Aspiration Pneumonia/Pneumonitis (When to Treat)

Report
Aspiration Pneumonia/Pneumonitis
(Treatment)
Sepehr Khashaei
Assistant Professor of Internal Medicine
University of New Mexico
• Aspiration is a common event even in
healthy individual and usually resolves
without detectable sequelae.
• Most pneumonia arises following the
microaspiration of organisms from
the oral cavity or nasopharynx.
• The pathogens that commonly produce
pneumonia, such as streptococcus
pneumoniae, H. influenzae, gram-negative
bacilli, and Staph aureus, are relatively
virulent bacteria so that only a small inoculum
is required and the aspiration is usually subtle.
Classification of aspiration syndromes
• Aspiration (chemical) pneumonitis
• Secondary bacterial infection of chemical
pneumonitis
• Primary bacterial aspiration pneumonia
• Aspiration pneumonia/pneumonitis statistics
(overall incidence is hard to ascertain):
 5-15% of CAP
 18% of pneumonias in nursing home residents
 Aspiration pneumonitis occurs in approximately
10% of patients who are hospitalized after a drug
overdose.
 Aspriration pneumonitis is a complication of
general anesthesia, occurring in approximately 1
of 3,000 operations in which anesthesia is
administered and accounting for 10-30 % of all
deaths associated with anesthesia.
• In most aspirations, CXR or CT scan
usually show infiltrate in the most
dependent regions of the lung:
–If aspiration occurs while the patient is
supine, the posterior segments of the
upper lobes and the apical segments
of the lower lobes are most affected.
–If aspiration occurs while the patient is
upright, the basal segments of the
lower lobes are most affected.
• Conditions that predispose to aspiration
pneumonia:
– Reduced consciousness (cause decreased cough
reflux and compromise in glottis closure): e.g. HE,
alcohol, drugs, etc.
– Dysphagia from neurologic deficits
– Gastric reflux/esophageal disease
– Surgery involving the upper airway or esophagus
– Endotracheal intubation
– Bronchoscopy/upper endoscopy
– Nasogastric/gastrostomy feeding especially with
recombent position
– Protracted vomiting
• A history of coughing while eating or
drinking is likely to indicate aspiration but
aspiration may also be silent.
• Dysphagia can easily be confirmed with a
bedside swallowing test using fluids in
various volumes and consistencies, or by
use of videofloroscopic swallow studies.
• The use of percutaneous endoscopic
gastrostomy tube has NOT been shown to be
superior to the use of nasogastric tube for
preventing aspiration.
• Feeding tubes offer no protection from
colonized oral secretions, which are serious
threat to patients with dysphagia.
• Over the long term, aspiration pneumonia is
the most common cause of death in patients
fed by gastrostomy tube.
• The most common symptoms of aspiration
pneumonia are: dyspnea and cough.
• The most common physical findings of
aspiration pneumonia are cyanosis, fever,
tachycardia, rhonchi, rales, and wheezes.
Aspiration (chemical) Pneumonitis
• Aspiration of large volume sterile acidic
gastric contents into the lower airways.
• Symptoms can range from asymptomatic to
severe dysnea, hypoxia, cough, and low grade
fever.
• Symptoms may develop quickly (1-2 hours).
• Clinical course (per one study with 88
patients):
– 62% improvement of symptoms with resolution of
infiltrates within 2-4 days
– 26% improve initially but worsen as a secondary
bacterial infection sets in (this is called secondary
bacterial infection of chemical pneumonitis).
– 12% deteriorate quickly, within 24 to 36 hours,
with hypoxic respiratory failure and ARDS.
• Because gastric acid prevents the growth of
bacteria, the contents of the stomach are
sterile under normal conditions.
• Colonization of the gastric contents by
potentially pathogenic organisms may occur
when the PH in the stomach is increased by
the use of antacids, H2-blockers, or PPIs.
Aspiration Pneumonitis (Treatment)
• Uncomplicated cases: supportive measures
such as airway clearance, oxygen
supplementation, and positive pressure
ventilation.
• Antibiotics do not seem to alter the clinical
outcome, including radiographic resolution,
duration of hospitalization, or death rate, nor
do they influence the subsequent
development of infection.
