for people ages 18 years and up (full criteria)
Healthy Volunteers
healthy people welcome
at La Jolla, California
study started
estimated completion
Principal Investigator
by Rodney Gabriel
Photo of Rodney Gabriel
Rodney Gabriel



The purpose of this study is to understand how changes to breathing patterns in the chest affect blood flow to the heart from the inferior vena cava in the abdomen. Ultrasound of the upper abdomen will be used to visualize changes in breathing patterns in the chest and blood flow in the abdomen.

Official Title

Evaluating the Mechanism of Changes to Inferior Vena Cava Diameter Using Point of Care Ultrasound in Patients Undergoing Interscalene Brachial Plexus Block


In recent practice, point-of-care ultrasound has been used to assess the size and respiratory variation of the inferior vena cava as a marker for volume status and fluid responsiveness. Little investigation has occurred regarding the mechanism of observed respiratory variation. Anesthetic plans for surgery (e.g. shoulder replacement) frequently employ interscalene injections to target and block the brachial plexus, which (on the same side) results in phrenic nerve palsy and paralysis of the diaphragm. The goal of this study is to examine the relationship between diaphragmatic function and variation in IVC diameter. Specifically, the investigators will evaluate and compare the size and variability of the inferior vena cava by point-of-care ultrasound before and after brachial plexus block.


IVC - Inferior Vena Cava Abnormality Congenital Abnormalities Interscalene Brachial Plexus Block


You can join if…

Open to people ages 18 years and up

  • Adult (age > 18 years)
  • Scheduled to receive an interscalene block

You CAN'T join if...

  • Any person with known, pre-existing phrenic nerve, diaphragmatic, or inferior vena cava anomaly.
  • Patients who cannot be successfully imaged by ultrasound or who cannot participate in spirometry will additionally be excluded.
  • Non-English speaking patients will be excluded as well as there is no research funding to translate consent forms. Given that there is no potential benefit to participation in the study, this does not exclude these individuals from any potentially beneficial therapy.


  • UCSD Medical Center accepting new patients
    La Jolla California 92037 United States

Lead Scientist at UCSD

  • Rodney Gabriel
    Dr. Rodney A. Gabriel holds position as Chief of the Division of Regional Anesthesia and Acute Pain Medicine and is the Medical Director at the Koman Family Outpatient Pavilion surgery center. He is an Associate Professor of Anesthesiology and Associate Adjunct Professor in Biomedical Informatics.


accepting new patients
Start Date
Completion Date
University of California, San Diego
Study Type
Last Updated