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Kemper M, Kemper M, Nicolai T, Dave MH, Henze G, Weiss M. Dimensional compatibility of rigid ventilating bronchoscopes with pediatric airway anatomy using different recommendations for age-related sizing-A bench study. Paediatr Anaesth 2021; 31:1140-1149. [PMID: 34369047 DOI: 10.1111/pan.14270] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 07/29/2021] [Accepted: 08/03/2021] [Indexed: 11/29/2022]
Abstract
BACKGROUND Appropriate size selection of pediatric rigid bronchoscopes is fundamental to avoidance of airway trauma and to a high success rate with the first intubation attempt. The aim of the present study was to compare the outer diameters of pediatric rigid bronchoscopes with the anatomical data on the pediatric airway. METHODS Outer diameters (OD) of pediatric rigid ventilating bronchoscopes as given by the manufacturer were compared with published computed tomography internal diameters (ID) of the cricoid outlet, the trachea as well as the left and right proximal mainstem bronchus, using six published recommendations for age-related size selection. The ratios between a specific OD and ID were calculated and given as percentage values (%) for lower and upper age ranges. RESULTS Nominal sized 2.5, 3, 3.5, 3.7, 4, 4.5, 5, and 6 rigid bronchoscopes were included. In five recommendations, the rigid bronchoscopes' OD was larger than the internal cricoid diameter in the upper age range, whereas in one recommendation the ratio (OD rigid bronchoscope to ID of cricoid) ranged between 77% and 90% for the upper age and between 95% and 109% for the lower age range. In only one of the six recommendations was the rigid bronchoscope OD larger than the tracheal ID. Ratios for the left and right proximal mainstem bronchus ranged from 70% to 146% for the upper and from 78% to 156% for the lower age range, with the highest ratios for the left proximal mainstem bronchus. CONCLUSION Based on this in vitro study, most of the recommendations analyzed result in a balanced fit of rigid bronchoscopes within the cricoid. Since the left mainstem bronchus is considerably smaller than the cricoid, any insertion on this level will require careful endoscopic guidance to avoid damage to the left mainstem bronchus.
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Affiliation(s)
- Melanie Kemper
- Department of Anaesthesia, University Children's Hospital, Zurich, Switzerland
| | - Michael Kemper
- Department of Anaesthesia, University Children's Hospital, Zurich, Switzerland
| | - Thomas Nicolai
- Dr. v. Haunersches Children's Hospital, Ludwig-Maximilians-University Munich, München, Germany
| | - Mital H Dave
- Department of Anaesthesia, University Children's Hospital, Zurich, Switzerland
| | - Georg Henze
- Department of Anaesthesia, University Children's Hospital, Zurich, Switzerland
| | - Markus Weiss
- Department of Anaesthesia, University Children's Hospital, Zurich, Switzerland
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2
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Kemper M, Fischer M, Grass B, Dave MH, Weiss M. Insertion of cuff inflation line into pediatric tracheal tubes related to oral and nasal tracheal intubation depth. Paediatr Anaesth 2021; 31:695-701. [PMID: 33711205 DOI: 10.1111/pan.14180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 02/22/2021] [Accepted: 03/08/2021] [Indexed: 11/29/2022]
Abstract
BACKGROUND In clinical practice, the cuff inflation line of cuffed pediatric tracheal tubes often interferes with securing tracheal tubes. METHODS The insertion site of the cuff inflation lines and the lengths of four different brands and nine sizes of commonly used cuffed pediatric tracheal tubes were measured and compared in vitro with oral and nasotracheal intubation depths as calculated by different formulas for pediatric patients aged from birth to 16 years. Motoyama's recommendation was used for age-related size selection of cuffed pediatric tracheal tubes. RESULTS The proportion of the distance from the tracheal tube tip to the insertion site of the cuff inflation line varied considerably between the tracheal tubes (Microcuff: 48.5-60.7%; Parker: 48.7-73.2%; Ruesch: 59.1-77.8%; and Shiley: 46.0-60.3%). Using different formulas for oral or nasotracheal intubation depth, the insertion site of the cuff inflation line was placed within the oral or nasal cavity or within an area 1 cm beyond the teeth or the nostrils in almost all tracheal tubes tested. Positioning the insertion site 2 cm from the proximal end of the tracheal tubes resulted in a cuff line-free tube area of ≥1 cm in all orally and almost in all nasally inserted tracheal tubes, considering maximum recommended tracheal intubation depths. CONCLUSION The cuff inflation line in almost all commonly used cuffed pediatric tracheal tubes interferes with securing the tracheal tube due to its insertion site into the tracheal tube. This potentially carries the risk of kinking, obstruction, or damage to the cuff inflation line with ensuing failure to deflate or inflate the cuff. The proposed position of the insertion of the cuff inflation line 2 cm from the proximal end of the tracheal tube would ensure a 1-cm-wide cuff line-free circular area beyond the oral or nasal cavity in nearly all assessed tracheal tube sizes.
