Passive Leg Raising Test to Predict Hypotension During Induction of Anesthesia in Patients Undergoing Cardiac Surgery
Condition: Ischemic Heart Disease; Cardiac Valve Disease
MeSH terms: Heart Diseases; Hypotension; Myocardial Ischemia; Coronary Artery Disease; Heart Valve Diseases
Study type: Interventional
Phase: Phase 2

Summary: 
      Hypotension frequently occurs during anesthesia induction. Preload decrease by anesthetics
      was often considered as one of main causes for this hypotension. However, the studies on this
      topic have been lacking. Dynamic preload indices are more suitable than static preload
      indices to predict the effect of preload changes. And, recently, passive leg raising test
      showed successful results to predict fluid responsiveness in patient with spontaneous
      ventilation.

      The investigators hypothesized that hypotension after induction of anesthesia is caused by
      decrease of preload by anesthetics and passive leg raising test could predict this
      hypotension. In this study, the investigators will try to evaluate whether passive leg
      raising induced hemodynamic changes could predict hypotension during anesthesia induction.
    

Detailed description: 
      In this randomized controlled clinical trial, the investigators hypothesized that passive leg
      raising induced changes in hemodynamic parameters could predict the hypotension during
      anesthesia induction. To evaluate this, before anesthesia, the investigators will conduct
      passive leg raising test. At first, the patient's trunk was elevated 45 degrees for the first
      set of measurements. Then, the lower limbs were raised to a 45° angle while the patient's
      trunk was lowered to a supine position to measure peak CO (usually within 1-2 min).
      Hemodynamic profiles planned to be measured are mean arterial pressure, heart rate, cardiac
      index, stoke volume and stroke volume variation. After this, the occurrence of hypotension
      (systolic blood pressure < 90mmHg or mean arterial pressure decrease > 30% of baseline) will
      be recorded during the time from anesthesia induction to surgical skin incision. Hypotension
      will be treated by a standardized method. If heart rate (HR) is less than 70 beats/min, 5mg
      of ephedrine will be administered and if HR is greater than 70 beats/min, 30 mcg of
      phenylephrine will be administered. This will repeated until hypotension subsided. Refractory
      hypotension will be defined as continuous hypotension despite the total infused dose of
      ephedrine > 0.5 mg/kg or phenylephrine > 4 mcg/kg. The ability to predict hypotension and
      refractory hypotension during anesthesia induction by passive leg raising test will be
      evaluated by receiver operating characteristic curve analysis.
    

Intervention name(s): passive leg raising (45 degree leg elevation for 1-2 min)
Intervention type(s): Procedure
Intervention description(s): the patient's trunk was elevated 45 degrees for the first set of measurements. Then, the lower limbs were raised to a 45° angle while the patient's trunk was lowered to a supine position to measure peak CO (usually within 1-2 min)
Other intervention name(s): PLR
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Prevention
Keywords: Passive leg raising; FloTrac/Vigileo; Anesthesia hypotension