Aspiration pneumonia

Contents of this page: Illustrations Alternative names Definition Causes, incidence, and risk

factors Symptoms

Signs and tests

Treatment Expectations (prognosis) Complications Calling your health care

provider

Prevention

Illustrations

Pneumococci organism

Bronchoscopy Lungs Respiratory system

Alternative names    Return to top

Anaerobic pneumonia; Aspiration of vomitus; Necrotizing pneumonia

Definition    Return to top

Aspiration pneumonia is an inflammation of the lungs and bronchial tubes caused by inhaling foreign material (usually food, drink, vomit, or secretions from the mouth) into the lungs. This may progress to form a collection of pus in the lungs (lung abscess).

Causes, incidence, and risk factors    Return to top

Aspiration of foreign material (often the stomach contents) into the lung can be a result of disorders that affect normal swallowing, disorders of the esophagus (esophageal stricture, gastroesophageal reflux), or decreased or absent gag reflex in unconscious or semi-conscious individuals. Old age, dental problems, use of sedative drugs, anesthesia, coma, and excessive alcohol consumption are also causal or contributing factors. The response of the lungs depends upon the characteristics and amount of the aspirated substance. The more acidic the material, the greater the degree of lung injury, although this may not necessarily lead to pneumonia.

The injured lungs may become infected with multiple species of anaerobic bacteria or aerobic bacteria. A collection of pus may form in the lung. A protective membrane may form around the abscess.

Symptoms    Return to top

Fever Fatigue Cough:

o With foul-smelling sputum o With sputum containing pus or blood o With greenish sputum

Chest pain Shortness of breath Bluish discoloration of the skin caused by lack of oxygen Rapid pulse (heart rate) Wheezing

Additional symptoms that may be associated with this disease: Sweating, excessive Swallowing difficulty Breath odor

Signs and tests    Return to top

Physical examination may reveal crackling sounds in the lungs.

These tests also help diagnose this condition:

Chest x-ray Sputum culture CBC Blood culture Bronchoscopy Swallowing studies

Treatment    Return to top

Hospitalization may be required for management of the illness. Treatment measures vary depending on the severity of the pneumonia. Antibiotics, which treat the organisms in the environment, may be given. Patients may receive special antibiotics to treat organisms that may live in the mouth.

The types of organisms present depend on the health of the patient and where they live (private residence, chronic nursing facility, for instance).

Patients may need to have their swallowing function assessed. If there is difficulty with proper swallowing, other methods of feeding the patient may be necessary.

Expectations (prognosis)    Return to top

The outcome depends on the severity of the pneumonia, the type of organism, the extent of lung involvement. If acute respiratory failure develops, the patient may have a prolonged illness or die.

Complications    Return to top

Spread of infection to the blood stream (bacteremia) Spread of infection to other areas of the body Low blood pressure Shock Acute respiratory distress syndrome

Pneumonia with lung abscess

Calling your health care provider    Return to top

Call your health care provider, go to the emergency room, or call the local emergency number (such as 911) if shortness of breath, wheezing, chills, fever, or chest pain occur.

Prevention    Return to top

Awareness of the risk of aspiration Avoid behaviors which may lead to aspiration

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Pneumonia, AspirationLast Updated: April 7, 2005

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Synonyms and related keywords: Mendelson syndrome, pneumonitis, altered level of consciousness, abnormal swallowing reflexes, acute respiratory distress syndrome, acute respiratory failure, bacterial pneumonitis, chemical pneumonitis, community-acquired aspiration pneumonia, Staphylococcus aureus, nosocomial infection, empyema, stress dyspnea, rest dyspnea, cyanosis, putrid expectoration, tachypnea, tachycardia, bradycardia, crackles, bronchial rales, pleural effusion, egophony, cerebrovascular accident, intracranial mass lesions, sepsis, meningitis

 AUTHOR INFORMATION

Section 1 of 11   

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Author: Philippe Le Conte, MD, PhD, Consulting Staff, Department of Emergency Medicine, University Hospital of Nantes in

