Point of Care Ultrasound Measurements of Perioperative Edema in Infants With Congenital Heart Disease
Condition: Congenital Heart Disease; Edema; Fluid Overload
MeSH terms: Heart Diseases; Heart Defects, Congenital; Edema
Study type: Observational

Summary: 
      Babies can be born with heart problems and sometimes need a heart surgery to fix the heart
      problem. Heart surgery can cause swelling from the build-up of extra fluid. Swelling can make
      it harder for babies to breath and has to be treated with medicine called diuretics. Swelling
      is hard to measure in babies, so it can be hard to know how much diuretic they need to treat
      the swelling. The investigators are looking for a better way to measure swelling in babies
      who have had heart surgery. Ultrasound uses sound waves to take pictures of the inside of the
      body. Ultrasound is used to take pictures of babies before they are born and to take pictures
      of their heart after they are born. New ultrasound software has been made from a company
      called MuscleSound that can quickly measure the amount of swelling in adults, usually in less
      than 2 minutes. This software has not yet been used to measure swelling in kids. This study
      plans to learn more about swelling in babies and will try to measure swelling in babies
      before and after heart surgery with the new ultrasound software. The study will also make the
      same measurements in babies who do not have heart disease to compare to babies having heart
      surgery.
    

Detailed description: 
      Congenital heart disease is the most common birth defect and occurs in ~8 per 1000 live
      births in the United States. Approximately 25% of these infants require surgery in the first
      year of life to repair or palliate their heart defect. Many cardiac surgeries require the use
      of cardiopulmonary bypass to maintain systemic blood flow and oxygen delivery during surgery.
      Cardiopulmonary bypass is not a natural process, and, as a result, contributes to
      post-operative physiologic derangements including ischemia-reperfusion injury, systemic
      inflammatory response, and subsequent fluid overload.

      Fluid overload, in particular, is a common issue in children undergoing cardiac surgery,
      particularly in the immediate post-operative period. The rates of fluid overload following
      cardiothoracic surgery are high, reported between 31% and 100% in different studies depending
      on the method of assessment and the degree of fluid overload analyzed. Diaz et al
      demonstrated approximately 55% of children requiring mechanical ventilation or inotropic
      support in the intensive care unit developed fluid overload. Fluid overload is defined as a
      positive fluid balance and can occur extra or intravascularly. The buildup of excess
      extravascular fluid is also known as edema. The etiology of fluid overload and edema is
      multifactorial and includes fluid retention due neurohormonal pathway activation such as
      vasopressin and renin-angiotensin system, congestive heart failure, iatrogenic fluid
      administration, and capillary leak. Intravascular fluid overload can cause elevated central
      venous pressure, potentially leading to poor renal perfusion and subsequent acute kidney
      injury (AKI) while extravascular edema compromises abdominal and thoracic compliance and can
      make ventilation difficult. In the post-operative period, fluid overload has been associated
      with significant morbidity including AKI, longer mechanical ventilation dependence, prolonged
      length of stay, and increased mortality.

      Unfortunately, management and treatment of fluid overload and edema are not standardized as
      it is currently difficult to accurately quantify the degree of fluid overload. Methods for
      monitoring fluid status include trending body weights, monitoring net fluid balance (intake
      versus output), trending central venous pressure, and physical exam findings. All of these
      current methods for monitoring fluid status can easily be confounded in the intensive care
      unit. A paucity of data exists regarding accurate methods of assessing edema in infants.
      Objective methods of evaluating fluid overload have been attempted, but are limited to
      measuring only intravascular volume, such as ultrasound of the jugular vein, or are difficult
      to apply clinically, such as skin bioelectric impedance. Additional research is needed to
      better understand and directly measure edema in infants.

      Ultrasound of the skin is one possible method for quantifying extravascular fluid overload
      and edema through measurement of the thickness of skin and underlying subcutaneous layers.
      Ultrasound has previously been utilized in pediatric patients to diagnose skin and soft
      tissue infections, but there are no dedicated studies performed to solely measure edema.
      MuscleSound, an ultrasound technology company, has developed an automated software system to
      measure skin tissue structures, including edema, in adults. This technology has been studied
      in adults, however, it has not yet been trialed or validated in children. The ability to
      evaluate edema with a reliable, automated, non-invasive, bedside tool would provide objective
      measurements into a patient's fluid status. This tool would be of particular importance in
      infants with congenital heart disease who have many risk factors for fluid overload but whose
      fluid status can be difficult to appropriately assess.
    

Intervention name(s): Point of care ultrasound measurements
Intervention type(s): Diagnostic Test
Intervention description(s): i. Ultrasound images will be obtained using a commercial, high frequency, linear Philips ultrasound probe attached to small, portable tablet. This tablet will have the capability of transferring the saved images to the secure MuscleSound cloud-based server.
Observational model: Case-Control
Time perspective: Prospective
Sampling method: Probability Sample
Study population: 
        Case subjects: Infants with hemodynamically significant congenital heart disease.

        Control subjects: Healthy infants with no heart disease or non-hemodynamically significant
        congenital heart disease.
      
Keywords: MuscleSound