AUTHOR INFORMATION

Section 1 of 11

Authored by Anand Swaminathan, MD, Staff Physician, Department of Emergency Medicine, New York University/Bellevue Hospital Center

Coauthored by Sassan Naderi, MD, Staff Physician, Department of Emergency Medicine, New York University/Bellevue Medical Center

Anand Swaminathan, MD, is a member of the following medical societies: American Academy of Emergency Medicine, American Medical Association, and American Medical Student Association

Edited by Dana A Stearns, MD, Assistant Director of Undergraduate Education, 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

Author's Email:	Anand Swaminathan, MD
Editor's Email:	Dana A Stearns, MD

eMedicine Journal, June 21 2006, VOLUME 7, Number 6

INTRODUCTION

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Background: Aspiration is defined as the inhalation of either oropharyngeal or gastric contents into the lower airways. Inhalation of these contents can lead to aspiration pneumonia and aspiration pneumonitis. Although these two entities are managed differently, they are often interchangeably referred to as aspiration pneumonia.

Aspiration pneumonitis represents chemical damage to the tracheobronchial tree caused by acute, often witnessed, inhalation of regurgitated gastric contents in patients with an acute change in mental status. Aspiration pneumonia results from chronic, usually unwitnessed, inhalation of small amounts of oropharyngeal contents leading to an infectious process.

Pathophysiology: Aspiration pneumonitis represents an acute, chemical lung injury resulting from the inhalation of gastric contents. This disease occurs in people with altered levels of consciousness resulting from seizures, CVA, CNS mass lesions, drug intoxication or overdose, and head trauma.

The risk of aspiration is indirectly related to the level of consciousness of the patient (ie, decreasing GCS is related with increased risk of aspiration). The extent and severity of this disease is directly related to the volume and acidity of the fluid aspirated. Aspiration of a massive amount of gastric contents, also know as Mendelson syndrome, can produce acute respiratory distress within 1 hour. The acidity of gastric contents results in chemical burns to the tracheobronchial tree involved in the aspiration.

Because of the relative sterility of normal gastric contents, bacteria do not play an important role in the early stages of the disease. This does not hold true in patients with gastroparesis or small-bowel obstruction or in those using antacids (PPI, H2-receptor antagonists). Regardless of the bacterial load of the inoculum, bacterial superinfection may occur after the initial chemical injury.

Aspiration pneumonia is defined as the development of an infiltrate in a patient at increased risk of oropharyngeal aspiration. It occurs when a patient inhales material from the oropharynx that is colonized by upper airway flora.

Initial bacteriologic studies into the causative organisms revealed the anaerobic species to be the predominant pathogens in community-acquired aspiration pneumonia. However, subsequent studies revealed that Streptococcus pneumoniae, Staphylococcus aureus, Haemophilus influenzae, and Enterobacteriaceae are the most common organisms. Hospital-acquired aspiration pneumonia, on the other hand, is often caused by gram-negative organisms including Pseudomonas aeruginosa, particularly in intubated patients. These studies demonstrated a limited role of anaerobic pathogens in both the community and nosocomial variants of the disease.

This syndrome most commonly occurs in individuals with chronically impaired airway defense mechanisms. This includes gag reflex, coughing, ciliary movement, and immune mechanisms, all of which aid in removing infectious material from the lower airways. Other risk factors include poor dentition and poor oral care, which both increase the bacterial burden of oropharyngeal secretions. Clinicians must thus surmise this diagnosis when a patient presents with risk factors and radiographic evidence of an infiltrate suggestive of aspiration pneumonia. The location of the infiltrate on chest radiograph depends on the position of the patient when the aspiration occurred.

Frequency:

• In the US: Few studies have been designed that distinguish between aspiration pneumonia and aspiration pneumonitis. Several studies suggest that 5-15% of the 4.5 million cases of community-acquired pneumonia result from aspiration pneumonia.

  Approximately 10% of patients who are hospitalized after drug overdoses will have an aspiration pneumonitis.

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

Mortality/Morbidity:

• The mortality associated with aspiration pneumonia mimics that of community-acquired pneumonia: approximately 1% in the outpatient setting and up to 25% in those requiring hospitalization. This mortality range depends on complications of the disease.

• The mortality rate for severe chemical pneumonitis (Mendelson syndrome) can be up to 70%.

