A Comparison of Proximal and Tracheal Airway Pressures During Pressure Controlled Ventilation

Mark O Zander; Nikola Stankovic; Mirko Meboldt; Thomas O Erb; Jürg Hammer; Marianne Schmid Daners

doi:10.4187/respcare.10539

A Comparison of Proximal and Tracheal Airway Pressures During Pressure Controlled Ventilation

Respir Care. 2023 Nov 25;68(12):1639-1645. doi: 10.4187/respcare.10539.

Authors

Mark O Zander¹, Nikola Stankovic², Mirko Meboldt¹, Thomas O Erb², Jürg Hammer³, Marianne Schmid Daners⁴

Affiliations

¹ Product Development Group Zurich, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland.
² Department of Anesthesiology, University Children's Hospital Basel, University of Basel, Basel, Switzerland.
³ Division of Respiratory and Critical Care Medicine, University Children's Hospital Basel, University of Basel, Basel, Switzerland.
⁴ Institute for Dynamic Systems and Control, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland. marischm@ethz.ch.

PMID: 37580124
PMCID: PMC10676261 (available on 2024-12-01)
DOI: 10.4187/respcare.10539

Abstract

Background: Airway pressure is usually measured by sensors placed in the ventilator or on the ventilator side of the endotracheal tube (ETT), at the Y-piece. These remote measurements serve as a surrogate for the tracheal or alveolar pressure. Tracheal pressure can only be predicted correctly by using a model that incorporates the pressure at the remote location, the flow through the ETT, and the resistance of the ETT if the latter is a predictable function of Y-piece flow. However, this is not consistently appropriate, and accuracy of prediction is hampered.

Methods: This in vitro study systematically examined the ventilator pressure in dependence of compliance of the respiratory system (C_RS), inspiratory time, and expiratory time during pressure-controlled ventilation by using a small intratracheal pressure sensor and a mechanical lung simulator. Pressures were measured simultaneously at the ventilator outlet, at the Y-piece, and in the trachea during pressure-controlled ventilation with a peak inspiratory pressure of 20 cm H₂O and a PEEP of 5 cm H₂O while changing C_RS (10, 30, 60, 90, and 100 mL/cm H₂O) and varying inspiratory time and expiratory time.

Results: Tracheal pressures were always lower (maximum 8 cm H₂O during inspiration) or higher (maximum 4 cm H₂O during expiration) than the pressures measured proximal to the ETT if zero-flow conditions were not achieved at the end of the breathing cycles.

Conclusions: Dependent on C_RS and the breathing cycle, tracheal pressures deviated from those measured proximal to the ETT under non-zero-flow conditions. Intratracheal pressure and pressure curve dynamics can differ greatly from the ventilator pressure, depending on the ventilator setting and the C_RS. The small pressure sensor may be used as a measurement method of tracheal pressure via integration onto an ETT.

Keywords: intratracheal pressure; intratracheal pressure sensor; invasive ventilation; mechanical lung simulator; pressure-controlled ventilation; respiratory system compliance.

MeSH terms

Humans
Intubation, Intratracheal
Positive-Pressure Respiration* / methods
Respiration
Respiration, Artificial / methods
Trachea*
Ventilators, Mechanical