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Affiliation(s)
- Michael Kemper
- Department of Anesthesiology, RWTH Aachen University Hospital, Aachen, Germany.,Department of Anesthesia, University Children's Hospital, Zurich, Switzerland
| | - Martina Fischer
- Department of Anesthesia, University Children's Hospital, Zurich, Switzerland
| | - Beate Grass
- Department of Intensive Care and Neonatology, University Children's Hospital, Zurich, Switzerland
| | - Mital H Dave
- Department of Anesthesia, University Children's Hospital, Zurich, Switzerland
| | - Markus Weiss
- Department of Anesthesia, University Children's Hospital, Zurich, Switzerland
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Goetschi M, Kemper M, Kleine-Brueggeney M, Dave MH, Weiss M. Inflation volume-balloon diameter and inflation pressure-balloon diameter characteristics of commonly used bronchial blocker balloons for single-lung ventilation in children. Paediatr Anaesth 2021; 31:474-481. [PMID: 33406307 DOI: 10.1111/pan.14123] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 12/28/2020] [Accepted: 12/29/2020] [Indexed: 11/28/2022]
Abstract
BACKGROUND Balloon-tipped bronchial blocker catheters are widely used in pediatric thoracic anesthesia to establish single-lung ventilation. In clinical practice, their balloons demonstrate sudden expansion when inflated with air. In addition, there are concerns related to the high inflation pressures required to expand the balloons. METHODS This in vitro study assessed inflation volume- and inflation pressure-balloon diameter characteristics of the Fogarty arterial embolectomy catheters and Arndt endobronchial blockers. Balloon diameters were photographically assessed during unrestricted volume- and pressure-guided inflation, using air up to the maximum allowed inflation volume as indicated by the manufacturers. Inflation pressures required to open the blocker balloons and inflation pressures needed to expand them to maximum indicated diameter were measured. RESULTS Volume-guided inflation demonstrated a late acute rise in diameter in Fogarty blocker balloons, whereas in the Arndt endobronchial blocker balloons almost linear inflation volume-to-diameter characteristics were observed. Pressure-guided inflation on the other hand demonstrated low-volume, high-pressure characteristics in the Fogarty blocker balloons, with inflation pressures required to expand the balloons to maximum diameters ranging from (mean (SD)) 636 (75) to 947 (152) cmH2 O. The inflation pressures required to open the Fogarty blocker balloons were even >1000 cmH2 O. Inflation pressures required to expand the 5 F, 7 F, and 9 F Arndt endobronchial blocker balloons to maximum indicated diameter were much lower, namely at 218 (15), 252 (28), and 163 (8) cmH2 O. CONCLUSION Based on these study findings, the balloons of Fogarty arterial embolectomy catheters represent high-pressure devices and do not permit stepwise controlled bronchial blockage. The Arndt endobronchial blockers have some advantages over the Fogarty blocker devices, but also represent high-pressure equipment and must be used with caution and limited duration. Manufacturers are asked to design pediatric endobronchial blocker catheters with truly high-volume, low-pressure balloons in accordance to age-related pediatric airway dimensions.
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Affiliation(s)
- Markus Goetschi
- Department of Anesthesia, University Children's Hospital Zurich, Zurich, Switzerland
| | - Michael Kemper
- Department of Anesthesia, University Children's Hospital Zurich, Zurich, Switzerland.,Department of Anesthesiology, RWTH Aachen University Hospital, Aachen, Germany
| | | | - Mital H Dave
- Department of Anesthesia, University Children's Hospital Zurich, Zurich, Switzerland
| | - Markus Weiss
- Department of Anesthesia, University Children's Hospital Zurich, Zurich, Switzerland
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Moser B, Kemper M, Dullenkopf A, Dave MH, Buehler PK, Weiss M. Simulated dimensional compatibility of uncuffed and cuffed tracheal tubes for selective endobronchial intubation in children. Paediatr Anaesth 2021; 31:167-177. [PMID: 33128267 DOI: 10.1111/pan.14058] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 09/30/2020] [Accepted: 10/23/2020] [Indexed: 11/30/2022]
Abstract
BACKGROUND Cuffed tracheal tubes have recently been recommended for selective endobronchial intubation to establish single-lung ventilation even in smaller children. This implies that, compared with uncuffed tracheal tubes, the cuffed tracheal tubes selected will be smaller and therefore have a shorter length. We hypothesized that cuffed tracheal tubes might be of insufficient length for selective endobronchial intubation if the tube cuff were fully immersed in the left or right mainstem bronchus. METHODS The distance from the proximal end of the tracheal tube to the upper border of the cuff in cuffed tracheal tubes and to the upper margin of the Murphy eye in uncuffed tracheal tubes, respectively, was assessed in sizes 3.0-7.0 mm internal diameter. The raw data sets of two previously performed studies obtained from 337 children aged from birth to 16 years, including the distances "teeth to tracheal tube tip" and "tracheal tube tip to carina," were used to calculate age-, weight-, and height-related data for the distance from "teeth to carina." Tracheal tube dimensions were compared with age-related distances from "teeth to carina," applying published recommendations for the selection of uncuffed and cuffed tracheal tubes for selective endobronchial intubation in children. RESULTS The differences between the length of the age-related tracheal tube and the tracheal tube insertion length required to guarantee full insertion of the tracheal tube cuff or the Murphy eye within the mainstem bronchus ranged from -3.5 to 52.6 mm in cuffed tracheal tubes and from 42.3 to 83.3 mm in uncuffed tracheal tubes. CONCLUSIONS For many age groups of patients requiring selective endobronchial intubation, the lengths of cuffed tracheal tubes, in contrast to those of uncuffed tracheal tubes, were revealed to be critically short for safe taping outside the oral cavity with the cuff placed completely within the right or left mainstem bronchus.
