Pepsin and amylase in oral and tracheal secretions: a pilot study

Effect of invasive mechanical ventilation on the diversity of the pulmonary microbiota

Pulmonary microbial diversity may be influenced by biotic or abiotic conditions (e.g., disease, smoking, invasive mechanical ventilation (MV), etc.). Specially, invasive MV may trigger structural and physiological changes in both tissue and microbiota of lung, due to gastric and oral microaspiration, altered body posture, high O2 inhalation-induced O2 toxicity in hypoxemic patients, impaired airway clearance and ventilator-induced lung injury (VILI), which in turn reduce the diversity of the pulmonary microbiota and may ultimately lead to poor prognosis. Furthermore, changes in (local) O2 concentration can reduce the diversity of the pulmonary microbiota by affecting the local immune microenvironment of lung. In conclusion, systematic literature studies have found that invasive MV reduces pulmonary microbiota diversity, and future rational regulation of pulmonary microbiota diversity by existing or novel clinical tools (e.g., lung probiotics, drugs) may improve the prognosis of invasive MV treatment and lead to more effective treatment of lung diseases with precision.

Pepsin A in Tracheal Secretions From Patients Receiving Mechanical Ventilation

BACKGROUND

In patients in the intensive care unit (ICU) receiving mechanical ventilation, aspiration of gastric contents may lead to ventilator-associated events and other adverse outcomes. Pepsin in pulmonary secretions is a biomarker of microaspiration of gastric contents.

OBJECTIVES

To evaluate the association between tracheal pepsin A and clinical outcomes related to ventilator use.

METHODS

A subset of 297 patients from a larger clinical trial on aspiration of oral secretions in adults receiving mechanical ventilation consented to have pepsin A measured in their tracheal aspirate samples. A concentration ≥6.25 ng/mL indicated a positive result. Abundant microaspiration was defined as pepsin A in ≥30% of samples. Statistical analyses included analysis of variance, analysis of covariance, and χ2 tests.

RESULTS

Most patients were White men, mean age 59.7 (SD, 18.8) years. Microaspiration was found in 43.8% of patients (n = 130), with abundant microaspiration detected in 17.5% (n = 52). After acuity was controlled for, patients with tracheal pepsin A had a longer mechanical ventilation duration (155 vs 104 hours, P < .001) and ICU stay (9.9 vs 8.2 days, P = .04), but not a longer hospital stay.

CONCLUSIONS

Microaspiration of gastric contents occurred in nearly half of patients and was associated with a longer duration of mechanical ventilation and a longer stay in the ICU. Additional preventative interventions beyond backrest elevation, oropharyngeal suctioning, and management of endotracheal tube cuff pressure may be needed. Also, the timing of pepsin measurements to capture all microaspiration events requires additional exploration.

[Intraoperative Aspiration]

术中误吸是外科手术中常见的肺部并发症，麻醉和体位是导致术中误吸的主要因素。近年来，围手术期肺保护已受到外科和麻醉医师的广泛关注，如何加速术后康复进程，减少相关并发症发生，显著改善患者预后已成为当前外科治疗的主要目标。本文将以术中误吸为重点，从解剖、病理生理、表现、诊断、处理和预防等方面展开综述。

Is α-Amylase an Important Biomarker to Detect Aspiration of Oral Secretions in Ventilated Patients?

Alpha-amylase has emerged as a biomarker of interest in detecting aspiration of oral secretions. In several studies, most ventilated patients have α-amylase values detected in pulmonary secretions. Values of α-amylase are high (as expected) in oral secretions and lowest in bronchoalveolar lavage samples. Around 5-7% of oral α-amylase is detectable in tracheal secretions. Once secretions are aspirated, the duration of detection of α-amylase in pulmonary secretions is unknown. Evidence varies on the relationship between α-amylase and clinical outcomes. Although detection of α-amylase in pulmonary secretions is useful to identify that aspiration has occurred, the lack of standardized reference values, the lack of knowledge regarding duration of detection following aspiration, and mixed findings related to clinical outcomes, limit its usefulness as a measurement tool. If α-amylase is to be used in research and/or clinical practice, additional data are needed to assist in interpretation and application of findings.

Impact of deep oropharyngeal suctioning on microaspiration, ventilator events, and clinical outcomes: A randomized clinical trial

AIMS

To evaluate a deep oropharyngeal suction intervention (NO-ASPIRATE) in intubated patients on microaspiration, ventilator-associated events and clinical outcomes.

DESIGN

Prospective, two-group, single-blind, randomized clinical trial.

METHODS

The study was conducted between 2014 - 2017 in 513 participants enroled within 24 hr of intubation and randomized into NO-ASPIRATE or usual care groups. Standard oral care was provided to all participants every 4 hr and deep oropharyngeal suctioning was added to the NO-ASPIRATE group. Oral and tracheal specimens were obtained to quantify α-amylase as an aspiration biomarker.

RESULTS

Data were analysed for 410 study completers enrolled at least 36 hr: NO-ASPIRATE (N = 206) and usual care (N = 204). Percent of tracheal specimens positive for α-amylase, mean tracheal α-amylase levels over time and ventilator-associated events were not different between groups. The NO-ASPIRATE group had a shorter hospital length of stay and a subgroup with moderate aspiration at baseline had significantly lower α-amylase levels across time.

CONCLUSION

Hospital length of stay was shorter in the NO-ASPIRATE group and a subgroup of intervention participants had lower α-amylase across time. Delivery of standardized oral care to all participants may have been an intervention itself and possibly associated with the lack of significant findings for most outcomes.

