Aspiration Pneumonia

7 Interesting Facts of Aspiration Pneumonia 

1. Aspiration pneumonia is pulmonary parenchymal infection caused by aspiration of oropharyngeal or upper gastrointestinal (via reflux or regurgitation) contents, along with microorganisms from the oral cavity or nasopharynx
2. Typically presents with cough, purulent sputum, dyspnea, and fever; however, symptoms may be minimal in elderly patients
3. Consider diagnosis in patients with conditions that predispose to aspiration (eg, dysphagia, reduced consciousness, upper gastrointestinal tract disorders) and in patients with radiographic infiltrate in a dependent lung segment
4. Initiate treatment promptly, choosing initial empiric antibiotic therapy based on the site (eg, community versus hospital) and likely pathogen
5. Recent guidelines identify specific risk factors for MRSA and Pseudomonas aeruginosa; the most significant are previous recovery of these organisms from respiratory secretions and hospitalization and IV antibiotics within 90 days; other locally validated risk factors may exist 
6. Evaluate for swallow dysfunction and aspiration risk; institute preventive measures such as modified diet, postural adjustments, and oral hygiene
7. Prognosis is influenced by underlying condition that predisposed patient to develop aspiration pneumonia

Pitfalls

• Aspiration may be silent (not associated with coughing while eating or drinking); evaluate elderly patients and those with neurologic disorders for swallow dysfunction
• Signs and symptoms of aspiration pneumonia may be minimal in elderly patients; mental status changes are often the first manifestation of pneumonia

• Aspiration pneumonia is pulmonary parenchymal infection caused by aspiration of oropharyngeal or upper gastrointestinal contents (via reflux or regurgitation), along with microorganisms from the oral cavity or nasopharynx 
  • Aspiration may be overt or “silent” 
  • Aspiration does not necessarily result in aspiration pneumonia 

Classification

• By setting:
  • Community-acquired
    • Pneumonia acquired outside hospital setting 
  • Hospital-acquired (nosocomial)
    • Pneumonia not incubating at time of hospital admission and occurring 48 hours or more after admission
  • 2019 Infectious Diseases Society of America and American Thoracic Society joint guidelines recommend abandoning categorization of “health care–associated” or “medical care–associated” pneumonia 
    • This category was based on the premise that patients who received extensive outpatient medical services (eg, hemodialysis, wound care) were at risk for infection to nosocomial-type pathogens; this conclusion has not been supported by evolving evidence

Clinical Presentation

History 

• Onset is often indolent
• Older adults and immunocompromised patients may have fewer or milder symptoms
• Condition predisposing to aspiration is usually present (eg, stroke, dementia, dysphagia)
• Fever
• Productive cough with purulent sputum, which may be malodorous
• Dyspnea
• Pleuritic chest pain
• Myalgia or malaise
• Mental status changes (often the first sign of pneumonia in elderly patients)
• May have a history of coughing while eating or drinking (suggestive of aspiration, but more often aspiration is silent)

Physical examination

• General findings
  • Hypotension (may be present in severe pneumonia)
  • Fever
  • Cyanosis, if patient is hypoxemic
  • Tachypnea
  • Tachycardia, with fever and severe disease
  • Altered mental status, especially in elderly patients
  • Periodontal disease may be present
• Auscultation findings
  • Localized dullness to percussion
  • Bronchial breath sounds or rales
  • Egophony
  • Whispered pectoriloquy

Causes

• Aspiration of colonized oropharyngeal contents into the lungs, usually in the presence of impaired mechanical, humoral, or cellular defense mechanisms 
• Causative bacteria
  • Pathogens vary according to setting (eg, community, long-term care facility, hospital)
    • Streptococcus pneumoniae
    • Staphylococcus aureus
      • MRSA (particularly in patients who are or have been hospitalized and have received parenteral antibiotics within the last 90 days) 
    • Haemophilus influenzae
    • Enterobacteriaceae
    • Pseudomonas aeruginosa (particularly in patients who are or have been hospitalized and have received parenteral antibiotics within the last 90 days) 
    • Anaerobic organisms (eg, Peptostreptococcus, Fusobacterium, Prevotella, Bacteroides) are less common than in previous years 
  • Infection may be polymicrobial

