Mital H. Dave

Comparison of air‐sealing characteristics of tapered‐ vs. cylindrical‐shaped high‐volume, low‐pressure tube cuffs

This study aimed at comparing air‐sealing characteristics of the new tapered‐shaped tracheal tube cuffs with cylindrical tube cuffs.

The prevalence of tracheal bronchus in pediatric patients undergoing rigid bronchoscopy.

Background:Tracheal bronchus (TB) is defined as an abnormal bronchus that originates directly from the lateral wall of the trachea above the carina and goes towards the upper lobe territory of the lung. We analyzed rigid endoscopies of the trachea in children to determine the incidence and characteristics of TB. Methods:In total, 1021 rigid endoscopies of the trachea recorded from children aged 0 to 6 years were analyzed. Endoscopic examination was performed from supraglottic region to carina using a 0-degree Hopkins rod-lens telescope. Patients with a TB were identified and the site of origin of the TB and its level above the carina was noted. Data of the identified patients was reviewed for the presence of preoperative airway findings such as stridor, upper lobe pneumonia and wheezing or atelectasis, other congenital anomalies, and intraoperative complications. Results:TB was detected in 11 (1.06%) of 1021 upper airway endoscopic examinations. All originated from the right lateral wall of the trachea. Six children had retained secretions in the TB, and 3 children had perioperative airway problems unrelated to the TB. One child showed right main stem bronchus narrowing as seen at the true carina, in the presence of a TB. All the children with TB exhibited at least 1 additional congenital anomaly at birth besides TB. Conclusions:TB is a relatively common congenital endoscopic lower airway anomaly in childhood, which is itself rarely symptomatic, but almost always coexists with other congenital anomalies.

Prevalence and characteristics of tracheal cobblestoning in children

Tracheal follicular pattern or so‐called tracheal cobblestoning is a poorly described entity in the literature and is depicted as a nodular or lumpy appearance of the tracheal wall mucosa suggesting tracheal irritation from factors like gastro‐esophageal reflux (GERD) or pulmonary infection. The aim of the present study was to investigate the prevalence and characteristics of tracheal cobblestones in a large pediatric population.

Endoscopic airway findings in children with or without prior endotracheal intubation

Airway alterations found after endotracheal intubation are usually associated with mechanical trauma from the tube. However, no studies are available concerning alterations in airways that have never been intubated before. It was the aim of the study to compare endoscopic findings in the larynx and trachea of children who had undergone prior endotracheal intubation with findings in children who had not been intubated before.

Massive aspiration past the tracheal tube cuff caused by closed tracheal suction system.

Background: Aspiration past the tracheal tube cuff has been recognized to be a risk factor for the development of ventilator-associated pneumonia (VAP). This study investigated the effect of closed tracheal suctioning on aspiration of fluid past the tracheal tube cuff in an in vitro benchtop model. Methods: High-volume low pressure tube cuffs of 7.5 mm internal diameter (ID) were placed in a 22 mm ID artificial trachea connected to a test lung. Positive pressure ventilation (PPV) with 15 cm H2O peak inspiratory pressure and 5 cm H2O positive end-expiratory pressure (PEEP) was used. A closed tracheal suction system (CTSS) catheter (size 14Fr) was attached to the tracheal tube and suction was performed for 5, 10, 15, or 20 seconds under 200 or 300 cm H2O suction pressures. Amount of fluid (mL) aspirated along the tube cuff and the airway pressure changes were recorded for each suction procedure. Fluid aspiration during different suction conditions was compared using Kruskal-Wallis and Mann-Whitney test (Bonferroni correction [α = .01]). Results: During 10, 15, and 20 seconds suction, airway pressure consistently dropped down to −8 to −13 cm H2O (P < .001) from the preset level. Fluid aspiration was never observed under PPV + PEEP but occurred always during suctioning. Aspiration along the tube cuff was higher with −300 cm H2O than with −200 cm H2O suction pressure (P < .001) and was much more during 15 and 20 seconds suction time as compared to 5seconds (P < .001). Conclusion: Massive aspiration of fluid occurs along the tracheal tube cuff during suction with the closed tracheal suction system.

