This prospective observational cohort study evaluates whether respiratory-cycle variation in internal jugular vein (IJV) diameter, measured by point-of-care ultrasound, correlates with clinical disease severity in infants 1-23 months of age presenting with acute bronchiolitis. Using a standardized M-mode protocol, the IJV Variability Index (\[IJVmax-IJVmin\]/IJVmax x 100) will be calculated and compared with the Wang Bronchiolitis Severity Score, four additional validated clinical severity instruments (Modified Tal Score, Respiratory Distress Assessment Instrument, Kristjansson Respiratory Score, Respiratory Assessment Change Score), oxygen saturation, respiratory rate, need for high-flow nasal cannula or supplemental oxygen, pediatric intensive care unit admission, and length of hospital stay. Concurrent lung and diaphragm point-of-care ultrasound will be performed to build a multimodal ultrasound severity model. No intervention is assigned; all ultrasound assessments are performed in addition to standard clinical care and do not alter treatment decisions.
Bronchiolitis is among the leading causes of hospitalization in infants under 2 years of age. Existing clinical severity scores show limited inter-observer agreement and weak correlation with oxygenation. Point-of-care ultrasound (lung ultrasound, diaphragm ultrasound) has been studied as an adjunct severity marker in bronchiolitis. Still, respiratory-cycle variability of the internal jugular vein (IJV) diameter has not previously been investigated in this population. A prior reliability study in healthy children demonstrated that right internal jugular vein (RIJV) diameter can be reliably measured by M-mode ultrasound and does not vary significantly across the respiratory cycle in the absence of respiratory distress; the study authors explicitly proposed that RIJV diameter and its respiratory variation be investigated as a surrogate marker of pulmonary function in children with respiratory distress. This study extends that proposed application to infants with acute bronchiolitis. Eligible infants aged 1-23 months meeting AAP (2014) clinical criteria for acute bronchiolitis will undergo a standardized ultrasound protocol (45-degree head elevation, linear probe, right internal jugular vein imaged approximately 1 cm cephalad to the sternoclavicular junction, B-mode identification followed by M-mode measurement of maximal inspiratory and expiratory diameters) performed by a blinded, trained sonographer. We will record concurrent clinical severity scoring, lung ultrasound, and diaphragm ultrasound (excursion, thickening fraction). The primary analysis will test the correlation between the IJV Variability Index and the Wang Bronchiolitis Severity Score; secondary analyses will examine correlations with additional validated severity scores, physiologic parameters, and clinical outcomes (respiratory support escalation, length of stay), as well as inter-/intra-observer reliability and the discriminative performance of a multimodal point-of-care ultrasound model.
Study Type
OBSERVATIONAL
Enrollment
120
A standardized point-of-care ultrasonography assessment will be performed in addition to routine clinical evaluation. The protocol includes M-mode assessment of the right internal jugular vein (IJV) to measure maximal and minimal respiratory-cycle diameters and calculate the IJV Variability Index (\[IJVmax-IJVmin\]/IJVmax × 100). Concurrent lung ultrasonography and diaphragm ultrasonography, including diaphragm excursion and thickening fraction, will also be performed. Ultrasonographic assessments are performed for research measurements only and do not determine or modify clinical treatment decisions.
Eskisehir Osmangazi University Faculty of Medicine, Pediatric Emergency Department
Eskişehir, Eskişehir, Turkey (Türkiye)
Correlation Between Internal Jugular Vein Respiratory Variability Index and Wang Bronchiolitis Severity Score
Correlation between the Internal Jugular Vein (IJV) Variability Index and the Wang Bronchiolitis Severity Score. The IJV Variability Index will be calculated as (\[IJVmax - IJVmin\] / IJVmax) × 100, where IJVmax and IJVmin represent the maximum and minimum IJV diameters measured during the respiratory cycle. The Wang Bronchiolitis Severity Score ranges from 0 to 12, with higher scores indicating greater disease severity. The association will be quantified using Pearson or Spearman correlation coefficients, as appropriate.
Time frame: At enrollment (baseline, within 6 hours of emergency department presentation)
Correlation Between IJV Variability Index and Oxygen Saturation, Respiratory Rate, and Retraction Severity
Correlation between the IJV Variability Index and oxygen saturation (SpO2, %), respiratory rate (breaths/minute), and the retraction component of the Wang Bronchiolitis Severity Score. The retraction component ranges from 0 to 3, with higher scores indicating more severe retractions.
Time frame: At enrollment (baseline, within 6 hours of emergency department presentation)
Association Between IJV Variability Index and Need for High-Flow Nasal Cannula or Supplemental Oxygen Therapy
Comparison of baseline IJV Variability Index between infants who require and do not require high-flow nasal cannula (HFNC) or supplemental oxygen therapy during hospitalization.
Time frame: From enrollment through hospital discharge, assessed up to approximately 7 days
Association Between IJV Variability Index and Pediatric Intensive Care Unit Admission
Comparison of baseline IJV Variability Index between infants admitted and not admitted to the pediatric intensive care unit (PICU) during hospitalization.
Time frame: From enrollment through hospital discharge, assessed up to approximately 7 days
Correlation Between Diaphragm Ultrasound Parameters and IJV Variability Index and Clinical Severity Scores
Correlation of diaphragm excursion, diaphragm thickening fraction, and inspiratory/expiratory ratio with the IJV Variability Index and clinical severity scores. Clinical severity measures will include the Wang Bronchiolitis Severity Score (range 0-12), Modified Tal Score (range 0-12), Respiratory Distress Assessment Instrument (range 0-17), and Kristjansson Respiratory Score (range 0-10). For all four clinical severity scores, higher scores indicate greater disease or respiratory distress severity.
Time frame: At enrollment (baseline, within 6 hours of emergency department presentation)
Correlation Between IJV Variability Index and Modified Tal Score
Correlation between the IJV Variability Index and the Modified Tal Score. The Modified Tal Score ranges from 0 to 12, with higher scores indicating greater bronchiolitis severity.
Time frame: At enrollment (baseline, within 6 hours of emergency department presentation)
Correlation Between IJV Variability Index and Respiratory Distress Assessment Instrument
Correlation between the IJV Variability Index and the Respiratory Distress Assessment Instrument (RDAI). The RDAI assesses wheezing and retractions and ranges from 0 to 17, with higher scores indicating greater respiratory distress.
Time frame: At enrollment (baseline, within 6 hours of emergency department presentation)
Association Between IJV Variability Index and Respiratory Assessment Change Score
Association between the baseline IJV Variability Index and the Respiratory Assessment Change Score (RACS). RACS quantifies change in respiratory status using the change in the Respiratory Distress Assessment Instrument together with a standardized change in respiratory rate between baseline and follow-up assessment. RACS is a change measure rather than a bounded scale and therefore does not have a fixed theoretical minimum or maximum.
Time frame: Baseline and 2-4 hours after enrollment
Correlation Between IJV Variability Index and Kristjansson Respiratory Score
Correlation between the IJV Variability Index and the Kristjansson Respiratory Score. The Kristjansson Respiratory Score ranges from 0 to 10, with higher scores indicating greater respiratory disease severity.
Time frame: At enrollment (baseline, within 6 hours of emergency department presentation)
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