Risk factors and/or associations

Age

• Highest risk for those older than 60 years, particularly frail older adults, owing to increased prevalence of predisposing factors in this population 

Sex

• More common in males 

Genetics

• ACE DD phenotype (angiotensin I–converting enzyme deletion/deletion) may confer a greater risk for developing aspiration pneumonia 

Other risk factors/associations

• Most commonly occurs in patients with chronically impaired airway defense mechanisms (eg, diminished gag reflex, decreased mucociliary clearance, decreased immune function)
  • Conditions causing disordered swallowing
    • Esophageal dysfunction
      • Dysphagia
      • Esophageal strictures, neoplasia, or diverticula
      • Tracheoesophageal fistula
      • Gastroesophageal reflux disease
    • Neurologic disorders
      • Dementia
      • Stroke
      • Poststroke
      • Multiple sclerosis
      • Parkinson disease
      • Myasthenia gravis
    • Advanced age 
  • Conditions causing altered level of consciousness or gag reflex dysfunction
    • Substance use disorder or overdose
    • Head trauma or intracranial mass
    • Stroke
    • Dementia
    • Seizure
    • General anesthesia or sedation
• Poor oral hygiene 
• Diabetes mellitus 
• Malnutrition 
• Mechanical medical procedures
  • Endotracheal intubation
  • Nasogastric tube
  • Bronchoscopy
  • Tracheostomy
  • Gastrostomy or postpyloric feeding tubes
• Medications
  • Antipsychotic drugs 
  • Proton pump inhibitors 

Diagnostic Procedures

Primary diagnostic tools

• Suspect diagnosis in patients with risk factors for aspiration (or less commonly, a witnessed aspiration event) and symptoms or signs of pneumonia; however, remember that clinical features may be absent or altered in elderly patients 
• Initial work-up and management is not specific to aspiration, but follows guidelines for pneumonia based on setting in which it occurred (hospital or community); subsequent efforts to document aspiration may be indicated if mechanism is in doubt
• Assess oxygen saturation with pulse oximetry in all patients in whom pneumonia is suspected 
• Obtain a chest radiograph in all patients in whom pneumonia is suspected (aspiration or otherwise) 
• Obtain additional diagnostic testing to identify causative agents as indicated by severity, setting, and risk factors for antibiotic-resistant pathogens 
  • Sputum Gram stain/culture and blood cultures are recommended in all patients with hospital-acquired disease 
  • Sputum Gram stain/culture and blood cultures are optional in community-acquired disease but are recommended for patients with:
    • Severe pneumonia
    • Risk factors for MRSA and/or Pseudomonas aeruginosa
      • Previous infection due to either organism
      • Hospitalization and parenteral antibiotic treatment (whether during hospitalization or not) within past 90 days
    • Other clinical presentations at the discretion of the clinician, including: 
      • Failed outpatient treatment
      • Pleural effusion and/or cavitary infiltrate
      • Specific comorbidities (eg, alcohol use disorder, liver disease, chronic lung disease, leukopenia, asplenia, other immunocompromised state)
  • Appropriate method of obtaining respiratory specimens for culture depends on clinical circumstances
    • Noninvasive methods of sampling (eg, expectorated sputum, nasotracheal suctioning, endotracheal aspiration) are preferred over invasive methods (eg, bronchoscopy) 
    • Thoracentesis may be indicated in patients with significant pleural effusion 
  • Other studies (eg, pneumococcal and legionella urinary antigens, influenza antigen test or nucleic acid amplification) may be appropriate if causes other than aspiration are under consideration 
• Obtain basic metabolic panel and CBC with differential in all patients to aid severity assessment (eg, pneumonia severity index and CURB-65 score) and ongoing management

