Predicting Volume Response Study (PVRS)

• Change in baseline cardiac stroke volume [ Time Frame: Passive Leg Raise: Baseline and at 3 minutes. Fluid/blood administration: Baseline to completion of administration. ] [ Designated as safety issue: No ]
  Stroke volume is measured prior to passive leg raise (PLR)and at 3 minutes after completion of the PLR. Stroke volume is measured at baseline after initiation of fluid/blood administration, every 1 minute for 10 minutes, then every 10 minutes until completion of the administration.
  
  

• Change in baseline stroke volume variance (SVV) [ Time Frame: Passive Leg Raise: Baseline and at 3 minutes. Fluid/blood administration: Baseline to completion of administration. ] [ Designated as safety issue: No ]
  Stroke volume variance is measured prior to passive leg raise (PLR)and at 3 minutes after completion of the PLR. Stroke volume variance is measured at baseline after initiation of fluid/blood administration, every 1 minute for 10 minutes, then every 10 minutes until completion of the administration.
  
  
• Change in baseline pulse pressure variance (PPV) [ Time Frame: Passive Leg Raise: Baseline and at 3 minutes. Fluid/blood administration: Baseline to completion of administration. ] [ Designated as safety issue: No ]
  Pulse pressure variance is measured prior to passive leg raise (PLR)and at 3 minutes after completion of the PLR. Pulse pressure variance is measured at baseline after initiation of fluid/blood administration, every 1 minute for 10 minutes, then every 10 minutes until completion of the administration.
  
  
• Change in baseline cardiac output [ Time Frame: Passive Leg Raise: Baseline and at 3 minutes. Fluid/blood administration: Baseline to completion of administration. ] [ Designated as safety issue: No ]
  Cardiac output is measured prior to passive leg raise (PLR)and at 3 minutes after completion of the PLR. Cardiac output is measured at baseline after initiation of fluid/blood administration, every 1 minute for 10 minutes, then every 10 minutes until completion of the administration.
  
  
• Change from baseline heart rate. [ Time Frame: Passive Leg Raise: Baseline and at 3 minutes. Fluid/blood administration: Baseline to completion of administration. ] [ Designated as safety issue: No ]
  Heart rate is measured prior to passive leg raise (PLR)and at 3 minutes after completion of the PLR. Heart rate is measured at baseline after initiation of fluid/blood administration, every 1 minute for 10 minutes, then every 10 minutes until completion of the administration.
  
  
• Change in baseline blood pressure (BP) [ Time Frame: Passive Leg Raise: Baseline and at 3 minutes. Fluid/blood administration: Baseline to completion of administration. ] [ Designated as safety issue: No ]
  Blood pressure is measured prior to passive leg raise (PLR)and at 3 minutes after completion of the PLR. Blood pressure is measured at baseline after initiation of fluid/blood administration, every 1 minute for 10 minutes, then every 10 minutes until completion of the administration.
  
  
• Change in baseline central venous pressure (CVP). [ Time Frame: Passive Leg Raise: Baseline and at 3 minutes. Fluid/blood administration: Baseline to completion of administration. ] [ Designated as safety issue: No ]
  Central venous pressure is measured prior to passive leg raise (PLR)and at 3 minutes after completion of the PLR. Central venous pressure is measured at baseline after initiation of fluid/blood administration, every 1 minute for 10 minutes, then every 10 minutes until completion of the administration.
  
  

The administration of intravenous fluid and blood products for treatment of hypovolemia is common in the ICU setting. Static resuscitation endpoints such as heart rate, blood pressure, and CVP are frequently used to guide this therapy, despite compelling evidence they are unreliable in predicting patient response to therapeutic volume administration or as an endpoint for ongoing therapy. Dynamic parameters such as continuous stroke volume and cardiac output (index) monitoring, along with pulse pressure and stroke volume variance measures are more reliable in predicting and measuring response to fluid challenge and therapeutic volume administration. The purpose of this study is to observe changes in stroke volume (SV) and cardiac output (CO) during a passive leg raise maneuver (PLR) as a surrogate to volume challenge, and to determine if these changes can predict changes in the same parameters with fluid or blood product administration in surgical patients. The PLR maneuver involves positioning the patient to the supine position and elevating the legs to 45 degrees. The PLR moves blood from the capacitance vessels of the legs to the heart, potentially improving stroke volume (SV) and cardiac output (CO), without the administration of intravenous fluids. PLR may predict whether SV or CO would improve with administration of fluids, and guide decisions on whether fluid administration would be beneficial. Stroke volume and cardiac output (index) will be calculated by a commercial pulse power arterial pressure cardiac output system (LIDCORapid), using the patients' measured heart rate and blood pressure imported from the bedside monitor. By using the combination of a reversible volume challenge (PLR) and a minimally invasive monitoring system, it is hoped that a more reliable method will emerge to both predict a response and guide therapeutic volume administration, while reducing the risk associated with fluid volume overload.