IMPACT

This trial compared usual care to oral care with a deep suctioning intervention on microaspiration and ventilator-associated events, as this has not been systematically studied. Further research on the usefulness of α-amylase as an aspiration biomarker and the role of oral suctioning, especially for certain populations, is indicated.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov: NCT02284178.

Analysis on evolutionary relationship of amylases from archaea, bacteria and eukaryota

Amylase is one of the earliest characterized enzymes and has many applications in clinical and industrial settings. In biotechnological industries, the amylase activity is enhanced through modifying amylase structure and through cloning and expressing targeted amylases in different species. It is important to understand how engineered amylases can survive from generation to generation. This study used phylogenetic and statistical approaches to explore general patterns of amylases evolution, including 3118 α-amylases and 280 β-amylases from archaea, eukaryota and bacteria with fully documented taxonomic lineage. First, the phylogenetic tree was created to analyze the evolution of amylases with focus on individual amylases used in biofuel industry. Second, the average pairwise p-distance was computed for each kingdom, phylum, class, order, family and genus, and its diversity implies multi-time and multi-clan evolution. Finally, the variance was further partitioned into inter-clan variance and intra-clan variance for each taxonomic group, and they represent horizontal and vertical gene transfer. Theoretically, the results show a full picture on the evolution of amylases in manners of vertical and horizontal gene transfer, and multi-time and multi-clan evolution as well. Practically, this study provides the information on the surviving chance of desired amylase in a given taxonomic group, which may potentially enhance the successful rate of cloning and expression of amylase gene in different species.

Gastroesophageal reflux disease in COPD: links and risks

COPD is a long-term condition associated with considerable disability with a clinical course characterized by episodes of worsening respiratory signs and symptoms associated with exacerbations. Gastroesophageal reflux disease (GERD) is one of the most common gastrointestinal conditions in the general population and has emerged as a comorbidity of COPD. GERD may be diagnosed by both symptomatic approaches (including both typical and atypical symptoms) and objective measurements. Based on a mix of diagnostic approaches, the prevalence of GERD in COPD ranges from 17% to 78%. Although GERD is usually confined to the lower esophagus in some individuals, it may be associated with pulmonary microaspiration of gastric contents. Possible mechanisms that may contribute to GERD in COPD originate from gastroesophageal dysfunction, including altered pressure in the lower esophageal sphincter (which normally protect against GERD) and changes in esophageal motility. Proposed respiratory contributions to the development of GERD include respiratory medications that may alter esophageal sphincter tone and changes in respiratory mechanics, with increased lung hyperinflation compromising the antireflux barrier. Although the specific cause and effect relationship between GERD and COPD has not been fully elucidated, GERD may influence lung disease severity and has been identified as a significant predictor of acute exacerbations of COPD. Further clinical effects could include a poorer health-related quality of life and an increased cost in health care, although these factors require further clarification. There are both medical and surgical options available for the treatment of GERD in COPD and while extensive studies in this population have not been undertaken, this comorbidity may be amenable to treatment.

Immunoserologic pepsin detection in the saliva as a non-invasive rapid diagnostic test for laryngopharyngeal reflux

BACKGROUND

The most common tool for the diagnosis of laryngopharyngeal reflux (LPR) is still 24-hours esophageal pH monitoring; there is lack of non-invasive, less expensive and accurate diagnostic tools for this frequent disease.

AIMS

To evaluate the accuracy of immunoserologic pepsin detection in the saliva for the diagnosis of LPR.

STUDY DESIGN

Cross-sectional study.

METHODS

A two channeled 24-hour esophageal pH monitoring catheter was placed in patients with a suspicion of LPR. During the 24-hour period, each patient gave one sample of sputum for the immunoserologic pepsin detection test. Pathologic gastroesophageal reflux (GER) findings, LPR findings, pH score in the proximal and distal probes when the sputum sample was given were recorded. The sensitivity, specificity, positive and negative predictive values of the pepsin detection test were analyzed and compared to pH monitoring scores.

RESULTS

The study group consisted of 20 patients who met the criteria. A positive pepsin detection test was elicited from 6 patients. The sensitivity and specificity of the pepsin detection test was 33% and 100%, respectively. A positive predictive value of 100% was recorded. When the pH results of the pepsin positive patients (PPP) and the rest of the study group in the proximal probe at the sample time were compared, the PPP had an apparent acidic pH value compared to the pepsin negative patients (pH: 3.26 for the PPP, pH: 6.81 for the pepsin negative patients).

CONCLUSION

Pepsin detection in the saliva is a recent method and becoming increasingly popular. Because of the benefits and ease of application, a positive salivary pepsin test in a patient suspected of having LPR can be a cost effective, accurate and alternative diagnostic method. Increasing the daily number of sputum samples may increase the sensitivity of the test.

Recent advances in multidisciplinary critical care

The intensive care unit is a work environment where superior dedication is crucial for optimizing patients' outcomes. As this demanding commitment is multidisciplinary in nature, it requires special qualities of health care workers and organizations. Thus research in the field covers a broad spectrum of activities necessary to deliver cutting-edge care. However, given the numerous research articles and education activities available, it is difficult for modern critical care clinicians to keep up with the latest progress and innovation in the field. This article broadly summarizes new developments in multidisciplinary intensive care. It provides elementary information about advanced insights in the field via brief descriptions of selected articles grouped by specific topics. Issues considered include care for heart patients, mechanical ventilation, delirium, nutrition, pressure ulcers, early mobility, infection prevention, transplantation and organ donation, care for caregivers, and family matters.