Laryngomalacia and Tracheomalacia or blind bronchial sampling) in diagnosing VAP^[3,8]
    • However, experts agree → others (including international guidelines) recommend distal bronchial aspirates^[19]
  • Due to risk of rapid progression of infection, upon suspicion of HAP or VAP, specimens should be immediately obtained and treatment should be initiated.^[16,18]
• Additional testing:
  • Blood cultures
  • Viral testing ( influenza Influenza Influenza viruses are members of the Orthomyxoviridae family and the causative organisms of influenza, a highly contagious febrile respiratory disease. There are 3 primary influenza viruses (A, B, and C) and various subtypes, which are classified based on their virulent surface antigens, hemagglutinin (HA) and neuraminidase (NA). Influenza typically presents with a fever, myalgia, headache, and symptoms of an upper respiratory infection. Influenza Viruses/Influenza, SARS-CoV-2) based on likelihood:
    • Influenza Influenza Influenza viruses are members of the Orthomyxoviridae family and the causative organisms of influenza, a highly contagious febrile respiratory disease. There are 3 primary influenza viruses (A, B, and C) and various subtypes, which are classified based on their virulent surface antigens, hemagglutinin (HA) and neuraminidase (NA). Influenza typically presents with a fever, myalgia, headache, and symptoms of an upper respiratory infection. Influenza Viruses/Influenza testing recommended in hospitalized patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship who develop acute respiratory symptoms.^[7]
  • Rapid nasal PCR PCR Polymerase chain reaction (PCR) is a technique that amplifies DNA fragments exponentially for analysis. The process is highly specific, allowing for the targeting of specific genomic sequences, even with minuscule sample amounts. The PCR cycles multiple times through 3 phases: denaturation of the template DNA, annealing of a specific primer to the individual DNA strands, and synthesis/elongation of new DNA molecules. Polymerase Chain Reaction (PCR) or culture for MRSA MRSA A strain of Staphylococcus aureus that is non-susceptible to the action of methicillin. The mechanism of resistance usually involves modification of normal or the presence of acquired penicillin binding proteins. Staphylococcus:
    • Commonly performed for surveillance Surveillance Developmental Milestones and Normal Growth screening Screening Preoperative Care
    • Only 30% of respiratory infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease in MRSA-positive patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship are caused by MRSA MRSA A strain of Staphylococcus aureus that is non-susceptible to the action of methicillin. The mechanism of resistance usually involves modification of normal or the presence of acquired penicillin binding proteins. Staphylococcus
    • Negative screen is associated with decreased probability Probability Probability is a mathematical tool used to study randomness and provide predictions about the likelihood of something happening. There are several basic rules of probability that can be used to help determine the probability of multiple events happening together, separately, or sequentially. Basics of Probability of MRSA MRSA A strain of Staphylococcus aureus that is non-susceptible to the action of methicillin. The mechanism of resistance usually involves modification of normal or the presence of acquired penicillin binding proteins. Staphylococcus infection → does not completely rule out possibility

Additional laboratory studies^[1,8]

• Leukocytosis Leukocytosis A transient increase in the number of leukocytes in a body fluid. West Nile Virus may be present, but is not specific
• Procalcitonin Procalcitonin Neutropenic Fever and C-reactive protein (CRP) are not recommended to guide initiation or duration of antibiotics.

Management

Recommendations may vary depending on practice location, regional epidemiology, and availability of drug therapy. The following is a summary derived largely from the ATS/IDSA guidelines. For detailed information, ATS/IDSA guidelines (US), UK guidelines, and European guidelines are available for review.

Antibiotic therapy

Empiric broad-spectrum Broad-Spectrum Fluoroquinolones antibiotics are given, with coverage for S.aureus, P. aeruginosa P. aeruginosa A species of gram-negative, aerobic, rod-shaped bacteria commonly isolated from clinical specimens (wound, burn, and urinary tract infections). It is also found widely distributed in soil and water. P. Aeruginosa is a major agent of nosocomial infection. Pseudomonas and other gram-negative bacilli Bacilli Shigella.

