Tube tip and cuff position using different strategies for placement of currently available paediatric tracheal tubes

Characteristics of lower airway parameters in an adult Asian population related to endotracheal tube design: a cadaveric study

The risk of endotracheal tube (ETT) placement includes endobronchial intubation and subglottic injury. This study aimed to describe the lengths of lower airway parameters related to cuff location and vocal cord markings in different adult-sized ETTs. Eighty cadavers were examined for the lengths of the lower airway, including their correlations and linear regressions with height. Thirty adult-sized ETTs from seven different brands were examined for Mark-Cuff and Mark-Tip distances. The depth of ETT placement was simulated for each brand using vocal cord marking. The mean (standard deviation) lengths from the subglottis, trachea, vocal cord to mid- trachea, and vocal cord to carina were 24.2 (3.5), 97.9 (8.6), 73.2 (5.3), and 122.1 (9.0) mm, respectively. Airway lengths were estimated as: (1) subglottis (mm) = 0.173 * (height in cm) - 3.547; (2) vocal cord to mid-trachea (mm) = 0.28 * (height in cm) + 28.391. There were variations in the Mark-Cuff and Mark-Tip distances among different ETTs. In the simulation, endobronchial intubation ranged between 2.5 and 5% and the cuff in the subglottis ranged between 2.5 and 97.5%. In summary, the lower airway parameters were height-related. ETT placement using vocal cord marking puts the patient at a high risk of cuff placement in the subglottis.

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 ).

Partial Obstruction of the Endotracheal Tube by a Part of the Metallic Stylet; Case Report and Review of the Literature

Endotracheal intubation is common in the emergency department, intensive care units, and operating rooms. It involves the insertion of an endotracheal tube (ETT) through the mouth or nose into the trachea to maintain a patent airway and facilitate mechanical ventilation. Using a stylet during intubation can guide the ETT through the vocal cords. However, complications can arise when the stylet is not removed after successful intubation. Herewith, we reported a patient who was two years old and suffered from respiratory failure. However, in the first 12 hours, we observed a foreign body in the trachea, a small end of a metal stylet immediately removed by bronchoscope. This case demonstrates that multiple uses of a stylet, especially by a single user, can result in impaction of the stylet in the ETT during intubation, requiring force when the stylet is withdrawn after intubation, which can result in breakage, shearing, and retention of the stylet or plastic sheath in the lumen of the ETT.

Endotracheal tube cuff position in relation to the cricoid in children: A retrospective computed tomography-based analysis

Background:

The use of cuffed endotracheal tubes (ETT) has become the standard of care in pediatric practice. The rationale for the use of a cuffed ETT is to minimize pressure around the cricoid while providing an effective airway seal. However, safe care requires that the cuff lie distal to the cricoid ring following endotracheal intubation. The current study demonstrates the capability of computed tomography (CT) imaging in identifying the position of the cuff of the ETT in intubated patients.

Methods:

In this retrospective study, the ETT cuff position was examined on the sagittal plane images of neck and chest CT scans of 44 children. The position of the proximal and the distal aspect of the ETT cuff inside the trachea was recorded in relation to the vertebral levels. The vertebral levels were used to estimate the location of the cricoid ring and its relationship to the cuff.

Results:

The vertebrae were used as the primary landmarks to define the position of the cricoid and its relationship to the cuff of the ETT. Correlating vertebral levels with the cricoid for different age groups, the proximal (cephalad) edge of the ETT cuff was below the cricoid in 41 of 44 patients (93%). The ETT cuff was deep in 6 patients, below the 1^st thoracic vertebra, with 2 ETTs in the right mainstem bronchus.

Conclusion:

This is the first study demonstrating that the cuff of the ETT and its position in the trachea can be identified on CT imaging in children. The ETT cuff was below the level of the cricoid in the majority of patients irrespective of the patient's age as well as the size, make, and type of ETT.

Insertion of cuff inflation line into pediatric tracheal tubes related to oral and nasal tracheal intubation depth

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.

Length of the Cricoid and Trachea in Children: Predicting Intubation Depth to Prevent Subglottic Stenosis

OBJECTIVE

Define the length of the subglottis and trachea in children to predict a safe intubation depth.