• Without treatment, aspiration pneumonia is associated with a high incidence of cavitation and abscess formation in comparison to community-acquired pneumonia. Other complications of both aspiration pneumonia and pneumonitis include empyema, acute respiratory distress syndrome, and respiratory failure. Aspiration pneumonitis can rapidly progress to respiratory failure.

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

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

CLINICAL

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History: The clinical presentation of both aspiration pneumonitis and pneumonia ranges from mildly ill and ambulating to critically ill with signs and symptoms of septic shock and/or respiratory failure.

Patient history in aspiration pneumonia is similar to that of community-acquired pneumonia and may include the following:

• Cough

• Fever or chills

• Malaise, myalgias

• Shortness of breath, dyspnea on exertion

• Pleuritic chest pain

• Putrid expectoration

• Nonspecific symptoms including headache, nausea/vomiting, anorexia, weight loss

• Host factors - Chronic conditions resulting in decreased ability to protect one's airway

• Previous CVA

• History of esophageal diseases including achalasia, esophageal web

• Nursing home patients

• Patients chronically fed by feeding tube (NG tube or gastric tube)

• Patients brought in after witnessed large-volume vomitus and subsequent aspiration pneumonitis will have a history consistent with an acute change in mental status. This history may include the following:

• Seizure

• Alcohol abuse

• Drug overdose

• Head trauma

Physical: Physical examination findings vary depending on severity of the disease, presence of complications, and host factors. Patients with aspiration pneumonitis secondary to seizure, head trauma, or drug overdose should be inspected for signs related to these processes. Both aspiration pneumonia and pneumonitis can present with the following:

• Fever or hypothermia

• Tachypnea

• Tachycardia

• Decreased breath sounds

• Dullness to percussion over areas of consolidation

• Rales

• Egophony and pectoriloquy

• Decreased breath sounds

• Pleural friction rub

• Altered mental status

• Hypoxemia

• Hypotension (in septic shock)

• In addition, patients may exhibit signs associated with the underlying disease that lead to their aspiration.

Causes: Any condition that reduces a patient's gag reflex and/or ability to maintain an airway increases the risk of aspiration pneumonia or pneumonitis.

• CVA

• Intracranial mass lesion

• Head trauma

• Alcohol abuse

• Drug overdose

• Isolated alteration of the swallowing reflex associated with pharyngeal disease

DIFFERENTIALS

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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

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Lab Studies:

• The lab studies obtained should be guided by the clinical presentation. Patients with signs or symptoms of sepsis or septic shock require further lab testing than those with uncomplicated aspiration syndromes. The following lab tests are useful in both aspiration pneumonia and pneumonitis.

• Complete blood count with differential

• Determine white count as marker of possible infection.

• Determine band count; a left shift further supports the diagnosis of bacterial pneumonia.

• Determine baseline hemoglobin/hematocrit and platelets for further management.

• Basic metabolic panel

• Serum electrolytes, BUN, and creatinine can be used to assess fluid status and the need for intravenous hydration. This is especially important in patients presenting with fever, vomiting, or diarrhea that may have significant fluid loss.

• Serum BUN and creatinine can also be used to assess renal function in order to appropriately dose antibiotics. In addition, these values can be used to assess end-organ damage in patients who present with sepsis or septic shock.

• Arterial blood gas

• Arterial blood gas is used to assess oxygenation and adds information to guiding oxygen supplementation.

• Assess the patient's pH status.

• Lactate (often included with blood gases) can be used as an early marker of severe sepsis or septic shock.

• Mixed venous gas

• This should be obtained in any patient in whom septic shock is suspected.

• Decreased mixed venous oxygen saturation is a marker for septic shock.

• Blood cultures

• Baseline screening for bacteremia

• In uncomplicated pneumonia (no signs of sepsis or septic shock), blood cultures have a low yield and are not necessary for initial management and treatment.

• Sputum culture and Gram stain - Generally not helpful in initial diagnosis or treatment

Imaging Studies:

• Chest radiograph - PA and Lateral

• Location of infiltrate
  • The right middle and lower lung lobes are the most common sites of infiltrate formation due to the larger caliber and more vertical orientation of the right main stem bronchus.
    
  • Patients who aspirate while standing can have bilateral lower lung lobe infiltrates.
    
  • Patients lying in the left lateral decubitus position are more likely to have left-sided infiltrates.
    
