Computed tomography findings of aspiration pneumonia in 53 patients

Chest and Chest Wall Manifestations in Rheumatic Diseases

Thoracic involvement is common in patients with rheumatic diseases, contributing to significant morbidity and mortality. Early detection and prompt treatment may prevent the establishment of irreversible changes, thus improving patients' outcomes. Imaging studies play a vital role in the early detection of chest and chest wall manifestations, especially in patients with subclinical disease. Familiarity with the frequently affected thoracic regions and their presentation on imaging is therefore essential for practicing radiologists to provide an accurate assessment of the disease burden and treatment response. This review summarizes the common and less well-known chest and chest wall imaging features of rheumatic diseases.

Imaging of Aspiration: When to Suspect Based on Imaging of Bacterial Aspiration, Chemical Aspiration, and Foreign Body Aspiration

Aspiration-related syndromes comprise a broad spectrum of diseases affecting the airways and lung parenchyma resulting from inadvertent entry of oropharyngeal or gastric contents into the respiratory tract. The diagnosis can be challenging given lack of self-reported symptoms and unwitnessed or silent aspiration events. Aspiration is a common finding in healthy individuals suggesting that host defenses play a critical role in the pathophysiology. In the absence of strict criterion, a high index of suspicion is necessary based on recognition of established risk factors and identification of characteristic imaging findings. Conditions predisposing to altered levels of consciousness and neuromuscular weakness can lead to dysphagia, impaired cough reflux, and subsequent aspiration. The most salient feature on imaging is the anatomic location of the abnormalities, with the superior segments of the lower lobes and posterior segments of upper lobes involved in the recumbent position, and basilar segments of lower lobes in the upright position. Acute syndromes include pneumonia, pneumonitis, and foreign body aspiration. In the more indolent form of aspiration, bronchiectasis, diffuse bronchiolitis, and interstitial lung disease can develop. A detailed understanding of associated radiographic findings for these syndromes can help to implicate aspiration as the cause for imaging abnormalities and ultimately optimize patient management.

Treatment strategy for older patients with pneumonia independent of the risk of drug resistance in the world's top country for longevity

The number of older people with impaired swallowing function increases with aging population. Aspiration pneumonia is one of the most cases of pneumonia developing among older people. As aspiration pneumonia may develop as a result of age-related deterioration, it is crucial to consider it as an unavoidable event with aging. While pneumonia is diagnosed based on respiratory symptoms and radiological features, the lung involvement of aspiration pneumonia may be undetectable via a frontal chest radiograph in some cases. Bacterial profiles show the predominance of drug-resistant bacteria, such as Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus (MRSA), but isolated bacteria from respiratory samples do not necessarily indicate causative pathogens. Furthermore, there is no evidence regarding treatment superiority using broad-spectrum antibiotics compared with narrow-spectrum antibiotics. Even if isolated pathogens are a causative factor for pneumonia among older patients, the use of broad-spectrum antibiotics covering the bacteria may not improve their outcomes. Therefore, we propose a treatment strategy independent of the risk of drug resistance focusing on the discrimination of patients who are unlikely to respond to broad-spectrum antibiotics. An aspiration risk is associated with increased in-hospital mortality in patients with pneumonia, which could also lead to a greater risk of poor long-term outcomes with increased 1-year mortality. Advance care planning is now recognized as a process for communication and medical decision-making across the life course. This approach would be widely recommended for older people with aspiration risk.

Early swallowing rehabilitation and promotion of total oral intake in patients with aspiration pneumonia: A retrospective study

OBJECTIVES

To investigate the impact of early swallowing assessment and rehabilitation on the total oral intake and in-hospital mortality in patients with aspiration pneumonia.

METHODS

We retrospectively analyzed the data of patients with aspiration admitted between September 1, 2015, and October 31, 2016. The inclusion criterion was total oral intake before admission. A new protocol-based intervention for appropriate early oral intake was implemented on April 1, 2016. The protocol consisted of two steps. First, a screening test was conducted on the day of admission to detect patients who were not at high risk of dysphagia. Second, patients underwent a modified water swallowing test and water swallowing test. Patients cleared by these tests immediately initiated oral intake. The primary outcome, the composite outcomes of no recovery to total oral intake at discharge, and in-hospital mortality were compared between the patients admitted pre- and post protocol intervention.

RESULTS

A total of 188 patients were included in the analysis (pre-, 92; post-, 96). The primary outcome did not differ between the pre- and post-intervention periods (23/92 [25.0%] vs. 18/96 [18.8%], p = 0.30). After adjusting for other variables, the intervention was significantly associated with a lower risk of composite outcomes (odds ratio, 0.22, 95%CI, 0.08-0.61, p = 0.004).

CONCLUSION

The new protocol for early swallowing assessment, rehabilitation, and promotion of oral intake in patients admitted with aspiration pneumonia may be associated with the lower risk for the composite outcomes of in-hospital mortality and no recovery to total oral intake.

Predictors of aspiration pneumonia: developing a new matrix for speech and language therapists

INTRODUCTION

The contributing factors of aspiration pneumonia have been well documented. However, there are gaps in the literature regarding identifying the weight associated with each factor and the relationship between factors.

METHOD

In this study, 20 potential predictors of aspiration pneumonia (with four additional variables) have been applied to historic Speech and Language Therapy records to greater understand the significance of each contributor of aspiration pneumonia. 152 cases with an oropharyngeal dysphagia, and a Speech and Language Therapy recommendation of eating and drinking with known aspiration and the associated potential risk of developing an aspiration pneumonia, were included in the data. These were inpatients and outpatients, and had various diagnoses but all had had a videofluoroscopy.

RESULTS

Logistic regression analysis found seven factors that were individually significant in predicting the development of aspiration pneumonia with 84.93% sensitivity and 91.03% specificity DISCUSSION: Logistic regression and random forest analyses led to the proposal of a new matrix of predictors of aspiration pneumonia with respective scoring weights for individual and cumulative contributors (a direction for future research).

