Related Experiment Video
Updated: Sep 11, 2025
Monitoring Lung Function with Electrical Impedance Tomography in the Intensive Care Unit
Published on: September 6, 2024
Differentiating Lung From Chest Wall Mechanics Is Difficult Without Esophageal Manometry in Children With Acute
Yukie Ito1, Meryl Vedrenne-Cloquet2,3, Daniel Chang1
1Department of Anesthesiology and Critical Care Medicine, Children's Hospital Los Angeles, Los Angeles, CA.
Insights
In pediatric acute respiratory distress syndrome (PARDS), respiratory system compliance (CRS) is linked to lung compliance. Low CRS suggests high elastance ratio (EL/ERS), making higher plateau pressures potentially unsafe without esophageal pressure monitoring.
Area of Science:
- Pediatric Critical Care Medicine
- Respiratory Physiology
- Mechanical Ventilation
Background:
- Pediatric acute respiratory distress syndrome (PARDS) guidelines suggest limiting airway plateau pressure (Pplat) to 28 cm H2O.
- Higher Pplat may be permissible with poor chest wall compliance (CCW) as less pressure transmits to the lungs.
- Transpulmonary pressure, crucial for lung injury assessment, depends on Pplat and the elastance ratio (EL/ERS).
Purpose of the Study:
- To determine if routinely available clinical data can predict EL/ERS in mechanically ventilated children with PARDS.
- To assess if Pplat can be safely increased above guidelines when CCW is poor.
- To understand the relationship between respiratory system compliance (CRS) and EL/ERS.
Main Methods:
- Secondary analysis of a randomized controlled trial involving esophageal manometry.
- Included 207 patients and 750 patient days in a quaternary pediatric intensive care unit (PICU).
- Utilized multivariable analysis to identify predictors of EL/ERS and CCW.
Main Results:
- Median EL/ERS was 0.83; CRS showed a weak negative correlation with EL/ERS (r = -0.26).
- CRS strongly correlated with lung compliance (Cl) (r = 0.94) and moderately with CCW (r = 0.53).
- Lower CRS predicted higher EL/ERS (AUC, 0.73), while higher CRS predicted lower EL/ERS (AUC, 0.60); daily EL/ERS changes were unpredictable.
Conclusions:
- In PARDS, CRS is more closely related to Cl than CCW.
- EL/ERS is not easily predictable from clinical variables alone.
- Increasing Pplat when CRS is low may be inappropriate and potentially harmful without esophageal pressure measurement.
Objectives:
Pediatric acute respiratory distress syndrome (PARDS) guidelines recommend limiting airway plateau pressure (Pplat) to 28 cm H 2 O, allowing for higher limits when chest wall compliance (C CW ) is poor since less of the pressure is transmitted to lung (transpulmonary pressure). Transpulmonary pressure depends on Pplat and the ratio of lung elastance to respiratory system elastance (E L /E RS ). E L /E RS measurement requires esophageal manometry, although it is not routinely available. We sought to determine if routinely available clinical data could reliably predict E L /E RS or changes in E L /E RS , to understand when Pplat greater than 28 cm H 2 O could be acceptable.
Design:
Secondary analysis of randomized controlled trial with esophageal manometry monitoring.
Setting:
Quaternary PICU.
Patients:
Mechanically ventilated children with PARDS.
Interventions:
None.
Measurements And Main Results:
Two hundred seven patients and 750 patient days were included. Using the first day per patient, median E L /E RS was 0.83 (interquartile range, 0.72-0.87), with a weak negative correlation with respiratory system compliance (C RS ) ( r = -0.26; p < 0.001). C RS was strongly correlated with lung compliance (C l ) ( r = 0.94; p < 0.001) and moderately correlated with C CW ( r = 0.53; p < 0.001). Multivariable analysis identified that higher C RS , younger age and peripheral neuromuscular disease were associated with higher C CW , while higher C RS was the only variable independently associated with higher C l (all p < 0.01). When trying to predict high (> 0.9) or low (< 0.7) E L /E RS , C RS was the only variable retaining an independent association: lower C RS (C RS × 10 [mL/cm H 2 O/kg × 1/10]) with high E L /E RS (odds ratio [OR], 0.70; 95% CI, 0.54-0.86; p = 0.002; area under the receiver operating characteristic curve [AUC], 0.73) and higher C RS (C RS × 10 [mL/cm H 2 O/kg × 1/10]) with low E L /E RS (OR, 1.14; 95% CI, 1.02-1.28; p = 0.017; AUC, 0.60). Change in E L /E RS from day to day was not predictable.
Conclusions:
In PARDS, C RS is more strongly tied to C l than C CW . While E L /E RS is not easily predictable from clinical variables, when C RS is low, E L /E RS is generally high. Therefore, increasing Pplat above the suggested thresholds when C RS is impaired may be inappropriate without measuring esophageal pressure.
Related Concept Videos
01:30Respiratory System Abnormal Finding I: Inspection and Percussion
Inspection Findings
During an inspection, several findings may suggest the presence of respiratory distress or disease. Pursed-lip breathing, where exhalation is slowed by...
01:31Respiratory System Abnormal Finding II: Palpation and Auscultation
Palpation Findings
During a respiratory assessment, palpation can reveal several vital abnormalities:
01:17Pulmonary Cycle: Exhalation
01:27Physical Assessment of the Respiratory Tract II: Inspection
Chest Configuration
The chest configuration...
01:24Pressure Relationships in Thoracic Cavity
Breathing Mechanisms
Both intra-alveolar and intrapleural pressures rely on specific lung properties. The ability to breathe—allowing air to enter the lungs...
01:30Assessment of Airway, Skin Color, and Use of Accessory Muscles
Introduction
The initial evaluation of a patient's respiratory system...