Project description:ObjectivesWhen patients with acute respiratory distress syndrome are moved out of an intensive care unit, the ventilator often requires changing. This procedure suppresses positive end expiratory pressure and promotes lung derecruitment. Clamping the endotracheal tube may prevent this from occurring. Whether or not such clamping maintains positive end-expiratory pressure has never been investigated. We designed a bench study to explore this further.How the study was doneWe used the Elysee 350 ventilator in 'volume controlled' mode with a positive end-expiratory pressure of 15 cmH2O, connected to an endotracheal tube with an 8 mm internal diameter inserted into a lung model with 40 ml/cmH2O compliance and 10 cmH2O/L/s resistance. We measured airway pressure and flow between the distal end of the endotracheal tube and the lung model. We tested a plastic, a metal, and an Extra Corporeal Membrane Oxygenation clamp, each with an oral/nasal, a nasal, and a reinforced endotracheal tube. We performed an end-expiratory hold then clamped the endotracheal tube and disconnected the ventilator. We measured the change in airway pressure and volume for 30 s following the disconnection of the ventilator.ResultsAirway pressure decreased thirty seconds after disconnection with all combinations of clamp and endotracheal tube. The largest fall in airway pressure (-17.486 cmH2O/s at 5 s and -18.834 cmH2O/s at 30 s) was observed with the plastic clamp combined with the reinforced endotracheal tube. The smallest decrease in airway pressure (0 cmH2O/s at 5 s and -0.163 cmH2O/s at 30 s) was observed using the Extra Corporeal Membrane Oxygenation clamp with the nasal endotracheal tube.ConclusionsOnly the Extra Corporeal Membrane Oxygenation clamp was efficient. Even with an Extra Corporeal Membrane Oxygenation clamp, it is important to limit the duration the ventilator is disconnected to a few seconds (ideally 5 s).
Project description:BackgroundAn abrupt lung deflation in rodents results in lung injury through vascular mechanisms. Ventilator disconnections during endo-tracheal suctioning in humans often cause cardio-respiratory instability. Whether repeated disconnections or lung deflations cause lung injury or oedema is not known and was tested here in a porcine large animal model.MethodsYorkshire pigs (~ 12 weeks) were studied in three series. First, we compared PEEP abruptly deflated from 26 cmH2O or from PEEP 5 cmH2O to zero. Second, pigs were randomly crossed over to receive rapid versus gradual PEEP removal from 20 cmH2O. Third, pigs with relative volume overload, were ventilated with PEEP 15 cmH2O and randomized to repeated ETT disconnections (15 s every 15 min) or no disconnection for 3 h. Hemodynamics, pulmonary variables were monitored, and lung histology and bronchoalveolar lavage studied.ResultsAs compared to PEEP 5 cmH2O, abrupt deflation from PEEP 26 cmH2O increased PVR, lowered oxygenation, and increased lung wet-to-dry ratio. From PEEP 20 cmH2O, gradual versus abrupt deflation mitigated the changes in oxygenation and vascular resistance. From PEEP 15, repeated disconnections in presence of fluid loading led to reduced compliance, lower oxygenation, higher pulmonary artery pressure, higher lung wet-to-dry ratio, higher lung injury score and increased oedema on morphometry, compared to no disconnects.ConclusionSingle abrupt deflation from high PEEP, and repeated short deflations from moderate PEEP cause pulmonary oedema, impaired oxygenation, and increased PVR, in this large animal model, thus replicating our previous finding from rodents. Rapid deflation may thus be a clinically relevant cause of impaired lung function, which may be attenuated by gradual pressure release.
Project description:BackgroundThe swapping of a supraglottic airway device or a tracheal tube in anaesthetised adult patients is a challenging procedure because potential complications through hypoxemia and loss of airway may occur, with life-threatening implications. This study aims to evaluate which airway technique offers the highest success rate concerning a secure airway in established supraglottic airway and tracheal tube airway exchange scenarios.MethodsAfter ethical approval, anaesthesiologists were randomised 1:1 into simulated scenarios: an LTS group (malpositioned laryngeal tube) and a Cuff group (relevant cuff leakage of a placed tracheal tube). After that, both groups completed a common scenario consisting of a partially obstructed tracheal tube lumen in a fixed prone position with a Mayfield clamp. The primary endpoint was a successful tracheal airway exchange within ten minutes after the start of the scenario and before severe hypoxemia (SpO2 < 80%) arose. Secondary endpoints were the evaluation of factors influencing success after 10 min.ResultsIn total, 60 anaesthesiologists (LTS group n = 30; Cuff group n = 30) with a median experience of 7 years (IQR 4-11) were observed. Within 10 min, a malpositioned laryngeal tube was successfully exchanged by 27/30 (90%) participants, compared to the exchange of a tracheal tube with a relevant cuff leakage by 29/30 (97%; p > 0.05). An airway exchange in an obstructed tube scenario occurred in 22/59 (37%). Loss of airway maintenance showed an obvious association with failure in the common scenario (p = 0.02).ConclusionThe results of this simulation-based study reflect that the exchange of an existing but insufficient airway device in clinical practice is a high-risk procedure. Especially in a fixed prone position, the deliberate evaluation of the existing airway patency and well-conceived airway management in the case of the accidental loss of the airway or obstructed airway access are crucial.
