Graduation Year


Embargo Period


Document Type

Research Paper

Degree Name

Medical Doctor (MD)


Department of Emergency Medicine

First Advisor

Brian Roberts, MD

Second Advisor

Matt Tyler, MD

Third Advisor

Alfred Cheng, MD


Emergency Medicine


Background: Post-cardiac arrest hypotension is associated with mortality and poor neurological outcome among survivors. Increased inferior vena cava (IVC) distensibility has previously been demonstrated to be predictive of fluid responsiveness. However, the utility of measuring IVC distensibility after cardiac arrest is currently unclear. Objective: Our objectives were to determine if increased IVC distensibility is common and associated with hypotension after cardiac arrest.

Methods: Prospective cohort study performed at a single academic hospital. We enrolled consecutive adult post-cardiac arrest patients who were mechanically ventilated after return of spontaneous circulation (ROSC). We performed bedside U/S during the initial 6 hours after ROSC and measured IVC distensibility. Mean arterial blood pressure (MAP) was recorded at the time of the U/S. IVC distensibility was calculated as: [maximum anterior/posterior (AP) diameter – minimum AP diameter value]/minimum AP diameter. We a priori defined increased IVC distensibility as ≥18% based on previous literature, and post-ROSC hypotension as MAP <70 mmHg.

Results: Of the 40 included patients, 14 (35%) had increased IVC distensibility. We found similar mean MAP among patients with IVC distensibility <18% vs. ≥18%, 91 mmHg (95% CI 77 - 105) vs. 98 mmHg (95% CI 83 - 112) respectively. Hypotension occurred in 24% of the entire cohort and increased IVC distensibility occurred in 22% of patients with hypotension and 36% of patients without hypotension, absolute risk difference -13% (95% CI -46 to 19).

Conclusion: Although IVC distensibility was common after cardiac arrest it was not associated with post-cardiac arrest hypotension.

Available for download on Wednesday, August 18, 2021