title: Sonographic evaluation of intravascular volume status: Can internal jugular or femoral vein collapsibility be used in the absence of IVC visualization?
abstract: BACKGROUND
  Inferior vena cava collapsibility index (IVC-CI) has been shown to correlate with both clinical and invasive assessment of intravascular volume status, but has important limitations such as the requirement for advanced sonographic skills, the degree of difficulty in obtaining those skills, and often challenging visualization of the IVC in the postoperative patient. The current study aims to explore the potential for using femoral (FV) or internal jugular (IJV) vein collapsibility as alternative sonographic options in the absence of adequate IVC visualization.
  
  
  METHODS
  A prospective, observational study comparing IVC-CI and Fem- and/or IJV-CI was performed in two intensive care units (ICU) between January 2012 and April 2014. Concurrent M-mode measurements of IVC-CI and FV- and/or IJV-CI were collected during each sonographic session. Measurements of IVC were obtained using standard technique. IJV-CI and FV-CI were measured using high-frequency, linear array ultrasound probe placed in the corresponding anatomic areas. Paired data were analyzed using coefficient of correlation/determination and Bland-Altman determination of measurement bias.
  
  
  RESULTS
  We performed paired ultrasound examination of IVC-IJV (n = 39) and IVC-FV (n = 22), in 40 patients (mean age 54.1; 40% women). Both FV-CI and IJV-CI scans took less time to complete than IVC-CI scans (both, P < 0.02). Correlations between IVC-CI/FV-CI (R(2) = 0.41) and IVC-CI/IJV-CI (R(2) = 0.38) were weak. There was a mean -3.5% measurement bias between IVC-CI and IJV-CI, with trend toward overestimation for IJV-CI with increasing collapsibility. In contrast, FV-CI underestimated collapsibility by approximately 3.8% across the measured collapsibility range.
  
  
  CONCLUSIONS
  Despite small measurement biases, correlations between IVC-CI and FV-/IJV-CI are weak. These results indicate that IJ-CI and FV-CI should not be used as a primary intravascular volume assessment tool for clinical decision support in the ICU. The authors propose that IJV-CI and FV-CI be reserved for clinical scenarios where sonographic acquisition of both IVC-CI or subclavian collapsibility are not feasible, especially when trended over time. Sonographers should be aware that IJV-CI tends to overestimate collapsibility when compared to IVC-CI, and FV-CI tends to underestimates collapsibility relative to IVC-CI.
authors.affiliation: Department of Surgery, The Ohio State University College of Medicine, Columbus, Ohio, USA.
authors.forename: Alistair
authors.initials: A
authors.lastname: Kent
authors.affiliation: Department of Anesthesiology, The Ohio State University College of Medicine, Columbus, Ohio, USA.
authors.forename: Prabhav
authors.initials: P
authors.lastname: Patil
authors.affiliation: Department of Anesthesiology, The Ohio State University College of Medicine, Columbus, Ohio, USA.
authors.forename: Victor
authors.initials: V
authors.lastname: Davila
authors.affiliation: Department of Surgery, The Ohio State University College of Medicine, Columbus, Ohio, USA.
authors.forename: J Kevin
authors.initials: JK
authors.lastname: Bailey
authors.affiliation: Department of Surgery, The Ohio State University College of Medicine, Columbus, Ohio, USA.
authors.forename: Christian
authors.initials: C
authors.lastname: Jones
authors.affiliation: Department of Surgery, The Ohio State University College of Medicine, Columbus, Ohio, USA ; OPUS 12 Foundation Multi-Center Trials Group, Inc, USA.
authors.forename: David C
authors.initials: DC
authors.lastname: Evans
authors.affiliation: Department of Emergency Medicine, The Ohio State University College of Medicine, Columbus, Ohio, USA.
authors.forename: Creagh T
authors.initials: CT
authors.lastname: Boulger
authors.affiliation: Department of Emergency Medicine, The Ohio State University College of Medicine, Columbus, Ohio, USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Adkins
authors.affiliation: Department of Emergency Medicine, Jubilee Mission Medical College and Research Institute, Kerala, India.
authors.forename: Jayaraj M
authors.initials: JM
authors.lastname: Balakrishnan
authors.affiliation: Department of Emergency Medicine, Jubilee Mission Medical College and Research Institute, Kerala, India.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Valiyaveedan
authors.affiliation: OPUS 12 Foundation Multi-Center Trials Group, Inc, USA ; Global Hospital Group, Mumbai, Maharashtra, India.
authors.forename: Sagar C
authors.initials: SC
authors.lastname: Galwankar
authors.affiliation: OPUS 12 Foundation Multi-Center Trials Group, Inc, USA ; Department of Emergency Medicine, The Ohio State University College of Medicine, Columbus, Ohio, USA.
authors.forename: David P
authors.initials: DP
authors.lastname: Bahner
authors.affiliation: OPUS 12 Foundation Multi-Center Trials Group, Inc, USA ; Department of Research and Innovation, St. Luke's University Health Network, Bethlehem, Pennsylvania, USA.
authors.forename: Stanislaw P
authors.initials: SP
authors.lastname: Stawicki
keywords: Femoral vein; hemodynamic resuscitation; inferior vena cava; intravascular volume status assessment; intensive care unit; internal jugular vein; point-of-care testing; portable ultrasound; venous collapsibility index