Biomarkers in the diagnosis of aspiration syndromes

Predicting ventilator-associated pneumonia in elderly patients requiring mechanical ventilation through the detection in tracheal aspirates

OBJECTIVE

In this study, we evaluated the clinical utility of tracheal aspirates α-amylase (AM), pepsin, and lipid-laden macrophage index (LLMI) in the early diagnosis of ventilator-associated pneumonia (VAP) in elderly patients on mechanical ventilation.

METHODS

Within 96 hours of tracheal intubation, tracheal aspirate specimens were collected from elderly patients on mechanical ventilation; AM, pepsin, and LLMI were detected, and we analyzed the potential of each index individually and in combination in diagnosing VAP.

RESULTS

Patients with VAP had significantly higher levels of AM, pepsin, and LLMI compared to those without VAP (P < 0.001), and there was a positive correlation between the number of pre-intubation risk factors of aspiration and the detection value of each index in patients with VAP (P < 0.001). The area under a receiver operating characteristic (ROC) curve (AUC) of AM, pepsin, and LLMI in diagnosis of VAP were 0.821 (95% CI:0.713-0.904), 0.802 (95% CI:0.693-0.892), and 0.621 (95% CI:0.583-0.824), the sensitivities were 0.8815, 0.7632, and 0.6973, the specificities were 0.8495, 0.8602, and 0.6291, and the cutoff values were 4,321.5 U/L, 126.61 ng/ml, and 173.5, respectively. The AUC for the combination of indexes in diagnosing VAP was 0.905 (95% CI:0.812-0.934), and the sensitivity and specificity were 0.9211 and 0.9332, respectively. In the tracheal aspirate specimens, the detection rate of AM ≥ cutoff was the highest, while it was the lowest for LLMI (P < 0.001). The detection rates of AM ≥ cutoff and pepsin ≥ cutoff were higher within 48 hours after intubation than within 48-96 hours after intubation (P < 0.001). In contrast, the detection rate of LLMI ≥ cutoff was higher within 48-96 hours after intubation than within 48 hours after intubation (P < 0.001). The risk factors for VAP identified using logistic multivariate analysis included pre-intubation aspiration risk factors (≥3), MDR bacteria growth in tracheal aspirates, and tracheal aspirate AM ≥ 4,321.5 U/L, pepsin ≥ 126.61 ng/ml, and LLMI ≥ 173.5.

CONCLUSION

The detection of AM, pepsin, and LLMI in tracheal aspirates has promising clinical utility as an early warning biomarker of VAP in elderly patients undergoing mechanical ventilation.

Bronchoalveolar lavage (BAL) amylase and pepsin levels as potential biomarkers of aspiration pneumonia

BACKGROUND AND OBJECTIVE

There are currently no established markers for aspiration pneumonia. We hypothesized that bronchoalveolar lavage (BAL) amylase and pepsin might be candidate biomarkers for aspiration pneumonia.

METHODS

This cross-sectional study reviewed consenting adults who underwent clinically-indicated bronchoscopy at Aizu Medical Center. BAL samples were obtained using standardized methods. Amylase levels were measured in our clinical laboratory, and pepsin levels were assessed by ELISA.

RESULTS

Aspiration pneumonia was clinically diagnosed based on the guidelines of the Japanese Respiratory Society in 48 of the 327 participants. Median BAL salivary amylase and pepsin levels in this group were 702.0 U/L and 12.7 ng/ml respectively, which were significantly higher than in non-aspiration pneumonia patients. BAL amylase ≥204 U/L had 77.1% sensitivity and 84.2% specificity as a diagnostic index, and the area under the receiver operating characteristic (ROC) curve was 0.859 (95% confidence interval (CI), 0.803-0.915). Similarly, BAL pepsin levels of ≥7.45 ng/ml had 87.2% sensitivity and 59.9% specificity for identifying aspiration, and the area under the ROC curve was 0.757 (95% CI, 0.688-0.826). Multivariate regression demonstrated that BAL amylase ≥204 U/L and BAL pepsin ≥7.45 ng/ml were associated with significantly higher odds for aspiration pneumonia (odds ratio (OR) 10.0, 95% CI, 4.51-22.2, and OR 8.81 95% CI, 3.32-23.4, respectively). There were no significant associations between risk factors for aspiration pneumonia and BAL amylase and pepsin levels.

CONCLUSION

BAL amylase and pepsin might be useful biomarkers for suggesting aspiration pneumonia, and could be objective markers without relying on known risk factors for aspiration.