CT appearances of gastric injury due to caustic ingestion and associated findings (a study of 30 cases)

The mortality and morbidity of acute caustic gastric injuries are high. The spectrum of gastric injury due to caustic ingestion varies from hyperemia, erosion, and extensive ulcers to mucosal necrosis. Severe transmural necrosis can be associated with fistulous complications in the acute and subacute phases and stricture formation in the chronic phase. Due to these important clinical implications, timely diagnosis and appropriate management of gastric caustic injury are crucial, and endoscopy plays a pivotal role. However, critically ill patients or those with overt peritonitis and shock cannot undergo endoscopy. Thoraco-abdominal computed tomography (CT) is preferable to endoscopy as it avoids the risk of esophageal perforation and allows the evaluation of the entire gastrointestinal tract, as well as of the surrounding organs. With the advantage of not being invasive, CT scan has a promising role in the early evaluation of caustic injury. It has an increasing role in the emergency setting with good accuracy in identifying patients who are likely to benefit from surgery. In this pictorial essay, we present the CT spectrum of caustic injury of stomach and associated thoraco-abdominal injuries, with clinical follow-up.

Clinical decision-making using an assessment protocol of swallowing function after aspiration pneumonia: a comparative retrospective study

Objective: Aspiration pneumonia is a challenge in Japan, with many elderly citizens; however, there are insufficient experts on swallowing. Non-expert doctors may suspend oral intake for an overly long period because of the fear of further aspiration. We devised and modified an assessment protocol for swallowing function with reference to the Japanese and American practical guidelines for dysphagia. This study aimed to demonstrate clinical decision-making using the protocol by reporting the results of decisions on the safe and timely restart of adequate food intake for patients with aspiration pneumonia. Patients and Methods: This comparative retrospective study included 101 patients hospitalized with aspiration pneumonia between April 2015 and November 2017. We compared the parameters of patients for whom decisions on resumption of oral intake were aided by our protocol against those of patients from the previous year when the protocol was not used. We counted the days until either resumption of oral intake or events of aspiration/choking. Results: The duration of days until oral intake in the two groups was 1.64 ± 2.34 days in the protocol group (56 patients) and 2.09 ± 2.30 days in the control group (45 patients) (P=0.52). The adverse events of aspiration/choking were less frequent in the protocol group (5 vs. 15, odds ratio (OR) 0.32, P<0.001) as compared to the control group. The protocol group showed a significant reduction in aspiration/choking (OR 0.19, P<0.01). Conclusion: Clinical decision-making based on the protocol seems to help non-expert doctors make informed decisions regarding resuming oral intake after aspiration pneumonia.

Viewpoint: a multidisciplinary approach to the assessment of patients with systemic sclerosis-associated interstitial lung disease

Systemic sclerosis (SSc) is a rare and heterogeneous disease affecting the skin and internal organs. SSc-associated ILD (SSc-ILD) is a common and often early manifestation of SSc. This article discusses the rationale for a multidisciplinary approach (MDA) to the early identification and assessment of patients with SSc-ILD. Diagnosis of SSc-ILD is often challenging as patients with early disease can be asymptomatic, and SSc-ILD symptoms, such as exertional dyspnea and cough, are non-specific. High-resolution computed tomography (HRCT) of the lungs is the gold standard for diagnosis of SSc-ILD since pulmonary function tests lack sensitivity and specificity, especially in early disease. On HRCT, most patients with SSc-ILD have a non-specific interstitial pneumonia (NSIP) pattern. In addition, findings of pulmonary hypertension and esophageal dysmotility may be present. The multi-organ involvement of SSc and the diverse spectrum of symptoms support an MDA for the diagnosis and assessment of patients with SSc-ILD, with input from rheumatologists, pulmonologists, gastroenterologists, radiologists, and other specialists. Key Points • Interstitial lung disease (ILD) is a common manifestation of systemic sclerosis (SSc). • Early diagnosis is key to reducing the morbidity and mortality associated with SSc-ILD and other manifestations of SSc. • The multi-organ involvement of SSc supports a multidisciplinary approach to the diagnosis and assessment of patients with SSc-ILD, with input from rheumatologists, pulmonologists, gastroenterologists, radiologists, and other specialists.

Computed tomographic findings in dogs with suspected aspiration pneumonia: 38 cases (2014‐2019)

OBJECTIVES

To describe computed tomographic (CT) findings in dogs diagnosed with aspiration pneumonia and to assess for any correlation with patient outcome.

MATERIALS AND METHODS

Retrospective analysis of 38 cases with a presumptive diagnosis of aspiration pneumonia at two UK referral centres. Medical records were reviewed for signalment, history, physical examination and clinicopathologic data. CT examinations of the thorax were reviewed by the European College of Veterinary Diagnostic Imaging board-certified radiologist for all dogs to describe the characteristics and distribution of the pulmonary lesions.

RESULTS

The most common CT findings were lung lobe consolidation associated with air bronchograms (100%) followed by ground-glass attenuation (89.4%), bronchial wall thickening (36.8%), bronchiolectasis (31.5%) and bronchiectasis (15.7%). Large-breed dogs were overrepresented. Duration of hospitalisation ranged between 0 and 8 days (mean 3 days). Overall, 89.4% of dogs survived the aspiration event and were discharged from the hospital. The four dogs that did not survive to discharge had five or more lobes affected on CT.

CLINICAL SIGNIFICANCE

CT findings in dogs with aspiration pneumonia are described. CT is a useful imaging modality to diagnose aspiration pneumonia.

Challenges in the Differential Diagnosis of COVID-19 Pneumonia: A Pictorial Review

COVID-19 pneumonia represents a maximum medical challenge due to the virus's high contagiousness, morbidity, and mortality and the still limited possibilities of the health systems. The literature has primarily focused on the diagnosis, clinical-radiological aspects of COVID-19 pneumonia, and the most common possible differential diagnoses. Still, few studies have investigated the rare differential diagnoses of COVID-19 pneumonia or its overlap with other pre-existing lung pathologies. This article presents the main radiological features of COVID-19 pneumonia and the most common alternative diagnoses to establish the vital radiological criteria for a differential diagnosis between COVID-19 pneumonia and other lung pathologies with similar imaging appearance. The differential diagnosis of COVID-19 pneumonia is challenging because there may be standard radiologic features such as ground-glass opacities, crazy paving patterns, and consolidations. A multidisciplinary approach is crucial to define a correct final diagnosis, as an overlap of COVID-19 pneumonia with pre-existing lung diseases is often possible and suggests possible differential diagnoses. An optimal evaluation of HRTC can help limit the clinical evolution of the disease, promote therapy for patients and ensure an efficient allocation of human and economic resources.

The diagnosis of aspiration pneumonia in older persons: a systematic review

PURPOSE

Community-acquired pneumonia (CAP) is highly common across the world. It is reported that over 90% of CAP in older adults may be due to aspiration. However, the diagnostic criteria for aspiration pneumonia (AP) have not been widely agreed. Is there a consensus on how to diagnose AP? What are the clinical features of patients being diagnosed with AP? We conducted a systematic review to answer these questions.