Laboratory

• Sputum Gram stain and culture
  • Gram stain may show WBCs and mixed bacterial flora (different morphologies and staining characteristics) reflecting oropharyngeal origin
  • Cultures usually grow oral flora, but isolation of a specific pathogen may dictate remaining course of treatment 
  • A semi-quantitative assessment of growth is usually provided, but guidelines do not provide interpretive criteria or make recommendations for incorporating this information in management 
• Blood culture
  • Yield in community-acquired infection is low; in hospital cases (especially ventilator-associated), yield is higher, but isolates often come from a nonpulmonary source (eg, central lines, urine) 
• CBC
  • Leukocytosis is suggestive of infection
  • Leukopenia signals impending sepsis and predicts a poor outcome
• Basic metabolic panel
  • Indicated to aid assessment of severity
  • BUN level can be used as a criterion to determine a severity score and guide disposition

Imaging

• Chest radiography
  • Aspiration pneumonia is suggested by presence of infiltrates in dependent area of lung (lower lobes if aspiration occurs in upright position, posterior segment of upper lobes if it occurs in recumbent position) 

Functional testing

• Pulse oximetry
  • Recommended for all patients to determine baseline and need for supplemental oxygen
  • Noninvasive indicator of illness severity and treatment response

Procedures

• Insertion of a flexible fiberoptic bronchoscope to visualize respiratory tract (ie, upper airway, trachea, proximal airways, segmental airways to third generation of branching); instrument has lavage, suction, and biopsy capabilities
• Procedure is performed under anesthesia by otolaryngologist, pulmonologist, or thoracic surgeon
• Obtain specimens of deep respiratory secretions primarily in patients who cannot expectorate sputum or those whose condition has failed to respond to therapy
• Can be used therapeutically to suction large volumes of respiratory secretions or aspirated material
• Absolute
  • Hemodynamic instability
  • Uncontrolled coagulopathy
• Relative
  • Severe pulmonary hypertension
  • Superior vena cava syndrome
• Hypoxia
• Hypotension related to sedation
• Bronchospasm
• Epistaxis
• Vomiting
• Pneumothorax
• Cardiac arrhythmias
• Laryngeal edema, injury, or spasm
• Culture and sensitivity results will inform modification of empiric antibiotic regimen
• Insertion of a small-gauge needle between the ribs, through the thorax, and into the pleural space to access pleural fluid for diagnostic or therapeutic purposes
• Procedure can be performed with or without ultrasonographic guidance
• May be performed diagnostically or therapeutically; specific indications include:
  • Pleural effusions more than 5 cm in height on a lateral view chest radiograph 
  • Enlarging effusion, especially if clinical condition is not improving or is deteriorating on appropriate antibiotic therapy
• No absolute contraindications
• Relative contraindications
  • Uncorrected coagulopathy
  • Small effusion with secure clinical diagnosis
  • Mechanically ventilated patient
  • Perform bilateral thoracentesis only after ensuring absence of pneumothorax in the first side
• Vasovagal events
• Bleeding (eg, hematoma, hemothorax, hemoperitoneum)
• Pneumothorax
• Reexpansion pulmonary edema
• Infection (empyema or soft tissue)
• Spleen or liver puncture
• Retained intrapleural catheter fragments
• Empyema is characterized by low pH, low glucose level, and high WBC count
  • Gram stain and culture may not be positive; when positive, may be polymicrobial in aspiration pneumonia

