Can bedside ultrasound make pediatric intubation safer?

Farias, Luis Gustavo Machado; Siqueira, Alan Cristian Cordeiro; Santos, Kammilly Fernanda Alves dos; Ribas, Fernanda Marcondes; Serra, Edgardo Emilio; Robles, Valeria Daniela

doi:10.55684/2026.84.pt.e00005

ABSTRACT

Introduction: Rapid and accurate confirmation of endotracheal tube positioning and caliber is critical in pediatric practice. Traditional methods, such as radiography and capnography, have limitations related to time, radiation exposure, and the inability to assess depth or selectivity.

Objective: To map and synthesize the evidence on the use of ultrasonography (US) to confirm the positioning, depth, and caliber of the endotracheal tube in pediatric populations.

Method: Scoping review conducted according to the PRISMA-ScR guidelines. The PubMed, Embase, and Cochrane Library databases were searched in September 2025, with no language restriction. Clinical studies comparing US with radiography, capnography, bronchoscopy, or anatomical formulas were included. Those with samples smaller than ten participants, exclusively adult populations, or simulations without clinical data were excluded. Two independent reviewers screened and extracted the data. The findings were narratively synthesized in five domains: tracheal versus esophageal distinction, depth and selectivity, caliber estimation, time to confirmation, and reproducibility.

Results: Were included 23 studies published between 2010 and 2025, covering emergency, operating room, and pediatric intensive care settings. Ultrasonography generally showed sensitivity ≥ 90% and confirmation times of less than one minute.

Conclusion: Bedside ultrasound is an effective, rapid, and reproducible method for confirming the positioning and estimating the caliber of the endotracheal tube in pediatrics. Large-scale implementation requires standardization of protocols and structured training.

KEYWORDS:
Airway ultrasonography; Pediatrics; Endotracheal intubation

VISUAL ABSTRACT

RESUMO

Introdução: A confirmação rápida e precisa do posicionamento e do calibre do tubo endotraqueal é fundamental na prática pediátrica. Métodos tradicionais, como radiografia e capnografia, apresentam limitações relacionadas ao tempo, à exposição à radiação e à incapacidade de avaliar profundidade ou seletividade.

Objetivo: Mapear e sintetizar as evidências sobre o uso da ultrassonografia (US) para confirmar o posicionamento, a profundidade e o calibre do tubo endotraqueal em populações pediátricas.

Método: Revisão de escopo conduzida conforme as diretrizes PRISMA-ScR. Foram pesquisadas as bases PubMed, Embase e Cochrane Library em setembro de 2025, sem restrição de idioma. Incluíram-se estudos clínicos que compararam US com radiografia, capnografia, broncoscopia ou fórmulas anatômicas. Excluíram-se aqueles com amostras menores que dez participantes, populações exclusivamente adultas ou simulações sem dados clínicos. Dois revisores independentes realizaram a triagem e a extração dos dados. Os achados foram sintetizados narrativamente em cinco domínios: distinção traqueal versus esofágica, profundidade e seletividade, estimativa de calibre, tempo de confirmação e reprodutibilidade.

Resultados: Foram incluídos 23 estudos publicados entre 2010 e 2025, abrangendo cenários de emergência, centro cirúrgico e terapia intensiva pediátrica. A ultrassonografia apresentou sensibilidade geralmente ≥ 90% e tempos de confirmação inferiores a um minuto.

Conclusão: A US à beira do leito é método eficaz, rápido e reprodutível para confirmar o posicionamento e estimar o calibre do tubo endotraqueal em pediatria. A implementação em larga escala requer padronização de protocolos e capacitação estruturada.

PALAVRAS-CHAVE:
Ultrassonografia de vias aéreas; Pediatria; Intubação endotraqueal

RESUMO VISUAL

INTRODUCTION

Rapid and accurate confirmation of endotracheal tube (ETT) positioning is essential for airway safety in pediatrics. Conventional methods, such as auscultation, observation of blurring, and radiography, may have limitations related to delay and operational accuracy. Capnography is useful for assessing ventilation, but does not provide information on the depth or selectivity of the ETT. Bedside ultrasonography (US), in turn, avoids radiation exposure and has been shown to be consistently faster than radiography, although it may, in some reports, be slightly slower than capnography.¹^-³

Point-of-care US (POCUS) allows direct visualization of tracheal structures and pleurodiaphragmatic assessment. In pediatric populations, studies conducted in the emergency department, intensive care unit, and operating room report sensitivity often ≥ 90%, variable specificity, and confirmation time of less than one minute, with high interobserver agreement (κ ≈ 0.87-0.93).¹^,³ The main technical approaches include suprasternal and tracheal scans, evaluation of pleural sliding and diaphragmatic movement, as well as direct visualization of the tip of the tube and the use of a cuff filled with saline solution. The most commonly used reference standards are radiography, capnography, and, to a lesser extent, bronchoscopy. This set of methods reinforces the role of US as a multimodal tool, which adds anatomical assessment - including depth assessment - to the functional surveillance provided by capnography.²^.⁴

Recent literature syntheses indicate high performance of US in confirming intubation and assessing the depth of ETT in different pediatric age groups, although there is still heterogeneity among techniques, protocols, and standards of comparison.⁵^,⁶ There are still gaps in the standardization of procedures and methodological reporting, with a predominance of single-center studies and significant variation in the experience of operators.