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Editor(s): Dana A Stearns, MD, Assistant Director of Undergraduate Education, Assistant, Department of Emergency Medicine, Massachusetts General Hospital; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Paul Blackburn, DO, Program Director, Department of Emergency Medicine, Maricopa Medical Center; Assistant Professor, Department of Surgery, University of Arizona; John Halamka, MD, Chief Information Officer, CareGroup Healthcare System, Assistant Professor of Medicine, Department of Emergency Medicine, Beth Israel Deaconess Medical Center; Assistant Professor of Medicine, Harvard Medical School; and Robert E O'Connor, MD, MPH, Director of Education and Research, Department of Emergency Medicine, Christiana Care Health System; Professor of Emergency Medicine, Thomas Jefferson University

Disclosure

  INTRODUCTION Section 2 of 11   

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Background: Aspiration pneumonia frequently is seen in emergency medicine. Its primary cause is impaired airway protection, which occurs in patients with an altered level of consciousness and/or abnormal swallowing reflexes. The risk is extremely high in any patient with an altered mental status. Therefore, the clinician must consider the condition as a coincident risk in the presence of drug ingestion, infection, metabolic and/or endocrine

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derangements, acute stroke and/or CNS mass lesions, or head trauma.

The extent and severity of the condition often depends on the volume and acidity of the inoculum. Aspiration of a massive amount of gastric contents can produce acute respiratory distress occur within 1 hour. Mechanical obstruction of the airways may occur after aspiration of fluid or particulate matter. Tracheobronchial suction may be indicated for acute respiratory failure. However, most frequently, the size of the inoculum is small, and the course of the illness more insidious. Bacterial pneumonitis often is caused by oropharyngeal flora, but gram-negative bacilli and other nosocomial pathogens must be considered in nursing home residents or those recently hospitalized.

Pathophysiology: Aspiration of gastric liquid may result in a chemical pneumonitis (Mendelson syndrome). Particulate matter or thick fluid may cause bronchial obstruction and ventilation-perfusion mismatch. Bacterial pneumonitis in this setting may be caused by a wide variety of pathogens ranging from preexisting oropharyngeal flora to nosocomial pathogens.

Community-acquired aspiration pneumonia often is associated with anaerobic bacteria alone (45-58%) or aerobic species (41-46%). However, in hospital-acquired infections, gram-negative bacilli and Staphylococcus aureus resistant to beta-lactam and/or methicillin are most common.

The clinician must consider nosocomial infection if the patient is from a nursing home or has been hospitalized recently.

Frequency:

In the US: Community-acquired cases number 1200 per 100,000 people per

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year. Nosocomial cases number 800 per 100,000 hospital admissions per year.

Internationally: Aspiration pneumonia is considered a common disease, but no statistics are available.

Mortality/Morbidity:

The 5% mortality rate increases to 20% in the presence of empyema. The mortality rate with Mendelson syndrome (severe chemical pneumonitis) is 70%.

Complications include acute respiratory failure and/or reactive airways caused by bronchiolar constriction and acute respiratory distress syndrome.

Empyema can occur in cases of inadequate antibiotic treatment.

Sex: Aspiration pneumonia is more common in males than in females.

Age: Aspiration pneumonia is more common in extremely young or old patients.

  CLINICAL Section 3 of 11   

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History: History-taking may reveal the following findings:

Sudden onset of coughing and shortness of breath associated with eating, drinking, or regurgitation

Altered mental status

Chemical Pneumonia Treatment

Stress dyspnea, rest dyspnea, cyanosis

Putrid expectoration

Fever

Chest pain (pleuritic)

Abdominal pain

Anorexia

Weight loss

Physical: Findings at physical examination may include the following:

Fever

Tachypnea, tachycardia, bradycardia

Cyanosis

Crackles and bronchial rales (most common on the right, but also may be present on the left or bilaterally)

Percussion dullness over the ipsilateral hemithorax in the presence of a pleural effusion and/or empyema

Altered mental status

Egophony

Decreased breath sounds

Pleural friction rub

Causes: Conditions that may reduce a patient's gag reflex and/or ability to maintain an airway include aspiration as a coincident risk.

