Fabrication and assessment of a bio-inspired synthetic tracheal tissue model for tracheal tube cuff leakage testing.

Introduction: Leakage 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. Methods: We 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. Results: The 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). Conclusion: A 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.

Positional relationships between a tracheal diverticulum and the tracheal tube under general anesthesia: a single-center observational and simulation study.

BACKGROUND: Incomplete sealing of tracheal diverticula by a tracheal tube cuff during positive-pressure ventilation causes barotrauma but the concrete possibility of incomplete sealing has not been indicated. We aimed to assess the possibility of incomplete sealing in a simulated situation of tracheal intubation for patients with tracheal diverticula with tube fixation where the tracheal tube's vocal cord guide overlaps with the patient's vocal cord. METHODS: We retrospectively assessed the characteristics of tracheal diverticula based on thoracic computed tomography data in our institution from January 2018 to July 2020. Then, we assessed the structural parameters of three single-lumen tracheal tubes (Parker Flex-Tip [Parker Medical, Bridgewater, CT, USA], Portex Soft Seal [ICU Medical, San Clemente, CA, USA], and Shiley TaperGuard [Medtronic, Dublin, Ireland]; 6.0-8.0 mm inner diameter size) and simulated the positional relationships between tracheal diverticula and the tracheal tube during tracheal intubation where the vocal cord guide overlaps with the patient's vocal cord. We assessed each tube product's possibility of incompletely sealing tracheal diverticula and the possibility of unintended bronchial intubation. RESULTS: In 5,854 patients, the prevalence of tracheal diverticula was 5.7%. The mean (SD) length from the vocal cord to the distal end of the tracheal diverticula was 52.2 (12.8) mm. Tracheal tubes with length from the distal end of the tracheal cuff to the vocal cord guide of ≥ 70 mm had a low risk of incompletely sealing tracheal diverticula (< 5%) and length from the distal end of the tube to the vocal cord guide of ≤ 95 mm had a low risk of unintended bronchial intubation (< 5%). No products in this study satisfied both outcomes. CONCLUSIONS: Tube fixation, where the vocal cord guide overlaps with the patient's vocal cord, is associated with risk of incompletely sealing of tracheal diverticula depending on the tube's manufacturer and tube's inner diameter size, although it was not a high risk. The use of small inner diameter sized tube relative to patient's body size is high risk of incomplete sealing of tracheal diverticula. TRIAL REGISTRATION: This trial was prospectively registered at University Hospital Medical Information Network (UMIN). CLINICAL TRIAL NUMBER AND REGISTRY URL: UMIN000043317 (URL: https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000048055 ).

Uncapped Metered-Dose Inhalers: A Risk for Foreign Body Aspiration. A Case Report and Review of the Literature.

The risk of foreign body aspiration associated with uncapped handheld metered-dose inhalers (MDIs) is underestimated. We report a case in which a plastic cable clip accidentally lodged in the mouthpiece of an uncapped pressurized MDI was aspirated during its use. A literature search revealed 16 other cases of foreign body aspiration associated with uncapped handheld inhalers, all but one of which were pressurized inhalers. Patients should be informed of the risk of foreign body aspiration associated with uncapped pocket inhalers. The use of an uncuffed armoured tracheal tube with a separate oxygen tubing during flexible bronchoscopy for foreign body removal ensures a safe airway. Foreign bodies that exceed the lumen size of the tracheal tube can be pulled to the distal opening with forceps and removed when the tube is withdrawn.

Supraglottic airway device versus tracheal tube for pediatric laparoscopic surgery-A systematic review and meta-analysis.

