Management of Aspiration Pneumonia in Critically Ill Patients: Review of Modern Trends
Ahmed Abdel Aziz Abdel Haliem Amer;
Abstract
Aspiration is defined as the inhalation of either oropharyngeal or gastric contents into the lower airways, that is, the act of taking foreign material into the lungs. This can cause a number of syndromes determined by the quantity and nature of the aspirated material, the frequency of aspiration, and the host factors that predispose the patient to aspiration and modify the response.
Specific predisposing factors for aspiration pneumonia focus on the risk for high frequency and/or large volume of aspiration. Some risks may be more pertinent for the macroaspiration characteristic of aspiration pneumonitis or anaerobic pleuropneumonia than for microaspiration. Additionally, factors that influence the resident bacterial flora leading to colonization by more virulent pathogens, which are more likely to overwhelm the normal protective mechanisms, also play a role in development of clinical disease.
Aspiration pneumonia can be a grave illness despite treatment, so prevention is important. Several randomized trials have been investigated to prevent aspiration pneumonia, but most are limited by enrollment.
There is no “gold standard” test to diagnose aspiration pneumonia. Furthermore, in patients with aspiration pneumonia, unlike the case of aspiration pneumonitis, the episode of aspiration is generally not witnessed. The diagnosis is therefore inferred when a patient with known risk factors for aspiration develops clinical features compatible with pneumonia (fever, shortness of breath, purulent sputum) with an infiltrate in a characteristic bronchopulmonary segment.
Like all pneumonias, the diagnosis of aspiration pneumonia rests mostly on the history of presenting illness, medical history, vital signs, and chest radiograph. In clinical practice, aspiration pneumonia is most often coded as the diagnosis when a new chest radiograph infiltrate in a dependent pulmonary segment is found in patients with risk factors for aspiration. In a bed-bound patient, the dependent pulmonary segments are the posterior segments of the upper lobes and the superior segments of the lower lobes. In ambulatory patients, lower lobes are classically involved, especially the right.
Bronchoscopy provides easy and relatively safe access to material in the tracheobronchial tree and distal alveolar spaces. A very useful bronchoscopic technique is BAL. Normal saline solution, devoid of any bacteriostatic material, is instilled into distal air spaces through the “wedged” bronchoscope and then aspirated through the instruments suction channel. The fluid collected in this manner is analyzed for gross appearance. The fluid may also be subjected to a variety of tests Microbiological testing, specific cytological analysis and cell count, immunological parameters, presence of various biochemical mediators related to pathological processes, tissue markers, polymerase chain reaction, electron microscopy, flow cytometry, and DNA probes.
The upper airway should be suctioned following a witnessed aspiration. Endotracheal intubation should be considered in patients who are unable to protect their airway. While common practice, the prophylactic use of antibiotics in patients with suspected or witnessed aspiration is not recommended. Similarly, the use of antibiotics shortly after an aspiration episode in a patient who develops a fever, leukocytosis, and a pulmonary infiltrate is discouraged as it may select for more resistant organisms in a patient with an uncomplicated chemical pneumonitis. However, empiric antimicrobial therapy is appropriate in patients who aspirate gastric contents in the setting of small bowel obstruction or in other circumstances associated with colonization of gastric contents.
Antimicrobial therapy should be considered in patients with an aspiration pneumonitis that fails to resolve within 48 hours. Empiric therapy with broad spectrum agents is recommended. Antimicrobials with anaerobic activity are not routinely required.
Antimicrobial therapy is indicated in patients with aspiration pneumonia. The choice of antibiotics should depend on the setting in which the aspiration occurs as well as the patient’s premorbid condition. This includes such factors as whether the aspiration occurred in the community or in a healthcare facility (healthcare-associated pneumonia [HCAP]) and patient characteristics such as alcoholism, oral hygiene, intravenous drug abuse, and the recent use of antibiotics or acid suppressive therapy.
Tube feeding is not essential in all patients who aspirate. Short-term tube feeding, however, may be indicated in elderly patients with severe dysphagia and aspiration in whom improvement of swallowing is likely to occur.