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Affiliation(s)
- Berthold Moser
- Department of Anaesthesia, University Children's Hospital Zurich, Zurich, Switzerland.,Department of Anaesthesia and Intensive Care, Spital Limmattal, Schlieren, Switzerland
| | - Michael Kemper
- Department of Anaesthesia, University Children's Hospital Zurich, Zurich, Switzerland
| | - Alexander Dullenkopf
- Department of Anaesthesia and Intensive Care, Kantonsspital, Frauenfeld, Switzerland
| | - Mital H Dave
- Department of Anaesthesia, University Children's Hospital Zurich, Zurich, Switzerland
| | - Philipp K Buehler
- Department of Anaesthesia, University Children's Hospital Zurich, Zurich, Switzerland
| | - Markus Weiss
- Department of Anaesthesia, University Children's Hospital Zurich, Zurich, Switzerland
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Goetschi M, Kemper M, Dave MH, Kleine-Brueggeney M, Henze G, Weiss M. Dimensional compatibility of balloon-tipped bronchial blockers with the pediatric airway anatomy using different recommendations for age-related size selection. Paediatr Anaesth 2020; 30:1245-1253. [PMID: 32688433 DOI: 10.1111/pan.13973] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 07/08/2020] [Accepted: 07/13/2020] [Indexed: 11/30/2022]
Abstract
BACKGROUND Age-related recommendations for size selection of bronchial blocker devices are based on a few dated anatomical autopsy and radiological studies determining lower airway dimensions in children. These recommendations are based on anterior-posterior internal bronchial diameters, which are smaller than the more relevant lateral internal bronchial diameters. METHODS Outer diameters of bronchial blocker balloons inflated with the maximum recommended volume of air were compared to age-related lateral internal bronchial diameters of left and right proximal mainstem bronchi using five different recommendations for age-related size selection of bronchial blocker equipment in children published in the literature. RESULTS The ratio of outer bronchial blocker diameters inflated with the maximal recommended volume of air to the median lateral internal diameters of the proximal mainstem bronchus ranged from 71.4% to 181.8% for the left side and from 61.7% to 162.6% for the right side. There were many settings where the blocker diameters did not reach the median lateral internal diameters of the proximal mainstem bronchus. This was more often observed for the right than for the left side (37 vs 22 settings). CONCLUSION This analysis demonstrates that irrespective of the recommendation for size selection used, neither the two balloon-tipped vascular catheters included nor the Arndt endobronchial blockers are ideal for lung isolation in children are compared with the age-related relevant dimensions of pediatric airway anatomy. A redesign of bronchial blocker equipment with age-related anatomically based high-volume, low-pressure blocker balloons made from ultrathin membranes and with smaller catheters would be desirable.
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Affiliation(s)
- Markus Goetschi
- Department of Anesthesia, University Children's Hospital Zurich, Zurich, Switzerland
| | - Michael Kemper
- Department of Anesthesia, University Children's Hospital Zurich, Zurich, Switzerland
| | - Mital H Dave
- Department of Anesthesia, University Children's Hospital Zurich, Zurich, Switzerland
| | | | - Georg Henze
- Department of Anesthesia, University Children's Hospital Zurich, Zurich, Switzerland
| | - Markus Weiss
- Department of Anesthesia, University Children's Hospital Zurich, Zurich, Switzerland
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Fischer M, Grass B, Kemper M, Weiss M, Dave MH. Cuffed pediatric endotracheal tubes-Outer cuff diameters compared to age-related airway dimensions. Paediatr Anaesth 2020; 30:424-434. [PMID: 31785036 DOI: 10.1111/pan.13776] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 11/15/2019] [Accepted: 11/26/2019] [Indexed: 12/15/2022]
Abstract
BACKGROUND Reliable sealing of the pediatric airway requires appropriately sized tracheal tube cuffs. The aim of this study was to compare residual cuff diameters of pediatric tracheal tubes with pediatric airway dimensions. METHODS Cuff diameters of five different brands of locally marketed pediatric cuffed tracheal tubes with internal diameters of 3.0-7.0 mm were measured at a cuff pressure of 20 cm H2 O and compared with cuff diameters indicated by their manufacturers. The latter values were compared to tracheal dimensions using the Motoyama and Khine formulas for cuffed tracheal tube size selection. RESULTS There is considerable heterogeneity in cuff diameters among pediatric tracheal tube brands, except for two brands from different manufacturers (Halyard and Parker Medical) which were identically designed. Cuffs made from polyurethane revealed fewer differences (91%-118%) between measured and manufacturer-indicated values for outer cuff diameters than did those made from polyvinylchloride (91%-146%). Particularly in smaller sized tracheal tubes, cuffs did not reach 100% of the tracheal lateral diameter, while others were oversized in larger tracheal tubes, independent of the two formulas used for cuffed tracheal tube size selection. Cuff diameters indicated by the manufacturer corresponded to 86%-188% of the median and 68%-157% of the maximum mid-tracheal lateral diameter of the corresponding upper age range. CONCLUSION Our findings show that many of the cuff diameters of currently marketed tracheal tube brands lack an age-related anatomical rationale. A proposal for age-related anatomically based cuff diameters is provided for both recommendations for cuffed tracheal tube size selection in children.