METHODS

Patients <18 years undergoing rigid bronchoscopy from 2013 to 2020 were included. The carina and inferior borders of the cricoid and true vocal folds were marked on a bronchoscope and distances were measured. Patient age, weight, height, and chest height were recorded. Four styles of cuffed pediatric endotracheal tubes (ETT) were measured and potential positions of each cuff and tip were calculated within each trachea using five depth of intubation scenarios. Multivariate linear regression was performed to identify predictors of subglottic and tracheal length.

RESULTS

Measurements were obtained from 210 children (141 male, 69 female), mean (SD) age 3.21 (3.66) years. Patient height was the best predictor of subglottic length (R² : 0.418): Length_sg (mm) = 0.058 * height (cm) + 2.8, and tracheal length (R² : 0.733): Length_t (mm) = 0.485 * height (cm) + 21.3. None of the depth of intubation scenarios maintained a cuff-free subglottis for all ETT styles investigated. A formula for depth of intubation: Length_di (mm) = 0.06 * height (cm) + 8.8 found that no ETT cuffs would be in the subglottis and all tips would be above the carina.

CONCLUSION

Current strategies for determining appropriate depth of intubation pose a high risk of subglottic ETT cuff placement. Placing the inferior border of the vocal cords 0.06 * height (cm) + 8.8 from the superior border of the inflated ETT cuff may prevent subglottic cuff placement and endobronchial intubation.

LEVEL OF EVIDENCE

4 Laryngoscope, 2021.

Cuffed endotracheal tubes in neonates and infants of less than 3 kg body weight-A retrospective audit

BACKGROUND

Large prospective clinical studies have shown that modern cuffed pediatric tracheal tubes can be used safely, even in children weighing ≥3 kg. There is a growing interest in their use in children weighing <3 kg so that they, too, can benefit from the potential advantages, particularly the high probability of these tubes fitting into and sealing the pediatric airway at the first intubation attempt. This study aimed to find a cut-off body weight for procedures requiring a cuffed tracheal tube to seal the airway in children weighing <3 kg and to evaluate the frequency and predictive factors for the requirement to place a cuffed instead of an uncuffed tracheal tube.

METHODS

This study was a retrospective analysis of 269 children weighing 2000-2999 g, primarily intubated by pediatric anesthetists. Frequency of intubation with uncuffed Sheridan tubes versus cuffed Microcuff^® Pediatric Endotracheal Tube (PET) 3.0 mm ID was studied. Predictive variables were assessed by means of logistic regression analysis. The ROC curve for weight at intubation time and Youden index was calculated.

RESULTS

The 149 (55.4%) children were finally intubated with a cuffed tracheal tube. Logistic regression demonstrated that body weight at tracheal intubation and birth weight were the strongest predictors for the appropriateness of cuffed/uncuffed tracheal tubes. The threshold weight at tracheal intubation was 2700 g for a probability >50% of using a cuffed tracheal tube.

CONCLUSION

Half of the children weighing 2000-2999 g received a Microcuff^® PET 3.0 mm ID, especially those with a body weight above 2700 g. Because of the anatomical dimensions in patients with a body weight of 2000-2999 g, cuffed tracheal tubes with smaller outer diameters may be required to better fit their airways.

Anatomical In Vitro Investigations of the Pediatric Larynx: A Call for Manufacturer Redesign of Tracheal Tube Cuff Location and Perhaps a Call to Reconsider the Use of Uncuffed Tracheal Tubes

BACKGROUND

Some in vivo studies question the traditional "funnel-shaped" infant larynx; further anatomic examinations were warranted. Examination of fixative free fresh autopsy laryngeal and upper tracheal specimens and multiple measurements was needed to determine consistency between current tracheal tube designs and anatomic observations.

METHODS

Larynges from 19 males and 11 females (Caucasian term newborn to 126 months) were examined by the same forensic pathologist. Measurements included anterior/posterior (A/P) and transverse (T) diameters of the cricoid outlet (CO), interarytenoid diameter (IAD), cricothyroid membrane (CTM), distance from the vocal cords (VC) to CO (VC-CO), and calibration of the larynx lumen with uncuffed tracheal tubes as measuring rods. Assessment of "safe tracheal tube placement" was assessed using manufacturer recommended cuffed Microcuff (Kimberly-Clark, Koblenz, Germany) tubes.

