Measuring Inspiratory Effort In Mechanically Ventilated Children

Summary

We demonstrate validated and standardized bedside techniques to quantify inspiratory effort and guide ventilator management.

Abstract

An accurate assessment of inspiratory effort in mechanically ventilated children is essential for optimizing ventilator support and avoiding lung- and diaphragmatic injury. Over-assistance leads to diaphragmatic disuse and atrophy, whereas under-assistance may result in fatigue, diaphragm weakness and patient self-inflicted lung injury (P-SILI). This manuscript demonstrates validated bedside techniques to quantify inspiratory effort. We describe the reference standard for respiratory muscle effort quantification, esophageal manometry, and present alternative approaches for routine clinical practice, given its practical limitations. We distinguish between respiratory drive, tidal inspiratory effort, and maximal inspiratory effort. Indirect parameters of effort include diaphragm electrical activity (EAdi), airway occlusion maneuvers (P0.1, Pocc, PMI) and diaphragm ultrasound parameters. The maximal inspiratory pressure (MIP) is discussed as a measure of maximal effort. Representative pediatric data are provided where available. Although reference values are included for selected parameters, evidence defining safe thresholds in children remains limited. Combined monitoring using these techniques allows individualized titration of mechanical ventilation and supports lung- and diaphragm-protective strategies in the pediatric ICU.

Introduction

During mechanical ventilation (MV) both excessive and insufficient inspiratory efforts may occur, each potentially harmful for the respiratory muscles^1,2,3. Insufficient effort can lead to diaphragm weakening. Diaphragmatic atrophy secondary to prolonged muscle relaxation was first described in a cohort of neonates back in 1988⁴. Subsequent evidence, predominantly from adult studies, has demonstrated that even short-term MV can disrupt the fibrous architecture of the diaphragm and reduce its contractility, collectively described as ventilator-induced d....

Protocol

1. Esophageal manometry

NOTE: Use an appropriate pediatric esophageal balloon catheter based on age and weight (see Table 1). Use a 1–10 mL syringe depending on the choice of esophageal balloon (see Table 2). Use rigid tubing and a ventilator or a dedicated monitor with a pressure transducer. Include integrated or external analysis software for optional pressure-time-product/pressure-rate-product (PTP/PRP) computation.

1. Prepare materials – Choose the balloon size based on age and weight (see Table 2). Prepare the pressure transducer of the selected ventilator or ....

Results

Pes

In children, typical ΔPes values during assisted ventilation range between 4–18 cmH₂O. ΔPes < 4–5 cmH₂O suggests low inspiratory effort or potential over-assistance, whilst ΔPes > 14–18 cmH₂O suggests excessive effort or patient–ventilator asynchrony^27,28.

Accurate placement is confirmed by the presence of cardiac oscillations on the esophageal pressure (Pes) tracing and stable, br.......

Discussion

Recent evidence has demonstrated the potential to mitigate diaphragm dysfunction in mechanically ventilated children through titration of inspiratory effort. As a result, the clinician needs easy-to-use and accurate tools to quantify effort and make informed decisions. Even though a structured clinical bedside approach to visually evaluate inspiratory effort in ventilated children is possible, it does not provide quantitative parameters and should only be used to complement the objective physiological measure.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
NAVA catheter	Getinge	Electrical Activity of the Diaphragm
NaCl 0,9%	Any	Electrical Activity of the Diaphragm	NAVA catheter is immersed in normal saline prior to insertion
EAdi data recording software	Getinge	Electrical Activity of the Diaphragm	ServoTracker software can be provided by Getinge
NAVA-enabled ventilator	Getinge	Electrical Activity of the Diaphragm
14fr NutriVent catheter	SIDAM	Esophageal manometry	Only for larger children
6fr, 7fr, 8fr esophageal catheter	Avea	Esophageal manometry
5fr esophageal catheter	Cooper	Esophageal manometry
Pressure transducer	Any	Esophageal manometry	Can be integrated into regular monitor or standalone device (E.g. FluxMed, MBMed, Argentina)
3-way luer lock connector	Any	Esophageal manometry
Sterile gel	Any	Esophageal manometry	Lubrification of esophageal balloon prior to insertion
Syringes for balloon inflation	Any	Esophageal manometry	Historically, glass syringes were used. Nowadays conventional plastic disposable syringes are used. Small volume (2-3 ml) is preferred for pediatric balloons. For adults use 10 ml syringe.
Data analysis software	Any	Esophageal manometry	E.g. FluxView (MBMed, Argentina)
Rigid luer-lock extension set	Any	Esophageal manometry
Ultrasound machine	Any	Diaphragm ultrasound	M-mode capabilities are needed
High-resolution linear probe (6–13 MHz)	Any	Diaphragm ultrasound
Low-frequency curvilinear or phased-array probe (2–5 MHz)	Any	Diaphragm ultrasound