  • The right upper lobe is a common area of consolidation in alcoholics who aspirate in the prone position.

• Presence of pleural effusion may indicate the need to perform thoracentesis to rule out empyema.

• Chest CT

• Not usually necessary on an emergent basis.

• In the presence of pleural effusion or empyema, may aid in further characterization of the infiltrate

Procedures:

• Bronchoscopy with protected brush or protected bronchial sample

• May be helpful in nosocomial aspiration pneumonia for guiding antibiotic therapy

• Not useful in the treatment of community-acquired aspiration pneumonia

• Thoracentesis

• Chest tube placement (for drainage of large empyema)

TREATMENT

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Prehospital Care: Prehospital care should focus on stabilizing the patient's airway, breathing, and circulation.

• In patients found with signs of gastric aspiration (ie, vomitus) suctioning of the upper airway may remove a significant amount of aspirate or potential aspirate.

• Intubation should be considered in any patient who is unable to protect his or her airway. The ability of paramedics to provide this intervention depends on the level of training. In addition, EMTs trained in intubation may choose to intubate patients with poor gag reflex prior to aspiration.

• Oxygen supplementation

• Cardiac monitoring and pulse oximetry

• Intravenous catheter placement and intravenous fluids as indicated

Emergency Department Care: Emergency department care should start with stabilizing the patient's airway, breathing, and circulation.

• Oropharyngeal/tracheal suctioning may be indicated to further remove aspirate.

• Reassess the need for intubation on a frequent basis depending on oxygenation, patient's mental status, signs of increased work of breathing, or impending respiratory failure.

• Continue supplemental oxygenation as needed.

• Continue cardiac monitoring and pulse oximetry.

• Provide continued supportive care with intravenous fluids and electrolyte replacement.

• Antibiotic therapy

• Aspiration pneumonia: Always indicated

• Aspiration pneumonitis
  • Prophylactic antibiotics are not recommended in most cases.
  • In addition, those patients with recent aspiration, fever, and leukocytosis should not be treated even in the presence of a pulmonary infiltrate due to the risk of development of resistant organisms.
    
  • When to use antibiotics: (1) Pneumonitis fails to resolve within 48 hours. (2) Patients with small bowel obstruction–lower; bacteria may colonize gastric contents. (3) Antibiotics should be considered for patients on antacids due to the potential for gastric colonization.

• Corticosteroids

• Historically corticosteroids have been used in the treatment of aspiration pneumonitis, but randomized control studies have been unable to demonstrate a benefit to using high-dose corticosteroids.

• Patients with septic shock requiring vasoactive substances to maintain blood pressure should receive stress-dose steroids.

Consultations:

• Pulmonary/critical care specialist in severe cases of respiratory failure requiring ventilatory support

• Infectious disease specialist for advice about proper antibiotic therapy

MEDICATION

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The antibiotics of choice should be tailored to the setting in which the aspiration occurred (community vs nosocomial); however, antibiotic agents with activity against gram-negative organisms as well as gram-positive organisms is usually required.

Microbiological evidence indicates that empiric coverage of anaerobes is not indicated unless the patient presents with putrid sputum, severe oropharyngeal disease, or evidence of lung abscess or necrotizing pneumonia on chest radiograph or CT.

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

Drug Name	Ceftriaxone (Rocephin) -- Third-generation cephalosporin with broad-spectrum, gram-negative activity; lower efficacy against gram-positive organisms; higher efficacy against resistant organisms. Bactericidal activity results from inhibiting cell wall synthesis by binding to one or more penicillin-binding proteins. Exerts antimicrobial effect by interfering with synthesis of peptidoglycan, a major structural component of bacterial cell wall. Bacteria eventually lyse due to the ongoing activity of cell wall autolytic enzymes while cell wall assembly is arrested. Highly stable in presence of beta-lactamases, both penicillinase and cephalosporinase, of gram-negative and gram-positive bacteria. Approximately 33-67% of dose excreted unchanged in urine, and remainder secreted in bile and ultimately in feces as microbiologically inactive compounds. Reversibly binds to human plasma proteins, and binding has been reported to decrease from 95% bound at plasma concentrations <25 mcg/mL to 85% bound at 300 mcg/mL.
Adult Dose	1-2 g IV qd or divided bid; not to exceed 4 g/d
Pediatric Dose	>7 days to 6 months: 25-50 mg/kg/d IV/IM; not to exceed 125 mg/d >6 months: 50-75 mg/kg/d IV/IM divided q12h; not to exceed 2 g/d
Contraindications	Documented hypersensitivity; hyperbilirubinemic neonates, particularly those who are premature
Interactions	Probenecid may increase ceftriaxone levels; coadministration with ethacrynic acid, furosemide, and aminoglycosides may increase nephrotoxicity
Pregnancy	B - Usually safe but benefits must outweigh the risks.
Precautions	Therapy should continue for a period of at least 10 d or until resolution of the clinical picture; adjust dose in severe renal insufficiency (high doses may cause CNS toxicity); superinfections, and promotion of nonsusceptible organisms may occur with prolonged use or repeated therapy; caution in breastfeeding women; may displace bilirubin from albumin-binding sites, increasing the risk of kernicterus; caution with gallbladder, biliary tract, liver, or pancreatic disease or in patients with history of colitis or penicillin hypersensitivity