The objective of this scoping review was to map and synthesize the evidence on the use of US in confirming the positioning and assessing the depth of ETT in pediatric populations, describing the techniques employed, reference standards, diagnostic performance, execution times, and reproducibility, in order to support integrated clinical protocols and guide future multicenter research.

METHOD

This scoping review was conducted in accordance with the recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews (PRISMA-ScR). The aim of this study was to identify and synthesize the evidence on the use of US to confirm the positioning and estimate the size of ETT in pediatric populations. Comprehensive searches were conducted in PubMed/MEDLINE, Embase, and Cochrane Library in September 2025, with no language restriction. The search strategy combined controlled vocabulary (MeSH/Emtree) and free terms related to ultrasonography, endotracheal intubation, and pediatric population, connected by Boolean operators (AND/OR). Relevant review references were also manually examined to identify additional studies. Clinical studies that evaluated ultrasound for confirmation of ETT or caliber estimation, compared with reference standards such as radiography, capnography, bronchoscopy, or anatomical formulas, were included. Prospective and retrospective designs, diagnostic accuracy studies, and systematic reviews were considered eligible. Series with fewer than 10 participants, studies exclusively in adults and investigations based only on simulations without clinical data, were also excluded. Two independent reviewers screened titles, abstracts, and full texts, resolving disagreements by consensus. The extracted data included clinical scenario, ultrasound technique, reference standard, diagnostic metrics (sensitivity, specificity, accuracy, and predictive values), time to confirmation, and interobserver agreement (κ). Due to the methodological heterogeneity between the studies, the results were synthesized in a narrative manner and organized into five domains: tracheal versus esophageal distinction, depth and selective intubation, caliber estimation, time to confirmation, and reproducibility. No meta-analysis or formal assessment of risk of bias was performed, in accordance with the scope of PRISMA-ScR. This study used only secondary data in the public domain; therefore, there was no need for approval by the Research Ethics Committee or to obtain informed consent.

RESULTS

The search included 23 articles directly related to the topic that were compiled in this review (Table).

Thumbnail

TABLE
Synthesis of references directly related to the theme (23 articles).¹^-²³

DISCUSSION

The search identified 76 records in the PubMed, Embase, and Cochrane Library databases. After removing duplicates, 55 titles and abstracts were screened and 31 full texts evaluated. Eight studies were excluded because they were based on simulations with no clinical outcomes or because they did not provide relevant diagnostic data. In total, 23 clinical trials were included in this scoping review (Table).

The studies covered the period from 2010 to 2025 and were conducted in several countries in Asia, Europe, and North America, covering a wide variety of settings, operating rooms, emergency services, and pediatric ICUs. Different methodological designs were identified, including prospective cohorts, diagnostic accuracy studies, and systematic reviews.¹^,⁵^,⁶ The populations evaluated included neonates, infants, children, and adolescents up to 17 years of age, with sample sizes ranging from 42 to 155 participants per study.¹^.³

The sonographic approaches were grouped into four main categories: 1) integrated airway and lung protocols, such as TRUCE and 5-AIR;²^,³ 2) visualization of the saline-filled cuff in the suprasternal notch or between the tracheal rings, as in the TR.U.S.T.;⁴ 3) isolated pleural and/or diaphragmatic evaluations;⁶^,⁷ and 4) subglottic measure protocol to predict the tube gauge.¹⁷^,¹⁸ Chest X-ray and capnography were the most frequently used reference standards, followed by bronchoscopy, fluoroscopy, or comparison with traditional anatomical formulas.¹^.⁹

In the set of pediatric studies, the diagnostic accuracy of US for confirmation of intubation and depth estimation varied according to the technique and the level of experience of the operators.¹^,⁵ The most comprehensive systematic review, consisting of 33 studies and 1,934 examinations, reported accuracy between 90.6% and 100% for confirming intubation and between 66.7% and 100% for depth assessment, demonstrating superior performance of ultrasound approaches compared to traditional anatomical formulas for choosing the ETT caliber.⁵^.¹⁰

Among the integrated protocols, the TRUCE (with suprasternal and bilateral pleural windows) showed correct identification of ETT in 97.4% of the cases, compared to 83.2% on radiography, with a sensitivity of 98% and interobserver agreement of 96.8% (κ = 0.53).¹ The 5-AIR protocol, which combines real-time tracheal US and pleurodiaphragmatic assessment, achieved a sensitivity of 100% for detection of selective intubation, an overall accuracy of 96%, and faster than capnography and auscultation - with a median of six seconds for confirmation of tracheal position versus 15 seconds (capnography) and 12 seconds (auscultation).²

