Physiological Dead Space and Intensive Care Mortality in Mechanically Ventilated Patients

NCT06963944 | Completed

• 1 other identifier: 2024/154
• Study Type: observational
• Target: 60
• Locations: 1 country
• Sites: 1

Brief Summary

This study investigates the relationship between physiological dead space and clinical outcomes, specifically mortality and discharge status, in adult patients receiving invasive mechanical ventilation in the intensive care unit (ICU). Physiological dead space refers to ventilated but non-perfused regions of the lungs and can be quantified using the Enghoff-modified Bohr equation based on capnographic and arterial CO₂ measurements. While volumetric capnography is a valuable tool in anesthesiology and perioperative care, its use in ICU settings remains limited. By continuously monitoring physiological dead space at the bedside, this study aims to provide real-time insight into ventilation-perfusion mismatch and assess its prognostic significance in critically ill patients.

Conditions

Invasive Mechanical Ventilation; Ventilation-Perfusion Mismatch; ICU Mortality; Critical Illness; End Tidal CO2

Keywords

Physiological Dead Space; Volumetric Capnography; Enghoff Equation; Mechanical Ventilation; ICU; Critical Care; Ventilation-Perfusion Mismatch; PaCO₂; EtCO₂; ICU Mortality; Gas Exchange; Respiratory Monitoring

Outcome Measures

Primary Outcomes (1)

• ICU Mortality

  All-cause mortality during the intensive care unit (ICU) stay.

  Up to ICU discharge day or 28 day

Secondary Outcomes (4)

• ICU Length of Stay

  Through ICU stay, up to 28 days

• Mechanical Ventilation Duration

  From initiation of invasive mechanical ventilation to extubation or death or, up to 28 days

• Change in Physiological Dead Space Over Time

  Daily measurements for up to 3 days in the ICU

• Relationship Between Physiological Dead Space and Oxygenation

  Daily during ICU stay (up to 3 days)

Study Arms (1)

Mechanically Ventilated Adult ICU Patients

Adult patients (aged ≥18 years) who received invasive mechanical ventilation in a tertiary intensive care unit. All participants were prospectively monitored with volumetric capnography and arterial blood gas analysis to evaluate physiological dead space. No interventions were applied as part of the study.

Eligibility Criteria

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

Study Population

The study population consisted of adult patients (aged 18 years and older) who were admitted to a tertiary academic intensive care unit and required invasive mechanical ventilation for respiratory failure of various etiologies. All patients were managed in the ICU setting with advanced monitoring capabilities, including arterial blood gas analysis and volumetric capnography. Patients were enrolled consecutively during the study period based on predefined eligibility criteria. Individuals with hemodynamic instability, severe acidosis, or technical limitations preventing accurate dead space measurement were excluded. The study population reflects a critically ill cohort typically encountered in university hospital ICUs.

You may qualify if:

• Admitted to the intensive care unit
• Receiving invasive mechanical ventilation
• Monitored with volumetric capnography and arterial blood gas analysis
• Informed consent obtained from legal representatives

You may not qualify if:

• Patients under 18 years of age
• ICU length of stay less than 24 hours
• Patient or legal representative refused participation
• Hemoglobin level \< 7 g/dL
• Arterial PaCO₂ \> 70 mmHg
• Signs of circulatory failure
• Lactate \> 4 mmol/L
• Capillary refill time \> 3 seconds
• PaCO₂ - Central venous CO₂ gradient \> 8 mmHg (if applicable)
• Mean arterial pressure (MAP) \< 65 mmHg
• Mottling score ≥ 2
• Body temperature \> 38°C
• Arterial pH \< 7.20
• Body mass index (BMI) \> 40 kg/m²
• Carbon dioxide production (VCO₂) \> 4 mL/kg

Sponsors & Collaborators

• Karadeniz Technical University: lead

Study Sites (1)

Karadeniz Technical University

Trabzon, 61080, Turkey (Türkiye)

Location

MeSH Terms

Conditions

Critical Illness

Condition Hierarchy (Ancestors)

Disease Attributes; Pathologic Processes; Pathological Conditions, Signs and Symptoms

Study Officials

• Mehtap Pehlivanlar Kucuk, MD, Assoc. Prof.

  Karadeniz Technical University, Faculty of Medicine

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: PROSPECTIVE
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: MD, Assist. Prof.

Study Record Dates

• First Submitted: April 20, 2025
• First Posted: May 9, 2025
• Study Start: January 1, 2024
• Primary Completion: April 19, 2025
• Study Completion: April 19, 2025
• Last Updated: May 9, 2025

Record last verified: 2025-04

Data Sharing

• IPD Sharing: Will not share

Locations

TU (1)