BACKGROUND: Conventionally, tracheal tubes have been used for general anesthesia in pediatric laparoscopic surgeries. Recently, supraglottic devices are being used for the same. The performance of supraglottic devices versus tracheal tubes in children undergoing laparoscopic surgery is uncertain. METHODS: A systematic review and meta-analysis of randomized controlled trials that compared supraglottic devices versus tracheal tubes in patients ≤18 years undergoing laparoscopic surgery under general anesthesia was conducted. The outcomes were peak airway pressures (cm H2 O), end-tidal carbon dioxide during pneumoperitoneum (mm Hg), recovery time (min), postoperative sore throat and adverse events. Mean difference and odds ratio, with 95% confidence intervals were reported using a random effect model. RESULTS: Eight trials (n = 591) were included in the final meta-analysis. There was no statistically significant difference in the peak airway pressures (MD 0.58, 95% CI: -0.65 to 1.8; p = .36) and end-tidal carbon dioxide (MD -0.60, 95% CI: -2.00 to 0.80; p = .40) during pneumoperitoneum in the supraglottic device and the tracheal tube group. The tracheal tube group had higher odds of sore throat (OR 3.30, 95% CI: 1.69-6.45; p = .0005) and the supraglottic airway group had faster recovery time (MD 4.21, 95% CI: 3.12-5.31; p < .0001), which were statistically significant. The certainty of evidence is graded low. CONCLUSION: There is low quality evidence to suggest that for pediatric laparoscopic surgeries of short duration, supraglottic devices could provide comparable intraoperative ventilation in terms of peak airway pressures and end tidal carbon dioxide, with lower odds of postoperative sore throat and faster recovery time when compared to tracheal tubes.

Aerosolized Antibiotics to Manage Ventilator-Associated Infections: A Comprehensive Review.

BACKGROUND: Ventilator-associated lower respiratory tract infectious complications in critically ill patients cover a wide spectrum of one disease process (respiratory infection), initiating from tracheal tube and/or tracheobronchial colonization, to ventilator associated tracheobronchitis (VAT) and ventilator-associated pneumonia (VAP). VAP occurence has been associated with increased intensive care unit (ICU) morbidity (ventilator days, as well as length of ICU and hospital stay) and ICU mortality. Therefore, treatments that aim at VAP/VAT incidence reduction are a high priority. AIM: The aim of the present review is to discuss the current literature concerning two major aspects: (a) can aerosolized antibiotics (AA) administered in a pre-emptive way prevent the occurrence of ventilator-associated infections? and (b) can VAT treatment with aerosolized avert the potential evolution to VAP? RESULTS: There were identified eight studies that provided data on the use of aerosolized antibiotics for the prevention of VAT/VAP. Most of them report favorable data on reducing the colonisation rate and the progression to VAP/VAT. Another four studies dealt with the treatment of VAT/VAP. The results support the decrease in the incidence to VAP transition and/or the improvement in signs and symptoms of VAP. Moreover, there are concise reports on higher cure rates and microbiological eradication in patients treated with aerosolized antibiotics. Yet, differences in the delivery modality adopted and resistance emergence issues preclude the generalisability of the results. CONCLUSION: Aerosolized antibiotic therapy can be used to manage ventilator-associated infections, especially those with difficult to treat resistance. The limited clinical data raise the need for large randomized controlled trials to confirm the benefits of AA and to evaluate the impact on antibiotic selection pressure.

The development of prediction model for cuffed tracheal tube size from the middle finger in pediatrics: a concise and feasible approach.