Among the techniques based on salinized cuffs, the TR.U.S.T. protocol had a sensitivity of 98.8%, specificity of 96.4%, a positive predictive value of 96.5% and a negative predictive value of 98.8%, with a mean examination time of four seconds and excellent reproducibility (κ = 0.93).4 In settings with less training, performance was reduced: in a pediatric ICU, a simplified pleural protocol demonstrated a sensitivity of 77% and specificity of 68% compared with radiography, although with faster confirmation (POCUS: two minutes; radiography: 10 minutes).⁶

The evaluation of the ETT depth also showed consistent performance. Studies comparing diaphragmatic ultrasound to radiography showed a sensitivity of 0.91 for detecting tracheal position and a specificity of 0.50 for selective intubation in the source bronchus, with a mean confirmation time eight minutes shorter than that of radiography.⁸ In critically ill children, US has shown high reliability for estimating depth, with the tracheal ring method being the most accurate among the techniques evaluated.⁴^,⁹ In an elective setting, the use of US-guided pleural sliding outperformed auscultation in identifying suboptimal tube positioning.³^.⁸

For the choice of ETT caliber, the measurement of subglottic diameter by US showed superior performance to age-based formulas. In a cohort of 118 children aged 1-5 years with microcuff tubes, the agreement between the diameter estimated by US and the best clinical fit was 99.2%, compared with 77.1% by the age formula, with correlation r = 0.994 and κ = 0.986. Primary use of US could have avoided approximately 22% of tube changes.¹⁷ Additional results confirmed that the minimum subglottic transverse diameter measured by US more accurately guides ETT selection than traditional methods, including in patients with reinforced tubes.¹⁸ A quantitative synthesis of 33 studies reported US accuracy between 23.3% and 100%, depending on the outcome and the protocol used.¹⁰

In general, confirmation of positioning by US was faster than radiography: 4-6 seconds in integrated protocols (TR.U.S.T. and 5-AIR) and a few minutes in isolated pleural approaches.²^,⁴^,⁶ Comparative studies have recorded a mean reduction of 8-10 minutes in the time to confirmation compared to radiography.⁸^,¹³ Reproducibility was high when the operators had formal training, with interobserver agreements often higher than κ = 0.9.3.⁴

In summary, the 23 clinical studies included corroborate the diagnostic efficacy and operational applicability of bedside ultrasound to: 1) confirm tracheal intubation; 2) detect inadequate depth or selective intubation, and 3) estimate the optimal ETT caliber in pediatrics.¹⁰^,¹⁷^,¹⁸ The methodological variation observed reflects both the versatility of the technique and the need for standardization and training. Performance is maximized when tracheal, pleural, and diaphragmatic windows are combined in integrated protocols and when subglottic measurement is used to guide tube choice.³^,⁵^,¹⁷

This scoping review demonstrates that bedside US is an accurate, rapid, and reproducible method for confirming the positioning of ETT in pediatric patients. The reported sensitivity is often ≥ 90%, while the specificity varies according to the technique and reference standard used.¹^,³^,⁵ Confirmation times are mostly below one minute, and interobserver agreement remains high (κ ≈ 0.87 - 0.93)^.³^.⁴

Integrated protocols that combine tracheal and pulmonary windows tend to have superior performance, whereas isolated approaches - such as pleural-only assessment - demonstrate greater variability in specificity.²^,⁶ The analysis of the studies shows consistently high sensitivity and more heterogeneous specificity, reinforcing the role of US as a multimodal verification tool, complementary to other diagnostic methods, rather than as an isolated test.¹^.⁵

From an operational perspective, ultrasound surpasses radiographs in terms of confirmation time and, in some series, it was also faster than auscultation. Although capnography may be occasionally faster, it does not provide information on the depth or selectivity of ETT with the same anatomical resolution.³^,⁸^,²¹ In comparative terms, typical times range from 4-17 seconds for US, approximately 14-20 minutes for radiography, and approximately six seconds for capnography in a specific study.²^,⁴ These findings support the role of US as an immediate decision-making tool, capable of reducing delays and unnecessary radiation exposure.²^.⁸

The predictive values reported, when available, were high, with positive predictive values in the range of 90% and variation of the negative predictive value according to the scenario and the technique employed. Likelihood ratios described in some studies reinforce the clinical robustness of US within well-defined protocols.⁴^,⁵ The high reproducibility (κ to 0.93) observed in different contexts confirms the interobserver consistency and supports the incorporation of US into pediatric care flows conducted by trained operators.³^,⁴^,¹⁶

The main limitations of the body of evidence include small sample sizes, predominance of single-center studies, heterogeneity in protocols and reference standards, and incomplete blinding between operators and evaluators, which increases the risk of measurement bias.¹^,⁵^,⁶ There is also a scarcity of data from prehospital contexts and underreporting of relevant clinical outcomes, such as severe desaturation, need for reintubation, and pulmonary complications.⁵^,⁶^,¹³ Such limitations restrict the generalization of the results and make it difficult to perform comparable meta-analyses between techniques.⁵^,¹⁰^,²³