Deciding on treatment initiation:^[8]

• Clinical findings should be used to guide the initiation of antibiotics. 
• Clinical scoring systems (clinical pulmonary infection score) are controversial and have not been shown to have adequate sensitivity or specificity.
• Use of biomarkers ( procalcitonin Procalcitonin Neutropenic Fever or CRP) is not recommended to guide antibiotic initiation.

Deciding on the regimen:^[8,18]

• The resistance Resistance Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow. Ventilation: Mechanics of Breathing patterns vary within ICUs, regions, and countries, so hospitals are recommended to have a local antibiogram showing the antimicrobial susceptibility of the organism specific to the ICU ICU Hospital units providing continuous surveillance and care to acutely ill patients. West Nile Virus population.
• Empiric treatment should be based on:
  • Local antimicrobial susceptibilities and prevalent pathogens associated with HAP and VAP
  • Prior hospitalization Hospitalization The confinement of a patient in a hospital. Delirium, previous infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease, and recent antibiotics taken by the individual
  • Risk factors for MDR pathogens 
  • Mortality Mortality All deaths reported in a given population. Measures of Health Status risk
• MRSA MRSA A strain of Staphylococcus aureus that is non-susceptible to the action of methicillin. The mechanism of resistance usually involves modification of normal or the presence of acquired penicillin binding proteins. Staphylococcus coverage is recommended if prevalence Prevalence The total number of cases of a given disease in a specified population at a designated time. It is differentiated from incidence, which refers to the number of new cases in the population at a given time. Measures of Disease Frequency of MRSA MRSA A strain of Staphylococcus aureus that is non-susceptible to the action of methicillin. The mechanism of resistance usually involves modification of normal or the presence of acquired penicillin binding proteins. Staphylococcus in the treatment unit is:
  • > 10%–20%
  • Unknown
• 2 antipseudomonal agents (from different classes) should be considered if:
  • There is a risk factor for antimicrobial resistance Resistance Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow. Ventilation: Mechanics of Breathing
  • > 10% of gram-negative organisms isolated from the treatment unit are resistant to an antibiotic being considered
  • Antimicrobial susceptibility data are not available
• Note: If the individual was on antibiotics before, give a drug from a class different from the one previously used.

Antibiotic options:^[1,8,18]