Drug and/or alcohol ingestion (includes drugs used for general anesthesia or conscious sedation)

CNS trauma, cerebrovascular accident, intracranial mass lesions

Sepsis or meningitis

Isolated alteration of the swallowing reflex associated with pharyngeal disease

  DIFFERENTIALS Section 4 of 11   

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Altitude Illness - Pulmonary Syndromes Asthma Bronchitis Chronic Obstructive Pulmonary Disease and Emphysema Epiglottitis, Adult Foreign Bodies, Trachea Pediatrics, Bacteremia and Sepsis Pediatrics, Bronchiolitis Pediatrics, Croup or Laryngotracheobronchitis Pediatrics, Epiglottitis Pediatrics, Pneumonia Pediatrics, Reactive Airway Disease Pediatrics, Respiratory Distress Syndrome Pneumonia, Bacterial Pneumonia, Empyema and Abscess Pneumonia, Immunocompromised Pneumonia, Mycoplasma Pneumonia, Viral Shock, Septic

Other Problems to be Considered:

Hypersensitivity pneumonitis

  WORKUP Section 5 of 11   

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Lab Studies:

ABG analysis

o Ventilation-perfusion mismatch and bronchiolar constriction and/or reactive airways are common in severe cases.

o As a guide to acute intervention with oxygen, bronchodilator therapy, continuous positive airway pressure ventilation, or intubation, ABG levels are considered in the presence of hypoxia to determine the extent of hypercarbia and acidosis.

CBC analysis

o Determine the baseline hematocrit level and platelet count.

o A differential test should be ordered, with the leukocyte count, to assess for a left shift and/or "bandemia."

Determine serum electrolytes, BUN, and creatinine levels to guide intravenous fluid therapy, especially in patients with a history of poor oral intake or recurrent episodes of emesis.

Blood cultures may be used in baseline screening for potential bacteremia.

Sputum culture and Gram staining can be used to screen for pathogenic infection and to guide appropriate antimicrobial therapy.

Imaging Studies:

Chest radiography

o The right middle and/or lower lobe are the most common sites of infiltration. However, left and bilobar processes are possible, depending on the amount of aspirate and the body position during aspiration.

o Empyema should be ruled out in the presence of pleural effusion.

Procedures:

Protected brush or protected bronchial sample - Used to guide initial antibiotic therapy in nosocomial aspiration pneumonia, but not necessary in community-acquired pneumonia

Bronchoscopy

Thoracentesis

  TREATMENT Section 6 of 11   

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Prehospital Care:

Oxygen supplementation as needed

Continuous pulse oximetry

Cardiac monitoring

Intravenous catheterization

Tracheal intubation may be necessary in patients with a poor gag reflex, altered mental status, or persistent hypoxia.

Emergency Department Care:

Continued oxygen supplementation as needed

Cardiac monitoring

Intravenous catheterization

Endotracheal intubation is indicated for patients with a poor gag reflex, altered mental status, or persistent hypoxia despite noninvasive measures (including high-flow oxygen, continuous positive airway pressure ventilation). Positive end expiratory pressure may be used in cases of bronchoconstriction and refractory hypoxemia.

Consider tracheobronchial suction or tracheobronchoscopy to remove particulates or plugs.

Use empiric antimicrobial therapy with coverage adequate for the given clinical scenario (eg, community-acquired or nosocomial infection).

Administer intravenous hydration with electrolyte supplementation as needed.

Consultations:

Consult a pulmonary and/or critical care specialist in severe cases of

respiratory failure that require ventilatory support.

Consult an infectious disease specialist for advice about proper antibiotic therapy when the patient is at risk for nosocomial, highly resistant microbial infections.