In practical terms, the integration of US with ETT confirmation algorithms immediately after intubation should be prioritized, with the use of standardized sequences that combine suprasternal or tracheal window and bilateral pleural evaluation, in addition to the observation of diaphragmatic movements when necessary.²^,³^,⁶^,²² In environments with slow or unavailable radiography, ultrasound allows confirmation in a few seconds and can reduce the occurrence of inappropriate positioning.²^,⁸ Capnography should remain a complementary method for monitoring continuous ventilation, whereas US provides anatomical information on depth and selectivity that capnography alone is not able to provide.¹^,⁴^,²¹

Regarding the research agenda, the need for standardization of protocols (with definition of anatomical landmarks, cutoff points, and window sequence), the establishment of minimum training curricula, and multicenter validation with adequate blinding are highlighted.⁵^,⁶^,¹⁹ Pragmatic trials comparing integrated diagnostic routes (US + capnography) with usual practices are essential to assess impact on clinical outcomes, process times, and costs.⁵^,¹⁰ Studies in prehospital settings and cost-effectiveness analyses are priorities to expand the safe adoption of US in systems with different levels of resources.⁵^.²⁰

In summary, airway ultrasound in pediatrics is a rapid, sensitive, and highly reproducible method for confirming ETT positioning, with the potential to reduce delays and radiation exposure.³^,⁴^,¹⁶ Considering the variability of specificity between techniques, its optimal use occurs within integrated protocols, applied by trained professionals and in complementarity to capnography, until standardized multicenter studies establish definitive parameters guided by robust clinical outcomes.⁵^,⁶^,²³

The technique has demonstrated consistent applicability in different clinical contexts, emergency, operating room, and intensive care, when performed by adequately trained operators.³^,⁶ Despite the growth of the body of evidence, methodological heterogeneities, lack of standardization of protocols, and scarcity of multicenter studies with objective clinical outcomes persist.⁵^,⁶^,¹⁰ The consolidation of US as a standard for verification in pediatrics requires large-scale validation, definition of consensual anatomical landmarks, and structured incorporation into training in anesthesiology, intensive care, and pediatric emergency medicine.⁵^.¹⁰

CONCLUSION

Bedside ultrasound demonstrated high diagnostic performance, speed, and reproducibility in confirming the positioning of ETT in children and neonates. Integrated protocols that combine tracheal, pleural, and diaphragmatic windows achieve sensitivities close to 100% and confirmation times of a few seconds. In addition to confirming the position, subglottic measurement by US was shown to be superior to age-based formulas in determining the ideal tube size, reducing exchanges and potentially the risk of mucosal injury.

References

¹ Gautam I, Angurana SK, Muralidharan J, Bansal A, Nallasamy K, Saxena A. Three-Point Ultrasonography for Confirmation of Endotracheal Tube Position in Children (TRUCE Study). Indian J Pediatr. 2025;92(5):495-501. https://doi.org/10.1007/s12098-023-05013-w
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² Baruah A, Ahmad Z, Waindeskar V, Jain S, Chanchlani R, Mandal P, et al. 5-point airway (5-AIR) ultrasound protocol for confirmation of endotracheal intubation and position in paediatric patients undergoing surgery: A prospective observational study. Indian J Anaesth. 2024;68(12):1068-74. https://doi.org/10.4103/ija.ija_682_24
» https://doi.org/10.4103/ija.ija_682_24
³ Tessaro MO, Salant EP, Arroyo AC, Haines LE, Dickman E. Tracheal rapid ultrasound saline test (T.R.U.S.T.) for confirming correct endotracheal tube depth in children. Resuscitation. 2015;89:8-12. https://doi.org/10.1016/j.resuscitation.2014.08.033
» https://doi.org/10.1016/j.resuscitation.2014.08.033
⁴ Datta S, Sankar J, Pathak M, Tungal S, Kandasamy D, Dhochak N, et al. Diagnostic accuracy of airway ultrasound in confirming the endotracheal tube depth in critically ill children. Am J Emerg Med. 2024;85:52-8. https://doi.org/10.1016/j.ajem.2024.08.012
» https://doi.org/10.1016/j.ajem.2024.08.012
⁵ Wani TM, John J, Rehman S, Bhaskar P, Sahabudheen AF, Mahfoud ZR, et al. Point-of-care ultrasound to confirm endotracheal tube cuff position in relationship to the cricoid in the pediatric population. Paediatr Anaesth. 2021;31(12):1310-5. https://doi.org/10.1111/pan.14303
» https://doi.org/10.1111/pan.14303
⁶ Guerder M, Maurin O, Merckx A, Foissac F, Oualha M, Renolleau S, et al. Diagnostic value of pleural ultrasound to refine endotracheal tube placement in pediatric intensive care unit. Arch Pediatr. 2021;28(8):712-17. https://doi.org/10.1016/j.arcped.2021.09.006
» https://doi.org/10.1016/j.arcped.2021.09.006
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Central Message
Rapid and accurate confirmation of endotracheal tube positioning and caliber is critical in pediatric practice. Traditional methods, such as radiography and capnography, have limitations related to time, radiation exposure, and the inability to assess depth or selectivity. Thus, mapping and synthesizing the evidence on the use of ultrasonography to confirm the positioning, depth, and caliber of the endotracheal tube in pediatric populations is interesting in the care of children
Perspective
Bedside ultrasonography is an effective, fast, and reproducible method for confirming the positioning and estimating the caliber of the endotracheal tube in pediatrics. It can assist with care; however, large-scale implementation requires standardization of protocols and structured training.
How to cite this article
Farias LGM, Siqueira ACC, Santos KFA, Ribas FM, Serra EE, Robles VD. A ultrassonografia à beira do leito pode tornar a intubação pediátrica mais segura? BioSCIENCE. 2026;84:e00005. https://doi.org/10.55684/2026.84.pt.e00005 BioSCIENCE. 2026;84:e00005. https://doi.org/10.55684/2026.84.en.e00005
Funding:
None
Data availability:
Data are available from the corresponding author upon reasonable request.

