Aspiration Pneumonia Aspiration Pneumonia by by Dr.jarahzadeh Dr.jarahzadeh Intensivist Intensivist.

Aspiration Aspiration PneumoniaPneumonia

byby

Dr.jarahzadehDr.jarahzadeh

IntensivistIntensivist

Aspiration Aspiration

DefinitionDefinition– Misdirection of gastric contents into Misdirection of gastric contents into

the larynx resulting from alteration the larynx resulting from alteration in lower airway defenses such as in lower airway defenses such as glottic closure and the cough reflexglottic closure and the cough reflex

IncidenceIncidence

Half of all adults aspirate small Half of all adults aspirate small amounts of oropharyngeal amounts of oropharyngeal contents in their sleepcontents in their sleep

Aspiration may occur in up to Aspiration may occur in up to 10% of nursing home residents 10% of nursing home residents annuallyannually

Risk aspirationRisk aspiration

The risk of aspiration with modern anesthesia is about 1 in 3,000 anesthetics, with a mortality of approximately 1: 125,000,accounting for between 10% to 30% of all anesthetic deaths.

The risk of aspiration is greatly increased inpatients intubated emergently in the field emergency department, or ICU.

Reduce the risk of Reduce the risk of aspiration in ETT aspiration in ETT intubationintubation

removing dentures removing dentures clearing the airway clearing the airway in certain circumstances placing a in certain circumstances placing a

nasogastric tube to empty the nasogastric tube to empty the Stomach before intubation.Stomach before intubation.

*If there is an immediate risk of airway compromise, endotracheal intubation should be performed before placement of a nasogastric tube.

clearing the airwayclearing the airway

Predisposing FactorsPredisposing Factors

Decreased consciousnessDecreased consciousness– AlcoholAlcohol– DrugsDrugs– Hepatic failureHepatic failure– CVACVA– AnesthesiaAnesthesia


Esophageal disordersEsophageal disorders– GERDGERD– StrictureStricture– Tracheoesophageal fistulaTracheoesophageal fistula– Incompetent cardiac sphincterIncompetent cardiac sphincter– Protracted vomitingProtracted vomiting


Disruption of glottic closureDisruption of glottic closure– Endotracheal intubationEndotracheal intubation– NG tubeNG tube– Endoscopy/bronchoscopyEndoscopy/bronchoscopy


Neuromuscular disordersNeuromuscular disorders– Multiple sclerosisMultiple sclerosis– Parkinson’sParkinson’s– Myasthenia gravisMyasthenia gravis

Aspiration Aspiration PneumonitisPneumonitis

Mendelson first described Mendelson first described aspiration pneumonitis in 1946aspiration pneumonitis in 1946– 44016 (po-obstetric patien-half resive 44016 (po-obstetric patien-half resive

anesthesia with mask ) 66 patients anesthesia with mask ) 66 patients aspirated gastric contents after ether aspirated gastric contents after ether anesthesiaanesthesia..

All patients had recovery within 2 All patients had recovery within 2 daysdays

Aspiration Aspiration PneumonitisPneumonitis

Definition Definition Acute lung injury Acute lung injury following the following the

aspiration of regurgitated gastric aspiration of regurgitated gastric contents and results in a chemical contents and results in a chemical burn of the tracheobronchial tree burn of the tracheobronchial tree and pulmonary parenchyma with an and pulmonary parenchyma with an intense parenchymal inflammatory intense parenchymal inflammatory reactionreaction

chemical Pneumonitischemical Pneumonitis

PathophysiologyPathophysiology– Animal models demonstrate that Animal models demonstrate that

clinically significant pneumonitis clinically significant pneumonitis results from aspirating at least results from aspirating at least 1ml/kg of pH<2.5 gastric contents1ml/kg of pH<2.5 gastric contents

– Fluids that are not harmful to the Fluids that are not harmful to the airwayairway Water, saline, barium, gastric contents Water, saline, barium, gastric contents

with pH>2.5with pH>2.5

Experimental studies have shown a biphasic pattern of lung injury after acid aspiration. The first phase peaks at ! to2 hours after aspiration and presumably results from thedirect caustic effect of the low pH on the alveolar-capillarywall lining cells. The second phase, which peaks at 4 to 6 hours, is associated with infiltration of neutrophils into the alveoli and lung interstitium with a histologic picture ofacute inflammation.

PathophysiologyPathophysiology

Chemical PneumonitisChemical Pneumonitis

Clinical featuresClinical features– Abrupt onset of dyspneaAbrupt onset of dyspnea– Low grade feverLow grade fever– Pink frothy sputumPink frothy sputum– Diffuse crackles on examDiffuse crackles on exam– CXR: diffuse infiltratesCXR: diffuse infiltrates


Xray of chemical Xray of chemical pneumonitis 2 hours pneumonitis 2 hours after aspiration eventafter aspiration event


TreatmentTreatment– Ventilatory support may be Ventilatory support may be

necessarynecessary– Corticosteriods: beneficial in animal Corticosteriods: beneficial in animal

models, unsuccessful in humansmodels, unsuccessful in humans– AntibioticsAntibiotics

Up to 25% of patients have bacterial Up to 25% of patients have bacterial superinfection (Dines et al)superinfection (Dines et al)

Bacterial PneumonitisBacterial Pneumonitis

Clinical featuresClinical features– Much more insidious onset than Much more insidious onset than

chemical pneumonitis (days to weeks)chemical pneumonitis (days to weeks)– CoughCough– FeverFever– Purulent sputumPurulent sputum– CXR: Infiltrate frequently in dependent CXR: Infiltrate frequently in dependent

segmentssegments


Patient aspirate in the recumbent position the most commonsites of involvement are the posterior segments of the upperlobes and the apical segments of the lower lobes.

patient aspirate in the upright or semi-recumbent position thebasal segments of the lower lobes are favored.


