High-Flow Nasal Cannula

Conventionally, oxygen is given at 4 to 6 L/min through nasal cannula for supplementation of oxygen. The FiO2 achieved through this can be up to 0.4. Flows more than this can cause dryness to the nasal mucosa without much increase in the FiO2. High-flow nasal cannula (HFNC) uses flow up to 60 L/min. Positive end-expiratory pressure is created in the nasopharynx and it is also conducted to the lower airways. Studies have shown HFNC improves washout of CO2 and decreases respiratory rate. Patient compliance also improves due to the comfort of the cannula compared to the non-invasive ventilation through a mask.

Oral Prevotella Species and Their Connection to Events of Clinical Relevance in Gastrointestinal and Respiratory Tracts

Prevotella is recognized as one of the core anaerobic genera in the oral microbiome. In addition, members of this genus belong to microbial communities of the gastrointestinal and respiratory tracts. Several novel Prevotella species, most of them of oral origin, have been described, but limited knowledge is still available of their clinical relevance. Prevotella melaninogenica is among the anaerobic commensals on oral mucosae from early months of life onward, and other early colonizing Prevotella species in the oral cavity include Prevotella nigrescens and Prevotella pallens. Oral Prevotella species get constant access to the gastrointestinal tract via saliva swallowing and to lower airways via microaspiration. At these extra-oral sites, they play a role as commensals but also as potentially harmful agents on mucosal surfaces. The aim of this narrative review is to give an updated overview on the involvement of oral Prevotella species in gastrointestinal and respiratory health and disease.

The lower airways microbiome and antimicrobial peptides in idiopathic pulmonary fibrosis differ from chronic obstructive pulmonary disease

Background The lower airways microbiome and host immune response in chronic pulmonary diseases are incompletely understood. We aimed to investigate possible microbiome characteristics and key antimicrobial peptides and proteins in idiopathic pulmonary fibrosis (IPF) and chronic obstructive pulmonary disease (COPD). Methods 12 IPF patients, 12 COPD patients and 12 healthy controls were sampled with oral wash (OW), protected bronchoalveolar lavage (PBAL) and right lung protected sterile brushings (rPSB). The antimicrobial peptides and proteins (AMPs), secretory leucocyte protease inhibitor (SLPI) and human beta defensins 1 and 2 (hBD-1 & hBD-2), were measured in PBAL by enzyme linked immunosorbent assay (ELISA). The V3V4 region of the bacterial 16S rDNA gene was sequenced. Bioinformatic analyses were performed with QIIME 2. Results hBD-1 levels in PBAL for IPF were lower compared with COPD. The predominant phyla in IPF were Firmicutes, Bacteroides and Actinobacteria; Proteobacteria were among top three in COPD. Differential abundance analysis at genus level showed significant differences between study groups for less abundant, mostly oropharyngeal, microbes. Alpha diversity was lower in IPF in PBAL compared to COPD (p = 0.03) and controls (p = 0.01), as well as in rPSB compared to COPD (p = 0.02) and controls (p = 0.04). Phylogenetic beta diversity showed significantly more similarity for IPF compared with COPD and controls. There were no significant correlations between alpha diversity and AMPs. Conclusions IPF differed in microbial diversity from COPD and controls, accompanied by differences in antimicrobial peptides. Beta diversity similarity between OW and PBAL in IPF may indicate that microaspiration contributes to changes in its microbiome.

Delivery Mode Shapes the Composition of the Lower Airways Microbiota in Newborns

Radical alterations in the human microbiota composition are well-known to be associated with many pathological conditions. If these aberrations are established at the time of birth, the risk of developing correlated pathologies throughout life is significantly increased. For this reason, all newborns should begin their lives with a proper microbiota in each body district. The present study aimed at demonstrating a correlation between the mode of delivery and the development of a well-balanced microbiota in the lower airways of newborns. 44 pregnant women were enrolled in this study. Microbiological comparative analysis was carried out on tracheobronchial secretions of babies born through vaginal delivery (VD) or caesarean section (CS). All samples showed the presence of bacterial DNA, regardless of the mode of delivery. No viable cultivable bacteria were isolated from the CS samples. On the contrary, VD allowed colonization of the lower airways by alive cultivable bacteria. The identification of bacterial species revealed that Lactobacillus spp. and Bacteroides vulgatus were the most common microorganisms in the lower airways of vaginally-delivered newborns. Data obtained from quantitative PCRs showed a significantly higher total bacterial load, as well as Firmicutes and Lactobacillus spp. amount, in VD samples than CS ones, while no statistically significant difference was found in Torque Teno Virus (TTV) load between samples. Taken together, our findings confirm the hypothesis that passage through the maternal vaginal canal determines more beneficial colonization of the lower airways in newborns.