Drug Name	Ampicillin and sulbactam (Unasyn) -- Drug combination of beta-lactamase inhibitor with ampicillin. Interferes with bacterial cell wall synthesis during active replication, causing bactericidal activity against susceptible organisms.
Adult Dose	1.5 (1 g ampicillin + 0.5 g sulbactam) to 3 g (2 g ampicillin + 1 g sulbactam) IV/IM q6h; not to exceed 4 g/d sulbactam or 8 g/d ampicillin
Pediatric Dose	<3 months: Not established 3 months to 12 years: 100-200 mg ampicillin/kg/d (150-300 mg Unasyn) IV divided q6h >12 years: Administer as in adults; not to exceed 4 g/d sulbactam or 8 g/d ampicillin
Contraindications	Documented hypersensitivity
Interactions	Probenecid and disulfiram elevate ampicillin levels; allopurinol decreases ampicillin effects and has additive effects on ampicillin rash; may decrease effects of oral contraceptives
Pregnancy	B - Usually safe but benefits must outweigh the risks.
Precautions	Therapy should continue for a period of at least 10 d or until resolution of the clinical picture; adjust dose in renal failure; evaluate rash and differentiate from hypersensitivity reaction

Drug Name	Piperacillin and tazobactam sodium (Zosyn) -- Antipseudomonal penicillin plus beta-lactamase inhibitor. Inhibits biosynthesis of cell wall mucopeptide and is effective during stage of active multiplication.
Adult Dose	3.375 g (piperacillin 3 g and tazobactam 0.375 g) IV q6h
Pediatric Dose	<12 years: Not established >12 years: Administer as in adults
Contraindications	Documented hypersensitivity; severe pneumonia, bacteremia, pericarditis, emphysema, meningitis and purulent or septic arthritis should not be treated with an oral penicillin during the acute stage
Interactions	Tetracyclines may decrease effects of piperacillin; high concentrations of piperacillin may physically inactivate aminoglycosides if administered in same IV line; effects when administered concurrently with aminoglycosides are synergistic; probenecid may increase penicillin levels; high dose parenteral penicillins may result in increased risk of bleeding
Pregnancy	B - Usually safe but benefits must outweigh the risks.
Precautions	Therapy should continue for a period of at least 10 d or until resolution of the clinical picture; perform CBCs prior to initiation of therapy and at least weekly during therapy; monitor for liver function abnormalities by measuring AST and ALT during therapy; exercise caution in patients diagnosed with hepatic insufficiencies; perform urinalysis, and BUN and creatinine determinations during therapy and adjust dose if values become elevated; monitor blood levels to avoid possible neurotoxic reactions