Project description:UnlabelledBackgroundThis clinical study evaluated the effect of a suctioning maneuver on aspiration past the cuff during mechanical ventilation.MethodsPatients intubated for less than 48 hours with a PVC-cuffed tracheal tube, under mechanical ventilation with a PEEP ≥5 cm H2O and under continuous sedation, were included in the study. At baseline the cuff pressure was set at 30 cm H2O. Then 0.5ml of blue dye diluted with 3 ml of saline was instilled into the subglottic space just above the cuff. Tracheal suctioning was performed using a 16-French suction catheter with a suction pressure of - 400 mbar. A fiberoptic bronchoscopy was performed before and after the suctioning maneuver, looking for the presence of blue dye in the folds within the cuff wall or in the trachea under the cuff. The sealing of the cuff was defined by the absence of leakage of blue dye either in the cuff wall or in the trachea under the cuff.ResultsTwenty-five patients were included. The size of the tracheal tube was 7-mm ID for 5 patients, 7.5-mm ID for 16 patients, and 8-mm ID for four patients. Blue dye was never seen in the trachea under the cuff before suctioning and only in one patient (4%) after the suctioning maneuver. Blue dye was observed in the folds within the cuff wall in 6 of 25 patients before suctioning and 11 of 25 after (p = 0.063). Overall, the incidence of sealing of the cuff was 76% before suctioning and 56% after (p = 0.073).ConclusionsIn patients intubated with a PVC-cuffed tracheal tube and under mechanical ventilation with PEEP ≥5 cm H2O and a cuff pressure set at 30 cm H2O, a single tracheal suctioning maneuver did not increase the risk of aspiration in the trachea under the cuff.Trial registrationClinicalTrials.gov, number NCT01170156.
Project description:Development is governed by a few conserved signalling pathways. Amongst them, the EGFR pathway is used reiteratively for organ and tissue formation, and when dysregulated can lead to cancer and metastasis. Given its relevance, identifying its downstream molecular machinery and understanding how it instructs cellular changes is crucial. Here we approach this issue in the respiratory system of Drosophila. We identify a new role for EGFR restricting the elongation of the tracheal Dorsal Trunk. We find that EGFR regulates the apical determinant Crb and the extracellular matrix regulator Serp, two factors previously known to control tube length. EGFR regulates the organisation of endosomes in which Crb and Serp proteins are loaded. Our results are consistent with a role of EGFR in regulating Retromer/WASH recycling routes. Furthermore, we provide new insights into Crb trafficking and recycling during organ formation. Our work connects cell signalling, trafficking mechanisms and morphogenesis and suggests that the regulation of cargo trafficking can be a general outcome of EGFR activation.
Project description:BackgroundTracheostomy insertion in patients with coronavirus disease 2019 (COVID-19) presents unique challenges. Patients frequently have high ventilatory requirements, and as an aerosol generating procedure, tracheostomy insertion creates the potential for staff transmission. Problems with tracheostomies contribute to morbidity and mortality, and tracheostomy changes may increase risks of staff transmission. We sought to quantify the incidence of clinically necessitated tracheostomy changes, establish the indications for change and investigate the incidence of staff transmission.MethodsWe conducted a single institution, retrospective, observational cohort study of all intensive care unit (ICU) patients with COVID-19 who had a tracheostomy between March 2020 and April 2021. The institution is a large tertiary referral centre in Ireland.ResultsForty-three patients had a tracheostomy during the study period. All were a Shiley™ Flexible Adult Taperguard or Shiley™ XLT Tracheostomy. 14 patients (33%) required a tracheostomy change, with the majority (57%) involving a change from a standard size to an extended length tracheostomy. Persistent leak was the most common indication for change (71.6%). Other indications included patient-ventilator dyssynchrony, persistent cough and accidental decannulation. No staff transmission of COVID-19 occurred during this study.ConclusionsThe incidence of tracheostomy change was 33%, highlighting the importance of selecting the right tracheostomy for each patient. We discuss how key characteristics of tracheostomies such as type, size, length and inner diameter may impact flow, resistance and work of breathing, leading to unplanned tracheostomy change. No staff transmission occurred arising from tracheostomy insertion, adding to increasing evidence that tracheostomy insertion in COVID-19 appears safe with adherence to guidelines describing the correct use of personal protective equipment.