Clinical Utility of Pepsin and Bile Acid in Tracheal Secretions for Accurate Diagnosis of Aspiration in ICU Patients

BACKGROUND

Aspiration of stomach content or saliva in critical conditions-e.g., shock, intoxication, or resuscitation-can lead to acute lung injury. While various biomarkers in bronchoalveolar lavage fluids have been studied for diagnosing aspiration, none have been conclusively established as early indicators of lung damage. This study aims to evaluate the diagnostic value of pepsin, bile acid, and other biomarkers for detecting aspiration in an intensive care unit (ICU).

MATERIALS AND METHODS

In this study, 50 ICU patients were enrolled and underwent intubation before admission. The evaluation of aspiration was based on clinical suspicion or documented instances of observed events. Tracheal secretion (TS) samples were collected within 6 h after intubation using sterile suction catheters. Additional parameters, including IL-6, pepsin, and bile acid, were determined for analysis. Pepsin levels were measured with an ELISA kit, while bile acid, uric acid, glucose, IL-6, and pH value in the tracheal secretion were analyzed using standardized lab methods.

RESULTS

The 50 patients admitted to the ICU with various diagnoses. The median survival time for the entire cohort was 52 days, and there was no significant difference in survival between patients with aspiration pneumonia (AP) and those with other diagnoses (p = 0.69). Among the AP group, the average survival time was 50.51 days (±8.1 SD; 95% CI 34.63-66.39), while patients with other diagnoses had a mean survival time of 32.86 days (±5.1 SD; 95% CI 22.9-42.81); the survival group comparison did not yield statistically significant results. The presence of pepsin or bile acid in TS patients did not significantly impact survival or the diagnosis of aspiration. The p-values for the correlations between pepsin and bile acid with the aspiration diagnosis were p = 0.53 and p > 0.99, respectively; thus, pepsin and bile acid measurements did not significantly affect survival outcomes or enhance the accuracy of diagnosing aspiration pneumonia.

CONCLUSIONS

The early and accurate diagnosis of aspiration is crucial for optimal patient care. However, based on this study, pepsin concentration alone may not reliably indicate aspiration, and bile acid levels also show limited association with the diagnosis. Further validation studies are needed to assess the clinical usefulness and reliability of gastric biomarkers in diagnosing aspiration-related conditions. Such future studies would provide valuable insights for improving aspiration diagnosis and enhancing patient care.

Change over time and agreement between clinical markers of disease resolution in dogs with aspiration-induced lung injury

BACKGROUND

There is a lack of consensus regarding which markers of disease resolution to prioritise when assessing treatment response in client-owned dogs with aspiration-induced lung injury. This study describes the change over time and the agreement between the clinical markers used to determine disease resolution.

METHODS

Physical examination (PE), owner-reported clinical signs (CS-O), thoracic radiographs (TXR) scores and C-reactive protein (CRP) concentrations were determined at enrolment, after 24, 48 and 72 hours, and after 7, 14 and 28 days.

RESULTS

PE scores were significantly improved at 48 hours, while CRP initially increased (24 hours) and then decreased (48 hours). PE, CS-O and CRP significantly improved earlier (7 days) than TXR (14 days). The median number of days to marker normalisation was 7, 9 and 14 for PE, CRP and CS-O, respectively. Marker agreement was excellent/very good at enrolment and fair/poor during disease recovery.

LIMITATIONS

Analysis did not control for differences aetiology of aspiration or the lack of standardisation in treatment approach.

CONCLUSIONS

PE was the earliest and most consistent marker indicating disease resolution. Serial CRP monitoring (72 hours) may provide an objective marker of early treatment response. Alongside PE normalisation, improvement in CS-O, CRP and TRX may assist in determining disease resolution and guide treatments, including limiting antibiotic exposure in dogs with aspiration-induced lung injury.

Salivary Alpha Amylase Bronchial Measure for Early Aspiration Pneumonia Diagnosis in Patients Treated With Therapeutic Hypothermia After Out-of-hospital Cardiac Arrest

Background

Aspiration pneumonia is the most common respiratory complication following out-of-hospital cardiac arrests (OHCA). Alpha-amylase (α-amylase) in pulmonary secretions is a biomarker of interest in detecting inhalation. The main goal of this study is to evaluate the performance of bronchoalveolar levels of α-amylase in early diagnosis of aspiration pneumonia, in patients admitted to intensive care unit (ICU) after OHCA.