Edited by

Associate Editor:
Attila Csendes https://orcid.org/0009-0000-1204-1545

Data availability

Data are available from the corresponding author upon reasonable request.

Publication Dates

Publication in this collection
21 Aug 2026
Date of issue
2026

History

Received
05 Jan 2026
Accepted
18 Feb 2026
Published
06 Mar 2026

Este é um artigo publicado em acesso aberto sob uma licença Creative Commons

[1] ¹ Gautam I, Angurana SK, Muralidharan J, Bansal A, Nallasamy K, Saxena A. Three-Point Ultrasonography for Confirmation of Endotracheal Tube Position in Children (TRUCE Study). Indian J Pediatr. 2025;92(5):495-501. https://doi.org/10.1007/s12098-023-05013-w
» https://doi.org/10.1007/s12098-023-05013-w

[2] ² Baruah A, Ahmad Z, Waindeskar V, Jain S, Chanchlani R, Mandal P, et al. 5-point airway (5-AIR) ultrasound protocol for confirmation of endotracheal intubation and position in paediatric patients undergoing surgery: A prospective observational study. Indian J Anaesth. 2024;68(12):1068-74. https://doi.org/10.4103/ija.ija_682_24
» https://doi.org/10.4103/ija.ija_682_24

[3] ³ Tessaro MO, Salant EP, Arroyo AC, Haines LE, Dickman E. Tracheal rapid ultrasound saline test (T.R.U.S.T.) for confirming correct endotracheal tube depth in children. Resuscitation. 2015;89:8-12. https://doi.org/10.1016/j.resuscitation.2014.08.033
» https://doi.org/10.1016/j.resuscitation.2014.08.033

[4] ⁴ Datta S, Sankar J, Pathak M, Tungal S, Kandasamy D, Dhochak N, et al. Diagnostic accuracy of airway ultrasound in confirming the endotracheal tube depth in critically ill children. Am J Emerg Med. 2024;85:52-8. https://doi.org/10.1016/j.ajem.2024.08.012
» https://doi.org/10.1016/j.ajem.2024.08.012

[5] ⁵ Wani TM, John J, Rehman S, Bhaskar P, Sahabudheen AF, Mahfoud ZR, et al. Point-of-care ultrasound to confirm endotracheal tube cuff position in relationship to the cricoid in the pediatric population. Paediatr Anaesth. 2021;31(12):1310-5. https://doi.org/10.1111/pan.14303
» https://doi.org/10.1111/pan.14303

[6] ⁶ Guerder M, Maurin O, Merckx A, Foissac F, Oualha M, Renolleau S, et al. Diagnostic value of pleural ultrasound to refine endotracheal tube placement in pediatric intensive care unit. Arch Pediatr. 2021;28(8):712-17. https://doi.org/10.1016/j.arcped.2021.09.006
» https://doi.org/10.1016/j.arcped.2021.09.006