Project description:IntroductionLeakage of orogastric secretions past the cuff of a tracheal tube is a contributory factor in ventilator-associated pneumonia. Current bench test methods specified in the International Standard for Anaesthetic and Respiratory Equipment (EN ISO 5361:2023) to test cuff leakage involve using a glass or plastic rigid cylinder model of the trachea. There is a need for more realistic models to inform cuff leakage.MethodsWe used human computerised tomography data and additive manufacturing (3D printing), combined with casting techniques to fabricate a bio-inspired synthetic tracheal model with analogous tissue characteristics. We conducted cuff leakage tests according to EN ISO 5361:2023 and compared results for high-volume low-pressure polyvinyl chloride and polyurethane cuffs between the rigid cylinder trachea with our bio-inspired model.ResultsThe tracheal model demonstrated close agreement with published tracheal tissue hardness for cartilaginous and membranous soft tissues. For high-volume low-pressure polyvinyl chloride cuffs the leakage rate was >50% lower in the bio-inspired tracheal model compared with the rigid cylinder model (151 [8] vs 261 [11] ml h-1). For high-volume low-pressure polyurethane cuffs, much lower leakage rates were observed than polyvinyl chloride cuffs in both models with leakage rates higher for the bio-inspired trachea model (0.1 [0.2] vs 0 [0] ml h-1).ConclusionA reproducible tracheal model that incorporates the mechanical properties of the human trachea can be manufactured from segmented CT images and additive manufactured moulds, providing a useful tool to inform future cuff development, leakage testing for industrial applications, and clinical decision-making. There are differences between cuff leakage rates between the bio-inspired model and the rigid cylinder recommended in EN ISO 5361:2023. The bio-inspired model could lead to more accurate and realistic cuff leakage rate testing which would support manufacturers in refining their designs. Clinicians would then be able to choose better tracheal tubes based on the outcomes of this testing.
Project description:ObjectivesThis study examines the histological findings of tracheal tissue samples obtained from COVID-19 positive mechanically ventilated patients, to assess the degree of tracheal inflammation/ulceration present.Design and participantsRetrospective single-centre observational cohort study. All patients admitted to Adult Intensive Care Unit (AICU) with COVID-19 infection, requiring mechanical ventilation and surgical tracheostomy between 1 April and 1 May 2020, were included (Group 1). Tracheal windows excised at tracheostomy underwent histological analysis. Comparison was made with: tracheal windows from COVID-19 positive AICU ventilated patients admitted between 1 January and 1 March 2021 (Group 2); tracheal windows from COVID-19 negative AICU ventilated patients (Group 3); and, tracheal autopsy samples from COVID-19 positive patients that died without undergoing prolonged mechanical ventilation (Group 4).ResultsGroup 1 demonstrated mild/moderate inflammation (tracheitis) in nearly all samples (15/16, 93.8%), with infrequent micro-ulceration (2/16, 12.5%). Group 2 demonstrated similar mild/moderate inflammation in all samples (17/17, 100%), with no ulceration. Histological findings of Groups 1 and 2 COVID-19 positive patients were similar to Group 3 COVID-19 negative patients, which demonstrated mild/moderate inflammation (5/5, 100%), with uncommon superficial erosion (1/5, 20%). Group 4 demonstrated mild chronic inflammation or no significant inflammation, with uncommon micro-ulceration (1/4, 25%).ConclusionsSevere tracheal inflammation was not demonstrated in mechanically ventilated COVID-19 positive patients at the level of the second/third tracheal rings, at the stage of disease patients underwent tracheostomy. Histological findings were similar between mechanically ventilated COVID-19 positive and negative patients. Tracheal ulceration may be a feature of early or severe COVID-19 disease.
Project description:BackgroundTracheobronchial injury (TBI) is a rare but potentially life-threatening trauma that requires prompt diagnosis and treatment. We present a case in which a patient with COVID-19 infection was successfully treated for a TBI through surgical repair and intensive care with extracorporeal membrane oxygenation (ECMO) support.Case presentationThis is the case of a 31-year-old man transported to a peripheral hospital following a car crash. Tracheal intubation was performed for severe hypoxia and subcutaneous emphysema. Chest computed tomography showed bilateral lung contusion, hemopneumothorax, and penetration of the endotracheal tube beyond the tracheal bifurcation. A TBI was suspected; moreover, his COVID-19 polymerase chain reaction screening test was positive. Requiring emergency surgery, the patient was transferred to a private negative pressure room in our intensive care unit. Due to persistent hypoxia and in preparation for repair, the patient was started on veno-venous ECMO. With ECMO support, tracheobronchial injury repair was performed without intraoperative ventilation. In accordance with the surgery manual for COVID-19 patients in our hospital, all medical staff who treated this patient used personal protective equipment. Partial transection of the tracheal bifurcation membranous wall was detected and repaired using 4-0 monofilament absorbable sutures. The patient was discharged on the 29th postoperative day without postoperative complications.ConclusionsECMO support for traumatic TBI in this patient with COVID-19 reduced mortality risk while preventing aerosol exposure to the virus.