Aspiration pneumonitis and aspiration pneumonia

Publication: 01/01/2009  
Last review: 20/09/2017  
Next review: 01/09/2020  
Clinical Guideline
CURRENT 
ID: 1869 
Approved By: Improving Antimicrobial Prescribing Group 
Copyright© Leeds Teaching Hospitals NHS Trust 2017  

 

This Clinical Guideline is intended for use by healthcare professionals within Leeds unless otherwise stated.
For healthcare professionals in other trusts, please ensure that you consult relevant local and national guidance.

Prevention and treatment of aspiration pneumonitis and aspiration pneumonia in adults

Summary
Aspiration pneumonitis and aspiration pneumonia

Prevention
The following groups are at increased risk of aspiration pneumonia therefore complete a swallowing test in these patients

  • Stroke - up to 45% unsafe to swallow on first day after event. Pneumonia is the commonest non-neurological complication in the first week occurring in up to 21% by discharge.
  • Multiple sclerosis
  • Parkinson’s disease
  • Motor Neurone Disease
  • Any neurological disorder resulting in dysphagia
  • Altered conscious level and inability to protect airway
  • Any upper gastro-intestinal pathology with increased risk of gastric reflux
  • Nasogastric and PEG tubes, even if nil by mouth

Reduce aspiration risk in tube fed patients:

  • Keep > 300 head up
  • Involve dietitians whenever tube feeding is contemplated
  • Build up feed regimes slowly as per protocol
  • Use the out of hours feeding policy when necessary to initiate feeding urgently
  • Avoid excessive infusion rates (start at low rate of 30mL/hour and up to 150 mL/hour is usually well tolerated)
  • Attend to oro-pharyngeal hygiene rigorously as these patients have higher colonisation rates with pathogenic organisms and this is thought to contribute to the chest sepsis after aspiration episodes
  • Prokinetic agents (such as domperidone 10mg 8-hourly) may be used but have limited evidence of benefit
  • Post-pyloric tubes have limited evidence of benefit

Key diagnostic criteria: See HAP guideline

Investigations required: See HAP guideline

Empirical (initial) antimicrobial treatment: See table 1.
If previous microbiology results are available i.e. is the patient colonised with particular strains of bacteria, consider discussion with microbiology.

Table 1: Antimicrobial management of aspiration pneumonia.
 

No penicillin allergy

Penicillin allergy

Mildx Infection

Amoxicillin electronic Medicines Compendium information on Amoxicillin PO 500mg 8 hourly
and
Metronidazole electronic Medicines Compendium information on Metronidazole PO 400mg 8 hourly

Clarithromycin electronic Medicines Compendium information on Clarithromycin 500mg PO 12 hourly
and
Metronidazole electronic Medicines Compendium information on Metronidazole 400mg PO 8 hourly

Moderate to Severex Infection or IV therapy

Piperacillin/tazobactam electronic Medicines Compendium information on Piperacillin/tazobactam IV 4.5g 8 hourly

Teicoplanin electronic Medicines Compendium information on Teicoplanin IV (see dosing guideline)
and
Metronidazole electronic Medicines Compendium information on Metronidazole IV 500mg 8 hourly
and
Ciprofloxacin IV 400mg 12-hourly

x severity of infection is based on clinician assessment.

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Background

Aspiration pneumonitis and pneumonia are thought to be common causes of hospital-acquired pneumonia (HAP) but exact figures depend on the patient population studied and definitions used.
Aspiration pneumonia refers to the pulmonary consequences resulting from the abnormal entry of fluid, particulate exogenous substances, or endogenous secretions into the lower airways. There are usually two requirements to produce aspiration pneumonia:

  • Compromise in the usual defenses that protect the lower airways including glottic closure, cough reflex, and other clearing mechanisms
  • An inoculum deleterious to the lower airways by a direct toxic effect, stimulation of an inflammatory process from a large enough bacterial inoculum, or obstruction due to a sufficient volume of material or particulate matter