Differential Diagnosis

Most common

• Chemical pneumonitis (also known as aspiration pneumonitis) 
  • Noninfectious pulmonary inflammatory condition caused by inhalation of sterile gastric contents, usually in large volume in a witnessed or otherwise identifiable event
  • Similarly to bacterial aspiration pneumonia, chemical pneumonitis may initially cause coughing, wheezing, or shortness of breath
  • Some cases present dramatically with gastric material in the oropharynx, wheezing, coughing, cyanosis, pulmonary edema, and hypoxemia, progressing rapidly to acute respiratory distress syndrome 
  • Compared with bacterial aspiration pneumonia, chemical pneumonitis tends to improve more quickly, both clinically and radiographically 
  • Differentiated by history, physical examination, and radiographic findings of diffuse bilateral patchy infiltrates involving nondependent areas
  • In chemical pneumonitis, gastric acid burns may be observed in the tracheobronchial tree during bronchoscopy
• Bronchitis
  • Acute bronchial inflammation, often caused by viral infection
  • Similarly to aspiration pneumonia, may present with fever, malaise, productive cough, hoarseness, and chest pain
  • Differentiated by chest radiography and physical examination
    • No radiographic infiltrate
    • Physical findings of consolidation that are indicative of pneumonia (eg, rales, egophony, fremitus) are absent
• Congestive heart failure
  • Like aspiration pneumonia, presents with cough and dyspnea; however, exertional dyspnea, paroxysmal nocturnal dyspnea, and peripheral edema suggest heart failure
  • Respiratory secretions are not purulent
  • Differentiated by:
    • Radiographic features such as pulmonary venous congestion, interstitial fluid, Kerley B lines, pleural effusion, and cardiomegaly
    • Left ventricular dysfunction on transthoracic echocardiogram
    • Increased serum levels of B-type natriuretic peptide and N-terminal pro–B-type natriuretic peptide levels
• Pulmonary embolism
  • Obstruction of a pulmonary artery by thrombus
  • Patients present with dyspnea and pleuritic chest pain
  • Unlike in pneumonia, patients usually do not have fever (although they may, if there is a large area of pulmonary infarction) or cough productive of purulent sputum
  • Calf tenderness and swelling (usually unilateral) may be present
  • Differentiated by history, physical examination, and imaging
    • Chest CT shows filling defects in the pulmonary arteries, and nuclear medicine scans demonstrate ventilation/perfusion mismatch

Treatment Goals

• Eradicate infection with antibiotics
• Relieve symptoms and ensure adequate oxygenation
• Prevent disease progression and complications
• Mitigate causes of aspiration

Admission criteria

Use illness severity scores in combination with clinical judgment to determine if patient can be safely managed as an outpatient or an inpatient 

• 2019 Infectious Diseases Society of America and American Thoracic Society guidelines recommend the pneumonia severity index preferentially over the CURB-65 score to assess community-acquired pneumonia; these scores have not been validated specifically for aspiration pneumonia
• Most patients with aspiration pneumonia are older adults with comorbid conditions and should be managed as inpatients

Pneumonia severity index 

• Uses a point system of several variables including patient age, vital signs, mental status, and presence of comorbid conditions (eg, neoplastic disease, liver disease, chronic heart failure, cerebrovascular disease, renal disease)
• Classifies patients into a mortality risk level
  • Class I and II patients (fewer than 70 points): may be treated as outpatients
  • Class III patients (71-90 points): treat in an observation unit or briefly hospitalize
  • Class IV (91-130 points) and V (greater than 130 points): treat as inpatients

CURB-65 score 

• Patients receive 1 point for each of the following indicators:
  • Confusion (compared to baseline)
  • BUN level greater than 20 mg/dL
  • Respiratory rate of 30 breaths or more per minute
  • Systolic blood pressure lower than 90 mm Hg or diastolic blood pressure of 60 mm Hg or lower
  • Older than 65 years
• Admission is recommended for patients with a score of 3 or more

Other considerations

• Admit patients with less than 92% oxygen saturation 
• Admit patients who are unable to safely and reliably take medication orally or who have insufficient personal support

Criteria for ICU admission

• Infectious Diseases Society of America and American Thoracic Society recommend ICU admission if either of the major criteria or 3 of 9 minor criteria for severe pneumonia (not specifically aspiration) are met: 
  • Major criteria
    • Respiratory failure requiring invasive mechanical ventilation
    • Septic shock that requires vasopressors
  • Minor criteria
    • Respiratory rate: 30 breaths or more per minute
    • Ratio of arterial oxygen tension to inspired oxygen fraction: 250 or less
    • Multilobar infiltrates
    • Confusion and/or disorientation
    • Uremia (BUN level: 20 mg/dL or higher)
    • Leukopenia (leukocyte count less than 4000 cells/μL)
    • Thrombocytopenia (platelet count less than 100,000 cells/μL)
    • Hypothermia (core temperature less than 36 °C)
    • Hypotension requiring aggressive fluid resuscitation