MEDICATION Section 7 of 11   

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In the case of community-acquired aspiration pneumonia, empiric therapy must cover anaerobic and streptococcal species. Patients at risk for nosocomial pneumonia must be covered for anaerobic species, gram-negative bacilli (eg, Pseudomonas aeruginosa), and methicillin-resistant S aureus until sputum culture results are available to guide therapy. Corticosteroids are not indicated but may be considered for use in adjunctive therapy for coincident reactive airways or bronchoconstriction.

Drug Category: Antibiotics -- Empiric antimicrobial therapy must be comprehensive and should cover all likely pathogens in the context of the clinical setting.

Drug Name

Amoxicillin and clavulanate (Augmentin) -- Drug combination that extends the antibiotic spectrum of this penicillin to include bacteria normally resistant to beta-lactam antibiotics; indicated for skin and skin structure infections caused by beta-lactamase-producing strains of S aureus.

Adult Dose 1 g IV q8h

Pediatric Dose 50-80 mg/kg/d in 3 IV injections

Contraindications Documented hypersensitivity

Interactions Coadministration with warfarin or heparin increases risk of bleeding

Pregnancy B - Usually safe but benefits must outweigh the risks.

Precautions

Give for a minimum of 10 d to eliminate organism and prevent sequelae (eg, endocarditis, rheumatic fever); after treatment, obtain cultures to confirm eradication of streptococci

Drug Name Clindamycin (Cleocin) -- Lincosamide for treatment of serious skin and soft tissue staphylococcal infections. Also effective against aerobic and anaerobic

streptococci (except enterococci). Inhibits bacterial growth, possibly by blocking dissociation of peptidyl t-RNA from ribosomes and causing RNA-dependent protein synthesis to arrest.

Adult Dose600 mg IV q6-8h; dilute 300 mg in 50 mL of saline; duration of perfusion must be >10 min

Pediatric Dose 15-40 mg/kg in 3-4 IV perfusions

ContraindicationsDocumented hypersensitivity; regional enteritis; ulcerative colitis; hepatic impairment; antibiotic-associated colitis

Interactions

Increases duration of neuromuscular blockade, induced by tubocurarine and pancuronium; erythromycin may antagonize effects; antidiarrheals may delay absorption

Pregnancy B - Usually safe but benefits must outweigh the risks.

PrecautionsAdjust dose in severe hepatic dysfunction; no adjustment necessary in renal insufficiency; associated with severe and possibly fatal colitis

Drug Name

Ceftazidime (Fortaz, Ceptaz) -- Third-generation cephalosporin with broad-spectrum gram-negative activity; lower efficacy against gram-positive organisms; higher efficacy against resistant organisms; arrests bacterial growth by binding to 1 or more penicillin-binding proteins.

Adult Dose 500 mg to 2 g IV/IM q8-12h

Pediatric Dose1-4 weeks: 30 mg/kg IV/IM q12h1 month to 12 years: 30-50 mg/kg/dose IV/IM q8h; not to exceed 6 g/d

Contraindications Documented hypersensitivity

InteractionsNephrotoxicity may increase with aminoglycosides, furosemide, and ethacrynic acid; probenecid may increase ceftazidime levels

Pregnancy B - Usually safe but benefits must outweigh the risks.

Precautions Adjust dose in renal impairment

Drug Name

Amikacin (Amikin) -- For gram-negative bacterial coverage of infections resistant to gentamicin and tobramycin; effective against Pseudomonas aeruginosa. Irreversibly binds to 30S subunit of bacterial ribosomes and blocks recognition step in protein synthesis.

Adult Dose 15 mg/kg/d in 2 IV perfusions of 30-min duration; use

the patient's IBW for dose calculation

Pediatric Dose Administer as in adults

Contraindications Documented hypersensitivity

Interactions

Coadministration with other aminoglycosides, penicillins, cephalosporins, and amphotericin B increases nephrotoxicity; enhances effects of neuromuscular blocking agents; causes respiratory depression; irreversible hearing loss may occur with coadministration of loop diuretics

PregnancyC - Safety for use during pregnancy has not been established.