Most cases of pneumonia arise following the aspiration of microorganisms from the oral cavity or nasopharynx. The term aspiration pneumonia should be reserved for pneumonitis resulting from the altered clearance defenses noted above. The pathogens that commonly produce pneumonia, such as Streptococcus pneumoniae, Haemophilus influenzae, gram-negative bacilli, and Staphylococcus aureus, are relatively virulent bacteria so that only a small inoculum is required and the aspiration is usually subtle. A true aspiration pneumonia, by convention, usually refers to an infection caused by less virulent bacteria, primarily anaerobes, which are common constituents of the normal flora in a susceptible host prone to aspiration [Evidence Level C].

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Clinical Diagnosis

Respiratory symptoms, especially dyspnoea and wheeze, are common after aspiration episodes.

Patients should be assessed by a doctor as soon as possible after such an episode and vital sign observations monitored at least 4 hourly.
If they do not have clinical features which satisfy the criteria for hospital acquired pneumonia, they should be observed closely but NOT receive antibiotics routinely. Many cases settle and are due to chemical pneumonitis, though this may be impossible to distinguish from bacterial pneumonia.

When doubt exists in particular clinical circumstances, senior medical advice should be sought [Evidence Level C and D].1

Review progress daily. In patients initially assessed as having a mild infection clinically deteriorate, manage according to the moderate-severe guidelines

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Severity Assessment

There are no recognised criteria for establishing the severity of aspiration pneumonia. A clinician must make an individual assessment to classify a patient as mild or moderate-severe severity [Evidence Level D].

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Investigation

See Hospital Acquired Pneumonia guideline

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Treatment
Non-Antimicrobial Treatment

Prevention
At risk patients
Certain patients are at higher risk of aspiration episodes and these are those with:

  • Stroke - up to 45% unsafe to swallow on first day after event. Pneumonia is the commonest non-neurological complication in the first week occurring in up to 21% by discharge.
  • Multiple sclerosis
  • Parkinson’s disease
  • Motor Neurone Disease
  • Any neurological disorder resulting in dysphagia
  • Altered conscious level and inability to protect airway
  • Any upper gastro-intestinal pathology with increased risk of gastric reflux
  • Nasogastric and PEG tubes, even if nil by mouth

Screening
All stroke patients MUST be screened on admission for dysphagia using a standardised swallow assessment, described on the stroke clerking proforma.
Other patients in high risk groups should be tested if any clinical suspicion of dysphagia from the history, any weight loss or recurrent chest infections.
Patients noted to be coughing persistently, particularly on liquids, should be screened with a standardised test swallow for neurological dysphagia as below [Evidence Level C].
Patients with moderate to severe dementia, of whatever cause, present particular challenges in management. It is important to involve senior clinicians as soon as possible because ethical and communication dilemmas occur. Often, when dementia progresses to the point where swallowing function is affected, artificial tube feeding does not alter the outcome in terms of survival and quality of life. A policy of careful hand feeding with the optimal consistency of feed and fluids is often more acceptable [Evidence Level D].

Standardised Swallow Test [Evidence Level B]
Ensure patient is sat upright and alert. The test may be performed by any dysphagia trained member of staff.

Reducing aspiration risks
To reduce aspiration risk in tube fed patients:

  • Keep > 300 head up
  • Involve dietitians whenever tube feeding is contemplated
  • Build up feed regimes slowly as per protocol
  • Use the out of hours feeding policy when necessary to initiate feeding urgently
  • Avoid excessive infusion rates (start at low rate of 30mL/hour and up to 150 mL/hour is usually well tolerated)
  • Attend to oro-pharyngeal hygiene rigorously as these patients have higher colonisation rates with pathogenic organisms and this is thought to contribute to the chest sepsis after aspiration episodes
  • Prokinetic agents (such as domperidone 10mg tds) may be used but have limited evidence of benefit
  • Post-pyloric tubes have limited evidence of benefit

Non antimicrobial therapy

Ensure swallow test has been completed and review all measures to reduce aspirations have been completed.

