EIT Evaluation of Different Antihypertensive Agents on the Ventilation-Perfusion Ratio in Patients With Acute Respiratory Failure

NCT07603037 | Not Yet Recruiting

• 1 other identifier: 2026-ICU03
• Study Type: interventional
• Target: 12
• Locations: 1 country
• Sites: 1

Brief Summary

his prospective, single-center interventional study aims to evaluate the effect of two commonly used intravenous antihypertensive agents - nicardipine and sodium nitroprusside - on lung ventilation-perfusion (V/Q) distribution in patients with acute respiratory failure complicated by hypertension. Electrical Impedance Tomography (EIT) will be used for noninvasive monitoring of pulmonary ventilation and perfusion distribution before and after drug administration. The study will compare the changes in V/Q ratio, oxygenation index, and hemodynamic variables after administration of the two drugs. The findings are expected to provide evidence for the optimal antihypertensive strategy in critically ill patients with respiratory failure and to clarify whether specific vasodilators exacerbate or improve ventilation-perfusion mismatch.

Conditions

Acute Respiratory Failure (ARF); Hypertension; Pulmonary Perfusion Imbalance; Aortic Dissection (Subset)

Keywords

Electrical Impedance Tomography; Ventilation-Perfusion Ratio; Nicardipine; Sodium Nitroprusside; Acute Respiratory Failure; Intensive Care Unit

Outcome Measures

Primary Outcomes (3)

• Change in Ventilation-Perfusion Matching Index

  The ventilation-perfusion matching index quantifies the correlation between regional ventilation and perfusion signals derived from EIT imaging. The index ranges from 0 to 1; higher values indicate better matching.

  Baseline (prior to infusion), 30 minutes after infusion initiation, 60 minutes after infusion initiation.

• Change in Physiological Dead Space Fraction (Vd/Vt)

  Physiological dead space is calculated as (PaCO₂ - PeCO₂)/PaCO₂, supplemented by EIT-based regional ventilation analysis. The expected range is 0 to 0.8; higher values indicate greater alveolar wastage and poorer gas exchange.

  Baseline, 30 minutes, and 60 minutes.

• Change in Intrapulmonary Shunt Fraction (%)

  The shunt fraction represents the percentage of non-oxygenated blood flowing through the lungs without gas exchange. It is computed as Qs/Qt = (CCO₂ - CaO₂) / (CCO₂ - CvO₂), approximated by EIT regional perfusion measurement. Typical range 0-40 %; higher values indicate worse oxygenation efficiency.

  Baseline, 30 minutes, and 60 minutes.

Secondary Outcomes (3)

• Change in Pulmonary Perfusion Distribution

  Baseline, 30 minutes, and 60 minutes.

• Change in Pulmonary Ventilation Distribution

  Baseline, 30 minutes, and 60 minutes.

• Change in Oxygenation Index (PaO₂/FiO₂ Ratio)

  Baseline, 30 minutes, and 60 minutes.

Study Arms (1)

Experimental Arm: Sequential Vasodilator Infusion

EXPERIMENTAL

All participants will receive sequential intravenous infusions of nicardipine and sodium nitroprusside under controlled ICU monitoring. Drug Intervention 1: Sodium Nitroprusside Dosage: 0.3-2 µg/kg/min continuous IV infusion. Duration: 30 minutes. EIT and arterial blood gas measurements will be taken before and after infusion. Drug Intervention 2: Nicardipine Dosage: 1-5 mg/h continuous IV infusion. Duration: 30 minutes. EIT and arterial blood gas measurements will be taken before and after infusion. Technique: Electrical Impedance Tomography (PulmoVista 500 or equivalent) used to obtain ventilation and perfusion maps and calculate V/Q matching indices. No placebo or parallel control arm - each subject serves as their own control in a crossover design.