Effect of Lanz pressure regulating valve on self-sealing mechanism and air leakage across the tracheal tube cuffs in a benchtop model.

Background: The aim of the present study was to investigate the effect of the Lanz system on air sealing by self-inflation in high volume–low pressure (HVLP) tube cuffs. Methods: In vitro tracheal air sealing was studied in HVLP tracheal tube cuffs (internal diameter [ID] 8.0 mm) made from polyurethane ([PU] Seal Guard tracheal tube, Covidien, Athlone, Ireland) and from polyvinylchloride ([PVC] HiLo tracheal tube, Covidien) with and without Lanz pressure regulating valve. Tube cuffs were placed in a vertical 22 mm ID artificial trachea and inflated to 5, 10, 15, 20, 25, or 30 cm H2O cuff pressures. Pressure control ventilation with peak inspiratory pressures (PIPs) of 20 or 25 cm H2O was applied and air leakage was assessed spirometrically as the ratio of expiratory to inspiratory tidal volumes. Nonparametric Mann-Whitney test was applied to compare the air leakage with and without Lanz system for both cuff types at each cuff pressure and PIP (P < .05). Results: The PVC tube cuffs with Lanz system resulted in significant air leakage at both 20 and 25 cm H2O PIP as compared to those without the Lanz system, especially at cuff pressures lower than the preset PIP (P < .05). Although PU tube cuffs with Lanz system showed reduced air sealing when compared with cuffs without Lanz, the difference was not statistically significant. Conclusion: Cuff pressure compensation with the Lanz system during cyclic respiratory pressure changes interferes with the self-sealing mechanism in HVLP tube cuffs at cuff pressures lower than PIP level. This results in larger air leak across tube cuffs particularly in tube cuffs made from PVC.

Vergleich von Antibeschlagmethoden in der Endoskopie

BACKGROUND The use of a flexible or rigid fiberoptic bronchoscope belongs to the standard repertoire in anesthesiology. Besides a lack of training these procedures may be considerably compromised by endoscopic lens fogging. Several antifogging approaches are commercially available but to date no controlled studies regarding the efficacy of these devices in bronchoscopes exists. The aim of the present study was to compare the efficacy of different commercially available anti-fogging techniques for rigid and flexible bronchoscopes. MATERIALS AND METHODS The study was performed at the department of anesthesia in a university childrens hospital. An artificial airway model was created to simulate in vivo conditions with respect to airflow, temperature and atmospheric moisture. A test picture was inserted into the artificial airway for assuring a standardized view through the bronchoscopes. Antifogging efficacy of two liquid antifog solutions (Ultrastop and Anti-Fog), two antifog wipes (Lina Clear and Reso Clear) and an induction endoscope preheater system (used after one and two induction preheating phases) was assessed by video taping of the bronchoscope view of the test picture. In addition the administration of continuous oxygen airflow of 2 l min⁻¹ through the suction channel of the flexible bronchoscope was tested as an alternative method to prevent lens fogging. All final pictures were rated by 10 staff anesthesiologists who were blinded to the antifog devices used. To assess the clinical relevance of the results, ratings were classified into a 5 grade rating scale (ranging from no visualization of any structure to excellent endoscopic view allowing safe endotracheal intubation). In addition, the failure rate of each anti-fog technique was calculated. RESULTS A total of 300 endoscopic test pictures were taken and assessed. Using the flexible bronchoscope, the use of anti-fog solution (failure rate 3 %) and Lina Clear wipes (failure rate 4%) showed the best results. In the rigid bronchoscope group Ultrastop solution (failure rate 5 %) and Lina Clear wipes (failure rate 3.5 %) showed superior results. The two-time use of the endoscope preheater system was effective using flexible (failure rate 6 %) and rigid bronchoscopes (failure rate 10 %). The application of a continuous oxygen flow of 2 l/min failed to provide a clear endoscopic view (failure rate 93.5 %). CONCLUSIONS All commercially available antifog liquids and wipes showed slightly different reduction of lens fogging. However, other factors such as frequency of usage, the type of endoscope, hygiene properties as well as cost-effectiveness might have a substantial impact on the comparison of all tested anti-fog devices. The use of an endoscope preheater system might be a conceivable alternative method to reduce lens fogging despite the higher initial cost. However, the multiple use of the preheater system cannot be recommended at present as additional handling procedures to ensure an appropriate but safe temperature of the endoscopic tip should be provided by the manufacturer. Application of a continuous oxygen flow was shown not to be effective in preventing lens fogging using a flexible fiberoptic bronchoscope.

