The comparison of pupillometry to standard clinical practice for pain and preemptive analgesia before endotracheal suctioning: A randomized controlled trial

Background: Pain during endotracheal aspiration (ETA) is frequent in critically ill patients. Managing pre-emptive analgesia before procedures remains a crucial aspect of care. We compared pupillometry to standard clinical practice for assessing preemptive-analgesia administration and pain before ETA according to Behavioural Pain Scale (BPS), the Behavioural Pain Indicator Scale (ESCID), and the Pupillary Dilation Reflex (PDR). Trial design: A multicentre parallel-group, controlled trial with balanced (1:1) randomization. Methods: Sedated, mechanically ventilated patients aged >= 18 with baseline BPS = 3, ESCID = 1, and RASS scores between-1 and-4 were included. Control group: preemptive-analgesia was administered according to nurse criteria. In the experimental group, preemptive analgesia was administered in patients with PDR >= 11.5% after a 20 mA stimulus measured using AlgiScan (R). The preemptive analgesia was fentanyl one mu g/kg iv bolus. We used the Chi-square statistic to compare post-intervention pain according to BPS, ESCID, and PDR pain values. A multivariate logistic regression study adjusting for sex, BIS, RASS, APACHE II, remifentanil, and preemptive analgesia was conducted. Results: Ninety-two patients were studied, 51 in control groups and 41 in intervention groups. Pain incidence was lower in the experimental group. Significantly, 43.9 % of patients in the experimental group were prescribed preemptive analgesia before ETA compared to 19.6 % in the control group (p = 0.03). Multivariate analysis showed significant reductions in pain in the group that received preemptive-analgesia before ETA guided by pupillometry across BPS [OR = 0.34 (95% CI: 0.12-0.99), p = 0.048], ESCID [OR = 0.29 (95% CI: 0.09-0.88), p = 0.030] and PDR [OR = 0.27 (95 % IC: 0.08-0.86), p = 0.027] compared to standard clinical practice. Conclusions: Preemptive analgesia monitored with pupillometry group had a lower percentage of patients with pain than those who received analgesia based on standard clinical practice. This effect was independent of the sex, patient severity, BIS score, remifentanil use, or preemptive- analgesia. Implications for clinical practice: The requirement for preemptive analgesia before aspiration, evaluated through routine clinical practice, was lower than detected by pupillometric monitoring of patients. The use of pupillometry to monitor preemptive analgesia reduced pain after secretion aspiration. Pupillometry would be an effective tool to individualize the need for preemptive analgesia before potentially painful interventions, applicable to all patients regardless of sex, severity, or sedation level.