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Empirical Antimicrobial Treatment

Aspiration pneumonia: aetiology
Streptococci and anaerobes have been identified as the cause of community acquired aspiration pneumonia where sample collection has been of good quality (transtracheal aspirates). In studies where sample collection was less good e.g. tracheal aspirates and in hospital acquired aspiration pneumonia, coliforms and S. aureus have been isolated in patients with aspiration pneumonia. It is unclear if these bacteria represent infecting or colonising isolates. Where the severity of infection is mild treatment is directed against streptococci and anaerobes. Treatment of mild-moderate aspiration pneumonia with clindamycin has been shown to be as effective as treatment with a co-amoxiclav equivalent and a carbapenem5. Clindamycin covers only Gram positive bacteria (staphylococci and streptococci) and anaerobes supporting our mild aspiration pneumonia regime which covers streptococci and anaerobes.

Where severity is moderate to severe, using the precautionary principal, S.aureus and coliform cover is also provided [Evidence Level C and D].2/3/4

In the event of an acute witnessed aspiration episode, commencing prophylactic antibiotic is not normally indicated. In this situation, instigate usual conservative management and observe. If the patient is improving after 36 hours antimicrobial therapy is not normally required.

Treatment

For empirical therapy see table 1. If previous microbiology results are available i.e. is the patient colonised with particular strains of bacteria, consider discussion with microbiology. Review progress daily. In patients initially assessed as having a mild infection clinically deteriorate, manage according to the moderate-severe guidelines

Table 1: Antimicrobial management of aspiration pneumonia.
 

No penicillin allergy

Penicillin allergy

Mildx Infection

Amoxicillin electronic Medicines Compendium information on Amoxicillin PO 500mg 8 hourly
and
Metronidazole electronic Medicines Compendium information on Metronidazole PO 400mg 8 hourly

Clarithromycin electronic Medicines Compendium information on Clarithromycin 500mg PO 12 hourly
and
Metronidazole electronic Medicines Compendium information on Metronidazole 400mg PO 8 hourly

Moderate to Severex Infection or IV therapy

Piperacillin/tazobactam electronic Medicines Compendium information on Piperacillin/tazobactam IV 4.5g 8 hourly

Teicoplanin electronic Medicines Compendium information on Teicoplanin IV (see dosing guideline)
and
Metronidazole electronic Medicines Compendium information on Metronidazole IV 500mg 8 hourly
and
Ciprofloxacin IV 400mg 12-hourly

x severity of infection is based on clinician assessment.

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Directed Antimicrobial Treatment (when microbiology results are known)

Directed Therapy (for specific HAP pathogens) [Evidence Level C]:

Sputum results may represent colonisation of the upper respiratory tract and not infection. Therefore assess the patient’s response to empirical therapy before changing to directed antimicrobial therapy.

Anaerobic cover should be maintained in all directed therapy regimes. Metronidazole electronic Medicines Compendium information on Metronidazole and Piperacillin/tazobactam electronic Medicines Compendium information on Piperacillin/tazobactam have anaerobic cover.

Methicillin-susceptible Staphylococcus aureus

Discuss with microbiology to review susceptibilities.
IV Flucloxacillin electronic Medicines Compendium information on Flucloxacillin 1g 6 hourly may need adding to treatments for mild infection.

Methicillin-resistant Staphylococcus aureus
If previous positive culture(s) for MRSA consider adding cover for MRSA with either:

1st line PO/IV Linezolid electronic Medicines Compendium information on Linezolid *600mg 12 hourly or 2nd line IV Teicoplanin electronic Medicines Compendium information on 

Teicoplanin (see dosing guideline) *Linezolid electronic Medicines Compendium information on 

Linezolid has a number of drug interactions/contraindications. Please see full guidance to check suitability for the patient.