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Affiliation(s)
- Martina Fischer
- Department of Anaesthesia and Children's Research Center, University Children's Hospital, Zürich, Switzerland
| | - Beate Grass
- Department of Intensive Care and Neonatology, University Children's Hospital, Zürich, Switzerland
| | - Michael Kemper
- Department of Anaesthesia and Children's Research Center, University Children's Hospital, Zürich, Switzerland
| | - Markus Weiss
- Department of Anaesthesia and Children's Research Center, University Children's Hospital, Zürich, Switzerland
| | - Mital H Dave
- Department of Anaesthesia and Children's Research Center, University Children's Hospital, Zürich, Switzerland
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7
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Dave MH, Kemper M, Schmidt AR, Both CP, Weiss M. Pediatric airway dimensions-A summary and presentation of existing data. Paediatr Anaesth 2019; 29:782-789. [PMID: 31087466 DOI: 10.1111/pan.13665] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 05/05/2019] [Accepted: 05/12/2019] [Indexed: 11/29/2022]
Abstract
BACKGROUND Age-related pediatric airway dimension reference values for cricoid, tracheal, and bronchial diameters as well as tracheal and bronchial lengths are essential for distinguishing normal from pathological airway findings and for manufacturing and selecting appropriately sized airway equipment. AIM The aim of this work was to summarize and present existing pediatric airway dimension data for the larynx, trachea, and main stem bronchi from fetus to adolescence. METHODS A systematic literature search was carried out using PubMed, Scopus, Embase, and Google Scholar. Publications containing original data on pediatric airway dimensions as mean or median in tabular form and spanning narrow age groups of 1 or 2 years were included in our study. Original data such as diameters, lengths, and cross-sectional areas of trachea, cricoid, left and right main bronchi in fetuses and children were collected and presented as figures. RESULTS Pediatric airway dimension data were gathered and compiled from 15 studies fulfilling the inclusion criteria. Data were obtained from different measurement methods such as autopsy, chest X-ray, computed tomography, magnetic resonance imaging, rigid and flexible bronchoscopy as well as ultrasound examinations. There was considerable variation among age-related data due to biologic heterogeneity, different presentation of data, different definitions, and various measurement techniques. CONCLUSION This investigation revealed heterogeneous data on pediatric airway dimensions, making it impossible to compile them into standard reference values for airway dimensions. New studies with structured and standardized measurements and data presentation in large populations of children are required to provide more valid pediatric airway dimension data.
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Affiliation(s)
- Mital H Dave
- Department of Anesthesia and Children's Research Center, University Children's Hospital, Zurich, Switzerland
| | - Michael Kemper
- Department of Anesthesia and Children's Research Center, University Children's Hospital, Zurich, Switzerland
| | - Alexander R Schmidt
- Department of Anesthesia and Children's Research Center, University Children's Hospital, Zurich, Switzerland
| | - Christian P Both
- Department of Anesthesia and Children's Research Center, University Children's Hospital, Zurich, Switzerland
| | - Markus Weiss
- Department of Anesthesia and Children's Research Center, University Children's Hospital, Zurich, Switzerland
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Moser B, Keller C, Audigé L, Dave MH, Bruppacher HR. Fiberoptic intubation of severely obese patients through supraglottic airway: A prospective, randomized trial of the Ambu ® AuraGain™ laryngeal mask vs the i-gel™ airway. Acta Anaesthesiol Scand 2019; 63:187-194. [PMID: 30088266 DOI: 10.1111/aas.13242] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Revised: 07/05/2018] [Accepted: 07/07/2018] [Indexed: 12/25/2022]
Abstract
INTRODUCTION Airway management in severely obese patients remains a challenging issue for anaesthetists and may lead to life-threatening situations. Supraglottic airway devices, such as the i-gel™ or the AuraGain™, were developed, with the possibility to ventilate the patient or use them as a conduit for endotracheal intubation. METHODS In our randomized prospective trial, we hypothesized a 10 seconds faster fiberoptic trans-device intubation time through the AuraGain™ laryngeal mask compared to the i-gel™ laryngeal mask in severely obese patients. We randomly assigned 44 patients to the AuraGain or i-gel group and measured trans-device intubation time after 5 minutes of successful ventilation through the device. Secondary parameters relating to the trans-device intubation success, oropharyngeal leak pressure, and parameters regarding insertion of the supraglottic airway devices were measured. Postoperative airway morbidity was determined 5 hours after surgery. RESULTS Mean (SD) intubation time was 55.7 (5.8) seconds for the AuraGain™ vs 54.1 (8.5) for i-gel™ mask (95% CI -2.7 to 5.9; P = 0.474), respectively, on a mean body mass index (BMI) of 39.4 kg/m2 in the AuraGain™ group vs 38.9 kg/m2 in i-gel™ group. No difference could be found in the other studied parameters. CONCLUSIONS Time for intubation through both supraglottic airway devices was similar. Attributed to fast possibility of securing the airway with both supraglottic airway devices, we believe that both, AuraGain™ and i-gel™, can be a good alternative in the airway management in obese patients.
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Affiliation(s)
- Berthold Moser
- Department of Anaesthesiology; Schulthess Clinic; Zürich Switzerland
| | - Christian Keller
- Department of Anaesthesiology; Schulthess Clinic; Zürich Switzerland
| | - Laurent Audigé
- Research and Development Department; Schulthess Clinic; Zürich Switzerland
| | - Mital H. Dave
- Department of Anaesthesiology; Schulthess Clinic; Zürich Switzerland
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Abstract
BACKGROUND 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. METHODS A systematic literature search was carried out in the PubMed database, Scopus, Embase, Web of Science, Prisma, and Google Scholar and secondarily completed by a reference search. Based on inclusion and exclusion criteria, a final selection of 109 studies with data on pediatric airway dimensions published from 1923 to 2018 were further analyzed. RESULTS Six different airway measurement methods were identified. They included anatomical examinations, chest X-ray, computed tomography, magnetic resonance tomography, bronchoscopy, and ultrasound. Anatomical studies were more abundant compared to other methods. Data provided were very heterogeneously presented and powered. In addition, due to different study conditions, they are hardly comparable. Among all, anatomical and computer tomography studies are thought to provide the most reliable data. Ultrasound is an upcoming technique to estimate airway parameters of fetus and premature infants. There was, in general, a lack of comprehensive studies providing a complete range of airway dimensions in larger groups of patients from birth to adolescence. CONCLUSIONS This work revealed a large heterogeneity of studies providing data on pediatric airway dimensions, making it impossible to compare, or assemble them to normograms for clinical use. Comprehensive studies in large population of children are needed to provide full range nomograms on pediatric airway dimensions.
