Comparison of the Effects of SIMV-PC and SIMV-VC Ventilation Modes on Resting Energy Expenditure

August 24, 2026 updated by: Savas Altinsoy, Diskapi Yildirim Beyazit Education and Research Hospital

Comparison of the Effects of SIMV-PC and SIMV-VC Ventilation Modes on Resting Energy Expenditure Measured by Indirect Calorimetry and Mechanical Power in Adult Intensive Care Unit Patients Receiving Invasive Mechanical Ventilation

The primary objective of this prospective observational study is to compare the effects of synchronized intermittent mandatory ventilation in pressure-controlled mode (SIMV-PC) and volume-controlled mode (SIMV-VC) on resting energy expenditure (REE) measured by indirect calorimetry in adult intensive care unit (ICU) patients receiving invasive mechanical ventilation.

The primary metabolic parameters to be evaluated are oxygen consumption (VO₂), carbon dioxide production (VCO₂), resting energy expenditure (REE), and respiratory quotient (RQ). Secondary objectives include comparison of respiratory rate, tidal volume, minute ventilation,arterial blood gas parameters, mechanical power, ventilator mechanics, hemodynamic variables, sedation level, and patient-ventilator synchrony between the two ventilation modes.

The results of this study may contribute to identifying ventilation strategies associated with lower energy expenditure while maintaining adequate ventilatory support in critically ill patients and may help optimize individualized ventilator management and nutritional therapy.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Detailed Description

Mechanical ventilation is a cornerstone of supportive therapy in critically ill patients. Although synchronized intermittent mandatory ventilation in pressure-controlled (SIMV-PC) and volume-controlled (SIMV-VC) modes are widely used in routine intensive care practice, limited data are available regarding their effects on patients' energy expenditure measured by indirect calorimetry.

Indirect calorimetry is recommended by the European Society for Clinical Nutrition and Metabolism (ESPEN) as the reference standard for determining energy expenditure in critically ill patients. Accurate estimation of energy expenditure is essential for optimizing nutritional therapy and avoiding both underfeeding and overfeeding. Overfeeding may increase carbon dioxide production, insulin requirements, respiratory workload, duration of mechanical ventilation, and intensive care unit length of stay.

This is a prospective, observational, repeated-measures study conducted in adult ICU patients receiving invasive mechanical ventilation. The study is non-interventional. Ventilation mode selection and all ventilator adjustments will be determined exclusively by the attending intensive care physician according to routine clinical practice. No study-specific ventilator changes, additional invasive procedures, or additional blood sampling will be performed.

Indirect calorimetry measurements will be performed during clinically stable periods under routine ICU monitoring. Measurements will be obtained only after at least 30 minutes of stabilization following any clinically indicated ventilation mode change. Patients receiving continuous enteral nutrition with no major changes in sedative or analgesic infusions during the preceding two hours will be eligible for metabolic measurements. Sedation level will be documented using the Richmond Agitation-Sedation Scale (RASS).

Metabolic parameters obtained by indirect calorimetry, including oxygen consumption (VO₂), carbon dioxide production (VCO₂), resting energy expenditure (REE), and respiratory quotient (RQ), will be compared between SIMV-PC and SIMV-VC ventilation modes. Ventilator parameters, respiratory mechanics, mechanical power, arterial blood gas findings, hemodynamic variables, and patient-ventilator synchrony will also be evaluated.

Because the study is observational and based entirely on routine clinical care, no additional risks beyond standard intensive care management are anticipated. If hemodynamic or respiratory instability develops during indirect calorimetry measurements, the measurement will be discontinued immediately and routine patient management will continue according to the attending physician's clinical judgment.

Study Type

Observational

Enrollment (Estimated)

41

Contacts and Locations

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

Study 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

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

Receiving invasive mechanical ventilation in the intensive care unit. Receiving continuous enteral nutrition during indirect calorimetry measurements.

Description

Inclusion Criteria

  • Adults aged 18 to 80 years.
  • Receiving invasive mechanical ventilation in the intensive care unit.
  • Receiving continuous enteral nutrition during indirect calorimetry measurements.
  • Hemodynamically stable (mean arterial pressure ≥65 mmHg without significant increase in vasopressor requirement).
  • Technically suitable for indirect calorimetry measurements.
  • Written informed consent obtained from the patient or the legally authorized representative.