Drug: Sodium Nitroprusside; Drug: Nicardipine

Interventions

Sodium Nitroprusside DRUG

Continuous intravenous infusion of sodium nitroprusside for blood pressure reduction in acute respiratory failure. The drug is prepared in 5% dextrose solution and administered at an initial rate of 0.3 µg/kg/min, titrated up to 2 µg/kg/min as needed to maintain target mean arterial pressure (MAP 65-85 mmHg). Each infusion period lasts 30 minutes under stable mechanical ventilation. Hemodynamic parameters, arterial blood gases, and electrical impedance tomography (EIT) data are recorded at Baseline, 30 min, and 60 min. A washout phase is observed before crossover to the second intervention.

Also known as: Nitroprusside Sodium; Nitropress®

Experimental Arm: Sequential Vasodilator Infusion

Nicardipine DRUG

Continuous intravenous infusion of nicardipine for blood pressure control during mechanical ventilation. The infusion begins at 1 mg/h and is titrated up to 5 mg/h according to real-time blood pressure monitoring to maintain target MAP 65-85 mmHg. Each infusion period lasts 30 minutes. Electrical impedance tomography (EIT) is used to record ventilation-perfusion matching, dead-space, and shunt fraction at Baseline, 30 min, and 60 min. After completion, a 30-minute washout period or until baseline hemodynamics are restored precedes the next crossover phase.

Also known as: Cardene; Nicardipine Hydrochloride

Experimental Arm: Sequential Vasodilator Infusion

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Requires intravenous antihypertensive infusion (such as nicardipine or sodium nitroprusside) to maintain controlled and stable blood pressure during ICU treatment.
• Written informed consent obtained from the patient or the legally authorized representative.

You may not qualify if:

• Body mass index (BMI) ≥ 50 kg/m² or presence of massive subcutaneous edema interfering with EIT signal acquisition.
• Implanted cardiac pacemaker, defibrillator, or any metallic thoracic device that may distort impedance measurements.
• Hemodynamic instability or severe hypotension occurring during drug titration. Pregnancy or lactation. Known hypersensitivity or contraindication to nicardipine or sodium nitroprusside.
• Incomplete clinical documentation preventing accurate evaluation of primary endpoints.

Sponsors & Collaborators

• First Affiliated Hospital of Wannan Medical College: lead

Study Sites (1)

The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College)

Wuhu, Anhui, 241001, China

Location

MeSH Terms

Conditions

Hypertension; Aortic Dissection

Interventions

Nitroprusside; Nicardipine

Condition Hierarchy (Ancestors)

Vascular Diseases; Cardiovascular Diseases; Dissection, Blood Vessel; Aneurysm; Acute Aortic Syndrome; Aortic Diseases

Intervention Hierarchy (Ancestors)

Ferricyanides; Cyanides; Anions; Ions; Electrolytes; Inorganic Chemicals; Ferric Compounds; Iron Compounds; Hydrogen Cyanide; Nitrogen Compounds; Dihydropyridines; Pyridines; Heterocyclic Compounds, 1-Ring; Heterocyclic Compounds

Central Study Contacts

qiancheng xu, PhD

CONTACT

+86-18297529106; qianchengxu@wnmc.edu.cn

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NA
• Masking: NONE
• Purpose: BASIC SCIENCE
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Principal Investigator

Model Details: This study uses a prospective single-center crossover design. Each participant serves as his or her own control and receives two sequential antihypertensive interventions, sodium nitroprusside and nicardipine, in different study phases under stable mechanical ventilation settings. The order of drug administration is alternated between participants according to a computer-generated assignment list to minimize sequence effect. A 30-minute washout period or until hemodynamic parameters return to baseline is maintained between the two infusion periods. Continuous monitoring with electrical impedance tomography (EIT) allows within-subject comparison of ventilation-perfusion matching, dead space, and shunt fraction at defined time points (Baseline, 30 min, 60 min). This crossover model permits reduction of inter-individual variability and optimizes statistical power with a limited sample size.

Study Record Dates

• First Submitted: May 18, 2026
• First Posted: May 22, 2026
• Study Start (Estimated): June 30, 2026
• Primary Completion (Estimated): July 30, 2027
• Study Completion (Estimated): July 30, 2027
• Last Updated: May 22, 2026

Record last verified: 2026-05

Locations

CN (1)