• For MDR P. aeruginosa P. aeruginosa A species of gram-negative, aerobic, rod-shaped bacteria commonly isolated from clinical specimens (wound, burn, and urinary tract infections). It is also found widely distributed in soil and water. P. Aeruginosa is a major agent of nosocomial infection. Pseudomonas and gram-negative bacilli Bacilli Shigella (1 or 2 agents are used, depending on the clinical scenario):
  • 1st agent choices:
    • Piperacillin-tazobactam Piperacillin-Tazobactam Multidrug-resistant Organisms and Nosocomial Infections 
    • Cefepime Cefepime A fourth-generation cephalosporin antibacterial agent that is used in the treatment of infections, including those of the abdomen, urinary tract, respiratory tract, and skin. It is effective against pseudomonas aeruginosa and may also be used in the empiric treatment of febrile neutropenia. Cephalosporins 
    • Imipenem Imipenem Semisynthetic thienamycin that has a wide spectrum of antibacterial activity against gram-negative and gram-positive aerobic and anaerobic bacteria, including many multiresistant strains. It is stable to beta-lactamases. Clinical studies have demonstrated high efficacy in the treatment of infections of various body systems. Its effectiveness is enhanced when it is administered in combination with cilastatin, a renal dipeptidase inhibitor. Carbapenems and Aztreonam 
    • Meropenem Meropenem A thienamycin derivative antibacterial agent that is more stable to renal dehydropeptidase I than imipenem, but does not need to be given with an enzyme inhibitor such as cilastatin. It is used in the treatment of bacterial infections, including infections in immunocompromised patients. Carbapenems and Aztreonam 
    • Aztreonam Aztreonam The carbapenems and aztreonam are both members of the bactericidal beta-lactam family of antibiotics (similar to penicillins). They work by preventing bacteria from producing their cell wall, ultimately leading to bacterial cell death. Carbapenems and Aztreonam 
  • 2nd agent choices:
    • Levofloxacin Levofloxacin The l-isomer of ofloxacin. Fluoroquinolones
    • Ciprofloxacin Ciprofloxacin A broad-spectrum antimicrobial carboxyfluoroquinoline. Fluoroquinolones
    • Aztreonam Aztreonam The carbapenems and aztreonam are both members of the bactericidal beta-lactam family of antibiotics (similar to penicillins). They work by preventing bacteria from producing their cell wall, ultimately leading to bacterial cell death. Carbapenems and Aztreonam (if not the 1st choice)
    • Amikacin
    • Gentamicin Gentamicin Aminoglycosides
    • Tobramycin
• S. aureus S. aureus Potentially pathogenic bacteria found in nasal membranes, skin, hair follicles, and perineum of warm-blooded animals. They may cause a wide range of infections and intoxications. Staphylococcus coverage options:
  • MRSA MRSA A strain of Staphylococcus aureus that is non-susceptible to the action of methicillin. The mechanism of resistance usually involves modification of normal or the presence of acquired penicillin binding proteins. Staphylococcus:
    • Vancomycin Vancomycin Antibacterial obtained from streptomyces orientalis. It is a glycopeptide related to ristocetin that inhibits bacterial cell wall assembly and is toxic to kidneys and the inner ear. Glycopeptides
    • Linezolid Linezolid An oxazolidinone and acetamide derived anti-bacterial agent and protein synthesis inhibitor that is used in the treatment of gram-positive bacterial infections of the skin and respiratory tract. Oxazolidinones
    • Telavancin Telavancin Lipopeptides and Lipoglycopeptides is an alternative if neither of the above can be used.
  • MSSA (choice of medication used should have anti-pseudomonal activity as well):
    • Piperacillin Piperacillin Semisynthetic, broad-spectrum, ampicillin derived ureidopenicillin antibiotic proposed for pseudomonas infections. It is also used in combination with other antibiotics. Penicillins– tazobactam Tazobactam A penicillanic acid and sulfone derivative and potent beta-lactamase inhibitor that enhances the activity of other anti-bacterial agents against beta-lactamase producing bacteria. Cephalosporins
    • Cefepime Cefepime A fourth-generation cephalosporin antibacterial agent that is used in the treatment of infections, including those of the abdomen, urinary tract, respiratory tract, and skin. It is effective against pseudomonas aeruginosa and may also be used in the empiric treatment of febrile neutropenia. Cephalosporins
    • Levofloxacin Levofloxacin The l-isomer of ofloxacin. Fluoroquinolones
    • Imipenem Imipenem Semisynthetic thienamycin that has a wide spectrum of antibacterial activity against gram-negative and gram-positive aerobic and anaerobic bacteria, including many multiresistant strains. It is stable to beta-lactamases. Clinical studies have demonstrated high efficacy in the treatment of infections of various body systems. Its effectiveness is enhanced when it is administered in combination with cilastatin, a renal dipeptidase inhibitor. Carbapenems and Aztreonam
    • Meropenem Meropenem A thienamycin derivative antibacterial agent that is more stable to renal dehydropeptidase I than imipenem, but does not need to be given with an enzyme inhibitor such as cilastatin. It is used in the treatment of bacterial infections, including infections in immunocompromised patients. Carbapenems and Aztreonam
• Inhaled antibiotics:^[8]
  • May be considered for VAP associated with gram-negative bacilli Bacilli Shigella susceptible only to aminoglycosides Aminoglycosides Aminoglycosides are a class of antibiotics including gentamicin, tobramycin, amikacin, neomycin, plazomicin, and streptomycin. The class binds the 30S ribosomal subunit to inhibit bacterial protein synthesis. Unlike other medications with a similar mechanism of action, aminoglycosides are bactericidal. Aminoglycosides or polymyxins
  • Should be used in combination with systemic antibiotics