METHODS

We performed a literature search in MEDLINE®, EMBASE, CINHAL, and Cochrane to review the steps taken toward diagnosing AP. Search terms for "aspiration pneumonia" and "aged" were used. Inclusion criteria were: original research, community-acquired AP, age ≥ 75 years old, acute hospital admission.

RESULTS

A total of 10,716 reports were found. Following the removal of duplicates, 7601 were screened, 95 underwent full-text review, and 9 reports were included in the final analysis. Pneumonia was diagnosed using a combination of symptoms, inflammatory markers, and chest imaging findings in most studies. AP was defined as pneumonia with some relation to aspiration or dysphagia. Aspiration was inferred if there was witnessed or prior presumed aspiration, episodes of coughing on food or liquids, relevant underlying conditions, abnormalities on videofluoroscopy or water swallow test, and gravity-dependent distribution of shadows on chest imaging. Patients with AP were older, more frailer, and had more comorbidities than in non-AP.

CONCLUSION

There is a broad consensus on the clinical criteria to diagnose AP. It is a presumptive diagnosis with regards to patients' general frailty rather than in relation to swallowing function itself.

Radiological patterns and prognosis in elderly patients with acute Klebsiella pneumoniae pneumonia: A retrospective study

Although Klebsiella pneumoniae pneumonia is an insidious threat among the elderly, the role of radiological features has not been elucidated. We aimed to evaluate thin-section chest computed tomography (CT) features and assess its associations with disease prognosis in elderly patients with acute K. pneumoniae pneumonia. We retrospectively included elderly patients, admitted for acute K. pneumoniae pneumonia, and investigated thin-section CT findings to determine whether bronchopneumonia or lobar pneumonia was present. The association between the radiological pattern of pneumonia and in-hospital mortality was analyzed. Eighty-six patients with acute K. pneumoniae pneumonia were included, and among them, the bronchopneumonia pattern was observed in 70 (81%) patients. Twenty-five (29%) patients died in hospital, and they had a greater incidence of lobar pneumonia pattern (40% in nonsurvivors vs 10% in survivors; P = .008), low albumin level (2.7 g/dL, range, 1.6-3.8 in nonsurvivors vs 3.0 g/dL, range, 1.7-4.2 in survivors; P = .026) and higher levels of aspartate aminotransferase (30 U/L, range, 11-186 in nonsurvivors vs 23 U/L, range, 11-102 in survivors, P = .017) and C-reactive protein (8.0 mg/dL, range, 0.9-26.5 in nonsurvivors vs 4.7 mg/dL, range, 0.0-24.0 in survivors; P = .047) on admission. Multivariate analysis showed that lobar pneumonia pattern was independently associated with increased in-hospital mortality (adjusted hazard ratio, 3.906; 95% CI, 1.513-10.079; P = .005). In elderly patients with acute K. pneumoniae pneumonia, the lobar pneumonia pattern may be less commonly observed, and this pattern could relate to poor prognosis.

Aspiration of Cerebrospinal Fluid Rhinorrhea as a Cause of Non-resolving Pneumonia

We herein report two cases of cerebrospinal fluid (CSF) rhinorrhea associated with lung infiltrates. One patient presented with symptomatic non-resolving pneumonia, while the other was asymptomatic. In both cases, the lung infiltrates completely resolved when CSF leakage had subsided. Pulmonary involvement in CSF rhinorrhea is under-recognized, and despite being the definitive treatment, surgery for CSF rhinorrhea is typically postponed due to the presence of lung infiltrates. However, meningitis is a serious complication due to a delay in surgical management. Physicians should be made aware that CSF rhinorrhea is a potential cause of intractable lung infiltrates.

Factors associated with gravity-dependent distribution on chest CT in elderly patients with community-acquired pneumonia: a retrospective observational study

Although lung involvement in aspiration pneumonia typically has a gravity-dependent distribution on chest images, which patient’s conditions contribute to its radiological pattern has not been fully elucidated. This study was designed to determine the factors associated with the gravity-dependent distribution of community-acquired pneumonia (CAP) on chest computed tomography (CT). This retrospective study included elderly patients aged ≥ 65 years with CAP who underwent chest CT within 1 week before or after admission. The factors associated with lower lobe- and posterior-predominant distributions of ground glass opacity or airspace consolidation were determined. Of the 369 patients with CAP, 348 (94%) underwent chest CT. Multivariate analyses showed that impaired consciousness, a low Barthel index of activities of daily living, and high hemoglobin levels were associated with lower lobe-predominant distribution, while male sex and impaired consciousness were associated with posterior-predominant distribution. Cerebrovascular diseases were unrelated to these distributions. While male sex, impaired consciousness, high hemoglobin levels, low albumin levels, and the number of involved lobes were associated with in-hospital mortality, gravity-dependent distributions were not. Impaired consciousness might be the most significant predictor of aspiration pneumonia; however, the gravity-dependent distribution of this disease is unlikely to affect disease prognosis.

High-resolution computed tomography features associated with differentiation of tuberculosis among elderly patients with community-acquired pneumonia: a multi-institutional propensity-score matched study

While high-resolution computed tomography (HRCT) is increasingly performed, its role in diagnosing pulmonary tuberculosis (TB) among elderly patients with community-acquired pneumonia (CAP) has not been fully elucidated. This study aimed to determine HRCT features that can differentiate pulmonary TB from non-TB CAP in elderly patients. This study included consecutive elderly patients (age > 65 years) admitted to two teaching hospitals for pulmonary TB or non-TB pneumonia who met the CAP criteria of the American Thoracic Society/Infectious Diseases Society of America guidelines. After propensity score matching for clinical background between patients with pulmonary TB and those with non-TB CAP, their HRCT features were compared. This study included 151 patients with pulmonary TB and 238 patients with non-TB CAP. The presence of centrilobular nodules, air bronchograms, and cavities and the absence of ground-glass opacities and bronchial wall thickening were significantly associated with pulmonary TB. The negative predictive values of centrilobular nodules, air bronchograms, and cavities for pulmonary TB were moderate (70.6%, 67.9%, and 63.0%, respectively), whereas the positive predictive value of cavities was high (96.6%). In elderly patients, although some HRCT features could differentiate pulmonary TB from non-TB CAP, no useful findings could rule out pulmonary TB with certainty.