Methods

This is a prospective single-center trial, led during 5 years (July 2015 to September 2020). We included patients admitted to ICU after OHCA. A protected specimen bronchial brushing and a mini-bronchoalveolar lavage (mini-BAL) were collected during the first 6 h after admission. Dosage of bronchial α-amylase and standard bacterial analysis were performed. Investigators confirmed pneumonia diagnosis using clinical, radiological, and microbiological criteria. Every patient underwent targeted temperature management.

Results

88 patients were included. The 34% (30 patients) developed aspiration pneumonia within 5 days following admission. The 55% (17) of pneumonias occurred during the first 48 h. The 57% of the patients received a prophylactic antibiotic treatment on their admission day. ICU mortality was 50%. Median value of bronchial α-amylase did not differ whether patients had aspiration pneumonia (15 [0–94]) or not (3 [0–61], p = 0,157). Values were significantly different concerning early-onset pneumonia (within 48 h) [19 (7–297) vs. 3 (0–82), p = 0,047]. If one or more microorganisms were detected in the initial mini-BAL, median value of α-amylase was significantly higher [25 (2–230)] than in sterile cultures (2 [0–43], p = 0,007). With an 8.5 IU/L cut-point, sensitivity and specificity of α-amylase value for predicting aspiration pneumonia during the first 2 days were respectively 74 and 62%. True positive and negative rates were respectively 44 and 86%. The area under the ROC curve was 0,654 (CI 95%; 0,524–0,785). Mechanical ventilation duration, length of ICU stay, and mortality were similar in both groups.

Conclusion

In our study, dosage of bronchial α-amylase was not useful in predicting aspiration pneumonia within the first 5 days after ICU admission for OHCA. Performance in predicting early-onset pneumonia was moderate.

Infection-associated decrease of serum creatine kinase levels in Fukuyama congenital muscular dystrophy

BACKGROUND

Marked decreases in serum creatine kinase levels have been noted in Duchenne and Becker muscular dystrophies as rare complications of autoimmune or autoinflammatory diseases.

SUBJECTS AND METHODS

The influence of systemic inflammation on serum creatine kinase levels was reviewed from the charts of three subjects with Fukuyama congenital muscular dystrophy.

RESULTS

A total of 30 infectious events were identified. Elevated serum C-reactive protein levels coincided with decreased creatine kinase levels on 19 occasions. In one subject, administration of 2 mg/kg/d prednisolone for bronchial asthma resulted in a decrease in creatine kinase level on six other occasions.

CONCLUSION

Apart from an increase in endogenous cortisol secretion, certain inflammation-related molecules could play a role in mitigating muscle cell damage in Fukuyama congenital muscular dystrophy during febrile infectious episodes. Corticosteroids may be a promising agent for the treatment of muscular symptoms in this disorder.

Metagenomic sequencing and evaluation of the host response in the pediatric aerodigestive population

OBJECTIVES

To assess the diagnostic utility of metagenomic sequencing in pediatric aerodigestive clinic patients being evaluated for chronic aspiration. We hypothesize that using a metagenomics platform will aid in the identification of microbes not found on standard culture.

STUDY DESIGN AND METHODS

Twenty-four children referred to an aerodigestive clinic were enrolled in a prospective, single-site, cross-sectional cohort study. At the time of clinical evaluation under anesthesia, two samples were obtained: an upper airway sample and a sample from bronchoalveolar lavage (BAL). Samples were sent for routine culture and analyzed using Explify® Respiratory, a CLIA Laboratory Developed Test which identifies respiratory commensals and pathogens through RNA and DNA sequencing. Since RNA was sequenced in the course of the metagenomic analysis to identify organisms (RNA viruses and bacteria), the sequencing approach also captured host derived messenger RNA during sample analysis. This incidentally obtained host transcriptomic data were analyzed to evaluate the host immune response. The results of these studies were correlated with the clinical presentation of the research subjects.

RESULTS

In 10 patients, organisms primarily associated with oral flora were identified in the BAL. Standard culture was negative in three patients where clinical metagenomics led to a result with potential clinical significance. Transcriptomic data correlated with the presence or absence of dysphagia as identified on prior videofluoroscopic evaluation of swallowing.

CONCLUSIONS

Clinical metagenomics allows for simultaneous analysis of the microbiota and the host immune response from BAL samples. As the technologies in this field continue to advance, such testing may improve the diagnostic evaluation of patients with suspected chronic aspiration.

Poor oral hygiene, oral microorganisms and aspiration pneumonia risk in older people in residential aged care: a systematic review

BACKGROUND

aspiration pneumonia increases hospitalisation and mortality of older people in residential aged care.

