title: Pulmonary blood volume measured by contrast enhanced ultrasound: a comparison with transpulmonary thermodilution.
abstract: BACKGROUND
  Blood volume quantification is essential for haemodynamic evaluation guiding fluid management in anaesthesia and intensive care practice. Ultrasound contrast agent (UCA)-dilution measured by contrast enhanced ultrasound (CEUS) can provide the UCA mean transit time (MTT) between the right and left heart, enabling the assessment of the intrathoracic blood volume (ITBV(UCA)). The purpose of the present study was to investigate the agreement between UCA-dilution using CEUS and transpulmonary thermodilution (TPTD) in vitro and in vivo.
  
  
  METHODS
  In an in vitro setup, with variable flows and volumes, we injected a double indicator, ice-cold saline with SonoVue(®), and performed volume measurements using transesophageal echo and thermodilution by PiCCO(®). In a pilot study, we assigned 17 patients undergoing elective cardiac surgery for pulmonary blood volume (PBV) measurement using TPTD by PiCCO(®) and ITBV by UCA-dilution. Correlation coefficients and Bland-Altman analysis were performed for all volume measurements.
  
  
  RESULTS
  In vitro, 73 experimental MTT's were obtained using PiCCO(®) and UCA-dilution. The volumes by PiCCO(®) and UCA-dilution correlated with true volumes; r(s)=0.96 (95% CI, 0.93-0.97; P<0.0001) and r(s)=0.97 (95% CI, 0.95-0.98; P<0.0001), respectively. The bias of PBV by PiCCO(®) and ITBV(UCA) were -380 ml and -42 ml, respectively. In 16 patients, 86 measurements were performed. The correlation between PBV by PiCCO(®) and ITBV(UCA) was r(s)=0.69 (95% CI 0.55-0.79; P<0.0001). Bland-Altman analysis revealed a bias of -323 ml.
  
  
  CONCLUSIONS
  ITBV assessment with CEUS seems a promising technique for blood volume measurement, which is minimally-invasive and bedside applicable.
  
  
  BACKGROUND
  ISRCTN90330260.
authors.affiliation: Department of Anaesthesiology and Intensive-Care, Catharina Hospital Eindhoven, Michelangelolaan 2, Eindhoven 5623 EJ, The Netherlands ingeborg.herold@cze.nl.
authors.forename: I H F
authors.initials: IH
authors.lastname: Herold
authors.affiliation: Department of Cardiac Surgery, Catharina Hospital Eindhoven, Michelangelolaan 2, Eindhoven 5623 EJ, The Netherlands.
authors.forename: M A
authors.initials: MA
authors.lastname: Soliman Hamad
authors.affiliation: Department of Electrical Engineering, Signal Processing Systems, University of Technology Eindhoven, Den Dolech 2, Eindhoven 5612 AZ, The Netherlands.
authors.forename: H C
authors.initials: HC
authors.lastname: van Assen
authors.affiliation: Department of Anaesthesiology and Intensive-Care, Catharina Hospital Eindhoven, Michelangelolaan 2, Eindhoven 5623 EJ, The Netherlands.
authors.forename: R A
authors.initials: RA
authors.lastname: Bouwman
authors.affiliation: Department of Anaesthesiology and Intensive-Care, Catharina Hospital Eindhoven, Michelangelolaan 2, Eindhoven 5623 EJ, The Netherlands Department of Electrical Engineering, Signal Processing Systems, University of Technology Eindhoven, Den Dolech 2, Eindhoven 5612 AZ, The Netherlands.
authors.forename: H H M
authors.initials: HH
authors.lastname: Korsten
authors.affiliation: Department of Electrical Engineering, Signal Processing Systems, University of Technology Eindhoven, Den Dolech 2, Eindhoven 5612 AZ, The Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: Mischi
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001810:Blood Volume; D001811:Blood Volume Determination; D003287:Contrast Media; D017548:Echocardiography, Transesophageal; D005260:Female; D006801:Humans; D007089:Image Enhancement; D008168:Lung / Q000098:blood supply* / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D010743:Phospholipids; D015203:Reproducibility of Results; D013459:Sulfur Hexafluoride; D013815:Thermodilution
chemical_list: D003287:Contrast Media; D010743:Phospholipids; C420843:contrast agent BR1; D013459:Sulfur Hexafluoride
keywords: blood volume determination; contrast echocardiography; indicator dilution techniques; thermodilution