Background: Selecting the optimal tracheal tube size is critically important for pediatric patients. Age-based formulas are often used, but still have limitations. The aim of this prospective study was to investigate whether middle finger measurements correlate with cuffed tracheal tube size and to further develop a prediction model based on these measurements. Methods: Patients under 12 years of age scheduled for elective surgery involving tracheal intubation were enrolled in the study. The length was determined from the tip of the distal metacarpal to the palm's root on the palm side, while the circumference was measured at the base of the palm using a soft tape measure. The appropriate cuffed tracheal tube size was determined based on specific criteria. If the tube encountered resistance during insertion or required an airway pressure >25 cmH2O to detect an audible leak, it was replaced with a tube 0.5 mm smaller. Conversely, if an audible leak occurred at an airway pressure <10 cmH2O, or peak pressure >25 cmH2O, or the cuff pressure >25 cmH2O to achieve a seal, the tube was exchanged for one with a 0.5 mm larger. Linear regression analysis was used to examine the association between middle finger circumference and length with the cuffed tracheal tube size. Subsequently, regression equations were constructed based on the results of the linear regression analysis and their predictive performance was compared to the conventional age-based formulas, including the Khine formula and Motoyama formula. The predictive performance was evaluated by mean absolute error (MAE), root mean square error (RMSE), and prediction accuracy. Results: A total of 261 patients were analyzed in our study. The mean age of the patients was 46.19±35.83 months. The linear relationship was observed between the cuffed tracheal tube size and the middle finger circumference and middle finger length with R2 values of 0.77 and 0.73, respectively. In comparison to conventional age-based formulas, both middle finger circumference and middle finger length demonstrated superior predictive performance, characterized by lower MAE and RMSE, as well as higher prediction accuracy. Notably, the regression equation based on the middle finger circumference obtained the higher predictive accuracy of 0.590, with an MAE of 0.259 and an RMSE of 0.333 as opposed to the predictive accuracy of 0.391, MAE of 0.349, and RMSE of 0.473 derived from conventional age-based formulas. Based on the regression coefficients of linear regression, simplified formulas were proposed, with the middle finger circumference-based formula emerging as the most accurate and simple option. Conclusions: The appropriate cuffed tracheal tube size could be predicted by the middle finger circumference. Our proposed formula 'cuffed tracheal tube internal diameter (mm) = middle finger circumference (cm) - 0.2' has the potential to improve the selection of the cuffed tracheal tube size in pediatric patients.

Prediction of endotracheal tube size in the pediatric age group by ultrasound: A systematic review and meta-analysis.

Anatomical differences in the airway in pediatric patients, compared to adults pose many challenges during endotracheal intubation, such as selecting the proper sized endotracheal tube (ETT) during intubation. Our primary objective was to assess how accurate is ultrasound (US) co-relation in comparison to standard age-based formulas in pediatric patients. Meta-analysis was registered in PROSPERO 2020, CRD42020220041. Online literature available in PubMed, Cochrane, and Embase, Goggle scholar was searched from year 2000 till November 30, 2020, using relevant Mesh terms, ('airway US' OR (('airway'/exp OR airway) AND ('US'/exp OR US))) AND ('endotracheal intubation'/exp OR 'endotracheal intubation') AND ('pediatric'/exp OR pediatric)" to Predict endotracheal tube size/placement in pediatric age (neonate till 18 years) by the US. Bibliographic cross-references of selected publications were further manually screened. The full texts of each article were studied, once the abstract was found appropriate independently by two reviewers. A total of 48 papers published between 2010 and 2020 were identified as relevant and read in detail. Average numbers of patients were 86 and total numbers of patients were 1978. Most of the studies included pediatric patients posted for elective surgeries under general anesthesia and excluded emergency procedures, known laryngeal or tracheal pathology, high-risk patients, recent upper respiratory tract infections or allergy to ultrasound gel. A total of 18 independent correlations were analyzed. Final combined r value calculated from all the included articles was 0.824 (95% CI 0.677, 0.908) with a P < 0.00001 {strong co-relation (r > 0.80)}. Q statistic of 756.484, and I2 statistics of 97.53% showed a large degree of heterogeneity in the effect size across the studies. Use of US for upper airway in pediatric patients is an effective modality and can effectively predict endotracheal tube size estimations in comparison to standard age-based or height-based formulae in the pediatric age group. US is a non-invasive, cost-effective, portable, and reproducible technique as compared to CT and MRI. It also takes less time with increasing expertise and experience.

One-lung ventilation and 3D image analysis in a case of tracheal bronchus with steeply angled branching of left main bronchus: a case report.