OBJECTIVES

determine potentially pathogenic microorganisms in oral specimens of older people with aspiration pneumonia and the effect of professional oral care in reducing aspiration pneumonia risk.

DATA SOURCES

PUBMED/MEDLINE, CINAHL, EMBASE, COCHRANE, PROQUEST, Google Scholar, Web of Science.

STUDY ELIGIBILITY CRITERIA

published between January 2001 and December 2019 addressing oral microorganisms, aspiration pneumonia, oral health and treatment.

PARTICIPANTS

people 60 years and older in residential aged care.

STUDY APPRAISAL AND SYNTHESIS METHODS

the Newcastle-Ottawa Scale and the Standard Protocol Items: Recommendations for Intervention Trials checklist.

RESULTS

twelve studies (four cross-sectional, five cohort and three intervention) reported colonisation of the oral cavity of older people by microorganisms commonly associated with respiratory infections. Aspiration pneumonia occurred less in people who received professional oral care compared with no such care. Isolation of Candida albicans, Staphylococcus aureus, methicillin-resistant S. aureus and Pseudomonas aeruginosa was related to mortality due to aspiration pneumonia. An interesting finding was isolation of Escherichia coli, a gut bacterium.

LIMITATIONS

more information may be present in publications about other co-morbidities that did not meet inclusion criteria. A high degree of heterogeneity prevented a meta-analysis. Issues included sampling size, no power and effect size calculations; different oral health assessments; how oral specimens were analysed and how aspiration pneumonia was diagnosed.

CONCLUSIONS AND IMPLICATIONS OF KEY FINDINGS

pathogenic microorganisms colonising the oral microbiome are associated with aspiration pneumonia in older people in residential care; professional oral hygiene care is useful in reducing aspiration pneumonia risk.

Clinical Management of Children with Oropharyngeal Aspiration - Physician Survey

Introduction: Pulmonary aspiration in infants and children is common, with 25% of the pediatric population reported to experience some type of nonspecific swallowing dysfunction. Diagnosing and managing oropharyngeal aspiration remain a challenging task due to the lack of distinguishing clinical or laboratory characteristics. We conducted a large, physician-based survey in an effort to determine the differences in the diagnosis and management of patients with oropharyngeal aspiration across different centers, using a quantitative online questionnaire. Methods: A survey was developed with the goal of understanding the physician demographics, diagnosis, management strategies, and the role of specialized centers for airway, voice, and swallowing disorders (also known as Aerodigestive Disease Centers). The questionnaire was sent to the pediatric membership of the American Thoracic Society. Results: A total of 136 questionnaires were completed and physicians from 42 different Aerodigestive Digestive Centers participated in the survey. Ninety-two percent of respondents believed that the evidence is unclear on the best methods for diagnosing lung disease related to oropharyngeal aspiration. Modified barium swallow (MBS) study and fiberoptic endoscopic evaluation of swallowing were the most useful studies in making the diagnosis of the oropharyngeal aspiration according to the participants. The majority of the participants preferred to repeat the feeding evaluations and MBS after the initial intervention. For children with suspected or confirmed aspiration, 68.6% of the respondents stated that they combine endoscopy and flexible and/or rigid bronchoscopy for further evaluation, while 27.1% preferred to perform the procedures individually at the discretion of each specialty provider. Inhaled corticosteroids were mostly prescribed if there was any component of bronchial hyperreactivity, and acid suppression therapy was primarily prescribed if there was a diagnosis or suspicion of gastroesophageal reflux disease. Empirical thickening of the feeds was not uniformly performed among the aerodigestive centers as a therapy method for the children with swallowing dysfunction with aspiration. Conclusion: In the survey, physicians mentioned about the importance of better guidelines for aspiration, the requirement of new diagnostic measures, the necessity of multicenter trials of sensitivity and specificity of current diagnostic tools, and developing a scoring system for reading the radiological studies for children with oropharyngeal aspiration.

Animal Models of Aspiration Pneumonia

Appropriate animal models of aspiration pneumonia may be required for studying the mechanism of aspiration and aspiration-induced pneumonia. Animal models of AP allow us to investigate distinct types of pneumonia at various disease stages, studies that are not possible in patients. AP animal models should have features of bacterial pneumonia and swallowing abnormality.

Our animal model of aspiration, using recombinant E1-deleted Ad vectors, may be advantageous relative to earlier models for assessing the development of aspiration pneumonia in association with disturbed upper airway reflexes, since DNA virus infection of bronchiolar epithelial cells in the lower respiratory tract can be assessed by the localization and intensity of LacZ gene expression The other candidate model of aspiration was applied for the experimental stroke in mice induced by occlusion of the middle cerebral artery. Aspiration pneumonia was caused by intranasal application of a small amount of Streptococcus pneumoniae.

