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Evolving approaches to assessing and monitoring patient–ventilator interactions

Unroe, Mark; MacIntyre, Neil

Current Opinion in Critical Care: June 2010 - Volume 16 - Issue 3 - p 261–268
doi: 10.1097/MCC.0b013e328338661e
Cardiopulmonary monitoring: Edited by Michael R. Pinsky

Purpose of review Patient–ventilator dyssynchrony (PVD) is prevalent in critically ill patients and causes increased work of breathing, which can lead to ventilatory muscle overload and fatigue as well as impairment in sleep efficiency, both important factors in determining ventilator duration.

Recent findings New ways to analyze and communicate information, such as embedded computerized algorithms that are able to calculate a dyssynchrony index and enhanced ventilator graphical displays, may assist the clinician with recognition of PVD. Esophageal pressure monitoring allows the clinician to address trigger, flow and cycle dyssynchrony as well as quantify the incremental work of breathing imposed by PVD. An analysis using relationships in the equation of motion allows for onset and cycling off of breaths that match closer with the patient effort compared with current algorithms. Monitoring diaphragmatic electrical activity permits the accurate assessment of relationships between neural drive and ventilator flow delivery, and can assess the workload of the diaphragm.

Summary Although computerized algorithms and user-friendly graphic displays show promise in minimizing the time to recognition of dyssynchrony, monitoring diaphragmatic electrical activity comes closest to representing the ideal in ventilator monitoring. Further work, however, is needed to demonstrate outcomes benefit to patients and to make this a reliable and user-friendly system for clinicians.

Division of Allergy, Pulmonary and Critical Care, Duke University Medical Center, Durham, North Carolina, USA

Correspondence to Neil MacIntyre, MD, Box 3911, Duke University Medical Center, Durham, NC 27710, USA Tel: +1 919 681 5691; fax: +1 919 681 2892; e-mail:

© 2010 Lippincott Williams & Wilkins, Inc.