Gram-negative bacilli (e.g. Coliforms, Acinetobacter baumannii, Stenotrophomonas maltophilia).
Therapy should be targeted on a case-by-case basis, dependent on the susceptibilities of the causative organism. Please discuss these cases with the duty microbiologist for further advice and approval
Pseudomonas aeruginosa
IV Piperacillin/tazobactam electronic Medicines Compendium information on Piperacillin/tazobactam 4.5g 8 hourly

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Duration of Treatment
Review daily after 72 hours

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Switch to oral agent(s)

Suggest complete IV therapy if initiated on empirical therapy.
Metronidazole electronic Medicines Compendium information on Metronidazole PO can be considered as equivalent to IV Metronidazole electronic Medicines Compendium information on Metronidazole .

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Treatment Failure
Discuss with a microbiologist.

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Referral Criteria

Referral and referral tests
When possible neurological dysphagia is detected, referral to speech and language therapy (SALT) is recommended. Further techniques such as videofluoroscopy (VF) and/or functional endoscopic evaluation of swallowing (FEES) may be very useful. VF is a procedure using radiolabelled boluses of food and taking video images of swallowing so it can be analysed in detail by SALT and radiologist together. In particular, clinically silent aspiration can be detected i.e. with no cough or wheeze etc triggered. Different consistencies may be used to find the safest and most well tolerated. FEES is an endoscopic technique which allows direct visualisation of the swallowing mechanism and any aspiration again with different consistencies. Both techniques are well validated and, in general, local expertise and availability determine which is more frequently utilised.

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Provenance

Record: 1869
Objective:

Aims

  • To improve the prevention and treatment of aspiration pneumonitis and aspiration pneumonia.

Objectives

  • To provide evidence-based recommendations for appropriate prevention and treatment of aspiration pneumonitis and aspiration pneumonia.
  • To provide evidence-based recommendations for appropriate prevention and non-antimicrobial management of aspiration pneumonitis and aspiration pneumonia.
  • To provide evidence-based recommendations for appropriate empirical and directed antimicrobial therapy of aspiration pneumonitis and aspiration pneumonia.
  • To recommend appropriate dose, route of administration and duration of antimicrobial agents.
  • To advise in the event of antimicrobial allergy.
  • To set-out criteria for referral to specialists.
Clinical condition:

Prevention and treatment of aspiration pneumonitis and aspiration pneumonia.

Target patient group:
Target professional group(s): Secondary Care Doctors
Pharmacists
Adapted from:

Evidence base

  1. Pulmonary aspiration of gastric contents. Bynum LJ, Pierce AK. Am Rev Respir Dis. 1976;114(6):1129.
  2. Bacteriology of aspiration pneumonia. A prospective study of community- and hospital-acquired cases.Lorber B, Swenson RM. Ann Intern Med. 1974;81(3):329.
  3. Bacteriology of aspiration pneumonia in children. Brook I, Finegold SMPediatrics. 1980;65(6):1115.
  4. Etiology and outcome of community-acquired lung abscess.AUTakayanagi N, Kagiyama N, Ishiguro T, Tokunaga D, Sugita YSORespiration. 2010;80(2):98.
  5. Kadowaki M, Demura Y, Mizuno S, Uesaka D, Ameshima S, Miyamori I, Ishizaki T. Reappraisal of clindamycin IV monotherapy for treatment of mild-to-moderate aspiration pneumonia in elderly patients. Chest. 2005 Apr;127(4):1276-82.

Evidence levels:
A. Meta-analyses, randomised controlled trials/systematic reviews of RCTs
B. Robust experimental or observational studies
C. Expert consensus.
D. Leeds consensus. (where no national guidance exists or there is wide disagreement with a level C recommendation or where national guidance documents contradict each other)

Approved By

Improving Antimicrobial Prescribing Group

Document history

LHP version 1.0

Related information

Not supplied

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