EIT Evaluation of Different Antihypertensive Agents on the Ventilation-Perfusion Ratio in Patients With Acute Respiratory Failure
Effect of Nicardipine and Nitroglycerin on the Ventilation-Perfusion Ratio in Patients With Acute Respiratory Failure Using Electrical Impedance Tomography: A Prospective Pilot Study
This prospective, single-center interventional study aims to evaluate the effect of two commonly used intravenous antihypertensive agents - nicardipine and nitroglycerin - 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.
Study Overview
Status
Conditions
Intervention / Treatment
Detailed Description
Eligible adult patients diagnosed with acute respiratory failure (PaO₂/FiO₂ ≤ 300 mmHg) and concomitant hypertension (including post-surgical or aortic dissection cases) admitted to the ICU will be enrolled after stabilization.
After baseline EIT and blood gas measurements, participants will sequentially receive nitroglycerin and nicardipine under controlled conditions, with each medication infused over a standardized time period while continuously monitoring vital signs.
EIT-derived ventilation and perfusion images will be acquired at baseline, 30 minutes after nitroglycerin, and 30 minutes after nicardipine.
The primary endpoint is the change in the regional ventilation-perfusion matching index (V/Q-MI). Secondary endpoints include changes in oxygenation, arterial blood gases, and hemodynamic parameters.
All data will be statistically analyzed using paired comparisons and multivariate regression to assess drug-specific effects on pulmonary gas exchange.
Study Type
Enrollment (Estimated)
Phase
- Not Applicable
Contacts and Locations
Study Contact
- Name: qiancheng xu, PhD
- Phone Number: +86-18297529106
- Email: qianchengxu@wnmc.edu.cn
Study Locations
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Anhui
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Wuhu, Anhui, China, 241001
- The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College)
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Contact:
- Shengsheng Tao
- Phone Number: 86-18315329399
- Email: taoshengsheng@yjsyy.com
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Participation Criteria
Eligibility Criteria
Ages Eligible for Study
- Adult
- Older Adult
Accepts Healthy Volunteers
Description
Inclusion Criteria Diagnosis of acute respiratory failure with PaO₂/FiO₂ ≤ 300 mmHg, requiring invasive mechanical ventilation.
Requires intravenous antihypertensive infusion (such as nicardipine or nitroglycerin) to maintain controlled and stable blood pressure during ICU treatment.
Written informed consent obtained from the patient or the legally authorized representative.
Exclusion Criteria:
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 nitroglycerin. Use of phosphodiesterase-5 inhibitors, such as sildenafil, tadalafil, or vardenafil, within the clinically relevant washout period.
Severe anemia, markedly increased intracranial pressure, or other clinical conditions in which nitroglycerin administration is considered inappropriate by the treating physician.
Incomplete clinical documentation preventing accurate evaluation of primary endpoints.
Study Plan
How is the study designed?
Design Details
- Primary Purpose: Basic Science
- Allocation: N/A
- Interventional Model: Single Group Assignment
- Masking: None (Open Label)
Arms and Interventions
Participant Group / Arm |
Intervention / Treatment |
|---|---|
|
Experimental: Experimental Arm: Sequential Vasodilator Infusion
All participants will receive sequential intravenous infusions of nicardipine and nitroglycerin under controlled ICU monitoring. Drug Intervention 1: nitroglycerin Dosage: 5-100 µg/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. |
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.
Other Names:
Continuous intravenous infusion of nitroglycerin for blood pressure reduction in acute respiratory failure.
The drug is administered at an initial rate of 5 µg/min, titrated up to 100 µg/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.
Other Names:
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What is the study measuring?
Primary Outcome Measures
Outcome Measure |
Measure Description |
Time Frame |
|---|---|---|
|
Change in Ventilation-Perfusion Matching Index
Time Frame: Baseline (prior to infusion), 30 minutes after infusion initiation, 60 minutes after infusion initiation.
|
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)
Time Frame: Baseline, 30 minutes, and 60 minutes.
|
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.
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Change in Intrapulmonary Shunt Fraction (%)
Time Frame: Baseline, 30 minutes, and 60 minutes.
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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.
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Baseline, 30 minutes, and 60 minutes.
|
Secondary Outcome Measures
Outcome Measure |
Measure Description |
Time Frame |
|---|---|---|
|
Change in Pulmonary Perfusion Distribution
Time Frame: Baseline, 30 minutes, and 60 minutes.
|
Regional perfusion ratio analyzed via EIT contrast impedance variation after saline bolus indicator; expressed as percentage of dependent to non-dependent lung regions.
Higher ratios reflect more homogeneous perfusion.
|
Baseline, 30 minutes, and 60 minutes.
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Change in Pulmonary Ventilation Distribution
Time Frame: Baseline, 30 minutes, and 60 minutes.
|
Regional ventilation heterogeneity index calculated from EIT ventilation waves; value ranges 0-1, where higher values represent less homogeneous ventilation.
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Baseline, 30 minutes, and 60 minutes.
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Change in Oxygenation Index (PaO₂/FiO₂ Ratio)
Time Frame: Baseline, 30 minutes, and 60 minutes.
|
Ratio of arterial oxygen partial pressure to fraction of inspired oxygen, unit mmHg; range ≤ 300 mmHg inclusion criterion; higher values indicate better oxygen exchange.
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Baseline, 30 minutes, and 60 minutes.
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Collaborators and Investigators
Study record dates
Study Major Dates
Study Start (Estimated)
Primary Completion (Estimated)
Study Completion (Estimated)
Study Registration Dates
First Submitted
First Submitted That Met QC Criteria
First Posted (Actual)
Study Record Updates
Last Update Posted (Actual)
Last Update Submitted That Met QC Criteria
Last Verified
More Information
Terms related to this study
Keywords
Additional Relevant MeSH Terms
Other Study ID Numbers
- 2026-ICU03
Plan for Individual participant data (IPD)
Plan to Share Individual Participant Data (IPD)?
Drug and device information, study documents
Studies a U.S. FDA-regulated drug product
Studies a U.S. FDA-regulated device product
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