CT features of community-acquired pneumonia at the emergency department

BACKGROUND

Chest computed tomography (CT) was reported to improve the diagnosis of community-acquired pneumonia (CAP) as compared to chest X-ray (CXR). The aim of this study is to describe the CT-patterns of CAP in a large population visiting the emergency department and to see if some of them are more frequently missed on CXR.

MATERIALS AND METHODS

This is an ancillary analysis of the prospective multicenter ESCAPED study including 319 patients. We selected the 163 definite or probable CAP based on adjudication committee classification; 147 available chest CT scans were reinterpreted by 3 chest radiologists to identify CAP patterns. These CT-patterns were correlated to epidemiological, biological and microbiological data, and compared between false negative and true positive CXR CAP.

RESULTS

Six patterns were identified: lobar pneumonia (51/147, 35%), including 35 with plurifocal involvement; lobular pneumonia (43/147, 29%); unilobar infra-segmental consolidation (24/147, 16%); bronchiolitis (16/147, 11%), including 4 unilobar bronchiolitis; atelectasis and bronchial abnormalities (8/147, 5.5%); interstitial pneumonia (5/147, 3.5%). Bacteria were isolated in 41% of patients with lobar pneumonia-pattern (mostly Streptococcus pneumoniae and Mycoplasma pneumonia) versus 19% in other patients (p = 0.01). Respiratory viruses were equally distributed within all patterns. CXR was falsely negative in 46/147 (31%) patients. Lobar pneumonia was significantly less missed on CXR than other patterns (p = 0.003), especially lobular pneumonia and unilobar infra-segmental consolidation, missed in 35% and 58% of cases, respectively.

CONCLUSION

Lobar and lobular pneumonias are the most frequent CT-patterns. Lobar pneumonia is appropriately detected on CXR and mainly due to Streptococcus pneumoniae or Mycoplasma pneumoniae. Chest CT is very useful to identify CAP in other CT-patterns. Prior the COVID pandemic, CAP was rarely responsible for interstitial opacities on CT.

Case Report: Next-Generation Sequencing in Diagnosis of Atypical Aspiration Pneumonia

Since the pandemic of Corona Virus Disease 2019 (COVID-19), especially in the centers most affected, the symptoms such as fever, cough, myalgia or fatigue, and radioactive signs typically related to COVID-19 like ground-glass opacity (GGO) often distract the attention of physicians from other diseases. Aspiration pneumonia and COVID-19 share similarities in some aspects. There may be risk of misdiagnosis in the case of considering radiological patterns of pneumonia. Early diagnosis and treatment often greatly improve prognosis. We herein reported a case of 40-year-old patient who underwent chest CT scan with the discovery of ground-glass opacity, intralobular reticular opacity and interlobular septal thickening, consolidation, and air bronchogram sign, which were mainly located in the middle and upper lobes of the right lung. It was considered to be infection related pneumonia based on the negative reverse transcription-PCR (RT-PCR) result of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The next-generation sequencing (NGS) of bronchoalveolar lavage fluid (BALF) was performed and detected nucleic acid sequences of Klebsiella sp. Consequently, the patient accepted sensitive intravenous antibiotics therapy for 13 days and had a remarkable clinical and radiological improvement. His case was followed up through imaging procedures. Because of possible radiologic and clinical similarities between aspiration and COVID-19 pneumonia, COVID-19 can be of some value in proposing a differential diagnosis of aspiration pneumonia. Clinicians could suggest a correct diagnosis by careful examination of the CT images together with attention to the clinical history and judicious utilization of NGS, especially.

COVID-19 and Aspiration Pneumonia: Similar Pulmonary Findings with Different Diagnoses—a Pitfall in [18F]FDG PET/CT

Since December 2019, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a worldwide pandemic. Especially in the centers most affected by the pandemic, symptoms (such as fever, cough, myalgia, or fatigue) and/or radiological signs (such as ground-glass opacity) typically related to COVID-19 often diverted clinicians’ attention from other diseases. Despite the urgency to recognize and cure SARS-CoV-2 infection, a plethora of differential diagnoses must be considered, and other diseases must be equally and promptly treated, as described in this case report.

Diagnostic accuracy of pocket-sized ultrasound for aspiration pneumonia in elderly patients without heart failure: A prospective observational study

Aim

To investigate the diagnostic accuracy of pocket‐sized ultrasound (PsUS) for aspiration pneumonia in elderly patients without heart failure.

Methods

This prospective observational study included patients with aspiration pneumonia. PsUS was performed in six areas (bilateral chest, four dorsal areas) by an independent examiner, blinded to the computed tomography (CT) results as a reference standard. Patients with heart failure were excluded.

Results

PsUS findings of 34 patients (median age, 87.5 years) and 204 areas were analyzed. Three or more B‐lines (comet tail artifacts) were strongly suggestive (positive likelihood ratio [LR+] 17.302) of consolidation on CT (CT‐consolidation, subpleural hypoechoic area with tissue‐like echostructure) or pleural change on CT. Consolidation on US (US‐consolidation) was suggestive of CT‐consolidation or pleural changes on CT (LR+ 6.453). Pleural effusion on US was strongly suggestive (LR+ 10.989) of CT‐consolidation or pleural change on CT. Absence of either three or more B‐lines, US‐consolidation, or US pleural effusion could not rule out CT‐consolidation or pleural change on CT (negative likelihood ratio [LR−] 0.482‐0.683). However, absence of all three findings could rule out abnormal CT findings (LR− 0.230). Chest radiograph findings proved difficult to confirm or exclude CT‐consolidation or pleural changes on CT (LR+ 1.584, LR− 0.489); when combined with PsUS findings, LR− improved to 0.124.

Conclusions

Three or more B‐lines or US‐consolidation on PsUS in elderly patients with aspiration pneumonia without heart failure suggested CT‐consolidation or pleural changes on CT. When both PsUS and chest radiograph findings were negative, CT‐consolidation and pleural change could be excluded. Geriatr Gerontol Int 2021; 21: 1118–1124.