Drug Name	Imipenem and cilastatin (Primaxin) -- For treatment of multiple-organism infections in which other agents do not have wide-spectrum coverage or are contraindicated due to potential for toxicity.
Adult Dose	Base initial dose on severity of infection, and administer in equally divided doses; dose may range from 500 mg to 1 g IV for maximum of 3-4 g/d; alternatively, 500-750 mg q12h IM or intra-abdominally
Pediatric Dose	<12 years: Not established; 15-25 mg/kg/dose IV q6h suggested for > 3 mo Fully susceptible organisms: Not to exceed 2 g/d Infections with moderately susceptible organisms: Not to exceed 4 g/d
Contraindications	Documented hypersensitivity; known hypersensitivity to amide local anesthetics; children with CNS infections (increased seizure risk); children <30 kg with renal impairment (lack of data)
Interactions	Coadministration with cyclosporine may increase CNS side effects of both agents; coadministration with ganciclovir may result in generalized seizures
Pregnancy	C - Safety for use during pregnancy has not been established.
Precautions	Therapy should continue for a period of at least 10 d or until resolution of clinical symptoms observed Adjust dose in renal insufficiency (adult adjustments) CrCl (mL/min) 80-50: 0.5 g q6-8h CrCl 50-10: 0.5 g q8-12h Hemodialysis (HD): 0.25-0.5 g after HD, then q12h Avoid use in children <12 y with CNS infections Caution with history of seizures, hypersensitivity to penicillins, cephalosporins, or other beta-lactam antibiotics; avoid use in children <12 y with CNS infections Caution with history of seizures, hypersensitivity to penicillins, cephalosporins, or other beta-lactam antibiotics

Drug Name	Amoxicillin and clavulanate (Augmentin, Augmentin XR) -- Amoxicillin inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins. Addition of clavulanate inhibits beta-lactamase producing bacteria. Good alternative antibiotic for patients allergic or intolerant to the macrolide class. Usually is well tolerated and provides good coverage to most infectious agents. Not effective against Mycoplasma and Legionella species. Half-life of oral dosage form is 1-1.3 h. Has good tissue penetration but does not enter cerebrospinal fluid. For children > 3 mo, base dosing protocol on amoxicillin content. Because of different amoxicillin/clavulanic acid ratios in 250-mg tab (250/125) vs 250 mg chewable-tab (250/62.5), do not use 250-mg tab until child weighs >40 kg.
Adult Dose	875 mg PO q12h or 500 mg PO q8h
Pediatric Dose	<3 months: 125 mg/5 mL PO susp based on amoxicillin; 30 mg/kg/d divided bid for 7-10 d >3 months: if using 200 mg/5 mL or 400 mg/5 mL susp, 45 mg/kg/d PO q12h; if using 125 mg/5 mL or 250 mg/5 mL susp, 40 mg/kg/d PO q8h for 7-10 d >40 kg: Administer as in adults
Contraindications	Documented hypersensitivity
Interactions	Coadministration with warfarin or heparin increases risk of bleeding; may act synergistically against selected microorganisms when coadministered with aminoglycosides; coadministration with allopurinol may increase incidence of amoxicillin rash; may decrease efficacy of oral contraceptives when administered concomitantly
Pregnancy	B - Usually safe but benefits must outweigh the risks.
Precautions	Therapy should continue for a period of at least 10 d or until resolution of clinical symptoms observed Hepatic impairment may occur with prolonged treatment in the elderly; diarrhea may occur; adjust dose in renal impairment; cross allergy may occur with other beta-lactams and cephalosporins

Drug Name	Levofloxacin (Levaquin) -- Used to treat community-acquired pneumonia caused by S aureus, S pneumoniae (including penicillin-resistant strains), H influenzae, H parainfluenzae, Klebsiella pneumoniae, M catarrhalis, Chlamydia pneumoniae, Legionella pneumophila, or M pneumoniae. Fluoroquinolones should be used empirically in patients likely to develop exacerbation due to resistant organisms to other antibiotics. Rapidly becoming a popular choice in pneumonia. This is the L stereoisomer of the D/L parent compound ofloxacin, the D form being inactive. Good monotherapy with extended coverage against Pseudomonas species, as well as excellent activity against pneumococcus. Agent acts by inhibition of DNA gyrase activity. PO form has bioavailability that reportedly is 99%.
Adult Dose	750 mg IV qd
Pediatric Dose	<18 years: Not recommended >18 years: Administer as in adults
Contraindications	Documented hypersensitivity
Interactions	Antacids, iron salts, and zinc salts may reduce serum levels; administer antacids 2-4 h before or after taking fluoroquinolones; cimetidine may interfere with metabolism of fluoroquinolones; levofloxacin reduces therapeutic effects of phenytoin; probenecid may increase levofloxacin serum concentrations
Pregnancy	C - Safety for use during pregnancy has not been established.
Precautions	Therapy should continue for a period of at least 10 d or until resolution of clinical symptoms observed In prolonged therapy, perform periodic evaluations of organ system functions (eg, renal, hepatic, hematopoietic); adjust dose in renal function impairment; superinfections may occur with prolonged or repeated antibiotic therapy