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Affiliation(s)
- Mital H Dave
- Department of Anesthesia and Children's Research Center, University Children's Hospital, Zürich, Switzerland
| | - Kathrin Schmid
- Department of Anesthesia and Children's Research Center, University Children's Hospital, Zürich, Switzerland
| | - Markus Weiss
- Department of Anesthesia and Children's Research Center, University Children's Hospital, Zürich, Switzerland
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10
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Abstract
BACKGROUND The aim of this study was to obtain lower airway dimensions in children by means of computed tomography (CT). METHODS Chest CT scans from 195 pediatric patients (118 boys/77 girls) aged 0.04-15.99 years were analyzed. Tracheal and bronchial lengths, anterior-posterior and lateral diameters, as well as cross-sectional area were assessed at the following levels: mid trachea, right proximal and distal bronchus, proximal bronchus intermedius, and left proximal and distal bronchus. Mediastinal angles of tracheal bifurcation were measured. Data were analyzed by means of linear and polynomial regression plots. RESULTS The strongest correlations were found between tracheal and bronchial diameters and age as well as between tracheal and bronchial lengths and body length. All measured airway parameters correlated poorly to body weight. Bronchial angles revealed no association with patient's age, body length, or weight. CONCLUSION This comprehensive anatomical database of lower airway dimensions demonstrates that tracheal and bronchial diameters correlate better to age, and that tracheal and bronchial length correlate better to body length. All measured airway parameters correlated poorly to body weight.
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Affiliation(s)
- Patricia Szelloe
- Department of Anesthesia, University Children's Hospital, Zurich, Switzerland.,Department of Neonatology and Intensive Care Medicine, University Children's Hospital, Zurich, Switzerland
| | - Markus Weiss
- Department of Anesthesia, University Children's Hospital, Zurich, Switzerland.,Department of Diagnostic Imaging, University Children's Hospital, Zurich, Switzerland
| | - Thomas Schraner
- Children's Research Center, University Children's Hospital, Zurich, Switzerland.,Department of Diagnostic Imaging, University Children's Hospital, Zurich, Switzerland
| | - Mital H Dave
- Department of Anesthesia, University Children's Hospital, Zurich, Switzerland.,Children's Research Center, University Children's Hospital, Zurich, Switzerland
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Dave MH, Gerber A, Bailey M, Gysin C, Hoeve H, Hammer J, Nicolai T, Weiss M. Prevalence and characteristics of tracheal cobblestoning in children. Pediatr Pulmonol 2015; 50:995-9. [PMID: 25462666 DOI: 10.1002/ppul.23142] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Revised: 09/08/2014] [Accepted: 09/17/2014] [Indexed: 11/11/2022]
Abstract
BACKGROUND 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. METHODS A large database of rigid tracheoscopies recorded in children (0-6 years of age) undergoing general anesthesia with planned tracheal intubation for elective surgical procedures was retrospectively analyzed. Tracheoscopy records were reviewed by five pediatric airway experts (authors 3-7). Data were compared using the Mann-Whitney test, chi-square or Fisher exact test as appropriate (P < 0.05). RESULTS A total of 971 rigid tracheoscopy records were analyzed. The median age of the patients was 3.3 years (range 0.4-6.0 yrs). Cobblestones were present in 377 out of 971 patients (38.8%) with a male to female prevalence of 254 (40.6%)/123 (35.5%). None of the children under four months of age showed the presence of cobblestones. The prevalence of cobblestones was significantly less in patients under 3 years of age compared to over 3 years (P < 0.01). There was no association between prevalence of cobblestones and GERD, current or recent respiratory infection or concomitant enlarged tonsils. CONCLUSION The prevalence of tracheal cobblestones in otherwise healthy children is high and is not associated with GERD or respiratory infection. The gender and age related differences are novel interesting findings that require further investigations.
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Affiliation(s)
- Mital H Dave
- Department of Anaesthesia, University Children's Hospital, Zurich, Switzerland
| | - Andreas Gerber
- Department of Anaesthesia, University Children's Hospital, Zurich, Switzerland
| | - Martin Bailey
- Department of Paediatric Otolaryngology, Great Ormond Street Hospital for Children, London, United Kingdom
| | - Claudine Gysin
- Department of Otorhinolaryngology, University Children's Hospital, Zurich, Switzerland
| | - Hans Hoeve
- Department of Otorhinolaryngology, Sophia Children's Hospital, Erasmus University Medical Centre, Rotterdam, The Netherlands
| | - Juerg Hammer
- Department of Paediatric Pulmonology and Intensive Care Medicine, UKBB, Basel, Switzerland
| | - Thomas Nicolai
- Department of Paediatric Pulmonology and Intensive Care Medicine, Dr. von Hauner Children's Hospital, University of Munich, Germany
| | - Markus Weiss
- Department of Anaesthesia, University Children's Hospital, Zurich, Switzerland
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12
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Dave MH, Spielmann N, Mauch J, Weiss M. Effect of Lanz Pressure Regulating Valve on Self-sealing Mechanism and Air Leakage Across the Tracheal Tube Cuffs in a Benchtop Model. J Intensive Care Med 2012; 28:247-51. [DOI: 10.1177/0885066612452847] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
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.
