Effects of Nitric Oxide on the Endothelium During Hemolysis.

November 8, 2022 updated by: Lorenzo Berra, MD, Massachusetts General Hospital

Effects of Nitric Oxide on Vascular Responsiveness and on Endothelial Cells During Hemolysis in Patients With Pre-operative Endothelial Dysfunction Undergoing Prolonged Cardiopulmonary Bypass.

This study is an ancillary (add-on) study to the clinical trial entitled "Effect of Nitric Oxide in Cardiac Surgery Patients With Endothelial Dysfunction", which has Clinical Trials.gov identifier NCT02836899. NCT02836899 trial randomizes cardiac surgical patients to receive either Nitric Oxide (NO) or a placebo during and after cardiac surgery.

This ancillary study aims to assess the effects of Nitric Oxide on vascular responsiveness and on endothelial function during hemolysis in patients with pre-operative endothelial dysfunction undergoing cardiac surgery requiring prolonged cardiopulmonary bypass.

Study Overview

Detailed Description

Endothelial cells regulate tissue perfusion by releasing nitric oxide (NO), a potent endogenous dilator of vascular smooth muscle cells, which modifies vascular tone. Under normal physiological conditions, vascular NO is released by endothelial NO synthase (eNOS). Impairment of the eNOS, as seen in patients with atherosclerosis, peripheral vascular disease, hypertension, obesity, and diabetes, is a feature of endothelial dysfunction.The inability to increment eNOS activity is particularly evident in conditions of decreased vascular NO bioavailability, such as during hemolysis associated with prolonged cardiopulmonary bypass (CPB>90 min). During hemolysis, ferrous plasma free hemoglobin (Oxy-Hb) is released into the circulation and can be injurious for the endothelial cells by exerting an oxidative and proinflammatory effect. Moreover, plasma free Oxy-Hb can scavenge vascular NO, reducing its bioavailability as ferrous Oxy-Hb is transformed into ferric methemoglobin (Met-Hb). The clinical results of reduced bioavailability of vascular NO have been found to be associated with both systemic and pulmonary vasoconstriction, ultimately leading to reduced tissue perfusion.

The exogenous administration of NO has been shown to prevent the scavenging of endogenous NO by inactivating the highly oxidative-reactive ferrous plasma Oxy-Hb to ferric Met-Hb. Our group is conducting a randomized controlled trial at Massachusetts General Hospital (Boston, USA) in patients with signs and symptoms of endothelial dysfunction, undergoing cardiac surgery requiring prolonged CPB and randomized to receive NO or placebo. However, the mechanisms underlying the beneficial systemic effects of NO administration have still to be determined. This is an ancillary study that aims to (I) assess the effects of hemolysis on vascular responsiveness and on endothelial function in patients with pre-operative endothelial dysfunction and (II) to determine the vascular protective effects of NO administration.

Study Type

Interventional

Enrollment (Anticipated)

40

Phase

  • Phase 2

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

    • Massachusetts
      • Boston, Massachusetts, United States, 02114
        • Recruiting
        • Massachusetts General Hospital
        • Contact:
      • Boston, Massachusetts, United States, 02118
        • Recruiting
        • Boston Medical Center
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Eligible and randomized in the trial NCT02836899
  • Provide written informed consent
  • Age ≥ 18 years of age
  • Elective cardiac or aortic surgery with CPB >90 minutes
  • Clinical evidence of endothelial dysfunction assessed by a specifically designed questionnaire

Exclusion Criteria:

  • Estimated Glomerular Filtration Rate less than 30 ml/min/1.73 m2
  • Emergent cardiac surgery
  • Life expectancy < 1 year at the time of enrollment
  • Hemodynamic instability as defined by a systolic blood pressure <90 mmHg.
  • Mean pulmonary artery pressure ≥ 40 mm Hg and PVR > 4 Wood Units.
  • Left ventricular ejection fraction < 30% by echocardiography obtained within three months of enrollment
  • Administration of one or more Packed Red Blood Cell (PRBC) transfusions in the week prior to enrollment
  • X-ray contrast infusion less than 48 hours before surgery
  • Evidence of hemolysis from any other origin:

    a. Intravascular: i. Intrinsic RBC defects leading to hemolytic anemia (eg, enzyme deficiencies, hemoglobinopathies, membrane defects) ii. Extrinsic: liver disease, hypersplenism, infections (eg, bartonella, babesia, malaria), treatment with oxidizing exogenous agents (eg, dapsone, nitrites, aniline dyes), exposure to other hemolytic agents (eg, lead, snake and spider bites), lymphocyte leukemia, autoimmune hemolytic disorders b. Extravascular: Infection (eg, clostridial sepsis, severe malaria), paroxysmal cold hemoglobinuria, cold agglutinin disease, paroxysmal nocturnal hemoglobinuria, iv infusion of Rho(D) immune globulin, iv infusion of hypotonic solutions