• Patients with an observed aspiration should
have immediate tracheal suction to clear
fluids and particulate matter that may cause
obstruction. However, this maneuver will not
protect the lungs from chemical injury, which
occurs instantly in a manner that has been
compared with “flash burn”.
• Bronchodilators can be used to treat the
underlying bronchospasm.
• At times chemical pneumonitis can be difficult
to differentiate from bacterial aspiration
pneumonia, and in this situation whether to
give antibiotics is controversial.
• In cases of witnessed or strongly suspected
aspiration of gastric contents, antibiotics are
not warranted since bacterial infection is not
likely to be the cause of any signs or
symptoms.
• However, empiric antibiotic therapy may be
appropriate for patients who aspirate gastric
contents and who have small bowel
obstruction or other conditions associated
with colonization of the gastric contents.
• There is no role for use of corticosteroids in
treatment of aspiration pneumonia or
aspiration pneumonitis.
• If it is not clear whether the patient actually
has chemical pneumonitis or primary
bacterial aspiration pneumonia, it is prudent
to start antibiotics empirically after obtaining
lower-respiratory tract secretions for stains
and cultures, and then to reassess within 4872 hours. The antibiotics can be discontinued
if the patient had rapid clinical and
radiographic improvement and negative
cultures. Those whose condition does not
improve or who have positive cultures should
receive a full course of antibiotics.
Secondary bacterial infection of
chemical pneumonitis
• 26% of patients with aspiration chemical
pneumonitis.
• Chest radiographs show worsening of initial
infiltrate or the development of new ones.
• Treat as CAP or HAP or HCAP depending on
the time of aspiration.
• Consider anaerobic coverage if not sure if
primary or secondary.
• To detect secondary infection early, the
patient’s respiratory status should be
monitored carefully and chest radiography
should be repeated.
Primary bacterial aspiration
pneumonia
• Most cases involve anaerobic bacteria and
aerobic or microaerophilic streptococci that
normally reside in gingival crevices.
• Less common in patients with good dental
hygiene and those who are edentulous.
• A true aspiration pneumonia usually
refers to an infection caused by less
virulent bacteria, primarily anaerobes,
which are common constituents of the
normal flora in the susceptible host
prone to aspiration.
• Most patients present with the common
manifestations of pneumonia including cough,
fever, purulent sputum, and dyspnea, but the
process evolves over a period of several days
or weeks instead of hours.
• Clinical features, which are characteristic of
aspiration pneumonia involving anaerobic
bacteria, include:
– Indolent symptoms
– A predisposing condition
– Absence of rigors
– Failure to recover likely pulmonary pathogens with
cultures of expectorated sputum
– Sputum that often has a putrid odor
– Concurrent evidence of periodontal disease
– X-ray or CT scans showing evidence of pulmonary
necrosis with lung abscess and/or an empyema
– X-ray or CT showing involvement of the
dependent pulmonary segments.
• If untreated may present with:
–Lung abscess
–Necrotizing pneumonia
–Empyema secondary to a
bronchopleural fistula
• Clindamycin iv (600mg bid) followed by oral
(300mg qid) as first-line therapy.
• Alternative agents:
– Augmentin (875mg po bid) or iv Unasyn.
– Combination of metronidazole (500mg po
or iv tid) plus amoxicillin (500mg po tid) or
PCN G
– Imipenem
– Moxifloxacin, macrolides, and selected
cephalosporins are probably effective but
should not be used as first-line agents.
• Note: For nosocomial pneumonia, most
authorities feel that the companion aerobic
bacteria especially gram-negative bacilli and S.
aureus , are more important than the
anaerobes and that therapy should be
directed at these organisms.
• Duration of antibiotics:
–Arbitrary and not well studied.
–Consider 7-10 days in uncomplicated
cases
–Longer if complicated by empyema or
lung abscess.
• Prophylactic antibiotics therapy does not
prevent bacterial aspiration pneumonia and
should be avoided.
• Intravenous fluid support is also important,
particularly when there is hypotension.