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Affiliation(s)
- Mital H. Dave
- Department of Anaesthesia, University Children’s Hospital, Steinwiesstrasse, Zurich, Switzerland
| | - Nelly Spielmann
- Department of Anaesthesia, University Children’s Hospital, Steinwiesstrasse, Zurich, Switzerland
| | - Jacqueline Mauch
- Department of Anaesthesia, University Children’s Hospital, Steinwiesstrasse, Zurich, Switzerland
| | - Markus Weiss
- Department of Anaesthesia, University Children’s Hospital, Steinwiesstrasse, Zurich, Switzerland
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Dave MH, Frotzler A, Madjdpour C, Koepfer N, Weiss M. Massive Aspiration Past the Tracheal Tube Cuff Caused by Closed Tracheal Suction System. J Intensive Care Med 2011; 26:326-9. [DOI: 10.1177/0885066610392516] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2009] [Accepted: 03/05/2010] [Indexed: 11/17/2022]
Abstract
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.
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Affiliation(s)
- Mital H. Dave
- Department of Anaesthesia, University Children's Hospital, Zurich, Switzerland
| | - Angela Frotzler
- Department of Anaesthesia, University Children's Hospital, Zurich, Switzerland
| | - Caveh Madjdpour
- Department of Anaesthesia, University Children's Hospital, Zurich, Switzerland
| | - Nelly Koepfer
- Department of Anaesthesia, University Children's Hospital, Zurich, Switzerland
| | - Markus Weiss
- Department of Anaesthesia, University Children's Hospital, Zurich, Switzerland
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Dave MH, Frotzler A, Weiss M. Closed tracheal suction and fluid aspiration past the tracheal tube. Impact of tube cuff and airway pressure. Minerva Anestesiol 2011; 77:166-171. [PMID: 21283067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
BACKGROUND This study investigated the effect of different tube cuff types and airway pressures on fluid leakage past the tracheal tube cuff during suction with a closed tracheal suction system (CTSS). METHODS Unlubricated high-volume, low-pressure tracheal tube cuffs made from polyvinylchloride (PVC) and polyurethane (PU) with a size 7.5 mm internal diameter (ID) were placed in a 22 mm ID artificial trachea connected to a test lung and inflated to 25 or 50 cmH2O of cuff pressure. Positive pressure ventilation (PPV) with peak inspiratory pressures of 15, 20 or 25 cmH2O and positive end expiratory pressures (PEEP) of 5 or 10 cmH2O were used. A CTSS catheter (14 Fr) was attached to the tracheal tube and suction was performed for 5, 10, 15 or 20 s with 200 or 300 cmH2O of negative suction pressures. The volume of fluid leaking across the tube cuff at the end of the suction procedure was measured (mL), and the airway pressure was simultaneously recorded. Fluid leakage and airway pressures during different suction conditions were compared using a Kruskal Wallis test and Mann Whitney test (P<0.05). RESULTS The airway pressure drop during suction was similar for both tube cuffs. The PU tube cuff resulted in significantly less fluid leakage (range 0.00-0.12 mL) than the PVC tube cuff (P<0.001). For the PVC tube cuff, fluid leakage at higher cuff pressures was significantly less (P<0.01).Varying PEEP and PIP did not change the fluid leakage or the drop in airway pressure. CONCLUSION The use of PU tube cuffs and intermittent transient increases in cuff pressure during suction can effectively reduce fluid leakage past the tracheal tube during closed tracheal suctioning.
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Affiliation(s)
- M H Dave
- Department of Anaesthesia, University Children's Hospital, Zurich, Switzerland.
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15
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Schulz N, Dave MH, Stehberger PA, Chau T, Wagner CA. Differential localization of vacuolar H+-ATPases containing a1, a2, a3, or a4 (ATP6V0A1-4) subunit isoforms along the nephron. Cell Physiol Biochem 2007; 20:109-20. [PMID: 17595521 DOI: 10.1159/000104159] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/08/2007] [Indexed: 11/19/2022] Open
Abstract
Vacuolar H(+)-ATPase are multi-subunit containing pumps important for several processes along the nephron such as receptor mediated endocytosis, acidification of intracellular organelles, bicarbonate reabsorption and secretion, and H(+)- extrusion. Mutations in the human a4 (ATP6V0A4) subunit cause distal renal tubular acidosis (dRTA). There are 4 known isoforms of the 'a' subunit (a1-a4). Here we investigated the expression and localization of all four isoforms in mouse kidney. Real-time PCR detected mRNAs encoding all four 'a' isoforms in mouse kidney with a relative abundance in the following order: a4>a2=a1>a3. Immunolocalization demonstrated expression of all 'a' subunits in the proximal tubule and in the intercalated cells of the collecting system. In intercalated cells a1 and a4 isoforms appeared on both the apical and basolateral side and were expressed in all subtypes of intercalated cells. In contrast, a2, and a3 were only found in the apical membrane. a1 and a4 were colocalized in the same cells with AE1 or pendrin, whereas a2 was only found in AE1 positive cells but absent from pendrin expressing intercalated cells. These results suggest that vacuolar H(+)-ATPases containing different 'a' isoforms may serve specific and distinct functions and may help explaining why loss of the a4 isoform causes only dRTA without an apparent defect in the proximal tubule.
