Inhaled NO as an Anti-inflammatory and Anti-reperfusion Agent in Infants and Children Undergoing Cardiopulmonary Bypass
Status: | Completed |
---|---|
Conditions: | Peripheral Vascular Disease, Cardiology |
Therapuetic Areas: | Cardiology / Vascular Diseases |
Healthy: | No |
Age Range: | Any - 16 |
Updated: | 4/21/2016 |
Start Date: | January 2008 |
End Date: | June 2011 |
A Trial of Inhaled Nitric Oxide (NO) as an Anti-Inflammatory and Anti-Reperfusion Agent in the Treatment of Infants and Children Undergoing Cardiopulmonary Bypass for Repair of Congenital Heart Disease
Each year, there are over 400,000 cardiac surgical operations performed in the United
States; of which 10,000 are performed on children. These operations are made possible by the
use of the heart-lung bypass machine, also known as cardiopulmonary bypass. This machine
allows for the body to be supported while the heart is repaired. While this machine has been
life saving, it has risks and can lead to a variety of complications.
One such complication results from the fact that the patient's blood is exposed to the
foreign material of the machine, such as plastic tubing. In nearly all cases of cardiac
surgery, this leads to a whole body response in the patient following the operation. This
response, inflammation, is characterized by alterations in the function of the heart and
lungs, fever, fluid retention, and bleeding disorders in the postoperative period. While
this is usually temporary and self limiting, significant morbidity occurs in approximately
1-2% of cases where this inflammatory response is present. Additionally, children appear to
be more susceptible to this response. This can lead to significant postoperative
complications that are not associated with the actually surgical procedure performed on the
heart.
The exact cause of this response is not fully understood. However, it is important to
understand the triggers, timing, and pattern of this complex inflammatory response in order
to modify or arrest it. Unlike other situations associated with this type of whole-body
inflammatory reaction such as trauma or overwhelming infection, cardiac surgical teams have
the advantage of knowing when the trigger will occur (i.e. during the cardiac operation) and
hence have the opportunity for preemptive intervention in an effort to minimize the
response. One such effort is the focus of this proposal.
Nitric oxide (NO) is a gas that has been used for years in the treatment of lung disease in
infants. It has been life saving and safe. Recently, it has been investigated for its
anti-inflammatory effects outside the lungs. We propose delivering NO to the source of the
greatest inflammation in cardiac surgery, the cardiopulmonary bypass machine. It is our
intention to show that in doing so; we can minimize the inflammation found in the first 24
hours following cardiac surgery in children. If we are correct, the reduction of this
inflammation will result in less damage to other organs of the child's body and improved
outcome following surgery.
States; of which 10,000 are performed on children. These operations are made possible by the
use of the heart-lung bypass machine, also known as cardiopulmonary bypass. This machine
allows for the body to be supported while the heart is repaired. While this machine has been
life saving, it has risks and can lead to a variety of complications.
One such complication results from the fact that the patient's blood is exposed to the
foreign material of the machine, such as plastic tubing. In nearly all cases of cardiac
surgery, this leads to a whole body response in the patient following the operation. This
response, inflammation, is characterized by alterations in the function of the heart and
lungs, fever, fluid retention, and bleeding disorders in the postoperative period. While
this is usually temporary and self limiting, significant morbidity occurs in approximately
1-2% of cases where this inflammatory response is present. Additionally, children appear to
be more susceptible to this response. This can lead to significant postoperative
complications that are not associated with the actually surgical procedure performed on the
heart.
The exact cause of this response is not fully understood. However, it is important to
understand the triggers, timing, and pattern of this complex inflammatory response in order
to modify or arrest it. Unlike other situations associated with this type of whole-body
inflammatory reaction such as trauma or overwhelming infection, cardiac surgical teams have
the advantage of knowing when the trigger will occur (i.e. during the cardiac operation) and
hence have the opportunity for preemptive intervention in an effort to minimize the
response. One such effort is the focus of this proposal.
Nitric oxide (NO) is a gas that has been used for years in the treatment of lung disease in
infants. It has been life saving and safe. Recently, it has been investigated for its
anti-inflammatory effects outside the lungs. We propose delivering NO to the source of the
greatest inflammation in cardiac surgery, the cardiopulmonary bypass machine. It is our
intention to show that in doing so; we can minimize the inflammation found in the first 24
hours following cardiac surgery in children. If we are correct, the reduction of this
inflammation will result in less damage to other organs of the child's body and improved
outcome following surgery.
I. Hypothesis
Treatment of children during surgery employing cardiopulmonary bypass with inhaled,
exogenous nitric oxide (iNO) delivered to the cardiopulmonary bypass circuit will:
1. Modulate ischemia/reperfusion injury
2. Influence endothelial dysfunction
3. Ameliorate the bypass-triggered systemic inflammatory response
II. Specific Aims
Three specific aims will test this hypothesis:
Delivery of iNO to the cardiopulmonary bypass circuit will result in a decrease in:
1. Measures of end-organ dysfunction often associated with CPB; pulmonary function,
cardiac injury markers, serum creatinine, and neurologic injury markers.
2. Measures of inflammatory response, specifically IL-6 and TNFa via its antioxidant
properties.
3. Platelet activation and aggregation leading to reduced transfusion requirements.
III. Introduction and Background
- Cardiopulmonary bypass leads to ischemia/reperfusion injury. One of the mediators of
this injury is oxygen radical production. NO is known to bind oxygen radical species.
- Cardiopulmonary bypass leads to endothelial dysfunction. This is mediated through
cell-free hemoglobin binding endogenous NO, as seen in sickle cell disease.