Global airways – a novel Standard Tests for Asthma, allergic Rhinitis, and chronic Rhinosinusitis (STARR-15)

Background: Global airway disease, with symptoms from both upper and lower airways, is a challenging problem for clinicians. Our goal is to design one single standard test for the awareness of global airway diseases to be used in clinical setting. Material and Methods: During 2019, rhinologists and pulmonologists generated a pool of items based on literature, patient-reported outcome measures and clinical experience. The items were administered to 206 patients with known asthma, CRS, allergic rhinitis, or a combination thereof. The patients also completed the Asthma Control Questionnaire (ACQ-5) and the Sino-Nasal Outcome Test (SNOT-22). Using a mix of clinical knowledge and data-driven methods a global airways questionnaire was developed. Results: Mean ACQ score was highest in patients with all three, whereas the highest SNOT-22 score was observed in patients with CRS and asthma. After the development process, analysis of responses from 206 patients to 44 items on a new global airway’s questionnaire led to identification of 15 items that form the STARR-15 questionnaire with three underlying domains (an allergic rhinitis sub-factor, a CRS sub-factor and an asthma sub-factor). Conclusion: STARR-15 represents the first global airways questionnaire, to be used when examining patients with upper and lower airways symptoms. Future analyses are warranted to evaluate the clinical and psychometric properties of STARR-15.

Differences in the anatomy of the lower respiratory tract in selected species of the order Testudines

The lower airways of turtles consist of the larynx, trachea and bronchi. Due to incomplete information about the anatomical structure of the lower respiratory tract in turtles, we decided to explore this topic more deeply. The material for this study included 95 turtle cadavers. Terrestrial tortoises were represented by 63 individuals from 8 species, aquatic and semi-aquatic turtles by 32 individuals from 11 species. The sex ratio was 54 females to 41 males. In addition to the anatomical autopsies and assessments of the macroscopic structures, numerous measurements were performed. The length, width and height of the larynx and trachea, and the length of the bronchi were measured. We found clinical significance in two parameters. The first one is the formation of the rima glottidis, which is significantly shorter and narrower in the aquatic turtles than in the terrestrial tortoises. It follows that for these species, we should use a smaller diameter of endotracheal cannula for intubation. The second parameter is a very short trachea in tortoises of the genus Testudo. The length of the trachea is only a few centimetres, which significantly increases the risk of intubation into one bronchus only.

A safe procedure? The unusual case of a fatal airway obstruction by silicone during the production process of a tracheostomal epithesis in a 13-year-old boy

A tracheostomal epithesis is a plastic prosthesis that serves for sealing a tracheostoma and ensuring the position of the tracheostomy tube. The production of a tracheostomal epithesis requires an impression of the tracheostoma. To this end, silicone impression material is applied by an anaplastologist in and around the tracheostomal region, including the trachea. The blocked cuff of the tracheostomy tube serves to prevent aspiration of the material. We report on a 13-year-old boy who died during this procedure because the lower airways were obstructed with cured silicone. Forensic autopsy confirmed asphyctic suffocation as cause of death. Forensic physical investigation of the tracheostomy tube and its cuff revealed no structural or functional defects. Yet, the investigation results prove that the viscous silicone must have passed the cuff. To conclude, this case report demonstrates that the production of an impression of a tracheostoma is a procedure with a potentially lethal outcome. Hence, professional guidelines, including clear safety precautions, are urgently needed.

Rothia mucilaginosa is an anti-inflammatory bacterium in the respiratory tract of patients with chronic lung disease

Chronic airway inflammation is the main driver of pathogenesis in respiratory diseases, such as severe asthma, chronic obstructive pulmonary disease (COPD), cystic fibrosis (CF), and bronchiectasis. While the role of common pathogens in airway inflammation is widely recognized, the influence of other microbiota members is still poorly understood. Here, we show that Rothia mucilaginosa, a common resident of the oral cavity that is also often detectable in the lower airways in chronic disease, has an inhibitory effect on pathogen- and LPS-induced pro-inflammatory responses, both in vitro (3-D cell culture model) and in vivo (mouse model). Furthermore, in a cohort of adults with bronchiectasis, the abundance of Rothia spp. was negatively correlated with pro-inflammatory markers (IL-8, IL-1β) and matrix metalloproteinases (MMP-1, MMP-8 and MMP-9) in sputum. Mechanistic studies revealed that R. mucilaginosa inhibits NF-κB pathway activation by reducing the phosphorylation of IκB-α and consequently the expression of NF-κB target genes. These findings indicate that the presence of R. mucilaginosa in the lower airways potentially mitigates inflammation, which could in turn influence severity and progression of chronic respiratory disorders.