Xray of bacterial aspiration pneumoniaXray of bacterial aspiration pneumonia


MicrobiologyMicrobiology– AnaerobesAnaerobes

PeptostreptococcusPeptostreptococcus FusobacteriumFusobacterium BacteroidesBacteroides

– Gram negative bacilliGram negative bacilli Klebsiella in alcoholicsKlebsiella in alcoholics E coli, serratia, proteusE coli, serratia, proteus

– Gram positive bacteriaGram positive bacteria Staph, Hemophilus, streptococcusStaph, Hemophilus, streptococcus


TreatmentTreatment The choice of antibiotics shouldThe choice of antibiotics should

depend on the setting in which the depend on the setting in which the aspiration occurs aspiration occurs (home,nursing (home,nursing home,hospital)home,hospital)or premorbid or premorbid condition.condition.


Antimicrobial agents withgram-negative activity such as fluoroquinolones, thirdgeneration cephalosporins, piperacillin, or a carbapenem are usually required.

Antimicrobials with specific anaerobicactivity are not routinely warranted and may be indicatedonly in patients with severe periodontal disease, patientsexpectorating putrid sputum, and patients with a necrotizing pneumonia or lung abscess


All elderly patients with CAP and all patients with aspirationpneumonia require consultation by a speech and languagepathologist to assess for the presence of dysphagia

Solid Particle Solid Particle AspirationAspiration

Large particlesLarge particles– Sudden respiratory distress, Sudden respiratory distress,

cyanosis, aphoniacyanosis, aphonia Heimlich!Heimlich!

Small particlesSmall particles– Irritative cough, unilateral wheezingIrritative cough, unilateral wheezing

Remember: bacterial superinfection is Remember: bacterial superinfection is commoncommon

Assessment of Assessment of DysphagiaDysphagia Clinical signs of dysphagiaClinical signs of dysphagia

– DroolingDrooling– Coughing before, during, or after Coughing before, during, or after

swallowswallow– Multiple swallows per mouthfulMultiple swallows per mouthful– Unusual head posturing while Unusual head posturing while

swallowingswallowing Clinical exam for diagnosisClinical exam for diagnosis

– Sensitivity 80%, Specificity 70%Sensitivity 80%, Specificity 70%

Assessment of Assessment of DysphagiaDysphagia

Modified barium swallow Modified barium swallow (MBS)(MBS)Patients swallow small amounts of different Patients swallow small amounts of different

textured barium and evaluated by textured barium and evaluated by flouroscopyflouroscopy

– One study demonstrated that MBS did not One study demonstrated that MBS did not change the sensitivity of clinical exam, but change the sensitivity of clinical exam, but did make the evaluation more specificdid make the evaluation more specific

Laryngoscopy

Modified Barium Modified Barium SwallowSwallow

Stasis of contrast at the level of the pyriform sinuses (blue arrows) with subsequent aspiration (yellow arrows)

Tube FeedingTube Feeding

Short term dysphagiaShort term dysphagia– In moderately disabled CVA patients In moderately disabled CVA patients

with dysphagia, tube feeding has with dysphagia, tube feeding has been shown to be associated with been shown to be associated with less pneumonia than oral feeds less pneumonia than oral feeds (54% vs. 13%, p<0.001) for stroke (54% vs. 13%, p<0.001) for stroke patients with dysphagia (Nakajoh)patients with dysphagia (Nakajoh)

PreventionPrevention

HOB elevated 30-45 degreesHOB elevated 30-45 degrees Oral decontamination with Oral decontamination with

chlorhexidinechlorhexidine Chin down - helps to narrow the airwayChin down - helps to narrow the airway Head tilt to stronger side when Head tilt to stronger side when

swallowingswallowing

PreventionPrevention

*Substance P*Substance PBelieved to play a major role in the coughBelieved to play a major role in the cough

and swallow sensory pathways and swallow sensory pathways

*ACE*ACE inhibitorsinhibitors prevent prevent breakdown of substance Pbreakdown of substance P

576 elderly patients with HTN: 3% 576 elderly patients with HTN: 3% pneumonia in those treated with ACEI pneumonia in those treated with ACEI vs. 9% in those treated with Ca channel vs. 9% in those treated with Ca channel blocker.blocker.

ReferencesReferences

Haruka Tohara, Eiichi Saitoh, Keith A. Mays, Keith Kuhlemeier and Jeffrey B. Palmer; Three Tests for Predicting Aspiration without Videofluorography; Dysphagia. 2003 Spring;18(2):126-34

Li, I. Feeding tubes in patients with severe dementia. American Family Physician. 2002 Apr 15;65(8):1605-10, 1515

Marek, PE. Aspiration pneumonia and dysphagia in the elderly. Chest. 2003 Jul;124(1):328-36

Paintal, HS. Kuschner, WG. Aspiration syndromes: 10 clinical pearls every physician should know. Int J Clinical Practice.2007 May;61(5):846-52.

Uptodate

www.radiologyassistant.nl/en/440bca82f1b77

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Aspiration Pneumonia Aspiration Pneumonia by by Dr.jarahzadeh Dr.jarahzadeh Intensivist Intensivist.

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