BACKGROUND: Establishing one-lung ventilation (OLV) in patients with tracheal bronchus (TB) may be challenging due to its unusual bronchial anatomy. We present a case of difficult OLV in a patient with right TB and steeply angled bifurcation of the left main bronchus. CASE PRESENTATION: A 79-year-old woman was scheduled to undergo video-assisted thoracic surgery left upper lobectomy. We planned right OLV with a bronchial blocker; however, it was difficult to place the blocker in the left main bronchus due to a steep bifurcation angle. Therefore, we changed the entry angle of the lumen tip by advancing the tracheal tube to just above the tracheal bifurcation, allowing successful placement of the bronchial blocker into the bronchus. CONCLUSION: For airway management in patients with TB, especially for OLV, it is essential to understand the anatomy of the trachea, bronchus, and TB and to select the appropriate device for each case.

A Tapered Cuff Tracheal Tube Decreases the Need for Cuff Pressure Adjustment After Surgical Retraction During Anterior Cervical Spine Surgery: A Randomized Controlled, Double-Blind Trial.

Background: Surgical retraction to expose the vertebrae during anterior cervical spine surgery increases tracheal tube cuff pressure and may worsen postoperative sore throat and dysphonia. This randomized double-blind study investigated the effect of cuff shape on intraoperative cuff pressure and postoperative sore throat and dysphonia. Methods: Eighty patients were randomized to tracheal intubation with a tapered cuff or a conventional cylindrical high-volume low-pressure cuff (control) during anesthesia. Intraoperative cuff pressures were compared. The primary outcome was the incidence of pressure adjustment needed when the cuff pressure increased to > 25 mm Hg after surgical retraction. The secondary outcome was the incidence of postoperative sore throat and dysphonia. Results: The incidence of pressure adjustment after surgical retraction was significantly lower in the tapered group than in the control group (13% vs. 48%; P = 0.001; relative risk reduction, 74%). The median [interquartile range (IQR)] cuff pressure (mm Hg) was significantly lower for the tapered cuff than for the control cuff before surgical retraction [9 (7-12) vs. 12 (10-15); P < 0.001] and after retraction [18 (15-23) vs. 25 (18-31); P = 0.007]. The median (IQR) postoperative dysphonia score assessed by a single speech-language pathologist was lower in the tapered group than in the control group [4 (3-6) vs. 5.5 (5-7); P = 0.008]. Conclusion: A tapered cuff tracheal tube decreased the need for the adjustment of cuff pressure after surgical retraction during anterior cervical spine surgery, thereby avoiding intraoperative pressure increase. It also has a better outcome in terms of dysphonia. Clinical Trial Registration: [www.clinicaltrials.gov], identifier [NCT04591769].

Positive versus negative pressure during removal of endotracheal-tube on prevention of post-extubation atelectasis in ventilated neonates: A randomized controlled trial.

Background: Post-extubation-atelectasis (PEA) is a common problem after the removal of an endotracheal tube in neonates which increases the rate of extubation failure. Different techniques have been introduced for the prevention of PEA. One technique is the removal of the endotracheal tube by negative or positive gradients of pressure. No RCT has yet been done to compare the use of these two methods in neonates. So this study aimed to compare the role of positive and negative pressure during extubation of neonates on the prevention of PEA. Materials and methods: We enrolled 100 newborns in this RCT that required at least 24 h of mechanical ventilation. The endotracheal tube in one group was removed by a T-Piece resuscitator at a PEEP level of 5 CmH2o while in another group extubation was done applying suction pressure of 100 mmHg by random selection. Prevalence of PEA in CXRs after extubation was compared between the two groups. Results: The prevalence of PEA in the extubation of the positive pressure group (24%) was significantly lower than that of the negative pressure group (46%) (p = 0.024). Extubation failure was found to be lower in the positive pressure group (6% versus 20% P = 0.037). No significant difference was observed between the two groups in the prevalence of apnea, pneumothorax, and death at 3 days after extubation. Conclusion: The use of positive pressure during removal of the endotracheal tube in newborn infants reduced the rate of PEA compared with the negative pressure so extubation by a positive pressure is recommended in neonates.

