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. 2009 Mar;24(1):74-80.
doi: 10.1016/j.jcrc.2008.08.011. Epub 2009 Jan 17.

Observational study of patient-ventilator asynchrony and relationship to sedation level

Marjolein de Wit  1 , Sammy Pedram, Al M Best, Scott K Epstein
Affiliations

Observational study of patient-ventilator asynchrony and relationship to sedation level

Marjolein de Wit et al. J Crit Care. 2009 Mar.

Abstract

Purpose: Clinicians frequently administer sedation to facilitate mechanical ventilation. The purpose of this study was to examine the relationship between sedation level and patient-ventilator asynchrony.

Materials and methods: Airway pressure and airflow were recorded for 15 minutes. Patient-ventilator asynchrony was assessed by determining the number of breaths demonstrating ineffective triggering, double triggering, short cycling, and prolonged cycling. Ineffective triggering index (ITI) was calculated by dividing the number of ineffectively triggered breaths by the total number of breaths (triggered and ineffectively triggered). Sedation level was assessed by the following 3 methods: Richmond Agitation-Sedation Scale (RASS), awake (yes or no), and delirium (Confusion Assessment Method for the intensive care unit [CAM-ICU]).

Results: Twenty medical ICU patients underwent 35 observations. Ineffective triggering was seen in 17 of 20 patients and was the most frequent asynchrony (88% of all asynchronous breaths), being observed in 9% +/- 12% of breaths. Deeper levels of sedation were associated with increasing ITI (awake, yes 2% vs no 11%; P < .05; CAM-ICU, coma [15%] vs delirium [5%] vs no delirium [2%]; P < .05; RASS, 0, 0% vs -5, 15%; P < .05). Diagnosis of chronic obstructive pulmonary disease, sedative type or dose, mechanical ventilation mode, and trigger method had no effect on ITI.

Conclusions: Asynchrony is common, and deeper sedation level is a predictor of ineffective triggering.

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Conflict of interest statement

Conflict of interest: No author has a conflict of interest to disclose.

Figures

Figure 1
Figure 1
Examples of asynchronies. Panel A demonstrates ineffective triggering which is marked by a decrease in airway pressure (arrow 1) and simultaneous increase in airflow (arrow 2). Panel B demonstrates an example of double triggering (arrow 3). Panel C shows an example of short cycling (arrow 4). Panel D shows an example of prolonged cycling (arrow 5).
Figure 1
Figure 1
Examples of asynchronies. Panel A demonstrates ineffective triggering which is marked by a decrease in airway pressure (arrow 1) and simultaneous increase in airflow (arrow 2). Panel B demonstrates an example of double triggering (arrow 3). Panel C shows an example of short cycling (arrow 4). Panel D shows an example of prolonged cycling (arrow 5).
Figure 2
Figure 2
The relationship between Richmond Agitation-Sedation Scale (RASS) and ineffective triggering index (ITI). For one unit decrease in RASS, ITI increased by 2.7%, p = 0.04.
See this image and copyright information in PMC

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