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Placebo Comparator: Control
Inhaled nitrogen will be administered via the cardiopulmonary bypass (CPB) machine and after CPB via the inspiratory limb of the anesthetic or ventilator circuit, and thereafter via the mechanical ventilator in the Intensive Care Unit (ICU). Test gas administration will commence at the onset of CPB and last for 24 hours.
Vascular responsiveness will be assessed with peripheral arterial tonometry which measures the transient increase in forearm blood flow (Reactive Hyperemia Index, RHI) in response to a five-minute occlusion of the brachial artery with a pressure cuff.
Endothelial cells are collected before and after surgery from a peripheral vessel using a soft J-shaped wire inserted through an intravascular catheter.
Experimental: Nitric Oxide
Inhaled nitric oxide (iNO) will be administered via the CPB machine and after CPB via the inspiratory limb of the anesthetic or ventilator circuit, and thereafter via the mechanical ventilator in the ICU. Test gas administration will commence at the onset of CPB and last for 24 hours. At the end of 24 hours, iNO will be weaned and discontinued.
Vascular responsiveness will be assessed with peripheral arterial tonometry which measures the transient increase in forearm blood flow (Reactive Hyperemia Index, RHI) in response to a five-minute occlusion of the brachial artery with a pressure cuff.
Endothelial cells are collected before and after surgery from a peripheral vessel using a soft J-shaped wire inserted through an intravascular catheter.
Inhaled nitric oxide (iNO) will be administered via the CPB machine and after CPB via the inspiratory limb of the anesthetic or ventilator circuit, and thereafter via the mechanical ventilator in the ICU. Test gas administration will commence at the onset of CPB and last for 24 hours. At the end of 24 hours, iNO will be weaned and discontinued.
Other Names:
  • iNO

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Reactive Hyperemia Index (RHI)
Time Frame: The test will be performed perioperatively before anesthesia induction and at 24 hours after CPB during ICU admission.
A finger plethysmograph will measure the transient increase in forearm blood flow (Reactive Hyperemia Index, RHI) in response to a 5 minutes occlusion of the brachial artery with a pressure cuff (Peripheral Artery Tonometry).
The test will be performed perioperatively before anesthesia induction and at 24 hours after CPB during ICU admission.

Other Outcome Measures

Outcome Measure
Measure Description
Time Frame
Endothelial Nitric Oxide Synthase (eNOS) enzymatic activity
Time Frame: Endothelial Cells will be collected perioperatively before anesthesia induction and at 24 hours after CPB during ICU admission.
eNOS enzymatic activity will be measured in endothelial cells. Activation of eNOS will be assessed through quantification of its expression by quantitative immunofluorescence and through evaluation of phosphorylation levels at different enzymatic sites at baseline and in response to specific agonists; NO bioavailability will be evaluated through fluorescence intensity after challenge with agonists as A23187; additionally, nitrotyrosine levels and other markers will be measured to evaluate endothelial oxidative stress.
Endothelial Cells will be collected perioperatively before anesthesia induction and at 24 hours after CPB during ICU admission.
Pulmonary vascular resistances (PVR)
Time Frame: PVR will be measured every 6 hours after surgery for 24 hours after cardiopulmonary bypass start.
PVR will be measured through a pulmonary artery catheter (PAC) placed in the internal jugular vein after induction of anesthesia. Cardiac output will be measured with the thermodilution technique and pulmonary vascular resistances will be calculated.
PVR will be measured every 6 hours after surgery for 24 hours after cardiopulmonary bypass start.
Systemic vascular resistances (SVR)
Time Frame: SVR will be measured every 6 hours after surgery for 24 hours after cardiopulmonary bypass start.
SVR will be measured through a pulmonary artery catheter (PAC) placed in the internal jugular vein after induction of anesthesia. Cardiac output will be measured with the thermodilution technique and systemic vascular resistances will be calculated.
SVR will be measured every 6 hours after surgery for 24 hours after cardiopulmonary bypass start.

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

December 5, 2018

Primary Completion (Anticipated)

November 1, 2023

Study Completion (Anticipated)

November 1, 2023

Study Registration Dates

First Submitted

November 16, 2018

First Submitted That Met QC Criteria

November 16, 2018

First Posted (Actual)

November 20, 2018

Study Record Updates

Last Update Posted (Actual)

November 10, 2022

Last Update Submitted That Met QC Criteria

November 8, 2022

Last Verified

November 1, 2022

More Information

Terms related to this study

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

No

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

Clinical Trials on Cardiovascular Diseases

Clinical Trials on Reactive Hyperemia Index

3
Subscribe