Micronodular lung disease on high-resolution CT: patterns and differential diagnosis

With the advent of high-resolution computed tomography (HRCT), micronodular lung disease is a routinely encountered pathology in thoracic imaging. This article will review how to differentiate the three main micronodular patterns and review the differential diagnosis for each. Differential diagnosis of micronodular lung disease may be extensive, but by identifying the pattern and using additional clues, such as distribution, additional imaging findings, and clinical history, a radiologist can make an accurate diagnosis. First, three micronodular patterns - centrilobular, peri-lymphatic, and random - can be identified by using a simple algorithm based on the location of nodules. This algorithm requires understanding of the anatomy and function of the secondary pulmonary lobule. Each micronodular pattern offers a unique differential diagnosis. Centrilobular nodules can be seen with inflammatory, infectious, or vascular aetiologies; peri-lymphatic nodules with sarcoidosis and lymphangitic carcinomatosis; and random nodules with haematogenous metastases or infections.

Investigation of high-resolution computed tomographic (HRCT) outcomes associated with chronic pulmonary microaspiration (CPM) in Tehran and Zahedan, Iran

Background

In patients with chronic pulmonary microaspiration (CPM) the recognition of high-resolution computed tomographic (HRCT) findings and their pattern is important.

Objective

To investigate the HRCT detections in patients with CPM.

Materials and Methods

This descriptive study enrolled 100 consecutive patients with CPM underwent HRCT of the lungs between 2017 and 2018 in Tehran and Zahedan Hospitals and private centers. The required variables were recorded for each patient with a questionnaire. Subsequently, HRCT was performed and abnormalities were then reported by two radiologists.

Results

Most of patients exhibited bronchial thickening in 33.6% of cases, followed by ground-glass opacity (12.4%), emphysema (11.1%), and bronchiectasis (8.5%). In addition, the most common HRCT findings were found in left lower lobe (LLL) (37.1%), followed by right lower lobe (RLL) (35.9 %), right upper lobe (RUL) (6,2%), and left upper lobe (LUL) (6%).

Conclusion

Our data showed the most common findings in HRCT were bronchial thickening ground-glass opacity, emphysema, and bronchiectasis, where these findings was dominantly found in LLL, RLL, RUL, and LUL, indicating its high tendency to dependent areas.

Review of the Chest CT Differential Diagnosis of Ground-Glass Opacities in the COVID Era

Coronavirus disease 2019 (COVID-19), a recently emerged lower respiratory tract illness, has quickly become a pandemic. The purpose of this review is to discuss and differentiate typical imaging findings of COVID-19 from those of other diseases, which can appear similar in the first instance. The typical CT findings of COVID-19 are bilateral and peripheral predominant ground-glass opacities. As per the Fleischner Society consensus statement, CT is appropriate in certain scenarios, including for patients who are at risk for and/or develop clinical worsening. The probability that CT findings represent COVID-19, however, depends largely on the pretest probability of infection, which is in turn defined by community prevalence of infection. When the community prevalence of COVID-19 is low, a large gap exists between positive predictive values of chest CT versus those of reverse transcriptase polymerase chain reaction. This implies that with use of chest CT there are a large number of false-positive results. Imaging differentiation is important for management and isolation purposes and for appropriate disposition of patients with false-positive CT findings. Herein the authors discuss differential pathology with close imaging resemblance to typical CT imaging features of COVID-19 and highlight CT features that may help differentiate COVID-19 from other conditions.

COVID-19 pneumonia: the great radiological mimicker

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has rapidly spread worldwide since December 2019. Although the reference diagnostic test is a real-time reverse transcription-polymerase chain reaction (RT-PCR), chest-computed tomography (CT) has been frequently used in diagnosis because of the low sensitivity rates of RT-PCR. CT findings of COVID-19 are well described in the literature and include predominantly peripheral, bilateral ground-glass opacities (GGOs), combination of GGOs with consolidations, and/or septal thickening creating a "crazy-paving" pattern. Longitudinal changes of typical CT findings and less reported findings (air bronchograms, CT halo sign, and reverse halo sign) may mimic a wide range of lung pathologies radiologically. Moreover, accompanying and underlying lung abnormalities may interfere with the CT findings of COVID-19 pneumonia. The diseases that COVID-19 pneumonia may mimic can be broadly classified as infectious or non-infectious diseases (pulmonary edema, hemorrhage, neoplasms, organizing pneumonia, pulmonary alveolar proteinosis, sarcoidosis, pulmonary infarction, interstitial lung diseases, and aspiration pneumonia). We summarize the imaging findings of COVID-19 and the aforementioned lung pathologies that COVID-19 pneumonia may mimic. We also discuss the features that may aid in the differential diagnosis, as the disease continues to spread and will be one of our main differential diagnoses some time more.

Noninfectious Granulomatous Diseases of the Chest

Granulomas are pathologically defined as focal aggregations of activated macrophages, Langerhans cells, and lymphocytes. Granulomas form in the lungs when the immune system barricades the substances it perceives as foreign but is unable to remove. Granulomas manifest with numerous imaging appearances in thoracic radiology, and their presence is a nonspecific finding. Granulomatous lung diseases comprise multiple entities with variable clinical manifestations and outcomes. Their imaging findings are rarely specific and can mimic malignancies, often triggering an extensive diagnostic workup. Radiologists must be familiar with the clinical manifestations and imaging findings of these entities to generate appropriate differential diagnoses. This review describes the imaging manifestations of various noninfectious, necrotizing, and nonnecrotizing granulomatous diseases that primarily affect the thorax. ©RSNA, 2020.

A case report with COVID-19 during perioperative period of lobectomy

RATIONALE

Currently, COVID-19 has made a significant impact on many countries in the world. However, there have been no reported cases of pulmonary lobectomy with Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-COV-2) infection. We are the first to report such a case.

PATIENT CONCERNS

We report a 63-year-old Wuhan male patient with smoking history of 40 cigarettes per day for 40 years. He sought medical consultation for right lower lung nodules found by CT scan.

DIAGNOSES AND INTERVENTIONS

The patient's postoperative pathological diagnosis was squamous cell carcinoma of the right lower lung. On the fourth day after the operation, the real-time reverse transcription polymerase chain reaction test showed a positive result. After the operation, we routinely give symptomatic treatments such as anti-infection, nebulization and oxygen inhalation. We also change antibiotics several times depending on the patient's condition.

OUTCOMES

The patient's condition continued to deteriorate. On the fifth day after surgery, the patient died despite medical treatment.

LESSONS

We are the first to report the diagnosis and treatment process of patients with COVID-19 during perioperative period of lobectomy. It provides a case for the postoperative management of such patients.

