Objectives: 
The Nociception Coma Scale – Revised (NCS-R) was developed to help assessing pain in patients with disorders of consciousness (DOC) [1,2], encompassing (1) patients showing only reflexive behaviors (the Unresponsive Wakefulness Syndrome [UWS] [3], also known as vegetative state) and (2) patients exhibiting purposeful, consistent but fluctuating behaviors, but unable to functionally communicate (Minimally Conscious State [MCS]) [4]. However, no study has investigated the influence of the presence of a tracheostomy tube, preventing the patient to emit any sound and thereby potentially impacting the verbal subscore of the scale. 

Methods:
In the present study, we included 125 patients (UWS: 46 patients, MCS: 74 patients, EMCS: 5 patients; mean age: 46 years +/- 16; time since injury: 817 days +/- 1280) who were evaluated with the NCS-R after noxious stimulation and we compared the NCS-R scores of patients with and without tracheostomy. U Mann-Whitney tests were used to investigate the difference in NCS-R verbal subscores and total scores in response to noxious stimulation between patients with and without a tracheostomy tube. In a second step, a receiver operating characteristic (ROC) analysis was used to determine the best cut-off score allowing to differentiate a behavioral response to noxious stimulation versus rest, in order to replicate the recent previous findings on a cut-off score of 2 for nociception [5]. Finally, to determine a possible influence of the tracheostomy on the cut-off score, we performed a ROC analysis on the NCS-R total score with and without the verbal subscore on a subset of patients with tracheostomy.

Results: 
Lower scores were observed on the NCS-R verbal subscores (p = 0.002, one-tailed) and total scores (p = 0.039, one-tailed) in the tracheostomy group as compared with patients without a tracheostomy in response to noxious stimulation. Therefore, the presence of a tracheostomy influenced the verbal subscores as well as the total scores. In a second step, we replicated, using a ROC analysis, the previously reported cut-off of 2, score allowing to differentiate a behavioral response to noxious stimulation versus rest. In addition, we showed that this cut-off score remained valid for the group of patients with tracheostomy, as well as when we excluded the verbal subscore of the NCS-R. 

Conclusion: 
These findings support the previously reported cut-off score of 2. Unfortunately, this score can easily be reached with only reflexive behaviors and is therefore of limited interest in a clinical context. They also suggest that the presence or the absence of a tracheostomy does not invalidate the use of NCS-R in a clinical setting. Nevertheless, the presence of a tracheostomy should clearly be mentioned in the medical file and a change of score in a tracheotomized patient should be cautiously interpreted.

Investigating the influence of a tracheostomy on the evaluation with the Nociception Coma Scale – Revised