Recommendations for specialist referral

• Refer to pulmonologist for:
  • Bronchoscopy, if indicated
  • Worsening hypoxemia or overt respiratory failure requiring noninvasive positive pressure ventilation or intubation and mechanical ventilation
  • Pleural effusion requiring chest tube drainage
  • Nonresolving pneumonia (characterized by persistent fever and absence of clinical improvement)
• Refer to infectious disease specialist for assistance with antibiotic management, especially in patients with severe pneumonia or pneumonia unresponsive to empiric antibiotics
• Refer to speech pathologist or gastroenterologist for assessment and management of swallowing dysfunction

Treatment Options

Initiate prompt antibiotic treatment

• For patients admitted to the hospital from the emergency department, ensure first dose of antibiotics is given before patient leaves the emergency department 
• As with nonaspiration acute pneumonia, initial choice of agents is dictated by: location in which the aspiration occurred (community versus hospital); severity of illness and treatment venue (outpatient or inpatient); local antibiogram; and cost, availability, and formulary restrictions. Computerized protocols for initial empiric therapy are available in many hospitals 
  • Because of recent data showing a decline in the role of anaerobes in aspiration pneumonia, 2019 Infectious Diseases Society of America and American Thoracic Society guidelines for community-acquired pneumonia recommend not routinely adding anaerobic coverage for suspected aspiration pneumonia unless lung abscess or empyema is suspected 
  • Review empiric antibiotic therapy when culture and antibiotic susceptibility results are available and modify as indicated 
• Community-acquired aspiration pneumonia
  • Outpatient treatment
    • For patients without significant comorbidities who can be treated as outpatients, either amoxicillin, doxycycline, or a macrolide can be used in single-drug therapy
    • For patients with comorbidities, a respiratory fluoroquinolone or a combination of amoxicillin-clavulanate plus a macrolide are recommended
    • Infectious Diseases Society of America and American Thoracic Society guidelines suggest that patients with recent exposure to 1 of these antibiotic classes should be treated with the therapeutic option to which they have not been exposed
  • Inpatient treatment
    • For patients without risk factors for MRSA or Pseudomonas aeruginosa
      • Nonsevere pneumonia
        • Monotherapy with an appropriate respiratory fluoroquinolone
        • A β-lactam plus either a macrolide or doxycycline
      • Severe pneumonia
        • A β-lactam plus a macrolide
        • A β-lactam plus a respiratory fluoroquinolone
      • Suitable respiratory fluoroquinolones include levofloxacin or moxifloxacin
      • Appropriate β-lactams include ampicillin-sulbactam, cefotaxime, ceftriaxone, or ceftaroline
      • Macrolide options include azithromycin or clarithromycin
    • For patients with risk factors for MRSA or Pseudomonas aeruginosa
      • 2019 Infectious Diseases Society of America and American Thoracic Society guidelines recommend empiric coverage for MRSA or Pseudomonas aeruginosa only in the following situations:
        • Patients with history of MRSA or Pseudomonas recovered from respiratory specimens
          • Strongest risk factor for etiologic role of these organisms in current infection