RESULTS

In 77% (95% confidence interval [CI], 58-90) of specimens, the proximal end of the cuff was within the CO and in 23% even with or close to the CO. The VC-CO varied from 9.1 to 13.17 mm in infants, 11.55 to 15.17 mm in toddlers, and 13.19 to 18.34 mm in children. The AP/T ratio of the CO was nearly 0.99 in most larynges; the IAD was greater than CO in all specimens. The CTM could be minimally distended in all specimens.

CONCLUSIONS

First, despite being marketed as a safer tracheal tube design, the proximal end of the Microcuff cuff rested within or close to the cricoid cartilage theoretically increasing potential cuff-induced injury when using the VC markings for positioning. Our data suggest that the optimal cuff free distance (VC-CO) would be ~13.5 mm for a Microcuff internal diameter (ID) size 3.0, ~15 mm for size 3.5, and ~16 to 19 mm for greater sizes.Second, the CO was virtually circular in all specimens, suggesting that appropriately sized uncuffed tubes should provide an adequate seal in most neonates and toddlers, thus avoiding the potential for cuff-related necrosis injury.Third, the IAD was always greater than CO confirming that the narrowest point of the infant larynx is the nondistensible cricoid cartilage and not the easily distended glottis.Fourth, appropriately sized Microcuff tubes with the cuff deflated completely filled the lumen of the CO and proximal trachea in all specimens. Our data suggest the need for all manufacturers to further evaluate tracheal tube cuff locations and lengths in relation to the VC safe insertion markings, particularly for neonates and toddlers.Fifth, the CTM is minimally distensible, thus having important implications for emergency surgical airway access with most currently available emergency airway devices.

Complications Associated With the Anesthesia Transport of Pediatric Patients: An Analysis of the Wake Up Safe Database

BACKGROUND

Transporting patients under anesthesia care incurs numerous potential risks, especially for those with critical illness. The purpose of this study is to identify and report all pediatric anesthesia transport-associated adverse events from a preexisting database of perioperative adverse events.

METHODS

An extract of the Wake Up Safe database was obtained on December 14, 2017, and screened for anesthesia transport-associated complications. This was defined as events occurring during or immediately after transport or movement of a pediatric patient during or in proximity to their care by anesthesiologists, including repositioning and transfer to recovery or an inpatient unit, if the cause was noted to be associated with anesthesia or handover. Events were excluded if the narrative clearly states that an event was ongoing and not impacted by anesthesia transport, such as a patient who develops cardiac arrest that then requires emergent transfer to the operating room. The search methodology included specific existing data elements that indicate transport of the patient, handover or intensive care status preoperatively as well as a free-text search of the narrative for fragments of words indicating movement. Screened events were reviewed by 3 anesthesiologists for inclusion, and all data elements were extracted for analysis.

RESULTS

Of 2971 events in the database extract, 63.8% met screening criteria and 5.0% (148 events) were related to transport. Events were primarily respiratory in nature. Nearly 40% of all reported events occurred in infants age ≤6 months. A total of 59.7% of events were at least somewhat preventable and 36.4% were associated with patient harm, usually temporary. Of the 86 reported cardiac arrests, 50 (58.1%) had respiratory causes, of which 74% related to anesthesia or perioperative team factors. Respiratory events occurred at all stages of care, with 21.4% during preoperative transport and 75.5% postoperatively. Ninety-three percent of unplanned extubations occurred in patients 6 months and younger. Ten medication events were noted, 2 of which resulted in cardiac arrest. Root causes in all events related primarily to provider and patient factors, with occasional references to verbal miscommunication.

CONCLUSIONS

Five percent of reported pediatric anesthesia adverse events are associated with transport. Learning points highlight the risk of emergence from anesthesia during transport to recovery or intensive care unit (ICU). ICU patients undergoing anesthesia transport face risks relating to transitions in providers, equipment, sedation, and physical positioning. Sedation and neuromuscular blockade may be necessary for transport in some patients but has been associated with adverse events in others.

