Endothelial Dysfunction and Nitric Oxyde During Laparoscopic Surgery (ED-NOanesth)

Endothelial Dysfunction and Inhaled Nitric Oxyde During Laparoscopic Surgery: : a Pilot Prospective Randomized Study

This single-centre, pilot, prospective, randomized, open-label clinical trial evaluated the effect of intraoperative inhaled nitric oxide (iNO) on endothelial function, intestinal and renal injury biomarkers, and early clinical outcomes in high-risk cardiovascular patients undergoing prolonged laparoscopic abdominal surgery (>120 minutes). Forty adults with cardiovascular disease and an RCRI ≥2 were randomized 1:1 to receive either iNO at 40 ppm via the ventilator circuit from post-intubation to the end of surgery or standard anaesthetic management without iNO. The primary endpoint was the 12-hour postoperative change in endothelial dysfunction markers (total nitric oxide, endothelin-1, von Willebrand factor); secondary endpoints included markers of intestinal and renal injury (I-FABP, LBP, creatinine), tissue expression of VCAM-1 and iNOS, postoperative complications, gastrointestinal recovery, and hospital length of stay.

Study Overview

• Status: Completed
• Conditions: Laparoscopic Abdominal Surgeries
• Intervention / Treatment: Procedure: Inhaled nitric oxide at 40 ppm administered via the inspiratory limb of the anaesthesia ventilator circuit

Detailed Description

This is a single-centre, pilot, prospective, randomized, open-label, parallel-group clinical study. Adult patients (>18 years) with documented cardiovascular disease (including coronary artery disease, chronic heart failure, or cerebrovascular disease) and a Revised Cardiac Risk Index (RCRI) ≥2 scheduled for elective laparoscopic abdominal surgery lasting more than 120 minutes were eligible. Key exclusion criteria included pregnancy or lactation, baseline methemoglobin >3%, known hypersensitivity to nitric oxide, chronic use of NO donors or drugs increasing methemoglobin, severe neutropenia or thrombocytopenia, severe renal failure (eGFR <30 ml/min/1.73 m²), poorly controlled diabetes, significant electrolyte disturbances, and participation in another clinical trial.

Patients were randomized in a 1:1 ratio to the intervention or control group using a sealed opaque envelope method with 40 pre-prepared envelopes opened on the morning of surgery by an anaesthesiologist not involved in treatment or data collection. In the intervention group (n=20), iNO was administered at 40 ppm using the AIT-NO-01 "Tianox" generator (RFNC-VNIIEF, Russia) via the inspiratory limb of the anaesthesia ventilator circuit, starting immediately after tracheal intubation and continuing until the end of surgery, with a median inhalation duration of 168 [145; 185] minutes. In the control group (n=20), patients received standard anaesthetic management and mechanical ventilation without iNO. All patients underwent volatile-based general anaesthesia with sevoflurane, fentanyl infusion, and rocuronium, lung-protective ventilation (tidal volume 6-8 ml/kg ideal body weight, PEEP 5-14 cmH₂O), and goal-directed haemodynamic management with norepinephrine as needed; anaesthetic depth was guided by bispectral index monitoring.

The primary endpoint was the perioperative change (Δ from baseline to 12 hours postoperatively) in plasma markers of endothelial dysfunction: total nitric oxide (NOtotal, sum of nitrites and nitrates), endothelin-1 (ET-1), and von Willebrand factor (vWF). Secondary endpoints included 12-hour postoperative levels of intestinal injury markers (intestinal fatty acid-binding protein, I-FABP; lipopolysaccharide-binding protein, LBP), serum creatinine, tissue expression of vascular cell adhesion molecule-1 (VCAM-1) and inducible nitric oxide synthase (iNOS) in colonic samples assessed by immunohistochemistry, time to first defecation, length of hospital stay, and perioperative complications and adverse events classified by the Clavien-Dindo scale. Safety assessments encompassed methemoglobin levels measured every 30 minutes, continuous monitoring of inspired NO and NO₂ concentrations, and standard cardiorespiratory monitoring.

Venous blood was drawn 1 hour before surgery and 12 hours after surgery for measurement of NOtotal, ET-1, vWF, I-FABP, LBP, and creatinine using enzyme-linked immunosorbent assays and standard biochemical methods. Immunohistochemical analysis of VCAM-1 and iNOS expression in colonic tissue (0-3 point semi-quantitative score) was performed on paraffin-embedded specimens using monoclonal antibodies and a standard HRP/DAB detection system. Statistical analyses were conducted with IBM SPSS 26.0; data were described as median [Q1; Q3] or mean±SD, comparisons between groups used t-tests or Mann-Whitney U tests as appropriate, and Wilcoxon tests for within-group changes, with p<0.05 considered statistically significant.

As a pilot study, the sample size (n=40) was chosen empirically without formal power calculation, and the follow-up period was limited to the index hospital stay; the design was open-label with only patients and outcome assessors blinded to group allocation. The protocol was approved by the Local Ethics Committee of Sechenov University (Protocol No. 27-24, November 7, 2024). The authors conclude that intraoperative iNO at 40 ppm in high-risk cardiovascular patients undergoing prolonged laparoscopic surgery is feasible and appears to stabilize endothelial function, attenuate intestinal and renal injury, and shorten hospital stay, warranting confirmation in larger, prospectively registered randomized controlled trials with extended follow-up.