Deescalation and duration:^{[1,3,8,18,19]}

• Response is usually noted within 72 hours.
• Narrow antibiotic therapy when the causative pathogen and susceptibilities are known.
• Typical duration of therapy: 7 days (affected by the rate of improvement)

Consultations:^[18]

• May be indicated if:
  • Patient does not improve as expected
  • MDR bacteria Bacteria Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases. Bacteriology
• Specialties to consider:
  • Infectious disease
  • Pulmonology/critical care

HAP/VAP management checklist

• Suspicion of HAP ( pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia acquired 48 hours after hospitalization Hospitalization The confinement of a patient in a hospital. Delirium)/VAP ( pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia acquired 48 hours after endotracheal intubation Intubation Peritonsillar Abscess):
  • Laboratory tests as indicated, including cultures
  • Chest imaging (chest X-ray X-ray Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard x-rays are the higher energy, shorter wavelength x-rays. Soft x-rays or grenz rays are less energetic and longer in wavelength. The short wavelength end of the x-ray spectrum overlaps the gamma rays wavelength range. The distinction between gamma rays and x-rays is based on their radiation source. Pulmonary Function Tests/chest CT)
• Assess severity of illness (risk of mortality Mortality All deaths reported in a given population. Measures of Health Status):
  • Shock Shock Shock is a life-threatening condition associated with impaired circulation that results in tissue hypoxia. The different types of shock are based on the underlying cause: distributive (↑ cardiac output (CO), ↓ systemic vascular resistance (SVR)), cardiogenic (↓ CO, ↑ SVR), hypovolemic (↓ CO, ↑ SVR), obstructive (↓ CO), and mixed. Types of Shock or requiring mechanical ventilation Ventilation The total volume of gas inspired or expired per unit of time, usually measured in liters per minute. Ventilation: Mechanics of Breathing (in HAP) → add 2 antipseudomonal antimicrobial agents + MRSA MRSA A strain of Staphylococcus aureus that is non-susceptible to the action of methicillin. The mechanism of resistance usually involves modification of normal or the presence of acquired penicillin binding proteins. Staphylococcus coverage
  • Does not meet criteria above → proceed with further risk evaluation
• Assess risk for MDR pathogens:
  • HAP/VAP with risk factors for both MRSA MRSA A strain of Staphylococcus aureus that is non-susceptible to the action of methicillin. The mechanism of resistance usually involves modification of normal or the presence of acquired penicillin binding proteins. Staphylococcus and P. aeruginosa P. aeruginosa A species of gram-negative, aerobic, rod-shaped bacteria commonly isolated from clinical specimens (wound, burn, and urinary tract infections). It is also found widely distributed in soil and water. P. Aeruginosa is a major agent of nosocomial infection. Pseudomonas → add 2 antipseudomonal antimicrobial agents + MRSA MRSA A strain of Staphylococcus aureus that is non-susceptible to the action of methicillin. The mechanism of resistance usually involves modification of normal or the presence of acquired penicillin binding proteins. Staphylococcus coverage
  • HAP/VAP with risk factors for MRSA MRSA A strain of Staphylococcus aureus that is non-susceptible to the action of methicillin. The mechanism of resistance usually involves modification of normal or the presence of acquired penicillin binding proteins. Staphylococcus only →  add single agent with antipseudomonal activity + MRSA MRSA A strain of Staphylococcus aureus that is non-susceptible to the action of methicillin. The mechanism of resistance usually involves modification of normal or the presence of acquired penicillin binding proteins. Staphylococcus coverage 
  • HAP/VAP with risk factors for P. aeruginosa P. aeruginosa A species of gram-negative, aerobic, rod-shaped bacteria commonly isolated from clinical specimens (wound, burn, and urinary tract infections). It is also found widely distributed in soil and water. P. Aeruginosa is a major agent of nosocomial infection. Pseudomonas only → add 2 antipseudomonal antimicrobial agents
  • No MDR risk factors → add single agent with MSSA and antipseudomonal activity
• Follow-up culture results and de-escalate antibiotics when indicated

Complications and prognosis Prognosis A prediction of the probable outcome of a disease based on a individual’s condition and the usual course of the disease as seen in similar situations. Non-Hodgkin Lymphomas^[13,19]