        • Locally validated risk factors (eg, high local prevalence) for either pathogen are present and patient has a history of hospitalization and parenteral antibiotics within the previous 90 days
          • For patients with severe pneumonia, administer empiric coverage for MRSA and Pseudomonas aeruginosa
        • Infectious Diseases Society of America and American Thoracic Society guidelines do not recommend empiric coverage (pending culture results) for these organisms based on other individual risk factors or in patients with nonsevere pneumonia
      • Empiric treatment options for MRSA include vancomycin or linezolid
      • Empiric treatment options for Pseudomonas aeruginosa include piperacillin-tazobactam, cefepime, ceftazidime, aztreonam, meropenem, or imipenem
• Hospital-acquired aspiration pneumonia 
  • All patients with pneumonia acquired in the hospital (eg, aspiration, ventilator-associated, or otherwise) should be treated empirically for Pseudomonas aeruginosa and other resistant gram-negative bacilli
  • Patients with any of the following should receive coverage for MRSA with vancomycin or linezolid:
    • Prior IV antibiotics within the past 90 days
    • Hospitalization in a unit where more than 20% of Staphylococcus aureus isolates are methicillin-resistant or where MRSA prevalence is unknown
    • High risk for mortality (eg, septic shock, respiratory failure requiring mechanical ventilation)
  • Patients with either of the following should receive dual antipseudomonal coverage with agents from different drug classes:
    • Prior IV antibiotics within the past 90 days
    • Structural lung disease (eg, cystic fibrosis, bronchiectasis)
  • If patient has no risk factors for MRSA, is not at high risk for mortality, and does not have structural lung disease (eg, bronchiectasis, cystic fibrosis), use 1 of the following:
    • Piperacillin-tazobactam
    • Cefepime
    • Levofloxacin
    • Imipenem
    • Meropenem
  • If patient is not at high risk of mortality but has risk factors for MRSA infection, give 1 of the following plus either vancomycin or linezolid:
    • Piperacillin-tazobactam
    • Cefepime or ceftazidime
    • Ciprofloxacin or levofloxacin
    • Imipenem or meropenem
    • Aztreonam
  • If patient has received IV antibiotics within 90 days and/or has high risk for mortality (eg, septic shock, requiring ventilatory support), give 2 of the following (but avoid using 2 β-lactams) plus either vancomycin or linezolid:
    • Piperacillin-tazobactam
    • Cefepime or ceftazidime
    • Ciprofloxacin or levofloxacin
    • Imipenem or meropenem
    • Amikacin, gentamicin, or tobramycin
    • Aztreonam
  • If patient does not have risk factors for MRSA, ensure coverage against methicillin-sensitive Staphylococcus aureus; appropriate choices from among the agents otherwise recommended include:
    • Piperacillin-tazobactam
    • Cefepime
    • Levofloxacin
    • Imipenem
    • Meropenem
• Continue antibiotic therapy for a minimum of 5 days (usually 7-10 days); patient should be afebrile and clinically stable before discontinuing therapy
  • Treatment can be switched from IV to oral route once hemodynamic stability and clinical improvement are seen
• Reevaluate patients whose condition fails to respond to appropriate antibiotics; seek out the presence of an unrecognized pulmonary pathogen, a complicating factor (eg, empyema, endobronchial obstruction), infection at another site, or a noninfectious cause
  • Empyema and parapneumonic effusions may contribute to treatment nonresponse and may require drainage (thoracentesis or tube thoracostomy) 

