Background and importance: Although various strategies have been examined to mitigate discomfort during sampling, arterial blood gas (ABG) is a common and often painful procedure in emergency departments (EDs). Hypnotic communication, characterized by positive language/suggestions, may help reduce perceived procedural pain. Conversely, the traditional use of negative language may increase discomfort through a 'nocebo' effect.
Objective: To assess whether hypnotic communication reduces procedural pain during ABG sampling compared with neutral or nocebo communication, when delivered by emergency physicians who have not received training in hypnosis.
Design, setting, and participants: A single-center, triple-blind, randomized controlled trial with three parallel arms (hypnotic, neutral, and nocebo) was conducted from 4 April 2023 to 31 July 2024, in the ED of a Swiss Tertiary Care Hospital. All adult patients requiring ABG sampling were eligible for inclusion.
Intervention: Three standardized communication scripts were used during a standardized procedure for ABG sampling: nocebo with negative words (e.g. ' I'm going to prick '), neutral with neutral words (e.g. ' I am taking the sample '), and hypnotic with positive words, and dissociative sentences (e.g. ' What is the noise of the lights at your home?' ). Communications were audio-recorded and independently reviewed to ensure protocol adherence.
Outcomes measure and analysis: The primary outcome was the pain intensity, measured with a 0-10 numerical rating scale 3 min after the ABG sampling. Secondary outcomes included comfort and anxiety levels. Linear mixed-effects models were employed to conduct both intention-to-treat and per-protocol analyses.
Main results: A total of 216 participants (median age 72 years; 57% male) were included (hypnotic, n = 71; nocebo, n = 71; neutral, n = 74). Dyspnea was the leading reason for ED consultation ( n = 143; 66.2%). Hypnotic communication was associated with a statistically significant reduction in postprocedural pain compared with neutral communication [ β = -0.97, 95% confidence interval (CI): -1.80 to 0.14, P = 0.02]; however, no significant differences were observed among the three groups in terms of median (interquartile range) pain scores [nocebo: 3 (1-5), neutral: 4 (2-6), hypnotic: 3 (1-5)], comfort or anxiety levels.
Conclusion: Implementing hypnotic communication in the ED during ABG procedures did not lead to clinically meaningful reductions in pain, anxiety, or discomfort.
