Defense Date


Document Type


Degree Name

Doctor of Philosophy


Adult Health Nursing

First Advisor

Mary Jo Grap

Second Advisor

Cindy Munro

Third Advisor

Curtis Sessler

Fourth Advisor

Paul Wetzel


Patient ventilator dyssynchrony (PVD) occurs frequently, but little is known about the types, frequency and patterns of PVD for longer than 30 minutes. Deeper levels of sedation are associated with PVD. Evaluation of ventilator graphics and the ability to identify PVD should assist clinicians to optimize patient ventilator interactions and promote earlier interventions. The purpose of this study was to identify the different types, frequency and patterns of PVD in critically ill adults and determine the effect of sedation level on PVD. Thirty medical and surgical ICU adult patients were enrolled; 27 were used for analysis. Pressure/time and flow/ time waveform data were collected using the Noninvasive Cardiac Output monitor for up to 90 minutes per subject. Blinded waveform analysis was performed. Sedation level was measured every 20 minutes. A Dyssynchrony Index (DI) and PVD Type Indices were used to describe PVD frequency. Lag analysis was used to detect associated patterns of PVD. PVD occurred during all phases of ventilated breaths and during each of the ventilatory modes used. Heretofore undocumented dyssynchrony in the form of patient gasp PVD, active triggers and combined PVDs were found. The most common type of PVD was Ineffective Trigger (63%), followed by Premature Termination-Flow (17%), Premature Termination (9%), Multiple Trigger (1%), Flow (0.87%) and Delayed Termination (0.09%). The overall frequency of dyssynchronous breaths in the sample was 23% of total breaths analyzed, however 93% of subjects experienced at least one incident of PVD. The overall median DI (Interquartile Range [IQR]) was 4% (1% - 9%) with Ineffective Trigger Index having the highest median index (1.78%). The high DI group (6 subjects, 22%) had a DI (IQR) of 61% (42% - 85%). Seventy seven percent of subjects experienced multiple types of PVD. Premature Termination was followed by Multiple Triggers starting at 3 seconds, but Delayed Termination was followed by Ineffective Triggers, starting at 30 seconds. Clinicians need to recognize PVD, since this is a critical step in evaluating patient ventilator interaction and providing subsequent intervention. PVD interpretation is complex requiring clinicians to clearly understand the operational function of ventilator modes and waveform alterations that occur.


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