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[8] ⁸ Pillai R, Kumaran S, Jeyaseelan L, George SP, Sahajanandan R. Usefulness of ultrasound-guided measurement of minimal transverse diameter of subglottic airway in determining the endotracheal tube size in children with congenital heart disease: A prospective observational study. Ann Card Anaesth. 2018;21(4):382-7. https://doi.org/10.4103/aca.aca_220_17
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[9] ⁹ Gupta B, Ahluwalia P. Prediction of endotracheal tube size in the pediatric age group by ultrasound: A systematic review and meta-analysis. J Anaesthesiol Clin Pharmacol. 2022;38(3):371-83. https://doi.org/10.4103/joacp.joacp_650_20
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[10] ¹⁰ Liu Y, Ma W, Liu J. Applications of Airway Ultrasound for Endotracheal Intubation in Pediatric Patients: A Systematic Review. J Clin Med. 2023;12(4):1477. https://doi.org/10.3390/jcm12041477
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[11] ¹¹ Congedi S, Savio F, Auciello M, Salvadori S, Nardo D, Bonadies L. Sonographic Evaluation of the Endotracheal Tube Position in the Neonatal Population: A Comprehensive Review and Meta-Analysis. Front Pediatr. 2022;10:886450. https://doi.org/10.3389/fped.2022.886450
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[12] ¹² Levkovitz O, Schujovitzky D, Stackievicz R, Fayoux P, Morag I, Litmanovitz I, et al. Ultrasound assessment of endotracheal tube depth in neonates: a prospective feasibility study. Arch Dis Child Fetal Neonatal Ed. 2023;109(1):94-9. https://doi.org/10.1136/archdischild-2023-325855
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[13] ¹³ Dennington D, Vali P, Finer NN, Kim JH. Ultrasound confirmation of endotracheal tube position in neonates. Neonatology. 2012;102(3):185-9. https://doi.org/10.1159/000338585
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[14] ¹⁴ Huang D, Watkins LA, Weinschreider J, Ghazi A, Wang H, Dadiz R. Simulation-based Ultrasound Curriculum for Novice Clinicians to Assess Neonatal Endotracheal Tube Position. J Med Ultrasound. 2022;31(1):40-7. https://doi.org/10.4103/jmu.jmu_143_21
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[15] ¹⁵ Rajasekhar M, Moningi S, Patnaik S, Rao P. Correlation between ultrasound-guided subglottic diameter and little finger breadth with the outer diameter of the endotracheal tube in paediatric patients - A prospective observational study. Indian J Anaesth. 2018;62(12):978-83. https://doi.org/10.4103/ija.IJA_545_18
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[16] ¹⁶ Lin MJ, Gurley K, Hoffmann B. Bedside Ultrasound for Tracheal Tube Verification in Pediatric Emergency Department and ICU Patients: A Systematic Review. Pediatr Crit Care Med. 2016;17(10):469-76. https://doi.org/10.1097/pcc.0000000000000907
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[17] ¹⁷ Alonso Quintela P, Oulego Erroz I, Mora Matilla M, Rodríguez Blanco S, Mata Zubillaga D, Regueras Santos L. Utilidad de la ecografía comparada con la capnografía y la radiografía en la intubación traqueal [Usefulness of bedside ultrasound compared to capnography and X-ray for tracheal intubation]. An Pediatr (Barc). 2014;81(5):283-8. https://doi.org/10.1016/j.anpedi.2014.01.004
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[18] ¹⁸ Jaeel P, Sheth M, Nguyen J. Ultrasonography for endotracheal tube position in infants and children. Eur J Pediatr. 2017;176(3):293-300. https://doi.org/10.1007/s00431-017-2848-5
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[19] ¹⁹ Salvadori S, Nardo D, Frigo AC, Oss M, Mercante I, Moschino L, et al. Ultrasound for Endotracheal Tube Tip Position in Term and Preterm Infants. Neonatology. 2021;118(5):569-77. https://doi.org/10.1159/000518278
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[20] ²⁰ Zaytseva A, Kurepa D, Ahn S, Weinberger B. Determination of optimal endotracheal tube tip depth from the gum in neonates by X-ray and ultrasound. J Matern Fetal Neonatal Med. 2020;33(12):2075-80. https://doi.org/10.1080/14767058.2018.1538350
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[21] ²¹ Recker F, Kipfmueller F, Wittek A, Strizek B, Winter L. Applications of Point-of-Care-Ultrasound in Neonatology: A Systematic Review of the Literature. Life (Basel). 2024;14(6):658. https://doi.org/10.3390/life14060658
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[22] ²² Saravia A, Saravia RW, Mudd P, Jones JW. Examining the pediatric subglottic airway by ultrasound: A systematic review. Int J Pediatr Otorhinolaryngol. 2023;166:111482. https://doi.org/10.1016/j.ijporl.2023.111482
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[23] ²³ Yang JL, Zheng F, Zhu KL, Wang W, Ding LM, Wang CG. Utilizing ultrasonography to determine the minimal transverse diameter of the subglottic airway for informed selection of reinforced cuffed endotracheal tube models in children. Eur Arch Otorhinolaryngol. 2024;281(12):6533-8. https://doi.org/10.1007/s00405-024-08923-3
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Author and year	Type of study	Objective	Method	Conclusion
Gautam et al.¹ 2025	Prospective observational study (diagnostic accuracy)	To evaluate the accuracy of three-point ultrasonography (TRUCE) to confirm the position of ETT in children, using chest X-ray as the reference standard.	155 children (3 months to 12 years) intubated in the emergency room and pediatric ICU; US at three points (sternal notch and bilateral anterior thorax) compared with radiography, with interobserver agreement.	Three-point US identified the correct position of the ETT in 97.4% (vs. 83.2% on radiography), with a sensitivity of 98%; effective, sensitive, safe and reproducible method at the bedside.