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Affiliation(s)
- Nicole Schulz
- Institute of Physiology and Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
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16
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Moret C, Dave MH, Schulz N, Jiang JX, Verrey F, Wagner CA. Regulation of renal amino acid transporters during metabolic acidosis. Am J Physiol Renal Physiol 2006; 292:F555-66. [PMID: 17003226 DOI: 10.1152/ajprenal.00113.2006] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The kidney plays a major role in acid-base homeostasis by adapting the excretion of acid equivalents to dietary intake and metabolism. Urinary acid excretion is mediated by the secretion of protons and titratable acids, particularly ammonia. NH(3) is synthesized in proximal tubule cells from glutamine taken up via specific amino acid transporters. We tested whether kidney amino acid transporters are regulated in mice in which metabolic acidosis was induced with NH(4)Cl. Blood gas and urine analysis confirmed metabolic acidosis. Real-time RT-PCR was performed to quantify the mRNAs of 16 amino acid transporters. The mRNA of phosphoenolpyruvate carboxykinase (PEPCK) was quantified as positive control for the regulation and that of GAPDH, as internal standard. In acidosis, the mRNA of kidney system N amino acid transporter SNAT3 (SLC38A3/SN1) showed a strong induction similar to that of PEPCK, whereas all other tested mRNAs encoding glutamine or glutamate transporters were unchanged or reduced in abundance. At the protein level, Western blotting and immunohistochemistry demonstrated an increased abundance of SNAT3 and reduced expression of the basolateral cationic amino acid/neutral amino acid exchanger subunit y(+)-LAT1 (SLC7A7). SNAT3 was localized to the basolateral membrane of the late proximal tubule S3 segment in control animals, whereas its expression was extended to the earlier S2 segment of the proximal tubule during acidosis. Our results suggest that the selective regulation of SNAT3 and y(+)LAT1 expression may serve a major role in the renal adaptation to acid secretion and thus for systemic acid-base balance.
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Affiliation(s)
- Caroline Moret
- Institute of Physiology and Center for Integrative Human Physiology, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
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17
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Kirchhoff P, Dave MH, Remy C, Kosiek O, Busque SM, Dufner M, Geibel JP, Verrey F, Wagner CA. An amino acid transporter involved in gastric acid secretion. Pflugers Arch 2005; 451:738-48. [PMID: 16308696 DOI: 10.1007/s00424-005-1507-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2005] [Accepted: 08/04/2005] [Indexed: 11/27/2022]
Abstract
Gastric acid secretion is regulated by a variety of stimuli, in particular histamine and acetyl choline. In addition, dietary factors such as the acute intake of a protein-rich diet and the subsequent increase in serum amino acids can stimulate gastric acid secretion only through partially characterized pathways. Recently, we described in mouse stomach parietal cells the expression of the system L heteromeric amino acid transporter comprised of the LAT2-4F2hc dimer. Here we address the potential role of the system L amino acid transporter in gastric acid secretion by parietal cells in freshly isolated rat gastric glands. RT-PCR, western blotting and immunohistochemistry confirmed the expression of 4F2-LAT2 amino acid transporters in rat parietal cells. In addition, mRNA was detected for the B(0)AT1, ASCT2, and ATB(0+) amino acid transporters. Intracellular pH measurements in parietal cells showed histamine-induced and omeprazole-sensitive H+-extrusion which was enhanced by about 50% in the presence of glutamine or cysteine (1 mM), two substrates of system L amino acid transporters. BCH, a non-metabolizable substrate and a competitive inhibitor of system L amino acid transport, abolished the stimulation of acid secretion by glutamine or cysteine suggesting that this stimulation required the uptake of amino acids by system L. In the absence of histamine glutamine also stimulated H+-extrusion, whereas glutamate did not. Also, phenylalanine was effective in stimulating H+/K+-ATPase activity. Glutamine did not increase intracellular Ca2+ levels indicating that it did not act via the recently described amino acid modulated Ca2+-sensing receptor. These data suggest a novel role for heterodimeric amino acid transporters and may elucidate a pathway by which protein-rich diets stimulate gastric acid secretion.
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Affiliation(s)
- Philipp Kirchhoff
- Institute of Physiology and Center for Integrative Human Physiology (CIHP), University of Zurich, Winterthurerstr. 190, 8057 Zurich, Switzerland
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18
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Romeo E, Dave MH, Bacic D, Ristic Z, Camargo SMR, Loffing J, Wagner CA, Verrey F. Luminal kidney and intestine SLC6 amino acid transporters of B0AT-cluster and their tissue distribution in Mus musculus. Am J Physiol Renal Physiol 2005; 290:F376-83. [PMID: 16174864 DOI: 10.1152/ajprenal.00286.2005] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The B degrees transport system mediates the Na(+)-driven uptake of a broad range of neutral amino acids into epithelial cells of small intestine and kidney proximal tubule. A corresponding transporter was identified in 2004 (A. Broer, K. Klingel, S. Kowalczuk, J. E. Rasko, J. Cavanaugh, and S. Broer. J Biol Chem 279: 24467-24476, 2004) within the SLC6 family and named B degrees AT1 (SLC6A19). A phylogenetically related transporter known as XT3 in human (SLC6A20) and XT3s1 in mouse was shown to function as an imino acid transporter, to localize also to kidney and small intestine and renamed SIT1 or Imino(B). Besides these two transporters with known functions, there are two other gene products belonging to the same phylogenetic B degrees AT-cluster, XT2 (SLC6A18) and rodent XT3 that are still "orphans." Quantitative real-time RT-PCR showed that the mRNAs of the four B degrees AT-cluster members are abundant in kidney, whereas only those of B degrees AT1 and XT3s1/SIT1 are elevated in small intestine. In brain, the XT3s1/SIT1 mRNA is more abundant than the other B degrees AT-cluster mRNAs. We show here by immunofluorescence that all four mouse B degrees AT-cluster transporters localize, with differential axial gradients, to the brush-border membrane of proximal kidney tubule and, with the possible exception of XT3, also of intestine. Deglycosylation and Western blotting of brush-border proteins demonstrated the glycosylation and confirmed the luminal localization of B degrees AT1, XT2, and XT3. In summary, this study shows the luminal brush-border localization of the Na(+)-dependent amino and imino acid transporters B degrees AT1 and XT3s1/SIT1 in kidney and intestine. It also shows that the structurally highly similar orphan transporters XT2 and XT3 have the same luminal but a slightly differing axial localization along the kidney proximal tubule.