Provide oxygen supplementation, ventilatory assistance, IV fluids, nutritional support, and physical therapy as needed

• Consider venous thromboembolism prophylaxis if patient is confined to bed

It is important to evaluate for swallow dysfunction and aspiration risk, and initiate appropriate management

Drug therapy

• Penicillin antibiotics plus β-lactamase inhibitors
  • Ampicillin-sulbactam
    • Ampicillin Sodium, Sulbactam Sodium Solution for injection; Adults: 1.5 g (1 g ampicillin and 0.5 g sulbactam) or 3 g (2 g ampicillin and 1 g sulbactam) IV every 6 hours for at least 5 days.
  • Piperacillin-tazobactam
    • Piperacillin Sodium, Tazobactam Sodium Solution for injection; Adults: 4.5 g (4 g piperacillin and 0.5 g tazobactam) IV every 6 hours for at least 7 days.
• Cephalosporins
  • Ceftriaxone
    • Ceftriaxone Sodium Solution for injection; Adults: 1 to 2 g IV every 24 hours for at least 5 days.
  • Cefepime
    • Cefepime Hydrochloride Solution for injection; Adults: 2 g IV every 8 hours for at least 7 days.
  • Ceftazidime
    • Ceftazidime Sodium Solution for injection; Adults: 2 g IV every 8 hours for at least 7 days.
  • Ceftaroline
    • Ceftaroline fosamil Solution for injection; Adults: 600 mg IV every 12 hours for at least 5 days.
• Carbapenem antibiotics
  • Ertapenem
    • Ertapenem Solution for injection; Adults: 1 g IV/IM once daily for 10 to 14 days.
      • Consider transitioning to an appropriate oral therapy after at least 3 days of parenteral therapy, once clinical improvement has been demonstrated
  • Imipenem
    • Imipenem, Cilastatin Sodium Solution for injection; Adults: 500 mg IV every 6 hours for at least 7 days.
  • Meropenem
    • Meropenem Solution for injection; Adults: 1 g IV every 8 hours for at least 7 days.
• Monobactam
  • Aztreonam
    • Aztreonam Solution for injection; Adults: 2 g IV every 8 hours for at least 7 days.
• Fluoroquinolones
  • Levofloxacin
    • Levofloxacin Solution for injection; Adults: 750 mg IV every 24 hours for at least 5 days.
  • Ciprofloxacin
    • Ciprofloxacin Solution for injection; Adults: 400 mg IV every 8 to 12 hours for at least 5 days.
  • Moxifloxacin
    • Moxifloxacin Hydrochloride Oral tablet; Adults: 400 mg PO once daily for at least 5 days.
• Macrolide
  • Azithromycin
    • Azithromycin Solution for injection; Adults: 500 mg IV once daily for at least 5 days.
  • Erythromycin
    • Erythromycin Lactobionate Solution for injection; Adults: 15 to 20 mg/kg/day IV divided every 6 hours (Max: 4 g/day).
• Aminoglycoside (conventional dosing)
  • Gentamicin
    • Gentamicin Sulfate Solution for injection; Adults: 3 mg/kg/day IV/IM divided every 8 hours; doses up to 5 mg/kg/day IV/IM divided every 6 to 8 hours may be required in life-threatening infections.
  • Tobramycin
    • Tobramycin Sulfate Solution for injection; Adults: 3 mg/kg/day IV/IM divided every 8 hours; doses up to 5 mg/kg/day IV/IM divided every 6 to 8 hours may be required in life-threatening infections.
  • Amikacin
    • Amikacin Sulfate Solution for injection; Adults: 15 mg/kg/day IV/IM divided every 8 to 12 hours (Max: 1.5 g/day).
• Glycopeptide antibiotic
  • Vancomycin
    • Vancomycin Hydrochloride Solution for injection; Adults: 20 to 35 mg/kg/dose (Max: 3,000 mg/dose) IV loading dose, followed by 15 to 20 mg/kg/dose IV every 8 to 12 hours; adjust dose based on target PK/PD parameter. Consider loading dose in critically ill patients.
• Oxazolidinone
  • Linezolid
    • Linezolid Solution for injection; Adults: 600 mg IV every 12 hours for at least 7 days.
• Tetracyclines
  • Doxycycline
    • Doxycycline Hyclate Solution for injection; Adults: 100 mg IV every 12 hours for at least 5 days.

Nondrug and supportive care

Supplemental oxygen or mechanical ventilation 

• May be required in patients with severe pneumonia or underlying cardiopulmonary disease

Breathing exercises

• Strengthen chest wall muscles; particularly beneficial to sedentary patients
• Help patients mobilize secretions to improve expectoration

Respiratory therapy

• Postural drainage facilitated by chest percussion may be helpful in patients who have difficulty mobilizing respiratory secretions

Dysphagia management 

• Provide appropriate food consistency based on ability to swallow (eg, thickened liquids, modified diets)
• Teach swallow maneuvers and postural adjustments to be used during eating (eg, hard swallow, chin-down technique)
• Provide nonoral feeding if needed

Procedures

Tube thoracostomy

General explanation

• Surgical insertion of a tube into the pleural cavity to remove pus or effusion and relieve dyspnea

Indication 

• Parapneumonic pleural effusion
• Pleural fluid drainage by chest tube is recommended for patients with empyema or complicated parapneumonic effusion

Contraindications

• No absolute contraindications
• Relative contraindications
  • Uncorrected coagulopathy
  • Small effusion with secure clinical diagnosis
  • Mechanically ventilated patients
  • Perform bilateral thoracentesis only after ensuring absence of pneumothorax in the first side

Complications

• Bleeding (eg, hematoma, hemothorax, hemoperitoneum)
• Pneumothorax
• Reexpansion pulmonary edema
• Infection (empyema or soft tissue infection)
• Spleen or liver puncture
• Vasovagal events
• Retained intrapleural catheter fragments

Monitoring

• 2019 Infectious Diseases Society of America and American Thoracic Society guidelines recommend against routinely obtaining follow-up chest imaging in adults with community-acquired pneumonia (aspiration or otherwise) whose symptoms have resolved within 5 to 7 days 