Drug Name	Clindamycin (Cleocin) -- Semisynthetic antibiotic produced by 7(S)-chloro-substitution of 7(R)-hydroxyl group of parent compound lincomycin. Inhibits bacterial growth, possibly by blocking dissociation of peptidyl tRNA from ribosomes, causing RNA-dependent protein synthesis to arrest. Widely distributes in the body without penetration of CNS. Protein bound and excreted by the liver and kidneys. Available in parenteral form (ie, clindamycin phosphate) and oral form (ie, clindamycin hydrochloride). Oral clindamycin is absorbed rapidly and almost completely and is not appreciably altered by the presence of food in the stomach. Appropriate serum levels are reached and sustained for at least 6 h following an oral dose. No significant levels are attained in the cerebrospinal fluid. Also effective against aerobic and anaerobic streptococci (except enterococci).
Adult Dose	600 mg IV q6-8h; doses as high as 4800 mg qd have been used in life-threatening severe infections
Pediatric Dose	8-20 mg/kg/d PO as hydrochloride and 8-25 mg/kg/d as palmitate divided tid/qid 20-40 mg/kg/d IV/IM equally divided tid/qid Use higher dose for more severe infections
Contraindications	Documented 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 of clindamycin; antidiarrheals may delay absorption of clindamycin
Pregnancy	B - Usually safe but benefits must outweigh the risks.
Precautions	Therapy should continue for a period of at least 10 d or until resolution of clinical symptoms observed; for use when suspicious of anaerobic infection; use in conjunction with antibiotic that covers both gram-positive and gram-negative organisms Adjust dose in severe hepatic dysfunction; no adjustment necessary in renal insufficiency; associated with severe and possibly fatal colitis by allowing overgrowth of Clostridium difficile

Drug Name	Amikacin (Amikin) -- Irreversibly binds to 30S subunit of bacterial ribosomes; blocks recognition step in protein synthesis; causes growth inhibition. For gram-negative bacterial coverage of infections resistant to gentamicin and tobramycin. Effective against P aeruginosa. Use patient's IBW for dosage calculation. The same principles of drug monitoring for gentamicin apply to amikacin.
Adult Dose	5 mg/kg IV q8h; use 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
Pregnancy	D - Unsafe in pregnancy
Precautions	Not intended for long-term therapy; caution in patients with renal failure (not on dialysis), hypocalcemia, myasthenia gravis, and conditions that depress neuromuscular transmission; adjust dose based on creatinine clearance; follow trough values to guide therapy and avoid toxicity

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 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
Pediatric Dose	40 mg/kg/d IV divided tid/qid
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 when coadministered with nondepolarizing muscle relaxants
Pregnancy	C - Safety for use during pregnancy has not been established.
Precautions	Therapy should continue for a period of at least 10 days or until resolution of the clinical picture Caution in renal failure, neutropenia; red man syndrome is caused by too rapid IV infusion (dose given over a few minutes) but rarely happens when dose given IV over 2 h administration or as PO or IP administration; red man syndrome is not an allergic reaction; adjust dose based on creatinine clearance; follow trough values to guide therapy and avoid toxicity

FOLLOW-UP

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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.

• Patients with signs or symptoms indicating severe sepsis or septic shock should be transferred to a hospital with an ICU.

Deterrence/Prevention:

• Keep the head of the bed at a 30° angle. The semirecumbent body position reduces the risk or aspiration leading to pneumonia.

• 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 associated with aspiration pneumonia mimics that of community-acquired pneumonia: approximately 1% in the outpatient setting and up to 25% in those requiring hospitalization.

• The mortality rate of massive aspiration pneumonitis (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.

TEST QUESTIONS

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CME Question 1: Which pathogen is not likely to be responsible for aspiration pneumonia in a 45-year-old patient living at home?

A: Streptococcus pneumonia
B: Anaerobe
C: Methicillin-resistant Staphylococcus aureus (MRSA)
D: Escherichia coli
E: Streptococcus sanguis

The correct answer is B: Recent studies show that anaerobes are rarely the cause of aspiration pneumonia. Community-acquired MRSA is becoming more common in certain areas of the country.

CME Question 2: Which antibiotic can be given to a pregnant female patient with aspiration pneumonia?