Exclusion Criteria

  • Age <18 years or >80 years.
  • Pregnancy.
  • Hemodynamic instability.
  • High vasopressor requirement or marked increase in vasopressor dosage.
  • Requirement for frequent or major changes in ventilator settings or FiO₂.
  • FiO₂ >0.60.
  • Bronchopleural fistula, significant air leak, or other pulmonary conditions interfering with indirect calorimetry.
  • Extracorporeal membrane oxygenation (ECMO).
  • Continuous renal replacement therapy (CRRT).
  • Significant body temperature fluctuations.
  • Active agitation or severe patient-ventilator dyssynchrony.
  • Acute metabolic changes that may interfere with indirect calorimetry measurements.

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

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
Monitored with mechanical ventilation patients
In intensive care patients monitored with mechanical ventilation, energy consumption will be monitored using indirect calorimetry after volume-controlled or pressure-controlled ventilation.
Other: Volume-controlled ventilation
In intensive care patients monitored with mechanical ventilation, energy consumption will be monitored using indirect calorimetry after volume-controlled ventilation.
Other: Pressure-controlled ventilation
In intensive care patients monitored with mechanical ventilation, energy consumption will be monitored using indirect calorimetry after pressure-controlled ventilation.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Resting energy expenditure (REE) measured by indirect calorimetry.
Time Frame: After being monitored in mechanical ventilation mode (volume or pressure controlled) for 2 hours
Resting energy expenditure (REE) measured by indirect calorimetry.
After being monitored in mechanical ventilation mode (volume or pressure controlled) for 2 hours

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Respiratory rate
Time Frame: After being monitored in mechanical ventilation mode (volume or pressure controlled) for 2 hours
Respiratory rate
After being monitored in mechanical ventilation mode (volume or pressure controlled) for 2 hours
Tidal volume
Time Frame: After being monitored in mechanical ventilation mode (volume or pressure controlled) for 2 hours
Tidal volume
After being monitored in mechanical ventilation mode (volume or pressure controlled) for 2 hours
Peak inspiratory pressure (Ppeak)
Time Frame: After being monitored in mechanical ventilation mode (volume or pressure controlled) for 2 hours
Peak inspiratory pressure (Ppeak)
After being monitored in mechanical ventilation mode (volume or pressure controlled) for 2 hours
Positive end-expiratory pressure (PEEP)
Time Frame: After being monitored in mechanical ventilation mode (volume or pressure controlled) for 2 hours
Positive end-expiratory pressure (PEEP)
After being monitored in mechanical ventilation mode (volume or pressure controlled) for 2 hours
Fraction of inspired oxygen (FiO₂)
Time Frame: After being monitored in mechanical ventilation mode (volume or pressure controlled) for 2 hours
Fraction of inspired oxygen (FiO₂)
After being monitored in mechanical ventilation mode (volume or pressure controlled) for 2 hours
Arterial blood gas parameters (pH)
Time Frame: After being monitored in mechanical ventilation mode (volume or pressure controlled) for 2 hours
Arterial blood gas parameters (pH)
After being monitored in mechanical ventilation mode (volume or pressure controlled) for 2 hours
Arterial blood gas parameters (PaCO₂)
Time Frame: After being monitored in mechanical ventilation mode (volume or pressure controlled) for 2 hours
Arterial blood gas parameters (PaCO₂)
After being monitored in mechanical ventilation mode (volume or pressure controlled) for 2 hours
Arterial blood gas parameters (PaO₂)
Time Frame: After being monitored in mechanical ventilation mode (volume or pressure controlled) for 2 hours
Arterial blood gas parameters (PaO₂)
After being monitored in mechanical ventilation mode (volume or pressure controlled) for 2 hours
Arterial blood gas parameters (Lactate)
Time Frame: After being monitored in mechanical ventilation mode (volume or pressure controlled) for 2 hours
Arterial blood gas parameters (Lactate)
After being monitored in mechanical ventilation mode (volume or pressure controlled) for 2 hours

Collaborators and Investigators

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

Sponsor

Diskapi Yildirim Beyazit Education and Research Hospital

Investigators

  • Principal Investigator: Savaş Altınsoy, Ankara Etlik City Hospital

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.

General Publications

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 (Estimated)

August 30, 2026

Primary Completion (Estimated)

December 15, 2026

Study Completion (Estimated)

January 15, 2027

Study Registration Dates

First Submitted

August 7, 2026

First Submitted That Met QC Criteria

August 24, 2026

First Posted (Actual)

August 27, 2026

Study Record Updates

Last Update Posted (Actual)

August 27, 2026

Last Update Submitted That Met QC Criteria

August 24, 2026

Last Verified

August 1, 2026

More Information

Terms related to this study

Keywords

Other Study ID Numbers

  • Esra Selçuk Tez

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

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.

Subscribe