Precautions

Not intended for long-term therapy; caution in renal failure (not receiving dialysis), hypocalcemia, myasthenia gravis, and conditions that depress neuromuscular transmission

Drug Name

Vancomycin (Vancocin) -- Potent antibiotic against gram-positive organisms and active against Enterococcus species. Useful in the treatment of septicemia and skin structure infections. Indicated for use in patients who cannot receive or who have infections that fail to respond to penicillins and cephalosporins or infections with resistant staphylococci. For abdominal penetrating injuries, it is combined with an agent active against enteric flora and/or anaerobes. Used with gentamicin for prophylaxis in penicillin allergic patients who are allergic to penicillin and undergoing GI or genitourinary procedures.To avoid toxicity, assay vancomycin trough levels after third dose drawn 0.5 h prior to next dose; use CrCl value to adjust dose in patients with renal impairment.

Adult Dose 500 mg to 2 g/d IV divided tid/qid for 7-10 d

Pediatric Dose 40 mg/kg/d IV divided tid/qid for 7-10 d

Contraindications Documented hypersensitivity

Interactions

Erythema, histaminelike flushing and anaphylactic reactions may occur when administered with anesthetic agents; taken concurrently with aminoglycosides, risk of nephrotoxicity may increase above that with aminoglycoside monotherapy; effects in neuromuscular blockade may be enhanced with coadministration of nondepolarizing muscle relaxants

PregnancyC - Safety for use during pregnancy has not been established.

Precautions

Caution in renal failure, neutropenia; red man syndrome is caused by too-rapid IV infusion (dose given over a few minutes) but is rare when dose is given over 2 hours, PO, or IP; red man syndrome is not an allergic reaction

  FOLLOW-UP Section 8 of 11   

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Further Inpatient Care:

Admit patients with severe hemodynamic compromise and/or persistent respiratory distress to the ICU.

Admit the patient to a general-care floor if the patient's respiratory status is stabilized.

Transfer:

Intubated and ventilated patients must be transferred to a hospital with an ICU.

Deterrence/Prevention:

Keep the head of the bed at a 30° angle. Patients with dysphagia and/or a poor gag reflex should not be fed orally; feeding through a nasogastric or gastric tube may be required.

Complications:

Acute respiratory failure

Acute respiratory distress syndrome

Empyema

Pulmonary abscess

Superinfection

Prognosis:

The mortality rate of massive aspiration and/or Mendelson syndrome approaches 70%.

The mortality rate for aspiration pneumonitis complicated by empyema is approximately 20%.

The mortality for uncomplicated pneumonitis is approximately 5%.

Patient Education:

For excellent patient education resources, visit eMedicine's Pneumonia Center. Also, see eMedicine's patient education article Chemical Pneumonia.

  MISCELLANEOUS Section 9 of 11   

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Medical/Legal Pitfalls:

The airway must always be stabilized in patients with an abnormal gag reflex or altered mental status.

  PICTURES Section 10 of 11   

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Caption: Picture 1. Chest radiograph of a patient with aspiration pneumonia of the left lung after a benzodiazepine overdose - The patient was probably positioned to the left at the moment of aspiration.

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Picture Type: X-RAYCaption: Picture 2. Chest radiograph of a patient with massive aspiration pneumonia of the right lung

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Aspiration pneumonia Overview Symptoms Treatment Prevention

Definition:

Aspiration pneumonia is an inflammation of the lungs and bronchial tubes caused by inhaling foreign material (usually food, drink, vomit , or secretions from the mouth) into the lungs. This may progress to form a collection of pus in the lungs (lung abscess).