Risk factors for the development of aspiration pneumonia in elderly patients with femoral neck and trochanteric fractures: A retrospective study of a patient cohort

Aspiration pneumonia (AP) has been recognized as one of the most common postoperative complications after hip surgery in elderly. The objective of the present study was to evaluate risk for postoperative complications of AP in elderly patients with femoral neck fractures.We recruited 426 patients (age 84.9 ± 7.4 years) with a history of hip surgery carried out at Toyama Municipal Hospital. AP occurred in 18 out of 426 cases (4.23%). Statistical test has found significant differences in age, gender, serum albumin level, and cognitive impairment, between AP and non-AP groups. Subsequently multiple logistic regression analysis was conducted to investigate the risk factors for AP, including age, gender, serum albumin, cognitive impairment, and activities of daily living (ADL). Adjusted odds ratio showed significant differences in age, gender, and serum albumin, whereas no significant differences were found in cognitive impairment and ADL.This study suggested that serum albumin seemed to be a risk factor for AP but were necessary to assess under adjustment of confounding factors, including age and gender. Monitoring serum albumin level seemed to be important for the postoperative management of AP, especially in elderly patients receiving surgery of femoral neck and trochanteric fractures.

Educational Case: Aspiration Pneumonia

The following fictional case is intended as a learning tool within the Pathology Competencies for Medical Education (PCME), a set of national standards for teaching pathology. These are divided into three basic competencies: Disease Mechanisms and Processes, Organ System Pathology, and Diagnostic Medicine and Therapeutic Pathology. For additional information, and a full list of learning objectives for all three competencies, seehttp://journals.sagepub.com/doi/10.1177/2374289517715040.¹

New perspectives in aspiration community acquired Pneumonia

Introduction: Aspiration pneumonia is a subclass of community-acquired pneumonia that is expected to have an increasing contribution in mortality and morbidity, particularly in the elderly population over the next coming decades. While studies have revealed significant progress in identifying risk factors for aspiration pneumonia, the clinical presentation and diagnosis remain challenging to healthcare providers. Areas covered: We conducted a broad literature review using the MeSH heading in PubMed/MEDLINE of 'aspiration pneumonia' from January 1970 to July 2019. The understanding of the microbiology of aspiration pneumonia has evolved from a possible shift in the causative organisms away from anaerobes to traditional community-acquired pneumonia organisms. The importance of this shift is not yet known, but it has questioned the pathogenic role of anaerobes, appropriate anaerobic testing and the role of these pathogens in the pulmonary microbiome in patients with pneumonia. The identification of risk factors led to strategies to prevent or minimize the risk of aspiration pneumonia with moderate success. Expert opinion: Our expert opinion is that further research is needed to determine the role of the microbiome with aspiration pneumonia and patient risk factors. There is also a great need to develop clinical tools to help providers diagnose, treat, and prevent aspiration pneumonia.

Factors associated with atypical radiological findings of pulmonary tuberculosis

BACKGROUND

Unusual radiological images may delay diagnosis of pulmonary tuberculosis. This study aimed to analyze the risk factors for an atypical radiological image in patients with pulmonary tuberculosis.

METHODS

We retrospectively analyzed data from patients admitted to one hospital from January 2013 to December 2016 for sputum smear-positive lung tuberculosis who underwent chest computed tomography (CT) on admission. Patients whose sputum cultures were positive for general bacteria were excluded. Patient characteristics and laboratory data were compared between patients with cavity and those without and between patients with upper predominant lung involvement and those without.

RESULTS

This study included 94 (93%) of 101 patients who underwent chest CT. The non-cavity group was older, had a greater number of females, had a lower C-reactive protein (CRP) level, and had a lower glomerular filtration rate. Multivariate analysis showed that a low CRP level (OR 0.808; 95% CI 0.674-0.967; p = 0.020) significantly predicted non-cavity pulmonary tuberculosis. The non-upper predominant lung involvement group was older and had a greater number of females, poorer performance status, a higher CRP level, and a lower serum albumin level. A poor performance status (OR 2.155; 95% CI 1.257-3.693; p = 0.005) was found to significantly predict pulmonary tuberculosis with non-upper predominant lung distributions.

CONCLUSIONS

A low CRP level and poor performance status were associated with non-cavity and non-upper predominant lung distribution, respectively, in patients with pulmonary tuberculosis. Tuberculosis patients with these characteristics may present unusual chest images.

Proportion of Aspiration Pneumonia Cases Among Patients With Community-Acquired Pneumonia: A Single-Center Study in Korea

Objective

To investigate the proportion of aspiration pneumonia cases among patients with community-acquired pneumonia in Korea.

Methods

This retrospective study included patients with community-acquired pneumonia who had been admitted to the emergency department of a university-affiliated tertiary hospital in Gyeonggi Province, Korea between January 1, 2016 and December 31, 2016. Among these patients, those with aspiration pneumonia were identified using ICD-10 codes (J69.^*). Patients with recurrent pneumonia were excluded, as were those who were immunocompromised. The proportion of cases of aspiration pneumonia was calculated, and the characteristics and clinical outcomes of patients with aspiration pneumonia and non-aspiration pneumonia were compared.

Results

The proportion of aspiration pneumonia cases among patients with community-acquired pneumonia was 14.2%. Patients with aspiration pneumonia were significantly more likely to be older (p<0.001) and male (p<0.001), and to have a higher confusion, uremia, respiratory rate, blood pressure, and age ≥65 years (CURB-65) score (p<0.001) as compared to patients with non-aspiration pneumonia. They were also more likely to require admission to the intensive care unit (p<0.001) and a longer hospital stay (p<0.001).

Conclusion

Aspiration pneumonia accounts for 14.2% of all cases of community-acquired pneumonia in Korea. These data may contribute to the establishment of healthcare strategies for managing aspiration pneumonia among Korean adults.

Diagnosis and treatment of community-acquired pneumonia in adults: 2016 clinical practice guidelines by the Chinese Thoracic Society, Chinese Medical Association

Community‐acquired pneumonia (CAP) in adults is an infectious disease with high morbidity in China and the rest of the world. With the changing pattern in the etiological profile of CAP and advances in medical techniques in diagnosis and treatment over time, Chinese Thoracic Society of Chinese Medical Association updated its CAP guideline in 2016 to address the standard management of CAP in Chinese adults. Extensive and comprehensive literature search was made to collect the data and evidence for experts to review and evaluate the level of evidence. Corresponding recommendations are provided appropriately based on the level of evidence. This updated guideline covers comprehensive topics on CAP, including aetiology, antimicrobial resistance profile, diagnosis, empirical and targeted treatments, adjunctive and supportive therapies, as well as prophylaxis. The recommendations may help clinicians manage CAP patients more effectively and efficiently. CAP in pediatric patients and immunocompromised adults is beyond the scope of this guideline. This guideline is only applicable for the immunocompetent CAP patients aged 18 years and older. The recommendations on selection of antimicrobial agents and the dosing regimens are not mandatory. The clinicians are recommended to prescribe and adjust antimicrobial therapies primarily based on their local etiological profile and results of susceptibility testing, with reference to this guideline.