Anti-inflammatory and Anti-bacterial Effects of Allicin-coated Tracheal Tube on Trachea Mucosa.

BACKGROUND/AIM: Allicin has been known to improve wound healing via antimicrobial and anti-inflammatory properties. The aim of this study was to evaluate whether an allicin-coated tracheal tube can prevent tracheal stenosis through improving wound healing after tracheal injury. MATERIALS AND METHODS: Allicin-coated silicone tracheal tube (t-tube) was prepared by the polydopamine-mediated coating method. Tracheal mucosa was injured, and an allicin-coated t-tube was placed into the trachea to evaluate mucosal changes until designated time point. Anti-inflammatory, anti-bacterial and cytotoxic effects of allicin were also investigated in in vitro. RESULTS: Allicin- coated silicone was not cytotoxic, and it showed anti-inflammatory and anti-bacterial effects in in vitro analysis. The use of allicin-coated t-tube in a rabbit model showed favorable mucosal healing with significant decrease of proinflammatory cytokines compared to the non-coated tube group. The allicin-coated tube showed obvious decreased number of cocci-shaped bacterial attached to the tube surface. From the histological point of view, the allicin- coated tube showed faster regeneration of the normal respiratory epithelial structure compared to the non-coated group. CONCLUSION: Allicin-coated t-tube showed anti-inflammatory and anti-bacterial effects on injured tracheal mucosa. We suggest that allicin-coated t-tube can be used for promoting physiological wound healing to prevent laryngotracheal stenosis.

Changes in the cuff pressure in neonates in the absence of nitrous oxide.

BACKGROUND: Changes in the pressure of cuffed neonatal size tracheal tubes (TT) during anaesthesia without nitrous oxide are not well described. We determined whether the cuff pressure changes over time in neonates under general anaesthesia without nitrous oxide. METHODS: The airways of thirty neonates were secured with a high volume low pressure cuffed TT for meningocele surgery. The cuff was manually inflated until there was no audible leak and maintained at 10-15 cm H2O throughout by monitoring the pressure continuously with both a manometer and a pressure transducer. At baseline, the cuff pressure was assessed in the supine and then prone positions. During surgery, if the pressure exceeded 15 cm H2O, the cuff was deflated to < 15 cm H2O and if it was < 10 cm H2O, the cuff was inflated to 10-15 cm H2O. The time interval between corrections and the number of corrections were recorded. RESULTS: The cuff pressures in 18 neonates (60%) required correction during surgery. The cuff pressure exceeded 15 cm H2O in nine neonates (30%) and was corrected. The cuff pressures in 13 neonates were less than 10 cm H2O and required correction. The gender, weight, height, and duration of anaesthesia did not differ significantly between neonates who required correction of the cuff pressure and those who did not. Mean cuff pressures were similar at 15, 45, and 75 minutes of anaesthesia. CONCLUSIONS: In 60% of neonates undergoing surgery in the prone position under general anaesthesia without nitrous oxide, the cuff pressure exceeded 15 cm H2O. In such cases, cuff pressure should be monitored continuously throughout the surgery.

Bench testing of tracheostomy tube-related insults using an instrumented manikin.

