title: The estimation of cardiac output by the Nexfin device is of poor reliability for tracking the effects of a fluid challenge.
abstract: BACKGROUND
  The Nexfin device estimates arterial pressure by the volume clamp method through a finger pneumatic cuff. It also allows to estimate cardiac index (CInoninv) by pulse contour analysis of the non-invasive arterial pressure curve. We evaluated the ability of the device to track changes in cardiac index induced by a fluid challenge.
  
  
  METHODS
  We included 45 patients for whom a volume expansion (500 mL of saline infused over 30 min) was planned. The volume expansion-induced changes in cardiac index measured by transpulmonary thermodilution (CIinv, PiCCO device) and in CInoninv were recorded.
  
  
  RESULTS
  In seven patients, the Nexfin could not record the arterial curve due to finger hypoperfusion. Considering both the values obtained before and after volume expansion (n = 76 pairs of measurements), the bias (lower and upper limits of agreement) between CIinv and CInoninv was 0.2 (-1.8 to 2.2) L/min/m2. The mean change in CInoninv was 10 ± 11%. The percentage error of CInoninv was 57%. The correlation between the changes in CIinv and CInoninv observed during volume expansion was significant (P = 0.0002) with an r2 = 0.31.
  
  
  CONCLUSIONS
  The estimation of CI by the Nexfin device in critically ill patients is not reliable, neither for estimating absolute values of CI nor for tracking its changes during volume expansion.
authors.forename: Xavier
authors.initials: X
authors.lastname: Monnet
authors.forename: Fabien
authors.initials: F
authors.lastname: Picard
authors.forename: Elsa
authors.initials: E
authors.lastname: Lidzborski
authors.forename: Malcie
authors.initials: M
authors.lastname: Mesnil
authors.forename: Jacques
authors.initials: J
authors.lastname: Duranteau
authors.forename: Christian
authors.initials: C
authors.lastname: Richard
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Teboul
mesh_terms: D000368:Aged; D015924:Blood Pressure Monitors; D002302:Cardiac Output; D016638:Critical Illness; D005260:Female; D005440:Fluid Therapy; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D017156:Photoplethysmography / Q000295:instrumentation*; D013815:Thermodilution