• Complications:
  • Seen in about 50% of cases of HAP
  • More common in cases admitted to the ICU ICU Hospital units providing continuous surveillance and care to acutely ill patients. West Nile Virus
  • Includes shock Shock Shock is a life-threatening condition associated with impaired circulation that results in tissue hypoxia. The different types of shock are based on the underlying cause: distributive (↑ cardiac output (CO), ↓ systemic vascular resistance (SVR)), cardiogenic (↓ CO, ↑ SVR), hypovolemic (↓ CO, ↑ SVR), obstructive (↓ CO), and mixed. Types of Shock, respiratory and multiorgan failure, complicated pleural effusion Pleural Effusion Pleural effusion refers to the accumulation of fluid between the layers of the parietal and visceral pleura. Common causes of this condition include infection, malignancy, autoimmune disorders, or volume overload. Clinical manifestations include chest pain, cough, and dyspnea. Pleural Effusion, empyema Empyema Presence of pus in a hollow organ or body cavity. Pneumonia
• VAP mortality Mortality All deaths reported in a given population. Measures of Health Status rate: 20–50%
• Among the factors that are associated with increased mortality Mortality All deaths reported in a given population. Measures of Health Status:
  • Severe underlying conditions
  • Bacteremia Bacteremia The presence of viable bacteria circulating in the blood. Fever, chills, tachycardia, and tachypnea are common acute manifestations of bacteremia. The majority of cases are seen in already hospitalized patients, most of whom have underlying diseases or procedures which render their bloodstreams susceptible to invasion. Glycopeptides
  • Complications ( sepsis Sepsis Systemic inflammatory response syndrome with a proven or suspected infectious etiology. When sepsis is associated with organ dysfunction distant from the site of infection, it is called severe sepsis. When sepsis is accompanied by hypotension despite adequate fluid infusion, it is called septic shock. Sepsis and Septic Shock, respiratory failure Respiratory failure Respiratory failure is a syndrome that develops when the respiratory system is unable to maintain oxygenation and/or ventilation. Respiratory failure may be acute or chronic and is classified as hypoxemic, hypercapnic, or a combination of the two. Respiratory Failure, ARDS among others)
  • Rapidly progressive infiltrates
  • Delay in the initiation of antibiotics

Prevention^[1,2]

• Consistent infection-control measures and handwashing
• Appropriate use of noninvasive ventilation Ventilation The total volume of gas inspired or expired per unit of time, usually measured in liters per minute. Ventilation: Mechanics of Breathing
• Avoid unnecessary intubation Intubation Peritonsillar Abscess and reintubation 
• Minimize duration of intubation Intubation Peritonsillar Abscess
• If prolonged mechanical ventilation Ventilation The total volume of gas inspired or expired per unit of time, usually measured in liters per minute. Ventilation: Mechanics of Breathing required, consider early tracheostomy Tracheostomy Surgical formation of an opening into the trachea through the neck, or the opening so created. Laryngomalacia and Tracheomalacia
• Minimize sedation and encourage daily spontaneous awakening trials
• Judicious use of antibiotics
• Head elevation (30°–45°)
• Endotracheal tubes with special cuffs that reduce microaspiration
• Reducing transportation outside the ICU ICU Hospital units providing continuous surveillance and care to acutely ill patients. West Nile Virus
• Tight glycemic control
• Provide oral care:
  • Toothbrushing recommended
  • Chlorhexidine is not recommended.

