title: Stroke volume optimization in elective bowel surgery: a comparison between pulse power wave analysis (LiDCOrapid) and oesophageal Doppler (CardioQ).
abstract: BACKGROUND
  Goal-directed fluid therapy improves outcome in major surgery. We evaluated a new device (LiDCOrapid) against our standard oesophageal Doppler method (ODM) for stroke volume (SV) optimization during colorectal surgery.
  
  
  METHODS
  This was an observational study in 20 patients undergoing major colorectal surgery within a fast-track protocol. We compared SV values measured simultaneously by LiDCOrapid and ODM before and after 86 fluid challenges. We also evaluated the LiDCOrapid dynamic indices SV variation (SVV) and pulse pressure variation (PPV) as predictors for volume responsiveness, defined as an increase in SV ≥ 10% after 200 ml of colloid.
  
  
  RESULTS
  SV increased ≥ 10% after 27 out of 86 fluid challenges. For 172 paired SV values, the overall correlation was r=0.39, and bias (limits of agreement) -28 (-91-35) ml, percentage error 70%. The ability of LiDCOrapid to track changes in SV was weak with a concordance rate of 80%, and a sensitivity and specificity of 48% and 81%, respectively, to detect a positive fluid challenge. The area under the curve values (with 95% confidence intervals) for SVV and PPV were 0.72 (0.60-0.83) and 0.66 (0.52-0.79), respectively, indicating low predictive capacity in these setting.
  
  
  CONCLUSIONS
  LiDCOrapid and ODM devices are not interchangeable. We cannot recommend that the LiDCOrapid replace the standard Doppler method until further device-specific outcome studies on volume optimization are available. The dynamic indices SVV and PPV add little value to a fluid optimization protocol, and should not replace SV measurements with a validated technique.
authors.affiliation: Department of Anaesthesiology, Surgical Services and Intensive Care Medicine,  Karolinska University Hospital, 171 76 Stockholm,  Sweden.
authors.forename: J
authors.initials: J
authors.lastname: Nordström
authors.forename: C
authors.initials: C
authors.lastname: Hällsjö-Sander
authors.forename: R
authors.initials: R
authors.lastname: Shore
authors.forename: H
authors.initials: H
authors.lastname: Björne
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000768:Anesthesia, General; D019540:Area Under Curve; D001794:Blood Pressure / Q000502:physiology; D002302:Cardiac Output / Q000502:physiology; D003625:Data Collection; D003627:Data Interpretation, Statistical; D013505:Digestive System Surgical Procedures / Q000379:methods*; D004947:Esophagus / Q000000981:diagnostic imaging*; D005260:Female; D005440:Fluid Therapy / Q000379:methods*; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000295:instrumentation* / Q000379:methods; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012007:Rectum / Q000601:surgery; D013318:Stroke Volume / Q000502:physiology*; D018608:Ultrasonography, Doppler / Q000379:methods*; D058067:Wavelet Analysis