Acid pneumonitis is a major cause of sterile acute lung injury (ALI), resulting in acute respiratory distress syndrome (ARDS) or Mendelson’s syndrome. Several types of animal models of acid aspiration are available using a wide range of developed transgenic models.

Different types of animal models of both aspiration pneumonia and aspiration pneumonitis have considerably aided our understanding of disease pathogenesis and testing and developing of new treatment strategies.

Acute exposure of mice to hydrochloric acid leads to the development of chronic lung injury and pulmonary fibrosis

Objective: Accidental exposure to hydrochloric acid (HCl) is associated with acute lung injury in humans, development of long-term chronic airway obstruction, and fibrosis. However, the mechanisms responsible for the progression to pulmonary fibrosis remain unclear. We utilized a mouse model of progressive lung injury from a single exposure to HCl to investigate the effects of HCl on the lower respiratory tract. Materials and methods: HCl (0.05-0.3 N) or saline was injected intratracheally into male C57Bl/6J mice. At 1, 4, 10 and 30 days post instillation, bronchoalveolar lavage fluid (BALF) and lung tissues were collected and examined for multiple outcomes. Results and discussion: We observed an early inflammatory response and a late mild inflammation present even at 30 d post HCl exposure. Mice treated with HCl exhibited higher total leukocyte and protein levels in the BALF compared to the vehicle group. This was characterized by increased number of neutrophils, monocytes, and lymphocytes as well as pro-inflammatory cytokines during the first 4 d of injury. The late inflammatory response exhibited a predominant presence of mononuclear cells, increased permeability to protein, and higher levels of the pro-fibrotic mediator TGFβ. Pro-fibrotic protein biomarkers, phosphorylated ERK, and HSP90, were also overexpressed at 10 and 30 d following HCl exposure. In vivo lung function measurements demonstrated lung dysfunction and chronic lung injury associated with increased lung hydroxyproline content and increased expression of extracellular matrix (ECM) proteins. The acute inflammation and severity of fibrosis increased in HCl-concentration dependent manner. Conclusions: Our findings suggest that the initial inflammatory response and pro-fibrotic biomarker upregulation may be linked to the progression of pulmonary fibrosis and airway dysfunction and may represent valuable therapeutic targets.

Clinical Utility of Bronchoalveolar Lavage Pepsin in Diagnosis of Gastroesophageal Reflux among Wheezy Infants

Background. There is no gold standard test for diagnosis of gastroesophageal reflux disease (GERD) associated infantile wheezing. Objectives. To evaluate the value of bronchoalveolar lavage (BAL) pepsin assay in diagnosis of GERD in wheezy infants. Methods. Fifty-two wheezy infants were evaluated for GERD using esophageal combined impedance-pH (MII-pH) monitoring, esophagogastroduodenoscopy with esophageal biopsies, and BAL pepsin. Tracheobronchial aspirates from 10 healthy infants planned for surgery without history of respiratory problems were examined for pepsin. Results. Wheezy infants with silent reflux and wheezy infants with typical GERD symptoms but normal MII-pH had significantly higher BAL pepsin compared to healthy control (45.3 ± 8.6 and 42.8 ± 8 versus 29 ± 2.6, P < 0.0001 and P = 0.011, resp.). BAL pepsin had sensitivity (61.7%, 72 %, and 70%) and specificity (55.5%, 52.9%, and 53%) to diagnose GERD associated infantile wheeze compared to abnormal MII-pH, reflux esophagitis, and lipid laden macrophage index, respectively. Conclusion. A stepwise approach for assessment of GERD in wheezy infants is advised. In those with silent reflux, a trial of antireflux therapy is warranted with no need for further pepsin assay. But when combined MII-pH is negative despite the presence of typical GERD symptoms, pepsin assay will be needed to rule out GERD related aspiration.

Impact of tracheal cuff shape on microaspiration of gastric contents in intubated critically ill patients: study protocol for a randomized controlled trial

Background

Ventilator-associated pneumonia (VAP) is the most common infection in intubated critically ill patients. Microaspiration of the contaminated gastric and oropharyngeal secretions is the main mechanism involved in the pathophysiology of VAP. Tracheal cuff plays an important role in stopping the progression of contaminated secretions into the lower respiratory tract. Previous in vitro studies suggested that conical cuff shape might be helpful in improving tracheal sealing. However, clinical studies found conflicting results. The aim of this study is to determine the impact of conical tracheal cuff shape on the microaspiration of gastric contents in critically ill patients.