Differential Diagnosis

• Pulmonary edema Pulmonary edema Pulmonary edema is a condition caused by excess fluid within the lung parenchyma and alveoli as a consequence of a disease process. Based on etiology, pulmonary edema is classified as cardiogenic or noncardiogenic. Patients may present with progressive dyspnea, orthopnea, cough, or respiratory failure. Pulmonary Edema: individuals with heart failure Heart Failure A heterogeneous condition in which the heart is unable to pump out sufficient blood to meet the metabolic need of the body. Heart failure can be caused by structural defects, functional abnormalities (ventricular dysfunction), or a sudden overload beyond its capacity. Chronic heart failure is more common than acute heart failure which results from sudden insult to cardiac function, such as myocardial infarction. Total Anomalous Pulmonary Venous Return (TAPVR) can develop exacerbation in the setting of an illness requiring hospitalization Hospitalization The confinement of a patient in a hospital. Delirium. Generally, individuals would have orthopnea Orthopnea Pulmonary Edema and peripheral edema Peripheral edema Peripheral edema is the swelling of the lower extremities, namely, legs, feet, and ankles. Edema. A transthoracic echocardiogram Transthoracic echocardiogram Endocarditis would show a reduced ejection fraction Ejection fraction Cardiac Cycle, and symptoms would improve with IV diuretics Diuretics Agents that promote the excretion of urine through their effects on kidney function. Heart Failure and Angina Medication.
• Pulmonary embolism Pulmonary Embolism Pulmonary embolism (PE) is a potentially fatal condition that occurs as a result of intraluminal obstruction of the main pulmonary artery or its branches. The causative factors include thrombi, air, amniotic fluid, and fat. In PE, gas exchange is impaired due to the decreased return of deoxygenated blood to the lungs. Pulmonary Embolism: presents with shortness of breath Shortness of breath Dyspnea is the subjective sensation of breathing discomfort. Dyspnea is a normal manifestation of heavy physical or psychological exertion, but also may be caused by underlying conditions (both pulmonary and extrapulmonary). Dyspnea with/without chest pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways. In severe cases, shock Shock Shock is a life-threatening condition associated with impaired circulation that results in tissue hypoxia. The different types of shock are based on the underlying cause: distributive (↑ cardiac output (CO), ↓ systemic vascular resistance (SVR)), cardiogenic (↓ CO, ↑ SVR), hypovolemic (↓ CO, ↑ SVR), obstructive (↓ CO), and mixed. Types of Shock is present. Examination shows desaturation and may also reveal a unilateral leg Leg The lower leg, or just “leg” in anatomical terms, is the part of the lower limb between the knee and the ankle joint. The bony structure is composed of the tibia and fibula bones, and the muscles of the leg are grouped into the anterior, lateral, and posterior compartments by extensions of fascia. Leg: Anatomy swelling Swelling Inflammation. This condition is rarely associated with infiltrates on imaging. Pulmonary CT angiogram CT angiogram A non-invasive method that uses a ct scanner for capturing images of blood vessels and tissues. A contrast material is injected, which helps produce detailed images that aid in diagnosing vascular diseases. Pulmonary Function Tests will reveal a filling defect in the pulmonary vasculature.
• Acute respiratory distress syndrome Acute Respiratory Distress Syndrome Acute respiratory distress syndrome is characterized by the sudden onset of hypoxemia and bilateral pulmonary edema without cardiac failure. Sepsis is the most common cause of ARDS. The underlying mechanism and histologic correlate is diffuse alveolar damage (DAD). Acute Respiratory Distress Syndrome (ARDS) (ARDS): closely related to pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia, as lung infection Lung infection Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia is the most common condition leading to ARDS. While pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia is due to parenchymal infection, ARDS results from lung injury, triggering an inflammatory response and leading to diffuse alveolar damage. Symptoms occur within a week of the insult, with bilateral opacities seen on chest imaging. Oxygenation is impaired and respiratory failure Respiratory failure Respiratory failure is a syndrome that develops when the respiratory system is unable to maintain oxygenation and/or ventilation. Respiratory failure may be acute or chronic and is classified as hypoxemic, hypercapnic, or a combination of the two. Respiratory Failure is noncardiogenic. Aside from pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia, ARDS has multiple etiologies including sepsis Sepsis Systemic inflammatory response syndrome with a proven or suspected infectious etiology. When sepsis is associated with organ dysfunction distant from the site of infection, it is called severe sepsis. When sepsis is accompanied by hypotension despite adequate fluid infusion, it is called septic shock. Sepsis and Septic Shock, smoke inhalation Smoke Inhalation Carbon Monoxide Poisoning and trauma.