PURPOSE: Choosing the right tracheal tube for the right patient is a daily preoccupation for intensivists and emergency physicians. Tracheal tubes can generate severe complications, which are chiefly due to the pressures applied by the tube to the trachea. We designed a bench study to assess the frequency of pressure levels likely to cause tracheal injury. METHODS: We tested the pressure applied on the trachea by 17 tube models of a given size range. To this end, we added a pressure sensor to the posterior tracheal wall of a standardized manikin. RESULTS: Only 2 of the 17 tubes generated pressures under the threshold likely to induce tracheal injury (30 mmHg/3.99 kPa). The force exerted on the posterior wall of the trachea varied widely across tube models. CONCLUSION: Most models of tracheal tubes resulted in forces applied to the trachea that are usually considered capable of causing tracheal tissue injury. LEVEL OF EVIDENCE: Oxford Centre for Evidence-Based Medicine 2011 Levels of Evidence: How common is the problem?: step 1; Is this diagnostic or monitoring test accurate? (Diagnosis) step 5; What will happen if we do not add a therapy? (Prognosis) n/a; Does this intervention help? (Treatment Benefits) step 5; What are the COMMON harms?(Treatment Harms) step 5; What are the RARE harms? (Treatment Harms) step 5; Is this (early detection) test worthwhile? (Screening) step 5.

Efficacy of tracheal tube introducers and stylets for endotracheal intubation in the prehospital setting: a systematic review and meta-analysis.

PURPOSE: Tracheal tube introducers and stylets remain some of the most widely used devices for aiding practitioners in performing endotracheal intubation (ETI). The purpose of this systematic review is to evaluate the efficacy of tracheal tube introducers and stylets for ETI in the prehospital setting. METHODS: A literature search was conducted on the 2nd of March 2021 across PubMed, Embase (Ovid) and the Cochrane Central Register of Controlled Trials (CENTRAL) to identify relevant studies. Included studies had their data extracted and both a quality assessment and statistical analysis were performed. RESULTS: The summary estimate of prehospital studies with video technology showed a statistically significant increase in first pass ETI success in favour of bougies (RR 1.15, CI 1.10-1.21, p < 0.0001). The summary estimates of prehospital studies without video technology and simulation studies with and without video technology showed no statistical difference between methods for first pass or overall ETI success. Some of the highest success rates were recorded by devices that incorporated video technology. Stylets lead to a shorter time to ETI while bougies were easier to use. Neither device was associated with a higher rate of ETI complications than the other. CONCLUSION: Both tracheal tube introducers and stylets function as efficacious aids to intubation in the prehospital environment. Where video technology is available, bougies could offer a statistically significant advantage in terms of first pass ETI success. Where video technology is unavailable, a combination of clinical scenario, practitioner expertise and personal preference might ultimately guide the choice of device.

Cuffed versus uncuffed tracheal tubes in a rabbit training model for establishing an emergency front-of-neck airway in infants: a prospective trial.

BACKGROUND: There is a paucity of evidence regarding the optimal type of tracheal tube to be advanced over a Frova catheter when performing a 'bougie' emergency front-of-neck airway (eFONA) technique in infants during a 'cannot intubate, cannot oxygenate' situation. METHODS: A prospective non-inferiority trial in a rabbit cadaver surgical tracheotomy model to assess the performance of the eFONA technique with an uncuffed 3.5 mm ID tracheal tube vs a cuffed 3.0 mm ID tracheal tube. Queried outcomes include success rate, performance time, and severe secondary airway injuries among tracheal tube types. RESULTS: In 60 tracheostomies performed by 30 participants, the overall success rate was 98%. Performance time was independent from tracheal tube choice (uncuffed: 61 s [95% confidence interval (CI), 52-76], cuffed: 64 s [95% CI, 55-79]; P = 0.82). No tracheal tube type was preferred in terms of usability by participants. The cuffed tracheal tube required increased force to be advanced over the Frova catheter and was associated with a risk ratio of 2.5 (95% CI, 0.53-11.9; number needed to harm, 10) for severe secondary airway injuries when compared with the uncuffed tracheal tube. CONCLUSION: In performing eFONA in the rabbit cadaver model, an ID 3.5 uncuffed is non-inferior to an ID 3.0 cuffed tracheal tube regarding performance time and preference by the operator. Greater force application to advance the cuffed tube over the Frova catheter and more severe airway injuries may argue for the standardised performance of the eFONA technique with a uncuffed tracheal tube in infants.