Baruah et al.² 2024	Prospective observational study	To compare the accuracy and timing of the 5-point airway ultrasound protocol (5-AIR) with capnography and auscultation in confirming intubation and ETT positioning.	75 children (2 to 12 years old), ASA I and II, undergoing elective surgery; Real-time tracheal US followed by pleural and bilateral diaphragmatic US, compared to quantitative capnography and auscultation.	The 5-AIR was fast and accurate (sensitivity 100% and overall accuracy 96% for positioning), confirming tracheal position faster than capnography; useful as a complement to clinical signs.
Tessaro et al.³ 2015	Prospective feasibility study (diagnostic accuracy)	To evaluate the accuracy of tracheal ultrasound of the saline-filled cuff (T.R.U.S.T.) to confirm the correct depth of ETT insertion in children.	42 children in surgery; US in the sternal notch during endotracheal vs. endobronchial positioning, confirmed by bronchoscopy and assessed by two blinded reviewers.	Accurate and rapid method (sensitivity 98.8%, specificity 96.4%; κ = 0.93; mean 4 s scan) to confirm the correct depth of the ETT.
Datta et al.⁴ 2024	Prospective cross-sectional study (diagnostic accuracy)	To evaluate the diagnostic accuracy of airway US to confirm the depth of ETT in critically ill children.	62 children (2 months to 17 years) intubated with cuffed ETT in the pediatric ICU; three techniques (sternal notch, cricoid and tracheal rings) with salinized cuff, compared to radiography.	US is a good method to confirm the depth of ETT; The tracheal ring method had the best accuracy (κ = 0.87) and is easy to perform.
Wani et al.⁵ 2021	Prospective non-randomized clinical trial	To evaluate the use of POCUS to determine the position of the ETT cuff in relation to the cricoid cartilage in the pediatric population.	80 patients (1 to 78 months); after intubation, identification of the salinized cuff and the tracheal/cricoid rings in the longitudinal plane by POCUS.	POCUS is a fast and effective means to identify the position of the ETT cuff in relation to the cricoid, with applications in the perioperative, emergency room, and ICU.
Guerder et al.⁶ 2021	Single-center prospective study (diagnostic accuracy)	To evaluate the performance of a simplified pulmonary ultrasound (POCUS) to confirm the positioning of the ETT in the pediatric ICU and to compare time with radiography.	71 critically ill children with urgent intubation; pleural sliding sign compared to radiography; operators with 1-hour training.	Pleural ultrasound, although faster than radiography (2 vs. 10 min), was inadequate to identify selective intubation (sensitivity 77%, specificity 68%) in an unaccustomed team; Useful at the bedside by trained operators.
Bharathi et al.⁷ 2022	Comparative prospective study	Predict the appropriate size of the ETT by the subglottic diameter measured by US, compared to age/height-based formulas and clinical methods.	27 children (2 to 15 years old); intubation with ETT of a predetermined size by US; Optimal size defined by the leak test (cuff leak).	The subglottic diameter by US is an easy, effective, and noninvasive way to predict the size of the ETT, with higher accuracy than the age and height formulas.
Pillai et al.⁸ 2018	Prospective observational study	To evaluate the utility of minimum transverse subglottic airway diameter (MTDSA) by US for screening ETT in children with congenital heart disease.	51 children (1 day to 5 years) undergoing cardiac surgery; size of the ETT guided by MTDSA, with better fit by the escape test and comparison with Cole’s formula.	The MTDSA by US predicted the best ETT in 87.8% of cases (vs. 27.5% of the age formula); safe and accurate method in the pediatric cardiac population.
Gupta & Ahluwalia⁹ 2022	Systematic review and meta-analysis	To evaluate the accuracy of the ultrasound correlation vs. standard age formulas in predicting ETT size in pediatrics.	Systematic review (PubMed, Cochrane, Embase) with 48 studies (1,978 patients) and 18 independent correlations; registered in PROSPERO.	Ultrasound is an effective modality for estimating the size of the ETT, which is higher than the age/height formulas (combined correlation 0.824); non-invasive, cost-effective and reproducible technique.
Liu et al.¹⁰ 2023	Systematic review	Summarize the applications of airway US at each step of endotracheal intubation in pediatric patients.	Systematic review (MEDLINE, Embase, Cochrane, and Chinese database) with 33 studies and 1,934 US examinations; diagnostic accuracy as the outcome.	Ultrasound confirms intubation (accuracy 90.6 to 100%), depth (66.7 to 100%), and ETT size (23.3 to 100%), surpassing traditional methods; Unified protocol required.
Congedi et al.¹¹ 2022	Systematic review and meta-analysis	To evaluate the efficacy of US in the adequacy of ETT positioning in full-term and preterm newborns and to compare time with other methods.	Meta-analysis of 14 studies (602 TTET assessments) in the neonatal ICU and delivery room; radiography as the gold standard in about 80% of cases.	POCUS is a fast and effective technique to identify the correct intubation in neonates (pooled sensitivity 93.4%), being faster than radiography.
