title: Blood volume measured by ultrasound and radioisotope dilution in critically ill subjects.
abstract: Accurate bedside assessment of circulating blood volume (BV) continues to challenge clinicians in their attempt to implement goal-directed therapy in the critically ill subject. The aim of this investigation was to comparatively evaluate BV measurements obtained by ultrasound and radioisotope dilution methodologies in adult subjects admitted to a surgical intensive care unit.
  
  
  
  Fifty subjects with concurrent central venous catheters and peripheral arterial lines underwent measurement of BV using both ultrasound and radioisotope dilution (BV-RD) methods. The ultrasound dilution method was performed using a 30-mL injectate (BV-UD30) and a 60-mL injectate (BV-UD60) of isotonic saline.
  
  
  
  There were 24 paired data points for the BV-UD30 and 40 paired data points for the BV-UD60 measurements. Spearman's rank-order correlation demonstrated a positive relationship comparing both the BV-UD30 (r = 0.46, P = 0.0249) and the BV-UD60 (r = 0.80, P < 0.0001) to values obtained by radioisotope measurements. Bland-Altman analysis showed a mean bias of 1329 mL with limits of agreement (LOA) ± 2559 mL comparing BV-RD and BV-UD30, and a mean bias of 62 mL with LOA ±1353 mL for BV-RD and BV-UD60.
  
  
  
  This preliminary investigation shows that the BV-UD60 had better agreement with BV-RD, compared with the BV-UD30, but its utility appears limited by a large LOA. As this technology continues to evolve, the ultrasound dilution approach may potentially become a feasible means to calculate BV in critically ill surgical subjects.
authors.affiliation: Division of Surgical Critical Care, Department of Surgery, University of Hawaii, John A. Burns School of Medicine, Honolulu, Hawaii.
authors.forename: Sho
authors.initials: S
authors.lastname: Furuta
authors.affiliation: Division of Surgical Critical Care, Department of Surgery, University of Hawaii, John A. Burns School of Medicine, Honolulu, Hawaii; Department of Surgery, The Queen's Medical Center, Honolulu, Hawaii.
authors.forename: David S
authors.initials: DS
authors.lastname: Inouye
authors.affiliation: Division of Surgical Critical Care, Department of Surgery, University of Hawaii, John A. Burns School of Medicine, Honolulu, Hawaii; Department of Surgery, The Queen's Medical Center, Honolulu, Hawaii.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Hayashi
authors.affiliation: Division of Surgical Critical Care, Department of Surgery, University of Hawaii, John A. Burns School of Medicine, Honolulu, Hawaii; Department of Surgery, The Queen's Medical Center, Honolulu, Hawaii.
authors.forename: Danny M
authors.initials: DM
authors.lastname: Takanishi
authors.affiliation: Division of Surgical Critical Care, Department of Surgery, University of Hawaii, John A. Burns School of Medicine, Honolulu, Hawaii; Department of Surgery, The Queen's Medical Center, Honolulu, Hawaii. Electronic address: mihaey@hawaii.edu.
authors.forename: Mihae
authors.initials: M
authors.lastname: Yu
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001810:Blood Volume; D001811:Blood Volume Determination / Q000379:methods; D003422:Critical Care / Q000379:methods*; D016638:Critical Illness; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D000067716:Point-of-Care Testing; D011446:Prospective Studies; D011865:Radioisotope Dilution Technique; D014463:Ultrasonography; D055815:Young Adult
keywords: Blood volume; Critically ill; Radioisotope dilution; Ultrasound dilution