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Affiliation(s)
- Elisa Romeo
- Institute of Physiology, Univ. of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
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Abstract
Reabsorption of amino acids, similar to that of glucose, is a major task of the proximal kidney tubule. Various amino acids are actively transported across the luminal brush border membrane into proximal tubule epithelial cells, most of which by cotransport. An important player is the newly identified cotransporter (symporter) B0AT1 (SLC6A19), which imports a broad range of neutral amino acids together with Na+ across the luminal membrane and which is defective in Hartnup disorder. In contrast, cationic amino acids and cystine are taken up in exchange for recycled neutral amino acids by the heterodimeric cystinuria transporter. The basolateral release of some neutral amino acids into the extracellular space is mediated by unidirectional efflux transporters, analogous to GLUT2, that have not yet been definitively identified. Additionally, cationic amino acids and some other neutral amino acids leave the cell basolaterally via heterodimeric obligatory exchangers.
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Affiliation(s)
- François Verrey
- University of Zurich, Institute of Physiology, CH-8057 Zurich, Switzerland.
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20
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Kleta R, Romeo E, Ristic Z, Ohura T, Stuart C, Arcos-Burgos M, Dave MH, Wagner CA, Camargo SRM, Inoue S, Matsuura N, Helip-Wooley A, Bockenhauer D, Warth R, Bernardini I, Visser G, Eggermann T, Lee P, Chairoungdua A, Jutabha P, Babu E, Nilwarangkoon S, Anzai N, Kanai Y, Verrey F, Gahl WA, Koizumi A. Mutations in SLC6A19, encoding B0AT1, cause Hartnup disorder. Nat Genet 2004; 36:999-1002. [PMID: 15286787 DOI: 10.1038/ng1405] [Citation(s) in RCA: 200] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2004] [Accepted: 06/17/2004] [Indexed: 11/09/2022]
Abstract
Hartnup disorder, an autosomal recessive defect named after an English family described in 1956 (ref. 1), results from impaired transport of neutral amino acids across epithelial cells in renal proximal tubules and intestinal mucosa. Symptoms include transient manifestations of pellagra (rashes), cerebellar ataxia and psychosis. Using homozygosity mapping in the original family in whom Hartnup disorder was discovered, we confirmed that the critical region for one causative gene was located on chromosome 5p15 (ref. 3). This region is homologous to the area of mouse chromosome 13 that encodes the sodium-dependent amino acid transporter B(0)AT1 (ref. 4). We isolated the human homolog of B(0)AT1, called SLC6A19, and determined its size and molecular organization. We then identified mutations in SLC6A19 in members of the original family in whom Hartnup disorder was discovered and of three Japanese families. The protein product of SLC6A19, the Hartnup transporter, is expressed primarily in intestine and renal proximal tubule and functions as a neutral amino acid transporter.
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Affiliation(s)
- Robert Kleta
- Medical Genetics Branch, 10 Center Drive, MSC 1851, Building 10, Room 10C-107, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, USA
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Abstract
Members of the new heterodimeric amino acid transporter family are composed of two subunits, a catalytic multitransmembrane spanning protein (light chain) and a type II glycoprotein (heavy chain). These transporters function as exchangers and thereby extend the transmembrane amino acid transport selectivity to specific amino acids. The heavy chain rBAT associates with the light chain b degrees (,+)AT to form a cystine and cationic amino acid transporter. The other heavy chain, 4F2hc, can interact with seven different light chains to form various transporters corresponding to systems L, y(+)L, asc or x(-)(c). The importance of some of these transporters in intestinal and renal (re)absorption of amino acids is highlighted by the fact that mutations in either the rBAT or b degrees (,+)AT subunit result in cystinuria whereas a defect in the y(+)-LAT1 light chain causes lysinuric protein intolerance. Here we investigated the localization of these transporters in intestine since both diseases are also characterized by altered intestinal amino acid absorption. Real time PCR showed organ-specific expression patterns for all transporter subunit mRNAs along the intestine and Western blotting confirmed these findings on the protein level. Immunohistochemistry demonstrated basolateral coexpression of 4F2hc, LAT2 and y(+)-LAT1 in stomach and small intestine, whereas rBAT and b degrees (,+)AT were found colocalizing on the apical side of small intestine epithelium. In stomach, 4F2hc and LAT2 were localized in H(+)/K(+)-ATPase-expressing parietal cells. The abundant expression of several members of the heterodimeric transporter family along the murine small intestine suggests their involvement in amino acids absorption. Furthermore, strong expression of rBAT, b degrees (,+)AT and y(+)-LAT1 in the small intestine explains the reduced intestinal absorption of some amino acid in patients with cystinuria or lysinuric protein intolerance.
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Affiliation(s)
- Mital H Dave
- Institute of Physiology, University of Zurich, Winterthurerstr. 190, CH-8057 Zurich, Switzerland
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