Methods/Design

This prospective cluster randomized controlled crossover open-label trial is currently being conducted in ten French intensive care units (ICUs). Patients are allocated to intubation with a polyvinyl chloride (PVC) standard (barrel)-shaped or a PVC conical-shaped tracheal tube. The primary objective is to determine the impact of the conical shaped tracheal cuff on abundant microaspiration of gastric contents. Secondary outcomes include the incidence of microaspiration of oropharyngeal secretions, tracheobronchial colonization, VAP and ventilator-associated events. Abundant microaspiration is defined as the presence of pepsin at significant level (>200 ng/ml) in at least 30 % of the tracheal aspirates. Pepsin and amylase are quantitatively measured in all tracheal aspirates during the 48 h following inclusion. Quantitative tracheal aspirate culture is performed at inclusion and twice weekly. We plan to recruit 312 patients in the participating ICUs.

Discussion

BEST Cuff is the first randomized controlled study evaluating the impact of PVC tracheal-cuff shape on gastric microaspirations in patients receiving invasive mechanical ventilation. Enrollment began in June 2014 and is expected to end in October 2015.

Trial registration

ClinicalTrials.gov Identifier: NCT01948635 (registered 31 August 2013).

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.

Accuracy of alpha amylase in diagnosing microaspiration in intubated critically-ill patients

OBJECTIVES

Amylase concentration in respiratory secretions was reported to be a potentially useful marker for aspiration and pneumonia. The aim of this study was to determine accuracy of α-amylase in diagnosing microaspiration in critically ill patients.

METHODS

Retrospective analysis of prospectively collected data collected in a medical ICU. All patients requiring mechanical ventilation for at least 48 h, and included in a previous randomized controlled trial were eligible for this study, provided that at least one tracheal aspirate was available for α-amylase measurement. As part of the initial trial, pepsin was quantitatively measured in all tracheal aspirates during a 48-h period. All tracheal aspirates were frozen, allowing subsequent measurement of α-amylase for the purpose of the current study. Microaspiration was defined as the presence of at least one positive tracheal aspirate for pepsin (>200 ng.mL-1). Abundant microaspiration was defined as the presence of pepsin at significant level in >74% of tracheal aspirates.

RESULTS

Amylase was measured in 1055 tracheal aspirates, collected from 109 patients. Using mean α-amylase level per patient, accuracy of α-amylase in diagnosing microaspiration was moderate (area under the receiver operator curve 0.72±0.05 [95%CI 0.61-0.83], for an α-amylase value of 1685 UI.L-1). However, when α-amylase levels, coming from all samples, were taken into account, area under the receiver operator curve was 0.56±0.05 [0.53-0.60]. Mean α-amylase level, and percentage of tracheal aspirates positive for α-amylase were significantly higher in patients with microaspiration, and in patients with abundant microaspiration compared with those with no microaspiration; and similar in patients with microaspiration compared with those with abundant microaspiration. α-amylase and pepsin were significantly correlated (r2 = 0.305, p = 0.001).

CONCLUSION

Accuracy of mean α-amylase in diagnosing microaspiration is moderate. Further, when all α-amylase levels were taken into account, α-amylase was inaccurate in diagnosing microaspiration, compared with pepsin.

Risk factors for aspiration in community-acquired pneumonia: analysis of a hospitalized UK cohort

BACKGROUND

There is a move toward finding clinically useful "phenotypes" in community-acquired pneumonia: groups of patients displaying distinct clinical characteristics, microbiology, and prognosis. Aspiration pneumonia is an intuitive clinical phenotype; however, to date there are no recognized diagnostic criteria, and data regarding outcomes in suspected aspiration are limited.

METHODS

An observational study of 1348 patients hospitalized with community-acquired pneumonia in the United Kingdom examined both short- and long-term outcomes for patients at risk of aspiration pneumonia. Patients were defined as "at risk" in the presence of chronic neurologic disorders, esophageal disorders and dysphagia, impaired conscious level, vomiting, or witnessed aspiration. The primary outcome was 30-day mortality. Secondary outcomes included 1-year mortality, readmissions, and recurrent pneumonia within 1 year.