- Both of these factors, separately and in combination, perpetuate the inflammatory
response triggered by CPB. NO affects this response by interfering with this process.
Additionally, NO is known to affect neutrophil chemotaxis as well as platelet
activation and aggregation, both of which further amplify the inflammatory response.
IV. Basic Protocol Experimental Design In a prospective, randomized, controlled, blinded
pilot trial we will compare 20 ppm of iNO delivered to the CPB circuit. Our study will
target children undergoing cardiopulmonary bypass (CPB) for surgery for the correction of
transposition of great arteries (TGA) and Tetralogy of Fallot (TOF).
Subjects Inclusion Undergoing repair of TGA and TOF < 16 years of age Exclusion Age > 16
years of age Pregnancy Known bleeding disorder
Treatment Protocol Following informed consent, blood will be drawn pre-operatively for
baseline characteristics (methemoglobin, venous saturation, CBC, S100, gene expression
profiles, BNP, cTnI, IL-6, IL-8, lactate, TNFalpha)[Table, Blood sample for Study].
Intra-operatively we will use a standardized anesthetic protocol unless contraindicated by
specific patient clinical characteristics. Intraoperative measurements will include: aortic
cross clamp time, and total cardiopulmonary bypass time. Intraoperative hemodynamic
measurements will include: mean systemic blood pressure (MAP), central venous pressure,
right atrial pressure pulmonary artery pressure, and pulmonary capillary wedge pressure
(when available). Blood samples will be drawn following CPB upon arrival to the ICU and will
be analyzed as above. Repeat blood samples for each will be drawn again after 12, 24, and 48
hours. Patients will be followed to the time of discharge. Ventilator settings, length of
ICU and hospital stay will be recorded. All measurements in both groups will be the same.
Time points will be referenced from the time of admission to the PICU for both groups.
Treatment of children during surgery employing cardiopulmonary bypass with inhaled,
exogenous nitric oxide (iNO) delivered to the cardiopulmonary bypass circuit will:
1. Modulate ischemia/reperfusion injury
2. Influence endothelial dysfunction
3. Ameliorate the bypass-triggered systemic inflammatory response
II. Specific Aims
Three specific aims will test this hypothesis:
Delivery of iNO to the cardiopulmonary bypass circuit will result in a decrease in:
1. Measures of end-organ dysfunction often associated with CPB; pulmonary function,
cardiac injury markers, serum creatinine, and neurologic injury markers.
2. Measures of inflammatory response, specifically IL-6 and TNFa via its antioxidant
properties.
3. Platelet activation and aggregation leading to reduced transfusion requirements.
III. Introduction and Background
- Cardiopulmonary bypass leads to ischemia/reperfusion injury. One of the mediators of
this injury is oxygen radical production. NO is known to bind oxygen radical species.
- Cardiopulmonary bypass leads to endothelial dysfunction. This is mediated through
cell-free hemoglobin binding endogenous NO, as seen in sickle cell disease.
- Both of these factors, separately and in combination, perpetuate the inflammatory
response triggered by CPB. NO affects this response by interfering with this process.
Additionally, NO is known to affect neutrophil chemotaxis as well as platelet
activation and aggregation, both of which further amplify the inflammatory response.
IV. Basic Protocol Experimental Design In a prospective, randomized, controlled, blinded
pilot trial we will compare 20 ppm of iNO delivered to the CPB circuit. Our study will
target children undergoing cardiopulmonary bypass (CPB) for surgery for the correction of
transposition of great arteries (TGA) and Tetralogy of Fallot (TOF).
Subjects Inclusion Undergoing repair of TGA and TOF < 16 years of age Exclusion Age > 16
years of age Pregnancy Known bleeding disorder
Treatment Protocol Following informed consent, blood will be drawn pre-operatively for
baseline characteristics (methemoglobin, venous saturation, CBC, S100, gene expression
profiles, BNP, cTnI, IL-6, IL-8, lactate, TNFalpha)[Table, Blood sample for Study].
Intra-operatively we will use a standardized anesthetic protocol unless contraindicated by
specific patient clinical characteristics. Intraoperative measurements will include: aortic
cross clamp time, and total cardiopulmonary bypass time. Intraoperative hemodynamic
measurements will include: mean systemic blood pressure (MAP), central venous pressure,
right atrial pressure pulmonary artery pressure, and pulmonary capillary wedge pressure
(when available). Blood samples will be drawn following CPB upon arrival to the ICU and will
be analyzed as above. Repeat blood samples for each will be drawn again after 12, 24, and 48
hours. Patients will be followed to the time of discharge. Ventilator settings, length of
ICU and hospital stay will be recorded. All measurements in both groups will be the same.
Time points will be referenced from the time of admission to the PICU for both groups.
Inclusion Criteria:
- Patients with the following congenital heart lesions who require cardiopulmonary
bypass for surgical repair or palliation will be eligible:
- D-transposition of the great vessels (D-TGA)
- Tetralogy of Fallot (TOF)
- Children of age less than 16 years
Exclusion Criteria:
- Signs of persistently elevated pulmonary vascular resistance preoperatively
- Cardiac arrest one week prior to surgery
- Prior surgical procedure that required use of cardio-pulmonary bypass
- Acute or chronic infection such as sepsis or wound infections
- History of any pulmonary condition such as pneumonia or respiratory distress syndrome
- Patients that have received steroid treatment within the last month
- DiGeorge syndrome
- Active bleeding disorder
- Any other condition associated with non-cardiac morbidity
- Use of another investigational drug
- Age over 16 years.
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