Chest CT findings in patients with dysphagia and aspiration: a systematic review

The objective of this systematic review was to characterize chest CT findings in patients with dysphagia and pulmonary aspiration, identifying the characteristics and the methods used. The studies were selected from among those indexed in the Brazilian Virtual Library of Health, LILACS, Indice Bibliográfico Español de Ciencias de la Salud, Medline, Cochrane Library, SciELO, and PubMed databases. The search was carried out between June and July of 2016. Five articles were included and reviewed, all of them carried out in the last five years, published in English, and coming from different countries. The sample size in the selected studies ranged from 43 to 56 patients, with a predominance of adult and elderly subjects. The tomographic findings in patients with dysphagia-related aspiration were varied, including bronchiectasis, bronchial wall thickening, pulmonary nodules, consolidations, pleural effusion, ground-glass attenuation, atelectasis, septal thickening, fibrosis, and air trapping. Evidence suggests that chest CT findings in patients with aspiration are diverse. In this review, it was not possible to establish a consensus that could characterize a pattern of pulmonary aspiration in patients with dysphagia, further studies of the topic being needed.

Pulmonary computed tomography findings in patients with chronic aspiration detected by videofluoroscopic swallowing study

OBJECTIVE

To demonstrate CT findings in patients with chronic aspiration compared with a control group without aspiration, as detected by the videofluoroscopic swallowing study (VFSS).

METHODS

This retrospective, observational study included patients with and without diagnoses of aspiration confirmed by VFSS, who underwent CT examination of the lungs between 2010 and 2014. Two radiologists blinded to the presence of aspiration reviewed the images to detect the presence of any abnormality. Consensus was reached with a third radiologist. CT pulmonary findings (bronchial thickening, bronchiolectasis, centrilobular nodules, ground-glass opacities, atelectasis, consolidation and air trapping) were compared between the groups using the χ(2) test, with a significance level of 0.05.

RESULTS

A total of 56 patients (28 patients with diagnoses of aspiration; 52% male, mean age 65 ± 15 years) were included in the study. Patients with aspiration were more likely to than those in the control group to demonstrate atelectasis, centrilobular nodules, bronchiolectasis, consolidation and ground-glass opacities (all p < 0.05), with a significant predilection for the lower lobes (p < 0.001). Bronchial wall thickening and air trapping did not differ between groups.

CONCLUSION

Atelectasis, centrilobular nodules, bronchiolectasis, consolidation and ground-glass opacities occurred more frequently in patients with aspiration than in those without aspiration, with a pronounced tendency for distribution in the lower lobes.

ADVANCES IN KNOWLEDGE

CT findings of aspiration are very important, as pulmonary symptoms may be the first manifestation of this disorder. Knowledge of these findings is essential to enable the early diagnosis of aspiration disorders and prevent lung damage.

Dysphagia, dystussia, and aspiration pneumonia in elderly people

Despite the development and wide distribution of guidelines for pneumonia, death from pneumonia is increasing due to population aging. Conventionally, aspiration pneumonia was mainly thought to be one of the infectious diseases. However, we have proven that chronic repeated aspiration of a small amount of sterile material can cause the usual type of aspiration pneumonia in mouse lung. Moreover, chronic repeated aspiration of small amounts induced chronic inflammation in both frail elderly people and mouse lung. These observations suggest the need for a paradigm shift of the treatment for pneumonia in the elderly. Since aspiration pneumonia is fundamentally based on dysphagia, we should shift the therapy for aspiration pneumonia from pathogen-oriented therapy to function-oriented therapy. Function-oriented therapy in aspiration pneumonia means therapy focusing on slowing or reversing the functional decline that occurs as part of the aging process, such as "dementia → dysphagia → dystussia → atussia → silent aspiration". Atussia is ultimate dysfunction of cough physiology, and aspiration with atussia is called silent aspiration, which leads to the development of life-threatening aspiration pneumonia. Research pursuing effective strategies to restore function in the elderly is warranted in order to decrease pneumonia deaths in elderly people.

Clinical Usefulness of Serum Krebs von den Lungen-6 for Detecting Chronic Aspiration in Children with Severe Motor and Intellectual Disabilities

OBJECTIVE

To determine whether the serum level of Krebs von den Lungen-6 (KL-6), a circulating high-molecular weight glycoprotein and a diagnostic biomarker of interstitial lung diseases, is a clinically useful biomarker for detecting chronic aspiration in children with severe motor and intellectual disabilities (SMIDS).

STUDY DESIGN

Children with SMIDS undergoing videofluorography for assessment of dysphagia were prospectively evaluated. Based on the videofluorography results, the participants were classified into aspiration and non-aspiration groups. Age, sex, white blood cell count, and serum levels of C-reactive protein, lactate dehydrogenase, albumin, and KL-6 were compared between the 2 groups. Binary logistic regression was performed to identify factors independently associated with the presence of aspiration.

RESULTS

A total of 66 patients participated in this study, 37 who were classified as the aspiration group and 29 as the non-aspiration group. The serum KL-6 level in the aspiration group was significantly higher than that in the non-aspiration group (median, 344 U/mL vs 207 U/mL, P < .01). Logistic regression modeling showed that the number of prescribed antiepileptic drugs (OR, 1.978; 95% CI, 1.217, 3.214; P < .01) and serum KL-6 level (OR, 1.012; 95% CI, 1.005, 1.019; P < .01) were independent predictors of aspiration.

CONCLUSIONS

The study demonstrated that the KL-6 level is significantly higher in children with SMIDS who aspirate than in those who do not. KL-6 shows promise as a biomarker for chronic lung disease due to aspiration in these children.

Diffuse aspiration bronchiolitis: analysis of 20 consecutive patients

OBJECTIVE

Aspiration can cause a variety of pulmonary syndromes, some of which are not well recognized. The objective of this study was to assess the demographic, clinical, radiological, and histopathological correlates of diffuse aspiration bronchiolitis (DAB), a bronchiolocentric disorder caused by recurrent aspiration.

