JMIR Publications

ABSTRACT

Background:

In the intensive care unit (ICU), many patients are unable to communicate their pain through self-report or behaviors due to their critical care condition, mechanical ventilation, and medication (e.g., heavily sedated or chemically paralyzed). Therefore, alternative pain assessment methods are urgently needed for this vulnerable patient population. The Nociception Level (NOL) index is a multi-parameter technology initially developed for the monitoring of nociception and related pain in anesthetized patients, and its use in the ICU is new.

Objective:

To validate the NOL for the assessment of nociception and related pain in critically ill adults in the ICU. Specific objectives are to examine the ability of the NOL to: a) detect pain using standard criteria (i.e., self-report and behavioral measures), and b) discriminate between nociceptive and non-nociceptive procedures, and c) generate consistent values when ICU patients are at rest will be examined.

Methods:

The NOL will be monitored in three ICU patient groups: a) Group A: participants able to self-report their pain (the reference standard criterion using the 0-10 Faces Pain Thermometer) and express behaviors; b) Group B: participants unable to self-report but express behaviors (the alternative standard criterion using the Critical-Care Pain Observation Tool or CPOT); and c) Group C: participants unable to self-report and to express behaviors. The NOL will be tested before, during and after two types of standard care procedures: a) non-nociceptive (e.g., cuff inflation to measure blood pressure, soft touch), and b) nociceptive (e.g., tube or drain removal, endotracheal/tracheal suctioning). Receiver Operating Characteristic curve analysis of the NOL will be performed for Group A and B using pain standard measures as reference criteria. Mixed linear models for repeated measures will be used to compare time points, procedures, and their interaction in each group (A, B and C). Paired t tests will be performed at rest condition (i.e., pre and post procedures). Based on power analyses and considering an attrition rate of 25%, a total sample size of 146 patients (68 in Group A; 62 in Group B; 16 in Group C) is targeted.

Results:

Recruitment and data collection began at the primary site in July 2022 and have been implemented at the secondary sites in 2023 and 2024. Study implementation will be on-going until the end of 2025.

Conclusions:

The primary strength of this study protocol is based on rigorous validation strategies with the use of pain standard criteria (i.e., self-report and behavioral measures). If found to be valid, the NOL could be used as an alternative physiologic measure of pain in critically ill adults in whom no other pain assessment methods are available. Clinical Trial: ClinicalTrials.gov ID NCT05339737; https://clinicaltrials.gov/study/NCT05339737