Comparison of antifog methods in endoscopy. What really helps

BACKGROUND The use of a flexible or rigid fiberoptic bronchoscope belongs to the standard repertoire in anesthesiology. Besides a lack of training these procedures may be considerably compromised by endoscopic lens fogging. Several antifogging approaches are commercially available but to date no controlled studies regarding the efficacy of these devices in bronchoscopes exists. The aim of the present study was to compare the efficacy of different commercially available anti-fogging techniques for rigid and flexible bronchoscopes. MATERIALS AND METHODS The study was performed at the department of anesthesia in a university childrens hospital. An artificial airway model was created to simulate in vivo conditions with respect to airflow, temperature and atmospheric moisture. A test picture was inserted into the artificial airway for assuring a standardized view through the bronchoscopes. Antifogging efficacy of two liquid antifog solutions (Ultrastop and Anti-Fog), two antifog wipes (Lina Clear and Reso Clear) and an induction endoscope preheater system (used after one and two induction preheating phases) was assessed by video taping of the bronchoscope view of the test picture. In addition the administration of continuous oxygen airflow of 2 l min⁻¹ through the suction channel of the flexible bronchoscope was tested as an alternative method to prevent lens fogging. All final pictures were rated by 10 staff anesthesiologists who were blinded to the antifog devices used. To assess the clinical relevance of the results, ratings were classified into a 5 grade rating scale (ranging from no visualization of any structure to excellent endoscopic view allowing safe endotracheal intubation). In addition, the failure rate of each anti-fog technique was calculated. RESULTS A total of 300 endoscopic test pictures were taken and assessed. Using the flexible bronchoscope, the use of anti-fog solution (failure rate 3 %) and Lina Clear wipes (failure rate 4%) showed the best results. In the rigid bronchoscope group Ultrastop solution (failure rate 5 %) and Lina Clear wipes (failure rate 3.5 %) showed superior results. The two-time use of the endoscope preheater system was effective using flexible (failure rate 6 %) and rigid bronchoscopes (failure rate 10 %). The application of a continuous oxygen flow of 2 l/min failed to provide a clear endoscopic view (failure rate 93.5 %). CONCLUSIONS All commercially available antifog liquids and wipes showed slightly different reduction of lens fogging. However, other factors such as frequency of usage, the type of endoscope, hygiene properties as well as cost-effectiveness might have a substantial impact on the comparison of all tested anti-fog devices. The use of an endoscope preheater system might be a conceivable alternative method to reduce lens fogging despite the higher initial cost. However, the multiple use of the preheater system cannot be recommended at present as additional handling procedures to ensure an appropriate but safe temperature of the endoscopic tip should be provided by the manufacturer. Application of a continuous oxygen flow was shown not to be effective in preventing lens fogging using a flexible fiberoptic bronchoscope.

Lower airway dimensions in pediatric patients—A computed tomography study

The aim of this study was to obtain lower airway dimensions in children by means of computed tomography (CT).

Airway dimensions from fetal life to adolescence-A literature overview

Data on airway dimensions in pediatric patients are important for proper selection of pediatric airway equipment such as endotracheal tubes, double‐lumen tubes, bronchial blockers, or stents. The aim of the present work was to provide a synopsis of the available data on pediatric airway dimensions.