An aggressive protocol of oral care will reduce colonization with potentially pathogenic organisms and decrease the bacterial load, measures that have been demonstrated to reduce the risk of aspiration pneumonia
The prognosis of both chemical pneumonitis and bacterial aspiration pneumonia is dependent on underlying diseases, complications, and the patient's health status
Specific predisposing factors for aspiration pneumonia focus on the risk for high frequency and/or large volume of aspiration. Some risks may be more pertinent for the macroaspiration characteristic of aspiration pneumonitis or anaerobic pleuropneumonia than for microaspiration. Additionally, factors that influence the resident bacterial flora leading to colonization by more virulent pathogens, which are more likely to overwhelm the normal protective mechanisms, also play a role in development of clinical disease.
Aspiration pneumonia can be a grave illness despite treatment, so prevention is important. Several randomized trials have been investigated to prevent aspiration pneumonia, but most are limited by enrollment.
There is no “gold standard” test to diagnose aspiration pneumonia. Furthermore, in patients with aspiration pneumonia, unlike the case of aspiration pneumonitis, the episode of aspiration is generally not witnessed. The diagnosis is therefore inferred when a patient with known risk factors for aspiration develops clinical features compatible with pneumonia (fever, shortness of breath, purulent sputum) with an infiltrate in a characteristic bronchopulmonary segment.
Like all pneumonias, the diagnosis of aspiration pneumonia rests mostly on the history of presenting illness, medical history, vital signs, and chest radiograph. In clinical practice, aspiration pneumonia is most often coded as the diagnosis when a new chest radiograph infiltrate in a dependent pulmonary segment is found in patients with risk factors for aspiration. In a bed-bound patient, the dependent pulmonary segments are the posterior segments of the upper lobes and the superior segments of the lower lobes. In ambulatory patients, lower lobes are classically involved, especially the right.
Bronchoscopy provides easy and relatively safe access to material in the tracheobronchial tree and distal alveolar spaces. A very useful bronchoscopic technique is BAL. Normal saline solution, devoid of any bacteriostatic material, is instilled into distal air spaces through the “wedged” bronchoscope and then aspirated through the instruments suction channel. The fluid collected in this manner is analyzed for gross appearance. The fluid may also be subjected to a variety of tests Microbiological testing, specific cytological analysis and cell count, immunological parameters, presence of various biochemical mediators related to pathological processes, tissue markers, polymerase chain reaction, electron microscopy, flow cytometry, and DNA probes.
The upper airway should be suctioned following a witnessed aspiration. Endotracheal intubation should be considered in patients who are unable to protect their airway. While common practice, the prophylactic use of antibiotics in patients with suspected or witnessed aspiration is not recommended. Similarly, the use of antibiotics shortly after an aspiration episode in a patient who develops a fever, leukocytosis, and a pulmonary infiltrate is discouraged as it may select for more resistant organisms in a patient with an uncomplicated chemical pneumonitis. However, empiric antimicrobial therapy is appropriate in patients who aspirate gastric contents in the setting of small bowel obstruction or in other circumstances associated with colonization of gastric contents.
Antimicrobial therapy should be considered in patients with an aspiration pneumonitis that fails to resolve within 48 hours. Empiric therapy with broad spectrum agents is recommended. Antimicrobials with anaerobic activity are not routinely required.
Antimicrobial therapy is indicated in patients with aspiration pneumonia. The choice of antibiotics should depend on the setting in which the aspiration occurs as well as the patient’s premorbid condition. This includes such factors as whether the aspiration occurred in the community or in a healthcare facility (healthcare-associated pneumonia [HCAP]) and patient characteristics such as alcoholism, oral hygiene, intravenous drug abuse, and the recent use of antibiotics or acid suppressive therapy.
Tube feeding is not essential in all patients who aspirate. Short-term tube feeding, however, may be indicated in elderly patients with severe dysphagia and aspiration in whom improvement of swallowing is likely to occur.
An aggressive protocol of oral care will reduce colonization with potentially pathogenic organisms and decrease the bacterial load, measures that have been demonstrated to reduce the risk of aspiration pneumonia
The prognosis of both chemical pneumonitis and bacterial aspiration pneumonia is dependent on underlying diseases, complications, and the patient's health status
Other data
| Title | Management of Aspiration Pneumonia in Critically Ill Patients: Review of Modern Trends | Other Titles | علاج الالتهاب الرئوي التنفسي لدى المرضى ذوي الحالات الحرجة مع استعراض الاتجاهات الحديثة | Authors | Ahmed Abdel Aziz Abdel Haliem Amer | Issue Date | 2016 |
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