Detecting Lung's Closing Pressure by Capnography

Completed

• Conditions: Atelectasis
• Interventions: Diagnostic Test: Slow pressure-volume curve

• Registration Number: NCT05873998
• Lead Sponsor: Hospital Privado de Comunidad de Mar del Plata

Brief Summary

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.

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 Timeline

• Study Start: 2023-02-28
• Study First Submitted: 2023-02-28
• Study First Submitted QC: 2023-05-22
• Study First Posted: 2023-05-24
• Status Verified: 2025-05
• Primary Completion: 2025-05-01
• Study Completion: 2025-05-10
• Last Update Submitted: 2025-05-13
• Last Update Posted: 2025-05-16

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 20

Inclusion Criteria

• Age > 17 years ole
• Programmed surgery

Exclusion Criteria

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

Study & Design

• Study Type: OBSERVATIONAL
• Study Design: Not specified

Arm && Interventions

Group	Intervention	Description
Adults anesthetized patients undergoing mediastinoscopy	Slow pressure-volume curve	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.

Primary Outcome Measures

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

Trial Locations

Locations (1)

Hospital Privado de Comunidad; 🇦🇷 Mar del Plata, Buenos Aires, Argentina