RESULTS

Some 13.8% of the cohort were classified as "at risk of aspiration." These patients were older (median age, 74 years [interquartile range, 60-84] vs 66 years [interquartile range, 49-77]; P < .0001) and more likely to have comorbidities (chronic liver disease 11.3% vs 3.7%, P < .0001; congestive heart failure 28% vs 17.1%, P = .0004; and stroke 26.9% vs 9.5%, P < .0001). Patients at risk of aspiration pneumonia had a poorer short-term outcome (30-day mortality 17.2% vs 7.7%, P < .0001), but after adjusting for their greater severity of illness and comorbidities this difference was not significant (odds ratio 1.05; 95% confidence interval [CI], 0.63-1.76; P = .8). However, patients with aspiration risk factors were at greater risk of poor long-term outcomes with increased 1-year mortality (hazard ratio [HR], 1.73; 95% CI, 1.15-2.58), increased risk of rehospitalization (HR, 1.52; 95% CI, 1.21-1.91), and a strong association with recurrent admissions with pneumonia (HR, 3.13; 95% CI, 2.05-4.78) after multivariable adjustment.

CONCLUSIONS

Using risk factors to identify patients at risk of aspiration pneumonia identifies a distinct clinically useful phenotype of patients with greater severity of disease and poorer long-term outcomes.

Pepsin concentrations are elevated in the bronchoalveolar lavage fluid of patients with idiopathic pulmonary fibrosis after lung transplantation

BACKGROUND

Aspiration of gastroesophageal refluxate has been implicated in the pathogenesis of idiopathic pulmonary fibrosis (IPF) and the progression of bronchiolitis obliterans syndrome after lung transplantation. The goals of the present study were to identify lung transplant patients at the greatest risk of aspiration and to investigate the causative factors.

MATERIALS AND METHODS

From September 2009 to November 2011, 252 bronchoalveolar lavage fluid (BALF) samples were collected from 100 lung transplant patients. The BALF pepsin concentrations and the results of transbronchial biopsy, esophageal function testing, barium swallow, and gastric emptying scan were compared among those with the most common end-stage lung diseases requiring lung transplantation: IPF, chronic obstructive pulmonary disease, cystic fibrosis, and α1-antitrypsin deficiency.

RESULTS

Patients with IPF had higher BALF pepsin concentrations and a greater frequency of acute rejection than those with α1-antitrypsin deficiency, cystic fibrosis, or chronic obstructive pulmonary disease (P = 0.037). Moreover, the BALF pepsin concentrations correlated negatively with a lower esophageal sphincter pressure and distal esophageal amplitude; negatively with distal esophageal amplitude and positively with total esophageal acid time, longest reflux episode, and DeMeester score in those with chronic obstructive pulmonary disease; and negatively with the upright acid clearance time in those with IPF.

CONCLUSIONS

Our results suggest that patients with IPF after lung transplantation are at increased risk of aspiration and a greater frequency of acute rejection episodes, and that the risk factors for aspiration might be different among those with the most common end-stage lung diseases who have undergone lung transplantation. These results support the role of evaluating the BALF for markers of aspiration in assessing lung transplant patients as candidates for antireflux surgery.

Analysis of the protective biochemical and pathologic effects of aminoguanidine on an experimental aspiration pneumonitis model induced by bile acids

BACKGROUND

Gastroesophageal reflux (GER) is a common clinical pathology detected in childhood. Bile acids (BAs) are present in reflux and cause various pathologies in the esophagus, the larynx, and the lungs.

OBJECTIVE

We aimed to show if aminoguanidine (AG) contributes to the biochemical and histopathologic treatment of experimental aspiration pneumonitis induced by BAs.

METHODS

Twenty-eight female Sprague Dawley rats were used. There were 4 groups in the study: (1) group aspirated with 0.9% saline (n = 7), (2) group aspirated with 0.9% saline and treated with AG (n = 7), (3) group aspirated with a solution of 10 mg/kg taurocholic acid and 5 mg/kg taurochenodeoxycholate (n = 7), and (4) group aspirated with BA and treated with AG (n = 7). The saline and BA solutions were administered as 1 mL/kg intratracheally. The AG was administered intraperitoneally twice a day at a 150 mg/kg dose for 7 days. The different histopathologic and biochemical parameters were analyzed.

RESULTS

Clara cell protein 16 and malondialdehyde levels were found to be significantly higher in the BA group than in the group where saline was administered; however, they were significantly lower in the BA + AG group than in the BA group. The total superoxide dismutase activity decreased significantly in the BA group compared with the group where saline was administered. A significant increase in superoxide dismutase activity was observed in the BA + AG group when compared with the group where only BA was administered. When the group where BA was administered solely was compared with the group where saline was administered, peribronchial inflammatory cell infiltration, alveolar septal infiltration, alveolar histiocytes, interstitial fibrosis, and granuloma were significantly higher in the BA group than in the saline group. When the BA + AG group was compared with the BA group, peribronchial inflammatory cell infiltration, alveolar septal infiltration, alveolar histiocytes, interstitial fibrosis, and granuloma were found to be significantly lower.