• Xray film changes and frothy sputum may
suggest pulmonary edema due to CHF, but
the patient actually has intravascular volume
depletion and the central venous pressure is
low.
• At UNM, aspiration pneumonia cases
are excluded from ER measures
(Blood cultures, antibiotics within 6
hours, antibiotic regimen) but are
still included in the vaccination
measures (flu and pneumococcal)
and smoking cessation.
Conclusions for Wiki:
• Aspiration (chemical) pneumonitis: Antibiotics do not seem to alter
the clinical outcome, including radiographic resolution, duration of
hospitalization, or death rate, nor do they influence the subsequent
development of infection. Therefore, in cases of witnessed or
strongly suspected aspiration of gastric contents, antibiotics are not
warranted since bacterial infection is not likely to be the cause of
any signs or symptoms. However, empiric antibiotic therapy may be
appropriate for patients who aspirate gastric contents and who have
small bowel obstruction or other conditions associated with
colonization of the gastric contents.
• If it is not clear whether the patient actually has chemical
pneumonitis or primary bacterial aspiration pneumonia, it is
prudent to start antibiotics empirically after obtaining sputum for
stains and cultures, and then to reassess within 48-72 hours. The
antibiotics can be discontinued if the patient has rapid clinical and
radiographic improvement and negative cultures. Those whose
condition does not improve or who have positive cultures should
receive a full course of antibiotics.
• The use of percutaneous endoscopic gastrostomy tube has NOT
been shown to be superior to the use of nasogastric tube for
preventing aspiration.
References
• Berson, W. Adriani, J. Silent regurgitation and aspiration
during anesthesia. Anesthesiology 1954; 15:644.
• Smith Hammond, C. Cough and aspiration of food and liquids
due to oral pharyngeal dysphagia.
• Cameron JL, Caldini P, Toung JK, Zuidema GD. Apiration
pneumonia: physiologic data following experimental
aspiration. Surgery 1972; 72:238-245.
• Marik PE. Aspiration pneumonitis and aspiration pneumonia.
N Engl J Med 2001; 344:665-671
• Bynum LJ, Pierce AK. Pulmonary aspiration of gastric
contents. AM Rev Respir Dis 1976; 114:1129-1136.
• Arms RA, Dines, DE, Tinstman, TC. Aspiration pneumonia.
Chest 1974; 65:136-139.
• Cameron JL, Mitcell WH, Zuidema GD. Aspiration pneumonia.
Clinical outcome following documented aspiration. Arch Surg
1973; 106:49-52
References (continued)
• Daoud E,Guzman J. Are antibiotics indicated for the
treatment of aspiration pneumonia? Cleveland Clinic
Journal of Medicine, 2010;77:573-576.
• DePaso WJ. Aspiration pneumonia. Clin Chest Med 1991;
12:269-284.
• Mouw DR, Langlois JP, Turner LF, Neher JO. Clinical
inquiries. Are antibiotics effective in preventing pneumonia
for nursing home patients? J Fam Pract 2004; 53:994-996
• Barlett, JG, Gorbach, SL. The triple threat of aspiraton
pneumonia. Chest 1975; 68:560
• Lorber, B, Swenson, RM. Bacteriology of aspiration
pneumonia. A prospective study of community- and
hospital-acquired cases. Ann Intern Med 1974; 81:329.
• Levison, ME, Mangura, CT, Lorber, B, et al. Clindamycin
compared with penicillin for the treatment of anaerobic
lung abscess. Ann Intern Med 1983; 98:466.
References (continued)
• Kadowaki, M, Demura, Y, Mizuno, S, et al.
Reappraisal of clindamycin IV monotherapy for
treatment of mild-to-moderate aspiration
pneumonia in elderly patients. Chest 2005;
127:1276.
• Eykyn, SJ. The therapeutic use of metronidazole
in anaerobic infection: six years’ experience in
London hospital. Surgery 1983; 93:209.
• Sanders, CV, Hanna, BJ, Lewis, AC. Metronidazole
in the treatment of anaerobic infections. Am Rev
Respir Dis 1979; 120:337.
• Finegold, SM. Aspiration pneumonia. Rev Infect
Dis 1991; 13 Suppl 9:S737

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