Uncuffed Endotracheal Tube Experience in Pediatric Patients with Laparotomy and Laparoscopic Surgeries

Aim

The aim of this study is to compare endotracheal tube leak, tube selection, mechanical ventilation, and side effects in the use of uncuffed tubes in both laparoscopic and laparotomy surgeries in pediatric patients. Material and Method. Patients who underwent laparotomy (LT group) or laparoscopic (LS group) surgery between 1 and 60 months. In the selection of uncuffed tubes, it was also planned to start endotracheal intubation with the largest uncuffed tube and to start intubation with a small uncuffed tube if the tube encounters resistance and does not pass. Mechanical parameters, endotracheal tube size, tube changes, and side effects are recorded.

Results

A total of 102 patients, 38 females and 64 males, with a mean age of 10.9 ± 8.1 months, body weight 7.1 ± 3.7 kg, and height 67 ± 15 cm, were included. 54 patients underwent laparoscopic surgery, and 48 patients underwent laparotomy. Tube exchange was performed in a total of 18 patients. In patients who underwent tube exchange, 11 patients were intubated with a smaller ETT number and others endotracheal intubation; when the MV parameters were TVe < 8 ml/kg and ETT leak > 20%, a larger uncuffed tube was used due to PIP 30 cmH₂O pressure. Patients with aspiration were not found in the LT and LS groups. There was no difference in the intergroup evaluation for postoperative side effects such as cough, laryngospasm, stridor, and aspiration.

Conclusion

There was no significant difference between the groups in terms of tube changes and side effects. So that we can start with the largest possible uncuffed tube to decrease ETT leak, both laparotomy and laparoscopic operations in children can be achieved with safe mechanical ventilation and target tidal volume.

Pediatric airway dimensions-A summary and presentation of existing data

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.

Tracheal Size and Morphology on the Reconstructed CT Imaging

OBJECTIVES

To characterize the real size and morphology of tracheas in childhood for the optimal selection of endotracheal tube.

DESIGN

A retrospective cohort study of pediatric patients who received CT scan of the cervical spine from July 2011 to March 2018. Cross-sectional CT images vertical to trachea were reconstructed and the accurate tracheal diameters were measured. The validity of the traditional age-based formula for predicting the endotracheal tube size was assessed for the best fit to trachea.

SETTING

Tertiary Emergency and Critical Care Center of Kyushu University Hospital.

PATIENTS

Children, who are 1 month to 15 years old, received CT scan of the cervical spine.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We enrolled 86 children with median age of 53 months. The cross-sectional shape of pediatric trachea was circular at the cricoid level and elliptical at the infraglottic level. The narrowest part of pediatric trachea was the transverse diameter at the infraglottic level at any age. Significant positive correlation between age and the narrowest diameter was observed. When compared the transverse diameter at the infraglottic level with the outer diameter of endotracheal tubes, uncuffed endotracheal tubes selection based on the traditional age-based formula ran a significant risk of oversized endotracheal intubation until 10 years old compared with cuffed endotracheal tubes selection (60.0% vs 23.8%; p < 0.05).

CONCLUSIONS

These findings indicate the safety and efficacy of cuffed endotracheal tubes in infants and children and the reconsideration for the airway management in pediatric anesthesia and intensive care.

The pediatric airway: Historical concepts, new findings, and what matters

New observations from novel imaging techniques regarding the anatomy, dimensions, and shape of the pediatric airway have emerged and provide insight for potential changes in the clinical management of the airway in infants and children. These new findings are challenging the historical concepts of a funnel-shaped upper airway with the cricoid ring as the narrowest dimension. Although these tenets have been accepted and used to guide clinical practice in airway management, there are limited clinical investigations in children to support the validity of these concepts. Imaging modalities such as magnetic resonance imaging, computed tomography (CT) scanning, multi-detector CT imaging, and videobronchoscopy suggest the need to revisit the historical view of the pediatric airway. This manuscript reviews the historical evolution of pediatric airway studies, summarizes important scientific observations from recent investigations relevant to our clinical understanding of pediatric airway anatomy, and discusses the importance of these findings for pediatric airway management.