The Effect of Positive End-Expiratory Pressure on Functional Residual Capacity During Mechanical Ventilation

Although positive end-expiratory pressure (PEEP) has been widely used in mechanical ventilated patients with acute respiratory distress syndrome (ARDS), how to select the "optimal" PEEP is far from consensus. The application of PEEP may result in beneficial effect by recruiting previously collapsed lung areas, harmful effect by over-distending previously aerated lung areas, or a combination of the both. The net effect of PEEP in a certain patient may depend on the recruitability. Because recruitability varies extremely in ARDS patients and strongly correlates with the response to PEEP, estimation of end-expiratory lung volume (EELV) may be essential for individualized setting of PEEP. Whether the FRC changes at different PEEP levels remains unknown.

Study Overview

• Status: Unknown
• Conditions: Acute Respiratory Distress Syndrome; Mechanical Ventilation; Functional Residual Capacity
• Intervention / Treatment: Procedure: PEEP

Detailed Description

Although positive end-expiratory pressure (PEEP) has been widely used in mechanical ventilated patients with acute respiratory distress syndrome (ARDS), how to select the "optimal" PEEP is far from consensus. The application of PEEP may result in beneficial effect by recruiting previously collapsed lung areas, harmful effect by over-distending previously aerated lung areas, or a combination of the both. The net effect of PEEP in a certain patient may depend on the recruitability. Because recruitability varies extremely in ARDS patients and strongly correlates with the response to PEEP, estimation of end-expiratory lung volume (EELV) may be essential for individualized setting of PEEP.

Passive spirometry has long been used to measure the lung recruitment volume (VREC). A prolonged expiration to zero end-expiratory pressure (ZEEP) or airway release maneuver is required and PEEP induced lung volume change above functional residual capacity (FRC) is measured. This technique assumes that FRC does not change at different PEEP levels.

This assumption that PEEP has no effect on FRC can date back to the study of Valta et al in the early 1990s. Using respiratory inductive plethysmography (RIP), they found that in ALI/ARDS patients, after expiring from different PEEP levels to ZEEP, the plethysmography signal returned to the same baseline value. They concluded that FRC does not change with PEEP, and that changes of EELV are attributable only to change in ∆EELV. Ranieri et al arrived at similar conclusions by measuring differences in lung volumes at different PEEP levels using standardized pressure-volume (P-V) curves derived from the ventilator circuit monitors. However, Patroniti et al found an elevation of FRC as increasing of PEEP in patients with ARDS. In this study, FRC was measured with the helium dilution technique, and concluded that neglecting this effect resulted in marked underestimation of VREC. Whether the FRC changes at different PEEP levels remains controversial. The aim of the study is to assess the effect of PEEP on FRC during mechanical ventilation.

• Study Type: Interventional
• Enrollment (Anticipated): 30
• Phase: Not Applicable

Contacts and Locations

Study Locations

• China
  • Beijing
    • Beijing, Beijing, China, 100050
      • Jian-Xin Zhou

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 80 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion criteria include:

1. Diagnosed with ARDS according to the Berlin Definition;
2. Age 18-80 years;
3. Ventilated with volume-controlled ventilation using constant flow;
4. Deep sedation (RASS -4 to -5) and absence of spontaneous breathing (i.e., no triggering during tidal breaths and no inspiratory effort during a 5-second end-expiratory hold).

Exclusion criteria include:

1. Evidence of active air leak from the lung, including bronchopleural fistula, pneumothorax, pneumomediastinum, or existing chest tube;
2. Chest wall and/or abdominal injuries;
3. Evidence suggesting reduced chest wall compliance, such as existing large pleural effusion, thoracic trauma and intra-abdominal hypertension (i.e., intra-abdominal pressure > 20 mmHg).
4. Presence of pacemaker, defibrillator, and implantable pumps).

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Quadruple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Other: FRC at clinical PEEP level; Measuring FRC at clinical PEEP level	Procedure: PEEP; Two PEEP levels will be used during mechanical ventilation.
Experimental: FRC at clinical PEEP + 5cmH2O; Increasing PEEP to clinical PEEP + 5cmH2O	Procedure: PEEP; Two PEEP levels will be used during mechanical ventilation.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
The change of FRC	EELV measurement by ICU ventilator; PEEP Volume measured through airway release. FRC will be calculated as EELV minus PEEP volume. Correlation between EELV, PEEP volume, FRC at two different PEEP levels are tested by linear regression analysis.	1) One hour after using clinical PEEP 2) One hour after using clinical PEEP + 5cmH2O

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
The change of PaO2/FiO2 Ratio	Obtaining PaO2 according to blood gas analysis, and FiO2 according to the ventilator	1) One hour after using clinical PEEP 2) One hour after using clinical PEEP + 5cmH2O
The change of regional EELV	Regional EELV will be measured at clinical PEEP and clinical PEEP +5cmH2O	1) One hour after using clinical PEEP 2) One hour after using clinical PEEP + 5cmH2O
The change of homogeneity of distribution of tidal volume	EIT is used to monitoring the homogeneity of distribution of tidal volume that was divided into two contiguous regions of interest (ROI) equally, the dependent and non-dependent area. The ratio of relative distribution of tidal ventilation of two ROI was calculated.	1) One hour after using clinical PEEP 2) One hour after using clinical PEEP + 5cmH2O
The change of driving Pressure	The change of driving pressure will be measured.	1) One hour after using clinical PEEP 2) One hour after using clinical PEEP + 5cmH2O
The change of regional FRC	Regional FRC will be measured at clinical PEEP and clinical PEEP +5cmH2O	1) One hour after using clinical PEEP 2) One hour after using clinical PEEP + 5cmH2O
The change of blood pressure	The change of blood pressure will be measured	1) One hour after using clinical PEEP 2) One hour after using clinical PEEP + 5cmH2O

Collaborators and Investigators

• Sponsor: Capital Medical University
• Investigators: Principal Investigator: Jian-Xin Zhou, MD, Beijing Tiantan Hospital

Study record dates

Study Major Dates

• Study Start (Anticipated): August 1, 2020
• Primary Completion (Anticipated): February 28, 2021
• Study Completion (Anticipated): March 31, 2021

Study Registration Dates

• First Submitted: April 8, 2018
• First Submitted That Met QC Criteria: April 26, 2018
• First Posted (Actual): April 30, 2018

Study Record Updates

• Last Update Posted (Actual): May 29, 2020
• Last Update Submitted That Met QC Criteria: May 28, 2020
• Last Verified: May 1, 2020

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Respiratory Tract Diseases; Respiration Disorders; Lung Diseases; Infant, Newborn, Diseases; Lung Injury; Infant, Premature, Diseases; Respiratory Distress Syndrome; Respiratory Distress Syndrome, Newborn; Acute Lung Injury
• Other Study ID Numbers: KY2018-004-02

Drug and device information, study documents

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