Levkovitz et al.¹² 2023	Prospective observational feasibility study	To examine the reliability of a new sonographic method to assess the position of ETT in neonates.	42 exams in 33 neonates; distance from the tip of the ETT to the right pulmonary artery by US compared to the X-ray (gold standard).	The US measurement of the ETT distance to the right pulmonary artery had excellent accuracy (κ = 0.82; specificity 100%); Further clinical feasibility studies are needed.
Dennington et al.¹³ 2012	Prospective pilot study	To determine whether bedside US demonstrates the location of the ETT tip in preterm and term newborns.	30 newborns with position confirmed by radiography; US with 13 MHz linear transducer; measurement of the distance from the tip of the TET to the carina.	US visualized the position of the ETT in all neonates (good correlation with radiography; examination < 5 min); Requires additional validation prior to routine use.
Huang et al.¹⁴ 2022	Prospective educational study (simulation)	To evaluate the effectiveness of a simulation-based domain curriculum to train clinicians with no US experience to assess the position of neonatal ETT.	29 neonatologists; theoretical class and simulation session with 3D trachea/aorta model (phantom); performance checklist and pre/post evaluations.	Simulation-based training with 3D model has improved knowledge and skill in the ultrasound evaluation of TET by inexperienced operators.
Rajasekhar et al.¹⁵ 2018	Prospective observational study	To compare whether subglottic diameter by US or little finger width correlates better with ETT outer diameter (OD) in children.	60 patients (6 months to 8 years), ASA I and II, undergoing elective surgery; preoperative measurements of subglottic diameter (USGD) and little finger width (LFB); Lin’s agreement.	Neither USGD nor LFB were reliable predictors of ETT ND (low agreement: 0.29 and 0.46, respectively).
Lin et al.¹⁶ 2016	Systematic review	To describe the available data on the accuracy and feasibility of bedside US to verify tracheal tube position in children.	Systematic review (MEDLINE, Embase) of 9 articles (cervical, pulmonary/diaphragmatic and direct tip visualization); quality rated by QUADAS.	Bedside US is feasible and useful as an adjuvant in tracheal tube confirmation (transtracheal sensitivity 0.92 to 1.00); Randomized multicenter studies are lacking.
Alonso Quintela et al.¹⁷ 2014	Comparative prospective study	To evaluate the usefulness of bedside ultrasound compared to capnography and radiography for tracheal intubation in children and neonates.	31 intubations in 26 patients (pediatric and neonatal ICU); Simultaneous tracheal ultrasound and capnography, thoracic ultrasound vs. radiography, with time recording.	US was as effective as capnography (although slower) and as effective and faster than radiography; It can reduce the routine use of post-intubation radiography.
Jaeel et al.¹⁸ 2017	Literature review	To review the literature on the use of US for ETT positioning in the pediatric population.	Search in the Ovid and MEDLINE databases for US for intubation and positioning of ETT in infants and children.	Ultrasound for ETT verification is well tolerated and can complement the determination of correct positioning, associated with radiography and capnography; there is a lack of studies in technique and training.
Salvadori et al.¹⁹ 2021	Prospective study	To establish the reliability of US to assess the position of ETT in the neonatal ICU, the time required, and the tolerance of patients.	71 newborns; distance from the tip of the ETT to the right pulmonary artery by US compared to the distance from the tip to the carina on X-ray (Lin’s agreement; Bland-Altman).	ETT ultrasound is a fast, tolerable, and highly reliable method (mean time 3.2 min), with the potential to reduce radiation exposure in neonatology.
Zaytseva et al.²⁰ 2020	Prospective observational study	To define the optimal depth of the ETT from the gingiva in neonates and to compare the POCUS with the radiograph in the confirmation of the ETT tip.	Intubated neonates; measurements of the lip and gums during the radiography; POCUS (10 MHz heart probe, high parasternal window); linear regression by weight.	Marking on the gum (≈ 5.2 cm + weight in kg) is feasible; POCUS rapidly confirms the position of the ETT tip with accuracy similar to radiography (ICC 0.95).
Recker et al.²¹ 2024	Systematic review	Synthesize the evidence on applications, benefits, challenges, and educational strategies of POCUS in neonatology.	Systematic review (SPIDER scheme and MeSH terms) with 68 publications; narrative synthesis of the findings.	POCUS represents a significant advance in neonatal medicine (including the confirmation of ETT), reducing invasive procedures; requires training and standardized guidelines.
Saravia et al.²² 2023	Systematic review	To determine the ability of US to assess the subglottic airway in pediatrics to estimate the appropriate size of the ETT.	Systematic review (PubMed, Scopus, Embase) of 16 studies (1,633 children) with transcervical laryngeal ultrasound from the MTDSA.	Transcervical laryngeal US is a reliable predictor of ETT size (prediction in 48 to 100% vs. 24 to 95% of age formulas), with implications for the prevention of trauma by intubation.
Yang et al.²³ 2024	Randomized controlled trial	To explore the use of US to determine MTDSA in the selection of cuff-reinforced ETT model in children.	110 children (3 to 6 years) randomized into three groups (MTDSA by US, age formula, and height formula); comparison of predictive accuracy and complications.	The measurement of MTDSA by US was more accurate (87.2% vs. 54.3% and 47.2%), reducing tube changes and complications; helps the choice of cuff-reinforced ETT in pediatrics.