Expiratory Time Constant in Mechanically Ventilated Patients

Determining Expiratory Time Constant in Mechanically Ventilated Patients

Determining expiratory time constants in mechanically ventilated patients

Study Overview

• Status: Completed
• Conditions: Comparing Six Different Methods to Obtain Expiratory Time Constant
• Intervention / Treatment: Other: data recording using conventional ventilation strategies (PCV and VCV)

Detailed Description

Adult patients (n = 30) undergoing elective cardiac surgery with extracorporeal circulation (ECC) were included. Patients were excluded from the study if they had any known lung disease or had previous thoracic surgery. After the surgery, all patients were transferred to the intensive care unit (ICU) and connected to well-established Servo-U (Maquet, Getinge AB, Solna, Sweden) mechanical ventilator. First, the ventilation mode was set to mandatory volume-controlled ventilation (VCV) for 15 minutes. After that, mandatory pressure-controlled ventilation (PCV) for another 15 minutes was commenced. All patients were in supine position, sedated and paralyzed using continuous infusion of propofol and atracurium with no spontaneous breathing efforts. During VCV, an end-inspiratory pause (TPAUSE 10%) has been added to obtain inspiratory plateau pressure (P PLAT) under static conditions. Respiratory variables in VCV for all patients were as follows: PEEP 6 - 9 cmH 2 O depending on the local protocol, protective tidal volume (Vt) of 7 ml/kg/PBW, T PAUSE was set to 10%, I:E ratio of 1:2, rise time 5% and the respiratory rate was 14 breaths/min. After 15 minutes, VCV was changed to PCV with the same ventilator setting with inspiratory pressure set in the way to best match the Vt during the VCV. ARDSNet tables were used to determine PBW for all patients.

A novel device enabling data acquisition (Dr. Wave, Quadrus Medical Technologies, NY, White Plains, USA) has been connected to the Servo-U ventilator after admission to the ICU to record flow, pressure, and volume waveforms. All data in the study were derived from measurements and calculations from this device and included: Peak Inspiratory Pressure (PIP), PPLAT, PEEP, expiratory tidal volume (Vt) respiratory system compliance (C RS ), airway resistance (RTOT) and the peak expiratory flow rate (PEFR).

Based on obtained data of flow, volume and pressure during PCV and VCV, six different methods to determined expiratory time constant were examined

• Study Type: Observational
• Enrollment (Actual): 30

Contacts and Locations

Study Locations

• Slovakia
  • Košice, Slovakia, 040 01
    • East Slovak Institute for Cardiovascular Diseases

Participation Criteria

Eligibility Criteria

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

• Sampling Method: Probability Sample

Study Population

Patients undergoing elective cardiac surgery with extracorporeal circulation (mostly CABG or AVR).

Description

Inclusion Criteria: cardiac surgery with extracorporeal circulation

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Exclusion Criteria:

• known pulmonary disease
• previous thoracic surgery
• poor preoperative cardiac status

Study Plan

How is the study designed?

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Expiratory time constant	Six different methods to assess expiratory time constants in mechanically ventilated patients	3 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Validity of expiratory time constant definition	To prove if three time constant correspond to actual first time constant multiplied by the factor of 3	3 months

Collaborators and Investigators

• Sponsor: East Slovak Institute for Cardiovascular Diseases
• Investigators: Study Director: Dušan Rybár, PhD, East Slovak Institute for Cardiovascular Diseases

Study record dates

Study Major Dates

• Study Start (Actual): November 15, 2022
• Primary Completion (Actual): January 30, 2023
• Study Completion (Actual): January 30, 2023

Study Registration Dates

• First Submitted: April 12, 2023
• First Submitted That Met QC Criteria: April 12, 2023
• First Posted (Actual): April 25, 2023

Study Record Updates

• Last Update Posted (Actual): April 25, 2023
• Last Update Submitted That Met QC Criteria: April 12, 2023
• Last Verified: April 1, 2023

More Information

Terms related to this study

• Keywords: expiratory time constant, mechanical ventilation, exhalation
• Other Study ID Numbers: www.vusch.sk

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No