Alternative Names:

Anaerobic pneumonia; Aspiration of vomitus; Necrotizing pneumonia

Causes, incidence, and risk factors:

Aspiration of foreign material (often the stomach contents) into the lung can be a result of disorders that affect normal swallowing, disorders of the esophagus ( esophageal stricture , gastroesophageal reflux ), or decreased or absent gag reflex in unconscious or semi-conscious individuals. Old age, dental problems, use of sedative drugs, anesthesia, coma , and excessive alcohol consumption are also causal or contributing factors. The response of the lungs depends upon the characteristics and amount of the aspirated substance. The more acidic the material, the greater the degree of lung injury, although this may not necessarily lead to pneumonia.

The injured lungs may become infected with multiple species of anaerobic bacteria or aerobic bacteria . A collection of pus may form in the lung. A protective membrane may form around the abscess .

http://www.umm.edu/ency/article/000121.htm

Aspiration PneumoniaFactoid 2310 - Created: 2001-07-09 13:23:15-04 - Modified: 2002-09-01 20:54:35-04

ACR Codes: 6.-1Aspiration of a sufficient amount of gastric acid produces a chemical pneumonitis characterized by acute dyspnea and wheezing with hypoxemia and infiltrates on chest x-ray in one or both lower lobes. Clinical findings depend on the extent of endobronchial obstruction and ranges from acute apnea to persistent cough. Although the aspiration of oral anaerobes can initially lead to infiltrates, it ultimately results in putrid sputum, tissue necrosis and pulmonary cavities. In 75% of cases, the clinical course of an anaerobic abscess is indolent and mimics pulmonary tuberculosis, with cough, shortness of breath, chills, fevers, night sweats, weight loss, pleuritic chest pain and blood-streaked sputum for several weeks. Patients with anaerobic abscesses are usually prone to aspiration of oropharyngeal contents and have peridontal disease.

Chest x-ray is more sensitive than physical exam for detection of pulmonary infiltrates. Chest x-ray can confirm the presence and location of the pulmonary infiltrate, assess the extent of the pulmonary infection, detect pleural involvement, pulmonary cavitation, hilar lymphadenopathy and gauge the response of antibiotic therapy. However, chest x-ray may be normal when the patient is unable to mount an inflammatory response or is in the early stage of an infiltrative process. High-resolution CT can improve the accuracy of the diagnosis of pneumonia, especially when the process involves lung obscured by the diaphragm, liver, ribs, clavicles or heart.

The anatomic localization of the inflammatory process can have diagnostic implications. Most pulmonary pathogens produce focal lesions. A multicentric distribution suggests hematogenous infection. Heamtogenous pneumonia appears as multiple areas of pulmonary infiltration that subsequently may cavitate. A diffuse distribution suggests P. carini, CMV, hantavirus, measles virus or herpes zoster virus. Pluerisy and hilar nodal enlargement are unusual with PCP and CMV pneumonia. Oral anaerobes, S. aureus, S. pneumoniae serotype III, aerobic gram-negative bacilli, M. tuberculosis, and fungi can produce tissue necrosis and pulmonary cavities. In contrast, H. influenza, M pneumoniae, viruses and most other serotypes of S

pneumoniae almost never cause cavities. Apical disease, with or without cavities, suggests reactivation tuberculosis. Anaerobic abscesses are located in dependent, poorly ventilated, and poorly draining bronchopulmonary segments and characteristically have air-fluid levels, unlike the well-ventilated, well drained upperlobe cavities caused by M. tuberculosis, an obligate aerobe. Mucor and Aspergillus invade blood vessels and cause pleural-based, wedge-shaped area of pulmonary infarction which may subsequently cavitate.

In the patient with an uncomplicated course, chest x-ray need not be repeated before discharge, since the resolution of infiltrates may take up to 6 weeks after initial presentation. At times, CT may be especially helpful in distinguishing different processes: pleural effusion versus underlying pulmonary consolidation; hilar adenopathy versus pulmonary mass; and pulmonary abscess versus empyema with an air-fluid level

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