Handcarried Ultrasound Measurement of the Inferior Vena Cava for Assessment of Intravascular Volume Status in the Outpatient Hemodialysis Clinic

Abstract

Accurate intravascular volume assessment is critical in the treatment of patients who receive chronic hemodialysis (HD) therapy. Clinically assessed dry weight is a poor surrogate of intravascular volume; however, ultrasound assessment of the inferior vena cava (IVC) is an effective tool for volume management. This study sought to determine the feasibility of using operators with limited ultrasound experience to assess IVC dimensions using hand-carried ultrasounds (HCU) in the outpatient clinical setting. The IVC was assessed in 89 consecutive patients at two outpatient clinics before and after HD. Intradialytic IVC was recorded during episodes of hypotension, chest pain, or cramping. High-quality IVC images were obtained in 79 of 89 patients. Despite that 89% of patients presented at or above dry weight, 39% of these patients were hypovolemic by HCU. Of the 75% of patients who left HD at or below goal weight, 10% were still hypervolemic by HCU standards. Hypovolemic patients had more episodes of chest pain and cramping (33 versus 14%, P = 0.06) and more episodes of hypotension (22 versus 3%, P = 0.02). The clinic with a higher prevalence of predialysis hypovolemia had significantly more intradialytic adverse events (58 versus 27%; P = 0.01). HCU measurement of the IVC is a feasible option for rapid assessment of intravascular volume status in an outpatient dialysis setting by operators with limited formal training in echocardiography. There is a poor relationship between dry weight goals and IVC collapsibility. Practice variation in the maintenance of volume status is correlated with significant differences in intradialysis adverse events.