• Study Type: Interventional
• Enrollment (Actual): 40
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Russia
  • Moscow, Russia, 119048
    • First Moscow State Medical University named after I.M. Sechenov (Sechenov University)

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Age ≥18 years.
• Documented cardiovascular disease, including at least one of the following: coronary artery disease, stable angina pectoris (II-III functional class), chronic heart failure (NYHA I-III), prior myocardial infarction, or cerebrovascular disease.
• Revised Cardiac Risk Index (RCRI) ≥2 (moderate/high perioperative risk).
• Scheduled for elective laparoscopic abdominal surgery (e.g., colorectal, gastric, hepatic resections) with expected duration >120 minutes.
• Ability to provide written informed consent.

Exclusion Criteria:

• Pregnancy or lactation.
• Baseline methemoglobin level >3%.
• Known hypersensitivity or contraindication to inhaled NO.
• Chronic intake of NO donors (e.g., nitroglycerin, isosorbide) or drugs known to increase methemoglobin (e.g., lidocaine, prilocaine, benzocaine).
• Severe neutropenia (neutrophils <500/mm³) or severe thrombocytopenia (platelets <30,000/mm³).
• Haemoglobin <7 g/dl.
• Severe renal failure (estimated GFR <30 ml/min/1.73 m²).
• Poorly controlled diabetes mellitus (HbA1c >9% or frequent hypoglycaemia).
• Significant electrolyte disorders (K⁺ <3.0 or >5.5 mmol/l; Na⁺ <125 or >155 mmol/l).
• Any acute exacerbation of chronic disease on the day of surgery.
• Need to convert to open laparotomy during surgery (exclusion from analysis).
• Requirement for extracorporeal life support or other advanced organ support not compatible with protocol procedures.
• Participation in another interventional clinical trial.
• Withdrawal of consent by the patient at any point.
• Development of an allergic or severe adverse reaction to the study intervention

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: NO group; Patients receive inhaled nitric oxide at 40 ppm administered via the inspiratory limb of the anaesthesia ventilator circuit using the AIT-NO-01 "Tianox" generator (RFNC-VNIIEF, Russia). iNO is initiated immediately after tracheal intubation and continued until the end of surgery; the median iNO exposure in the pilot cohort was approximately 168 minutes. Inspired NO and NO₂ concentrations are continuously monitored according to device instructions.	Procedure: Inhaled nitric oxide at 40 ppm administered via the inspiratory limb of the anaesthesia ventilator circuit; Patients receive inhaled nitric oxide at 40 ppm administered via the inspiratory limb of the anaesthesia ventilator circuit. iNO is initiated immediately after tracheal intubation and continued until the end of surgery; the median iNO exposure in the pilot cohort was approximately 168 minutes. Inspired NO and NO₂ concentrations are continuously monitored according to device instructions.
No Intervention: Control group; Patients receive standard anaesthetic management and mechanical ventilation without iNO

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Markers of endothelial dysfunction	Total nitric oxide (NOtotal; sum of nitrites and nitrates, nmol/ml)	from baseline (1 hour pre-operatively) to 12 hours postoperatively
Markers of endothelial dysfunction	Endothelin-1 (ET-1, fmol/ml)	from baseline (1 hour pre-operatively) to 12 hours postoperatively
Markers of endothelial dysfunction	von Willebrand factor (vWF, %)	from baseline (1 hour pre-operatively) to 12 hours postoperatively

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Postoperative complications	Number of postoperative complications	28 days
length of hospital stay	length of hospital stay	28 days
Biomarkers	I-FABP (intestinal fatty acid-binding protein), ng/ml	12 hours
Biomarkers	LBP (lipopolysaccharide-binding protein), mkg/ml	12 hours
Biomarkers	Creatinine, mkmol/l	12 hours

Collaborators and Investigators

• Sponsor: Alexander Averyanov
• Collaborators: I.M. Sechenov First Moscow State Medical University
• Investigators: Principal Investigator: Irina A Mandel, MD, PhD, First Moscow State Medical University named after I.M. Sechenov (Sechenov University)

Study record dates

Study Major Dates

• Study Start (Actual): November 19, 2024
• Primary Completion (Actual): April 24, 2026
• Study Completion (Actual): May 15, 2026

Study Registration Dates

• First Submitted: May 31, 2026
• First Submitted That Met QC Criteria: June 4, 2026
• First Posted (Actual): June 10, 2026

Study Record Updates

• Last Update Posted (Actual): June 10, 2026
• Last Update Submitted That Met QC Criteria: June 4, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: Biomarkers; Nitric Oxide; Endothelium; Intra-Abdominal Pressure; Laparoscopic Abdominal Surgeries;; Сardiovascular Diseases
• Other Study ID Numbers: ED-NOanesth

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: No
• Studies a U.S. FDA-regulated device product: No