Evaluation of the depth of sedation in an intensive care unit based on the photo motor reflex variations measured by video pupillometry

Ouri Rouche,Joël Cousson,Damien Jolly,Thierry Floch,Aurore Wolak-Thierry,Quentin Destoop,Pascal Raclot,Lucas Milloncourt

doi:10.1186/2110-5820-3-5

Abstract

BackgroundEvaluating depth of sedation in the intensive care unit (ICU) is crucial for the management of mechanically ventilated patients but can be challenging in some situations. Because the depth of hypnosis is correlated with the decrease in photomotor reflex (PMR), we suggest using pupillometric video as an automated, noninvasive, simple, and reproducible technique to evaluate the depth of sedation in ICU patients. We compare the effectiveness of this procedure to the bispectral index (BIS).MethodsThirty-one patients requiring sedation and ventilation were included in this monocentric, observational study. The posology of hypnotics and morphinics were based on the Richmond Agitation and Sedation Scale (RASS). PMR was measured by the Neurolight® (IDMED) system and BIS value by BIS Vista® (Anandic Medical Systems). RASS, PMR, and BIS were measured three times daily in all patients. Data acquired by pupillometric video included variation in pupillary diameter (ΔPD), latency time (LT), and maximal speed of pupillary constriction (Vmax). These parameters were analyzed after having classified BIS values in three groups (<40 heavy sedation; 40 ≤ BIS ≤ 60 acceptable sedation; >60 light sedation). Exclusion criteria were neurological or ophthalmologic pathologies that could interfere with PMR.ResultsThere was a significant difference in Vmax and ΔPD between the BIS < 40 group and 40 ≤ BIS ≤ 60 groups (p < 0.0001 for each) and between the BIS < 40 and BIS > 60 groups (p < 0.0001 for each). There were no significant differences in Vmax and ΔPD between the 40 ≤ BIS ≤ 60 and BIS > 60 groups. There was no correlation between any of the BIS groups and LT.ConclusionsVmax and ΔPD seem to be relevant criteria compared with the BIS and the RASS. Pupillometric video monitoring of depth of sedation could be beneficial in ICU patients, especially for those under myorelaxant drugs, where no clinical evaluation of sedation is possible.

Highlights

Evaluating depth of sedation in the intensive care unit (ICU) is crucial for the management of mechanically ventilated patients but can be challenging in some situations
Because the depth of hypnosis is known to be correlated with a decrease in photomotor reflex (PMR) [5,6,7,8,9,10], it could be beneficial to develop an automated, noninvasive, simple, and reproducible technique to evaluate efficiently the depth of sedation in an ICU based on the pupillary reflex
A total of 167 measures of PMR and bispectral index (BIS) were conducted on 31 patients

Summary

Introduction

Evaluating depth of sedation in the intensive care unit (ICU) is crucial for the management of mechanically ventilated patients but can be challenging in some situations. Because the depth of hypnosis is correlated with the decrease in photomotor reflex (PMR), we suggest using pupillometric video as an automated, noninvasive, simple, and reproducible technique to evaluate the depth of sedation in ICU patients. Because the depth of hypnosis is known to be correlated with a decrease in photomotor reflex (PMR) [5,6,7,8,9,10], it could be beneficial to develop an automated, noninvasive, simple, and reproducible technique to evaluate efficiently the depth of sedation in an ICU based on the pupillary reflex. Values remain widely dispersed but are correlated to clinical sedation scale values (e.g., RASS −5)

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Results

Discussion

Conclusion