TS-2026-001

Ultrasonographic evaluation of the inferior vena cava (IVC) is widely used in emergency and critical care settings for noninvasive assessment of intravascular volume status. The subcostal (SC) window is the standard approach; however, it is frequently limited by obesity, bowel distension, or postoperative anatomical changes. In such cases, the right coronal (RC) and anterior transhepatic (aTH) windows have been proposed as alternatives. The existing literature presents conflicting results regarding the interchangeability of these windows. Several studies report significant discrepancies between SC and RC measurements, while others demonstrate strong agreement [1,2]. Direct comparison of the SC and aTH windows has received considerably less attention, with only a single prospective study to date reporting reliable agreement between these approaches under standardized imaging criteria [3]. Methodological heterogeneity, most likely arising from an unstandardized imaging technique, underlies much of the observed discordance. As a result, clinicians lack clear guidance on whether alternative windows can reliably substitute for the SC approach across diverse clinical settings. References 1. Kulkarni AP, et al. Agreement between inferior vena cava diameter measurements by subxiphoid versus transhepatic views. Indian J Crit Care Med. 2015 Dec;19(12):719-22. doi: 10.4103/0972-5229.171390. PMID: 26816446; PMCID: PMC4711204. 2. La Via L, et al. Agreement between subcostal and transhepatic longitudinal imaging of the inferior vena cava for the evaluation of fluid responsiveness: A systematic review. J Crit Care. 2022 Oct;71:154108. doi: 10.1016/j.jcrc.2022.154108. Epub 2022 Jul 5. PMID: 35797826. 3. Albayrak AK, Aslaner MA, Korkak ÖF, Bildik F. Reliability of Alternative Sonographic Approaches for Inferior Vena Cava: Comparison of Subcostal, Transhepatic, and Coronal Windows. J Emerg Med. 2026 Jan;80:64-73. doi: 10.1016/j.jemermed.2025.10.024. Epub 2025 Oct 23. PMID: 41270322.

This multicenter prospective study aims to evaluate the intermethod agreement of IVC diameter and collapsibility index measurements obtained from the SC, aTH, and RC ultrasonographic windows under a standardized imaging protocol, and to determine whether aTH and RC windows can serve as reliable alternatives to the SC approach across diverse clinical settings and operator profiles.

This prospective, multicenter agreement study will be conducted across emergency departments, intensive care units, and other acute care settings of participating hospitals. Adult patients (≥18 years) requiring ultrasonographic assessment of intravascular volume status will be consecutively enrolled. Exclusion criteria will include pregnancy, refusal to participate, and inability to obtain any IVC image via the SC approach. A standardized imaging protocol will be applied uniformly across all centers. Clear visualization of the anterior and posterior walls of the IVC will be defined as the mandatory imaging criterion. Visualization of the IVC–right atrium junction and the hepatic vein will be accepted as supportive criteria. IVC diameter will be measured at a standardized point 3 cm distal to the right atrial junction; in cases where this point is not visible, 2 cm distal to the hepatic vein–IVC junction will be used. All ultrasonographic examinations will be recorded as video clips of at least 8 seconds. Diameter measurements will be performed centrally by an observer blinded to the imaging window to minimize observer bias. Prior to enrollment, all participating operators will receive standardized training based on a common protocol developed by the coordinating center. Image acquisition time and operator-assessed ease of acquisition will be recorded using a 5-point Likert scale. Intermethod agreement will be assessed using intraclass correlation coefficients (ICC) and Bland–Altman analysis. A priori, acceptable limits of agreement will be ±5 mm for IVC diameter and ±10 percentage points for the collapsibility index. A mixed-effects ICC model will be used to account for center and operator variability. Subgroup analyses will be performed by BMI category and ventilation status.

Gözlemsel Çalışma Dizaynı / Prospective