Ninvasive Cardiac Output Measurements During Cesarean Delivery Under Spinal Anesthesia.
Condition: Hypotension During Cesarean Delivery; Spinal Anesthesia
MeSH terms: Hypotension
Study type: Interventional

Summary: 
      The purpose of the study is to learn more about how the heart works during cesarean delivery
      under spinal anesthesia (medicines given in the spine that numb parts of your body to block
      pain) in women. The investigators would like to find out if the information about the heart
      can help in treating blood pressure changes that occur during the cesarean delivery. The
      investigators would also like to find out if this information can help reduce the chances of
      nausea and vomiting during the cesarean delivery.

      The activity of the heart changes during spinal anesthesia and cesarean section. In the past,
      a sensor placed directly into the heart was the only way to see how the heart worked.
      Currently, there are monitors that can sense the heart's activity via sensors that are placed
      on the skin during cesarean delivery.

      In this study, the investigators will use the ICON cardiac output (ICON) monitor. The ICON
      monitor is approved by the US Food and Drug Administration (FDA) to monitor (check) the
      activity of your heart.

      This study aims to:

        1. Determine if additional cardiac output measurements help anesthesiologists maintain
           appropriate hemodynamics as defined as within 20% of baseline BP and if it changed their
           choice of vasopressors (primary outcome).

        2. Determine if additional cardiac output measurements help to decrease the incidence of
           nausea and vomiting during cesarean delivery (secondary outcome).
    

Detailed description: 
      Most women who undergo elective cesarean delivery in our hospital have spinal anesthesia for
      the surgery. You will receive standard spinal anesthesia techniques whether or not you take
      part in this study. You will be asked to sign a separate clinical consent form for the spinal
      anesthesia and for your cesarean delivery.

      After the anesthesiologist places your spinal anesthesia, the investigator will record your
      blood pressure every two minutes as is the standard practice in our institution. An
      anesthesiologist is a doctor who specializes in giving drugs or other agents to prevent or
      relieve pain during surgery or other procedures. The investigator will also continuously
      record your heart rate and the amount of oxygen in your blood as is the standard practice. If
      needed, the anesthesiologist will give you medications to maintain your blood pressure.

      In addition to the standard procedures described above, additional monitoring (checking) of
      your heart will be performed as part of this study. The investigator will use the ICON
      monitor to measure the amount of blood pumped by each heart beat.

      The anesthesiologist will put on the sensors (sticky pads). There are four sticky pads that
      are similar to what is used during electrocardiograms (EKGs). Two sensors are placed on the
      left side of your neck and two on the left side of your trunk. The sensors have wires
      attached that will be plugged into a small heart monitor device that records the information.

      The investigators will place the sensors on you before you receive the spinal anesthesia. The
      sensors will record what your heart is doing before placement of spinal anesthesia until the
      end of your surgery.

      The investigators will assign you by chance (like a coin toss) to one of the following
      groups:

        -  Group Study: Your anesthesiologist will have access to the amount of blood that is
           pumped during each heart beat. The anesthesiologist will treat and maintain the amount
           of blood pumped during each beat so that it is within the normal range.

        -  Group Control: Your anesthesiologist will NOT have access to the amount of blood that is
           pumped during each heart beat. The anesthesiologist will treat and maintain your blood
           pressure throughout your delivery. (This is the current routine care.)

      The control group and the study group will receive spinal anesthesia as is adapted in our
      institution. HR and BP will be measured every two minutes as is normal practice. Cardiac
      output will be measured in all patients in both groups. The subjects will have four surface
      ECG electrodes attached to the left side of the neck and the lower thorax (at the level of
      the xiphoid). Baseline hemodynamic parameters (SV (stroke volume), HR (heart rate), CO
      (cardiac output) , SVV (stroke volume variation), and SVR (systemic vascular resistance))
      will be determined before placing spinal anesthesia. Continuous CO data will be recorded by
      the unit.

      In the study group, phenylephrine and ephedrine will be used depending on the blood pressure
      and cardiac output data. If the CO is normal, and BP is below 20% of baseline, phenylephrine
      boluses of 40 micrograms at two minute interval (BP recording time) will be used to maintain
      BP within 20% of the baseline. If the BP is normal, but CO is lower than 20% baseline,
      ephedrine boluses (10 mg) will be used. If BP and CO is lower, a combination of both
      phenylephrine and ephedrine will be used.

      In the control group, the phenylephrine and ephedrine will be used as considered appropriate
      to maintain BP within 20% of baseline. The CO data will be blinded to the anesthesiologists
      in the control group

      Study group (algorithm in detail):

        1. If SBP<20%, CO is within (<,± ) 20% of baseline: Phenylephrine 40 mic boluses to bring
           BP within 20% of the baseline.

        2. If CO < 20%, and BP is within (<,± ) 20% of baseline, ephedrine boluses to bring the CO.

        3. If both are below 20% of baseline, phenylephrine 40 mic boluses and ephedrine 10 mg
           together will be used at 2 min intervals until both reach to within 20% of baseline.

        4. If SBP is normal, and CO is greater than 20% baseline, no treatment needed.

        5. If CO is normal, and SBP is greater than 20%, no treatment needed.

      Control group:

      Although BP and CO are being measured in the control group, CO data is blinded to the
      clinician. Therefore the clinician will use SPB data and current practice instincts to choose
      either of vasopressors considered appropriate to treat hypotension.

      The anesthesiologist has his or her discretion of treating BP, or CO if these parameters are
      not corrected with above protocol.

      Fluid inputs and outputs will be noted that includes blood loss. Apgar scores of newborns
      will be obtained from neonatologists' assessment. Incidence of nausea and vomiting and
      medications used will be also noted.

      The regional techniques will follow the standards adopted by our institution. Most placements
      are done in the sitting position. After disinfecting the skin with betadine in the usual
      fashion, the patients back will be draped with a sterile clear plastic and local anesthetic
      (1.5 % lidocaine, 2ml) injected at the site of placement. A 3 1/2 -inch 25-gauge Whittaker
      needle will be inserted into the spinal space at either the L3-L4 or L4-L5. Once the clear
      Cerebrospinal fluid (CSF) is obtained, spinal medication (1.6 - 1.8 ml of bupivacaine 0.75%
      with hyperbaric dextrose, 10 µgm fentanyl, 200 µgm morphine). Most patients receive oxytocin
      infusion titrated to uterine tone (3-5 units/hr) and ondansetron for prevention of
      postoperative nausea and vomiting after delivery of the baby.
    

Intervention name(s): Cardiac output monitor data
Intervention type(s): Device
Intervention description(s): The availability of cardiac output monitor provides additional hemodynamic indices that may help guide anesthesiologists to better select vasopressors
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: Investigator randomly assigns the subjects into one of the two groups. Control group and Interventional group
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: cardiac output pregnancy spinal anesthesia