A: Amoxicillin with clavulanic acid
B: Clindamycin
C: Cefotaxime
D: Vancomycin
E: Erythromycin

The correct answer is A: Amoxicillin with clavulanic acid covers all pathogens that can be responsible for aspiration pneumonia and is safe for use in pregnancy.

Pearl Question 1 (T/F): Anaerobes and Streptococcus species are the main pathogens that are isolated in community-acquired aspiration pneumonia.

The correct answer is False: Community-acquired aspiration pneumonia is most commonly associated with the same organisms that cause other forms of community-acquired pneumonia.

Pearl Question 2 (T/F): Empiric broad-spectrum antibiotics should be started immediately for patients with aspiration of gastric contents.

The correct answer is False: Antibiotics are not indicated as initial management in patients with aspiration of gastric contents or in patients with aspiration pneumonitis.

Pearl Question 3 (T/F): Drug or alcohol intoxication, severe head injuries, and intracranial mass lesions are a few of the most frequent situations responsible for aspiration pneumonitis.

The correct answer is True: Drug or alcohol intoxication, severe head injuries, and intracranial mass lesions are indeed a few of the most frequent situations responsible for aspiration pneumonia. Others include cerebrovascular accidents and altered mental status caused by infection, metabolic, environmental, or endocrine abnormalities.

Pearl Question 4 (T/F): Aspiration pneumonia can be prevented by securing the airway in patients with altered mental status and/or an abnormal gag reflex.

The correct answer is True: Endotracheal intubation is indicated for patients with a poor gag reflex, altered mental status, or persistent hypoxia despite noninvasive measures. Aspiration pneumonia can be prevented by securing the airway in these patients.

PICTURES

Section 10 of 11

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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Caption: Picture 2. Chest radiograph of a patient with massive aspiration pneumonia of the right lung
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BIBLIOGRAPHY

Section 11 of 11

• Adnet F, Baud F: Relation between Glasgow Coma Scale and aspiration pneumonia. Lancet 1996 Jul 13; 348(9020): 123-4[Medline].
• Akritidis N, Gousis C, Dimos G: Fever, cough, and bilateral lung infiltrates. Achalasia associated with aspiration pneumonia. Chest 2003 Feb; 123(2): 608-12[Medline].
• Drakulovic MB, Torres A, Bauer TT, et al: Supine body position as a risk factor for nosocomial pneumonia in mechanically ventilated patients: a randomised trial. Lancet 1999 Nov 27; 354(9193): 1851-8[Medline].
• Lumpkin JR, Westfall MD: Aspiration pneumonia. In: Emergency Medicine: Concepts and Clinical Practice. 1992: 1112-20.
• Marik PE: Aspiration pneumonitis and aspiration pneumonia. N Engl J Med 2001 Mar 1; 344(9): 665-71[Medline].
• Marik PE, Careau P: The role of anaerobes in patients with ventilator-associated pneumonia and aspiration pneumonia: a prospective study. Chest 1999 Jan; 115(1): 178-83[Medline].
• Marom EM, McAdams HP, Erasmus JJ: The many faces of pulmonary aspiration. AJR Am J Roentgenol 1999 Jan; 172(1): 121-8[Medline].
• Mier L, Dreyfuss D, Darchy B: Is penicillin G an adequate initial treatment for aspiration pneumonia? A prospective evaluation using a protected specimen brush and quantitative cultures. Intensive Care Med 1993; 19(5): 279-84[Medline].
• Moll J, Kerns W 2nd, Tomaszewski C: Incidence of aspiration pneumonia in intubated patients receiving activated charcoal. J Emerg Med 1999 Mar-Apr; 17(2): 279-83[Medline].
• Pennza PT: Aspiration pneumonia, necrotizing pneumonia, and lung abscess. Emerg Med Clin North Am 1989 May; 7(2): 279-307[Medline].
• Preston AJ, Gosney MA, Noon S: Oral flora of elderly patients following acute medical admission. Gerontology 1999 Jan-Feb; 45(1): 49-52[Medline].
• Sasaki H, Sekizawa K, Yanai M: New strategies for aspiration pneumonia. Intern Med 1997 Dec; 36(12): 851-5[Medline].
• Vadeboncoeur TF, Davis DP, Ochs M: The ability of paramedics to predict aspiration in patients undergoing prehospital rapid sequence intubation. J Emerg Med 2006 Feb; 30(2): 131-6[Medline].

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