Complications

• Pulmonary complications 
  • Acute respiratory distress syndrome
  • Necrotizing pneumonia
  • Lung abscess
  • Pneumothorax
  • Pleural effusions or empyema
  • Bronchopleural fistula
• Systemic complications
  • Systemic inflammatory response syndrome or sepsis
  • Septic shock
  • Cardiac or respiratory arrest
  • Coma
  • Weight loss and malnutrition

Prognosis

• Prognosis is influenced by underlying condition that predisposed patient to develop aspiration pneumonia
• Factors that worsen prognosis include incorrect or delayed diagnosis, comorbidities, inappropriate medication dose or route of administration, presence of an unusual or unanticipated pathogen, adverse drug reactions, and complications
• Recurrence is common in high-risk populations (eg, elderly, neurologically impaired) in whom some risk factors may not be reversible

Screening and Prevention

Prevention

• Evaluation for swallow dysfunction and aspiration is recommended in patients with neurologic diseases or other disorders that predispose to aspiration and in patients who choke or cough while eating or drinking 
• Address swallow dysfunction
  • Institute compensatory techniques for patients with dysphagia
    • Provide appropriate food consistency based on ability to swallow (eg, thickened liquids, modified diets)
    • Teach swallow maneuvers and postural adjustments to be used during eating (eg, hard swallow, chin-down technique)
    • Provide nonoral feeding if needed
      • Percutaneous gastrostomy tubes and nasogastric tubes allow more efficient delivery of nutrition in patients with dysphagia, but they have not been shown to reduce incidence of aspiration pneumonia 
      • In patients who receive enteral tube feeding, postpyloric position may reduce the risk of pneumonia by up to 30% compared to gastric placement 
  • Avoid medications and substances that cause or worsen dysphagia or xerostomia
  • Limit use of sedatives and paralytic agents that suppress gag reflex and effective cough 
• Reduce aspiration risk
  • Elevate head of bed to an angle of 30° to 45° for high-risk patients
  • Avoid flat positions, especially after meals, in debilitated elderly patients
  • In patients undergoing general anesthesia for a planned procedure, limit oral intake in advance 
• Treat underlying gastroesophageal reflux disease, gastroparesis, ileus, or protracted vomiting
• Maintain good oral care
  • Address dental hygiene issues
  • Consider chlorhexidine gluconate oral rinse
    • Reduces oropharyngeal colonization and risk for pneumonia in some populations studied; however, it is not proven to reduce incidence of aspiration pneumonia in high-risk nursing home residents
• Select appropriate method of respiratory support for patients who require supplementation or ventilation
  • Consider alternative methods of respiratory support, such as noninvasive positive pressure ventilation (using a face mask), an alternative to intubation and mechanical ventilation 
  • For patients requiring short- or long-term mechanical ventilation: 
    • Orotracheal intubation is preferred over nasotracheal
    • Prevent aspiration of oropharyngeal bacteria
      • Maintain endotracheal cuff pressure at more than 20 cm H₂O
      • Suctioning subglottal secretions (continuously or intermittently) decreases the incidence of ventilator-associated pneumonia by preemptively removing the source of infection
      • Unless contraindicated, place intubated patients in a semi-Fowler position, especially during feedings and flushes
    • Limit mechanical ventilation to shortest time possible
      • Weaning protocols and daily trials of reduced sedation shorten duration
• While not specific to prevention of aspiration, the following preventive measures are generally appropriate:
  • Recommend pneumococcal and influenza immunization for selected patients 
    • Pneumococcal vaccine for persons aged 65 years and older or those aged 19 to 64 years with certain underlying conditions or other risk factors, as described in Advisory Committee on Immunization Practices recommendations 
    • Annual influenza vaccination for patients aged 50 years or older and those at risk of influenza complications
  • Recommend smoking cessation if applicable 

References

Metlay JP et al: Diagnosis and treatment of adults with community-acquired pneumonia. An official clinical practice guideline of the American Thoracic Society and Infectious Diseases Society of America. Am J Respir Crit Care Med. 200(7):e45-67, 2019