Measures of tracheal lesions are more discriminatory and reproducible indications of chronic respiratory disease caused by Mycoplasma gallisepticum in poultry.

Mycoplasma gallisepticum is the primary causative agent of chronic respiratory disease in poultry, and vaccination is the measure most commonly used for its control. Pathological changes caused by M. gallisepticum are mainly observed in the trachea and air sacs, but assessment of air sac lesions is subjective. Standardized parameters for evaluation of pathological changes, and their reproducibility and discrimination in uninfected and infected groups, are critical when assessing the efficacy of M. gallisepticum vaccination. This study reviewed and critically appraised the published literature on evaluation of vaccine efficacy against pathological changes caused by M. gallisepticum in poultry in the trachea and air sacs. A search of four electronic databases, with subsequent manual filtering, identified 23 eligible papers published since 1962 describing the assessment of histopathological changes in the trachea using tracheal lesion scores and/or measurement of tracheal mucosal thicknesses and assessment of gross air sac lesions using lesion scores. Measurement of tracheal lesions proved a more reliable and robust method of assessing disease induced by M. gallisepticum when compared to assessment of air sac lesions, highlighting the importance of including assessment of tracheal lesions as the primary outcome variable in vaccine efficacy studies. In addition, this study also identified the necessity for use of a standardized model for evaluation and reporting on M. gallisepticum vaccines to minimize variations between vaccine efficacy studies and to allow direct comparisons between them.RESEARCH HIGHLIGHTS Tracheal and air sac lesions have been used to assess M. gallisepticum vaccine efficacy.The specific parameters and statistical tests used to compare tracheal and air sac lesions vary greatly.Measures of tracheal lesions are more discriminatory than measures of air sac lesions.A standardized model is needed to evaluate vaccines against infection with M. gallisepticum.

Experimental Assessment of Cuff Pressures on the Walls of a Trachea-Like Model Using Force Sensing Resistors: Insights for Patient Management in Intensive Care Unit Settings.

The COVID-19 outbreak has increased the incidence of tracheal lesions in patients who underwent invasive mechanical ventilation. We measured the pressure exerted by the cuff on the walls of a test bench mimicking the laryngotracheal tract. The test bench was designed to acquire the pressure exerted by endotracheal tube cuffs inflated inside an artificial model of a human trachea. The experimental protocol consisted of measuring pressure values before and after applying a maneuver on two types of endotracheal tubes placed in two mock-ups resembling two different sized tracheal tracts. Increasing pressure values were used to inflate the cuff and the pressures were recorded in two different body positions. The recorded pressure increased proportionally to the input pressure. Moreover, the pressure values measured when using the non-armored (NA) tube were usually higher than those recorded when using the armored (A) tube. A periodic check of the cuff pressure upon changing the body position and/or when performing maneuvers on the tube appears to be necessary to prevent a pressure increase on the tracheal wall. In addition, in our model, the cuff of the A tube gave a more stable output pressure on the tracheal wall than that of the NA tube.

Application of a bioengineered composite neotrachea in a dog model.

BACKGROUND: Surgical treatment of extensive tracheal lesions remains a major challenge because of lack of an ideal airway substitute that is well vascularized, rigid, and autologous. We describe a novel surgical technique of tracheal reconstruction using a combination of a polypropylene mesh material and anterior cervical myocutaneous flap in a dog model. MATERIALS AND METHODS: A 3.5-4 cm length of cervical trachea was resected in 16 dogs and replaced with a myocutaneous cervical neck flap wrapped around the plain polypropylene tube (group 1, n = 7) or wrapped around a composite of polypropylene tube with an implanted Z-type metallic-covered stent (group 2, n = 9). The cervical tracheal defect was repaired with the previously mentioned substitute that was directly sutured to the remaining tracheal ends. Dogs were followed up using bronchoscopy and x-rays and euthanized at predetermined times for histologic examination. RESULTS: In group 1, four dogs died within 2 wk from respiratory failure with varying degrees of airway collapse and difficulties in expectoration. In group 2, eight dogs survived, whereas one died of anastomotic dehiscence 1 wk after surgery. Necropsy and histologic examination of the anastomotic sites revealed good healing tissue. Pathologic examination also revealed excellent healing of the squamous epithelium of the neotrachea and the columnar epithelium of the native tracheal mucosa. CONCLUSIONS: The tissue compatibility of the polypropylene mesh material and anterior cervical myocutaneous skin flap makes this a promising therapeutic substitute for treatment of patients with extensive tracheal lesions.

Inflammatory Profiles of Tracheal Biopsies From SARS-CoV-2 Patients.

Purpose: An increasing number of laryngotracheal complications in mechanically ventilated COVID-19 patients has been reported in the last few months. Many etiopathogenetic hypotheses were proposed but no clear explanation of these complications was identified. In this paper we evaluated the possibility that the tracheal mucosa could be a high viral replication site that could weaken the epithelium itself. Methods: Subjects for the COVID-19 group and the control group were selected retrospectively according to specific criteria. Patients' basic and clinical data were recorded and analyzed. Tracheal samples of both groups were collected during surgical tracheostomies and then analyzed from a histological and genetic-transcriptional point of view. Results: Four COVID-19 patients were enrolled in this study and compared with four non-COVID-19 patients. No laryngotracheal complications were identified in both groups. The SARS-CoV-2 was detected in one out of four COVID-19 samples. A subepithelial inflammatory lymphomonocyte infiltrate was observed in all patients but two cases of the COVID-19 group showed vasculitis of small subepithelial vessels associated with foci of coagulative necrosis. Two gene sets (HALLMARK_INFLAMMATORY_RESPONSE and HALLMARK_ESTROGEN_RESPONSE_LATE) were significantly deregulated in COVID-19 patients compared to the control group. Conclusion: The altered inflammatory response of the COVID-19 patients could be another possible explanation of the increasing number of laryngotracheal complications.

Complications of invasive mechanical ventilation in critically Ill Covid-19 patients - A narrative review.

Critically ill COVID-19 patients have to undergo positive pressure ventilation, a non-physiological and invasive intervention that can be lifesaving in severe ARDS. Similar to any other intervention, it has its pros and cons. Despite following Lung Protective Ventilation (LPV), some of the complications are frequently reported in these critically ill patients and significantly impact overall mortality. The complications related to invasive mechanical ventilation (IMV) in critically ill COVID-19 patients can be broadly divided into pulmonary and non-pulmonary. Among pulmonary complications, the most frequent is ventilator-associated pneumonia. Others are barotrauma, including subcutaneous emphysema, pneumomediastinum, pneumothorax, bullous lesions, cardiopulmonary effects of right ventricular dysfunction, and pulmonary complications mimicking cardiac failure, including pulmonary edema. Tracheal complications, including full-thickness tracheal lesions (FTTLs) and tracheoesophageal fistulas (TEFs) are serious but rare complications. Non-Pulmonary complications include neurological, nephrological, ocular, and oral complications.