CONCLUSIONS

Oxidant stress increases and antioxidant capacity decreases in pneumonitis induced by BAs. AG administration as an antioxidant helps in recovery, both biochemically and histopathologically. Consequently, AG seems to be an alternative that should be considered in a conservative approach to treating aspiration pneumonitis.

The effect of curcumin on lung injuries in a rat model induced by aspirating gastrointestinal decontamination agents

BACKGROUND

Aspiration is one of the most feared complications of gastrointestinal decontamination procedures with nonabsorbed polyethylene glycol (PEG) solution and activated charcoal (AC). We aimed to investigate the protective effects of curcumin (CUR) on lung injury in rats induced by aspiration of these agents.

METHODS

Experimental rats were divided randomly into 6 groups (n = 7): a saline-aspirated control (group I), sterile saline aspirated with CUR treatment (group II), PEG aspirated (group III), PEG aspirated with CUR treatment (group IV), AC aspirated (group V), and AC aspirated with CUR treatment (group VI). After aspiration, treatment groups II, IV, and VI were given 150 mg/kg CUR intraperitoneally once a day for 7 days. After 7 days, the rats were humanely killed, and both the lungs and serum specimens from all groups were evaluated histopathologically, immunohistochemically, and biochemically.

RESULTS

Aspiration of gastrointestinal decontamination agents produced histopathologic changes, elevated levels of malondialdehyde and surfactant protein D, reduced levels of antioxidant enzymes, and increased expression of inflammatory cytokines interleukin-1β and tumor necrosis factor α. Curcumin treatments effectively attenuated the rats' pulmonary inflammation responses (as shown by reduced alveolar damage), decreased serum malondialdehyde and surfactant protein D levels, and inhibited the expressions of tumor necrosis factor α and interleukin-1β.

CONCLUSIONS

Because of its anti-inflammatory effects, CUR treatment may have preventive effects on lung injuries induced by aspirating gastrointestinal decontamination agents.

Aspiration-induced lung injury

OBJECTIVE

Aspiration of oropharyngeal or gastric contents into the lower respiratory tract is a common event in critically ill patients and can lead to pneumonia or pneumonitis. Aspiration pneumonia is the leading cause of pneumonia in the intensive care unit and is one of the leading risk factors for acute lung injury and acute respiratory distress syndromes. Despite its frequency, it remains largely a disease of exclusion characterized by ill-defined infiltrates on the chest radiograph and hypoxia. An accurate ability to diagnose aspiration is paramount because different modalities of therapy, if applied early and selectively, could change the course of the disease. This article reviews definitions, diagnosis, epidemiology, pathophysiology, including animal models of aspiration-induced lung injury, and evidence-based clinical management. Additionally, a review of current and potential biomarkers that have been tested clinically in humans is provided.

DATA SOURCES

Data were obtained from a PubMed search of the medical literature. PubMed "related articles" search strategies were used.

SUMMARY AND CONCLUSIONS

Aspiration in the intensive care unit is a clinically relevant problem requiring expertise and awareness. A definitive diagnosis of aspiration pneumonitis or pneumonia is challenging to make. Advances in specific biomarker profiles and prediction models may enhance the diagnosis and prognosis of clinical aspiration syndromes. Evidence-based management is supportive, including mechanical ventilation, bronchoscopy for particulate aspiration, consideration of empiric antibiotics for pneumonia treatment, and lower respiratory tract sampling to define pathogenic bacteria that are causative.

Management of pneumonia in the nursing home

Pneumonia is a major cause of morbidity and mortality among nursing home residents. The approach to managing these patients has lacked uniformity because of the paucity of clinical trials, complexity of underlying comorbid diseases, and heterogeneity of administrative structures. The decision to hospitalize nursing home patients with pneumonia varies among institutions depending on staffing level, availability of diagnostic testing, and laboratory support. In the absence of comparative studies, choice of empirical antibiotic therapy continues to be based on expert opinion. Validated prognostic scoring models are needed for risk stratification. Pneumococcal and influenza vaccination are the primary prevention measures. As of January 2010, Medicare no longer pays for consultation codes; thus, practitioners must instead use existing evaluation and management service codes when providing these services.