title: Applying mean systemic filling pressure to assess the response to fluid boluses in cardiac post-surgical patients.
abstract: OBJECTIVE
  To evaluate an analogue of mean systemic filling pressure (P(msa)) and derived variables to quantitatively assess the effectiveness of volume expansion in increasing cardiac output.
  
  
  METHODS
  Sixty-one cardiac post-surgical patients were studied and 107 fluid boluses were captured. Cardiac output, mean arterial pressure and right atrial pressure were recorded with P msa before and after a bolus fluid. An increase in cardiac output greater than 10 % following a fluid bolus defined a patient as a responder. Cardiac power (i.e. the product of arterial pressure and cardiac output) and P(msa) to right atrial pressure gradient (i.e. the driving pressure for venous return and hence cardiac output) were evaluated to assess the efficiency of volume expansion to increase cardiac output. Cardiac power relative to P(msa) (CP(vol)), its dynamic changes and the dynamic changes in P msa-right atrial pressure gradient relative to the P(msa) change (E(vol)) were investigated.
  
  
  RESULTS
  CP(vol) was lower and E(vol) was higher in responders vs. non-responders. Furthermore, in patients receiving a second fluid bolus, E(vol) correlated with the degree of increase in cardiac output. Multivariate regression analysis identified both CP(vol) and E(vol) as independent variables associated with volume responsiveness.
  
  
  CONCLUSIONS
  Using an algorithm to derive a mean systemic filling pressure analogue, cardiac power and dynamic measures of the venous return pressure gradient relative to the mean systemic filling pressure provided an assessment of the efficiency of volume expansion in post-surgical cardiac patients.
authors.affiliation: Intensive Care Unit, Liverpool Hospital, South West Sydney Clinical School, UNSW, Sydney, Australia.
authors.forename: Kapil
authors.initials: K
authors.lastname: Gupta
authors.forename: Soren
authors.initials: S
authors.lastname: Sondergaard
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Parkin
authors.forename: Mark
authors.initials: M
authors.lastname: Leaning
authors.forename: Anders
authors.initials: A
authors.lastname: Aneman
mesh_terms: D000368:Aged; D001794:Blood Pressure / Q000502:physiology*; D001810:Blood Volume; D002302:Cardiac Output / Q000502:physiology*; D006348:Cardiac Surgical Procedures; D005260:Female; D005440:Fluid Therapy / Q000379:methods*; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010952:Plasma Substitutes / Q000627:therapeutic use*; D011184:Postoperative Period; D012044:Regression Analysis
chemical_list: D010952:Plasma Substitutes