Noninvasive Measurement of CO Using Impedance Cardiography in Patients With CHD
| Status: | Recruiting |
|---|---|
| Conditions: | Peripheral Vascular Disease, Cardiology, Cardiology |
| Therapuetic Areas: | Cardiology / Vascular Diseases |
| Healthy: | No |
| Age Range: | Any |
| Updated: | 4/2/2016 |
| Start Date: | December 2014 |
| Contact: | Christopher Davis, MD |
| Email: | cdavis@rchsd.org |
| Phone: | 8589665855 |
Noninvasive Measurement of Cardiac Output Using Impedance Cardiography in Patients With Congenital Heart Disease
This study will test the capability of a non-invasive instrument (the PhysioFlow impedance
cardiography instrument) to measure cardiac output in patients with congenital heart disease
(CHD). This instrument works by placing electrodes on the skin of a patient and measuring
electrical impedance through the chest, which is proportional to blood volume and blood flow
at any given time. The instrument has been validated in patients with structurally normal
hearts, but in the only two studies using it for patients with CHD, it was deemed too
inaccurate for clinical use. The manufacturer of the device would require access to data on
the patients in order to improve its accuracy, and that has not been feasible thus far. This
study would begin by comparing cardiac output based on the PhysioFlow monitor to standard
techniques, then after possible changes to the instrument to enhance accuracy, would test
the instrument again in the same way.
cardiography instrument) to measure cardiac output in patients with congenital heart disease
(CHD). This instrument works by placing electrodes on the skin of a patient and measuring
electrical impedance through the chest, which is proportional to blood volume and blood flow
at any given time. The instrument has been validated in patients with structurally normal
hearts, but in the only two studies using it for patients with CHD, it was deemed too
inaccurate for clinical use. The manufacturer of the device would require access to data on
the patients in order to improve its accuracy, and that has not been feasible thus far. This
study would begin by comparing cardiac output based on the PhysioFlow monitor to standard
techniques, then after possible changes to the instrument to enhance accuracy, would test
the instrument again in the same way.
The measurement of cardiac output (CO) is important for a wide variety of patients under
multiple conditions. At present, gold standard techniques for measurement of CO include
velocity encoded phase contrast MRI. Both of these techniques are valid in patients with
structural CHD. Disadvantages of these techniques include the requirement of significant
time and expertise, and the high cost and anesthesia requirement. Accurate, non-invasive
tools to measure CO could be extremely valuable for patients with CHD that require one-time
of continuous monitoring of CO, such as during surgery, in intensive care settings, during
other diagnostic testing, and during different physiologic states such as sleep and
exercise. This study would begin by comparing cardiac output based on the PhysioFlow monitor
to cardiac outout by MRI.
Impedance cardiography is performed by placing electrodes on the thorax and neck to measure
electrical impedance over time. Cardiac output is derived from these measurements. The
technique has been studied, validated, and used extensively in adults and has also been
shown to be valid in children with structurally normal hearts. In contrast, recent studies
of children with CHD have shown a relatively poor agreement between impedance cardiography
and both thermodilution technique and velocity encoded phase contrast MRI. The reasons for
the poor agreement in CHD patients is not yet understood. There are proprietary algorithms
in each impedance device that use the raw data to calculate and report cardiac output. If
the physiologic and/or anatomic differences of patients with CHD require changing the
algorithm within each system to account for such differences, that needs to be done to each
system. In order to do this, owners of any given device (PhysioFlow, NeuMeDx Inc. in this
case) need access to the raw data in order to alter the algorithm. This study will involve a
concerted effort between investigators at RCHSD, UCSD, and NeuMeDx
multiple conditions. At present, gold standard techniques for measurement of CO include
velocity encoded phase contrast MRI. Both of these techniques are valid in patients with
structural CHD. Disadvantages of these techniques include the requirement of significant
time and expertise, and the high cost and anesthesia requirement. Accurate, non-invasive
tools to measure CO could be extremely valuable for patients with CHD that require one-time
of continuous monitoring of CO, such as during surgery, in intensive care settings, during
other diagnostic testing, and during different physiologic states such as sleep and
exercise. This study would begin by comparing cardiac output based on the PhysioFlow monitor
to cardiac outout by MRI.
Impedance cardiography is performed by placing electrodes on the thorax and neck to measure
electrical impedance over time. Cardiac output is derived from these measurements. The
technique has been studied, validated, and used extensively in adults and has also been
shown to be valid in children with structurally normal hearts. In contrast, recent studies
of children with CHD have shown a relatively poor agreement between impedance cardiography
and both thermodilution technique and velocity encoded phase contrast MRI. The reasons for
the poor agreement in CHD patients is not yet understood. There are proprietary algorithms
in each impedance device that use the raw data to calculate and report cardiac output. If
the physiologic and/or anatomic differences of patients with CHD require changing the
algorithm within each system to account for such differences, that needs to be done to each
system. In order to do this, owners of any given device (PhysioFlow, NeuMeDx Inc. in this
case) need access to the raw data in order to alter the algorithm. This study will involve a
concerted effort between investigators at RCHSD, UCSD, and NeuMeDx
Inclusion Criteria:
- Any form of congenital heart disease
- Any age
Exclusion Criteria:
- Subjects with significant clinical skin reactions to electrodes such as excessive
pain and/or skin inflammation, or significant previous skin reaction
- Subjects who are not able to provide consent
- Subjects with pacemaker
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