Detecting Lung's Closing Pressure by Capnography

Analysis of CO2/Volume and CO2-pressure Curves to Detect the Lung's Closing Pressure in Ventilated Patients

General anesthesia is associated with loss of pulmonary functional residual capacity and the consequent development of atelectasis and closure of the small airway.

Mechanical ventilation in a lung with reduced functional residual capacity and atelectasis increased the dynamic alveolar stress-strain, inducing a local inflammatory response in atelectatic lung areas known as ventilatory-induced lung injury. This phenomenon may appear even in healthy patients undergoing general anesthesia and predisposes them to hypoxemic episodes that can persist in the early postoperative period.

Lung recruitment maneuvers restore the functional residual capacity and, therefore, protect the lungs from lung injury. A key issue in this kind of treatment is detecting the lung's closing pressure in order to maintain the end-expiratory pressure above such a limit.

Study Overview

• Status: Completed
• Conditions: Atelectasis
• Intervention / Treatment: Diagnostic test: Slow pressure-volume curve

Detailed Description

This is a prospective and observational study designed to measure the lung's closing pressure. The investigators will study 20 mechanically ventilated patients scheduled for mediastinoscopy surgery under general anesthesia.

Lung mechanics and capnography will be assessed during surgery. A slow pressure-volume curve will be automatically performed by the ventilator, and the small airway closing pressure will be determined as the inflection point in the alveolar slope of the pressure-CO2 and volume-CO2 curves. Then, a lung recruitment maneuver will be applied following a descending positive end-expiratory pressure trial to determine the lung's closing pressure. The investigator will see if the lung's closing pressure found with these two techniques is similar.

• Study Type: Observational
• Enrollment (Actual): 20

Contacts and Locations

Study Locations

• Argentina
  • Buenos Aires
    • Mar del Plata, Buenos Aires, Argentina, 7600
      • Hospital Privado de Comunidad

Participation Criteria

Eligibility Criteria

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

• Sampling Method: Non-Probability Sample

Study Population

Adult patients undergoing general anesthesia for mediastinoscopy.

Description

Inclusion Criteria:

• Age > 17 years ole
• Programmed surgery

Exclusion Criteria:

• Pregnancy
• No programmed surgery
• Hemodynamic instability
• Severe COPD
• Acute respiratory infection

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Adults anesthetized patients undergoing mediastinoscopy; Determination of the lung's closing pressure by pressure-CO2 and volume-CO2 curves using a slow pressure-volume curve after anesthesia induction. Later on, a standard lung recruitment maneuver followed by a positive end-expiratory pressure trial was done to detect the lung's closing pressure.	Diagnostic test: Slow pressure-volume curve; Patients will be sequentially subjected to a slow pressure-volume curve and a lung recruitment maneuver; Other Names: Lung recruitment maneuver

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Airway pressure	Airway pressure will be measured at the airways opening and expressed in cmH2O.	30 minutes
Carbon dioxide	Expired carbon dioxide will be measured at the airways opening by a main-stream capnograph, expressed in mmHg.	30 minutes

Collaborators and Investigators

• Sponsor: Hospital Privado de Comunidad de Mar del Plata
• Investigators: Study Chair: Nora Fuentes, PhD, Hospital Privado de Comunidad

Study record dates

Study Major Dates

• Study Start (Actual): February 28, 2023
• Primary Completion (Actual): May 1, 2025
• Study Completion (Actual): May 10, 2025

Study Registration Dates

• First Submitted: February 28, 2023
• First Submitted That Met QC Criteria: May 22, 2023
• First Posted (Actual): May 24, 2023

Study Record Updates

• Last Update Posted (Actual): May 16, 2025
• Last Update Submitted That Met QC Criteria: May 13, 2025
• Last Verified: May 1, 2025

More Information

Terms related to this study

• Keywords: mechanical ventilation; carbon dioxide
• Additional Relevant MeSH Terms: Respiratory Tract Diseases; Lung Diseases; Pulmonary Atelectasis
• Other Study ID Numbers: CP2023

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
• product manufactured in and exported from the U.S.: No