METHODS

This was a retrospective study of 20 consecutive patients with DAB seen at the Mayo Clinic in Rochester, Minnesota, between January 1, 1998 and June 30, 2014.

RESULTS

The median age of the patients was 56.5 years (range, 22-76 years), and the male/female ratio was 2.3:1.0. In 18 patients, the diagnosis of DAB was based on the results of a lung biopsy; in the 2 remaining patients, it was based on clinical and radiological features, together with documented aspiration observed in a videofluoroscopic swallow study. In 19 patients (95%), we identified predisposing factors for aspiration, including gastroesophageal reflux disease (GERD), drug abuse, and dysphagia. Common presenting features included cough, sputum production, dyspnea, and fever. Twelve patients (60%) had a history of recurrent pneumonia. In all of the patients, chest CT revealed bilateral pulmonary infiltrates consisting of micronodules and tree-in-bud opacities. In the majority of patients, interventions aimed at preventing recurrent aspiration (e.g., anti-GERD therapies) led to improvement in the symptoms of DAB.

CONCLUSIONS

Young to middle-aged subjects with recognizable predisposing factors for aspiration and who report a history of recurrent pneumonia are at increased risk for DAB. Although DAB is not well recognized, certain chest CT features are characteristic of the disorder.

Chronic pulmonary microaspiration: high-resolution computed tomographic findings in 13 patients

PURPOSE

The aim of the study was to describe the high-resolution computed tomography (CT) manifestations of chronic pulmonary microaspiration, a condition characterized by recurrent subclinical aspiration of small droplets of gastric contents or foreign particles into the lungs.

MATERIALS AND METHODS

We reviewed the CT findings in 13 consecutive patients with clinical (n=13) and histologic (n=1) diagnosis of chronic pulmonary microaspiration. Twelve patients presented with persistent cough, but none had a clinical history of acute aspiration. One patient was asymptomatic. All patients had volumetric CT of the chest reconstructed using thin sections (1 to 1.3 mm) at the time of diagnosis. The CT scans were interpreted by 3 chest radiologists who reached a final decision by consensus.

RESULTS

All 13 patients had centrilobular nodules and ground-glass opacities that involved mainly the dependent lung regions in 11 patients and had a random distribution in 2. Other common findings included branching opacities (n=10), small foci of consolidation (n=7), septal lines (n=5), and bronchiectasis (n=7). The 13 patients had at least 1 risk factor for aspiration including gastroesophageal reflux (n=9), hiatus hernia (n=6), esophageal dysfunction (n=3), oropharyngeal dysphagia (n=1), esophageal carcinoma (n=1), and use of sedatives (n=2).

CONCLUSIONS

The high-resolution CT manifestations of chronic pulmonary microaspiration consist mainly of centrilobular nodules and ground-glass opacities that tend to involve predominately the dependent regions. Branching opacities and small foci of consolidation are seen in the majority of cases.

Detection failure rate of chest radiography for the identification of nursing and healthcare-associated pneumonia

AIM

To clarify the detection failure rate of chest radiography for the identification of nursing and healthcare-associated pneumonia (NHCAP), we compared high-resolution computed tomography (HRCT) with chest radiography simultaneously for patients with clinical symptoms and signs leading to a suspicion of NHCAP.

METHODS

We analyzed 208 NHCAP cases and compared them based on four groups defined using NHCAP criteria, patients who were: Group A) resident in an extended care facility or nursing home; Group B) discharged from a hospital within the preceding 90 days; Group C) receiving nursing care and had poor performance status; and Group D) receiving regular endovascular treatment.

RESULTS

Chest radiography was inferior to HRCT for the identification of pneumonia (149 vs 208 cases, p < 0.0001). Among the designated NHCAP criteria, chest radiography identified pneumonia cases at a significantly lower frequency than HRCT in Group A (70 vs 97 cases, p = 0.0190) and Group C (86 vs 136 cases, p < 0.0001). The detection failure rate of chest radiography differed among NHCAP criteria; 27.8% in Group A, 26.5% in Group B, 36.7% in Group C and 5.8% in Group D. Cerebrovascular disease and poor functional status were significantly more frequent in patients in Groups A and C compared with those in Groups B and D.

CONCLUSIONS

Physicians may underestimate pneumonia shadow in chest radiographs in patients with NHCAP, and the detection failure rate of chest radiography differed among NHCAP criteria. Poor functional status may correlate with the low accuracy of chest radiography in diagnosing pneumonia.

Aspiration-related deaths in 57 consecutive patients: autopsy study

Background

Aspiration can cause a diverse spectrum of pulmonary disorders some of which can lead to death but can be difficult to diagnose.

Patients and Methods

The medical records and autopsy findings of 57 consecutive patients in whom aspiration was the immediate cause of death at Mayo Clinic (Rochester, MN, USA) over a 9-yr period, from January 1 2004 to December 31 2012 were analyzed.

Results

The median age at death was 72 years (range, 13–95 years) and included 39 (68%) males. The most common symptom before death was dyspnea (63%) and chest radiography revealed bilateral infiltrates in the majority (81%). Most common precipitating factors for aspiration were depressed consciousness (46%) and dysphagia (44%). Aspiration-related syndromes leading to death were aspiration pneumonia in 26 (46%), aspiration pneumonitis in 25 (44%), and large airway obstruction in 6 patients (11%). Aspiration was clinically unsuspected in 19 (33%) patients. Antimicrobial therapy had been empirically administered to most patients (90%) with aspiration pneumonia and aspiration pneumonitis.

Conclusion

We conclude aspiration-related deaths occur most commonly in the elderly with identifiable risks and presenting bilateral pulmonary infiltrates. One-third of these aspiration-related pulmonary syndromes were clinically unsuspected at the time of death.

Healthcare-associated Pneumonia and Aspiration Pneumonia

Healthcare-associated pneumonia (HCAP) is a new concept of pneumonia proposed by the American Thoracic Society/Infectious Diseases Society of America in 2005. This category is located between community-acquired pneumonia and hospital-acquired pneumonia with respect to the characteristics of the causative pathogens and mortality, and primarily targets elderly patients in healthcare facilities. Aspiration among such patients is recognized to be a primary mechanism for the development of pneumonia, particularly since the HCAP guidelines were published. However, it is difficult to manage patients with aspiration pneumonia because the definition of the condition is unclear, and the treatment is associated with ethical aspects. This review focused on the definition, prevalence and role of aspiration pneumonia as a prognostic factor in published studies of HCAP and attempted to identify problems associated with the concept of aspiration pneumonia.