Can fluctuations in vital signs be used for pain assessment in critically ill patients with a traumatic brain injury?

Background. Many critically ill patients with a traumatic brain injury (TBI) are unable to communicate. While observation of behaviors is recommended for pain assessment in nonverbal populations, they are undetectable in TBI patients who are under the effects of neuroblocking agents. Aim. This study aimed to validate the use of vital signs for pain detection in critically ill TBI patients. Methods. Using a repeated measure within subject design, participants (N = 45) were observed for 1 minute before (baseline), during, and 15 minutes after two procedures: noninvasive blood pressure: NIBP (nonnociceptive) and turning (nociceptive). At each assessment, vital signs (e.g., systolic, diastolic, mean arterial pressure (MAP), heart rate (HR), respiratory rate (RR), capillary saturation (SpO2), end-tidal CO2, and intracranial pressure (ICP)) were recorded. Results. Significant fluctuations (P < 0.05) in diastolic (F = 6.087), HR (F = 3.566), SpO2 (F = 5.740), and ICP (F = 3.776) were found across assessments, but they were similar during both procedures. In contrast, RR was found to increase exclusively during turning (t = 3.933; P < 0.001) and was correlated to participants' self-report. Conclusions. Findings from this study support previous ones that vital signs are not specific for pain detection. While RR could be a potential pain indicator in critical care, further research is warranted to support its validity in TBI patients with different LOC.