Sorting pain out of salience: assessment of pain facial expressions in the human fetus.
Pain Rep 2021;
6:e882. [PMID:
33537520 PMCID:
PMC7850725 DOI:
10.1097/pr9.0000000000000882]
[Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 11/02/2020] [Accepted: 11/07/2020] [Indexed: 11/25/2022] Open
Abstract
Supplemental Digital Content is Available in the Text.
Acute pain facial expressions can be detected/scored in human fetuses. We propose a seven-item scale to differentiate pain facial expressions from rest/acoustic stimuli ones.
Introduction:
The question of whether the human fetus experiences pain has received substantial attention in recent times. With the advent of high-definition 4-dimensional ultrasound (4D-US), it is possible to record fetal body and facial expressions.
Objective:
To determine whether human fetuses demonstrate discriminative acute behavioral responses to nociceptive input.
Methods:
This cross-sectional study included 5 fetuses with diaphragmatic hernia with indication of intrauterine surgery (fetoscopic endoluminal tracheal occlusion) and 8 healthy fetuses, who were scanned with 4D-US in 1 of 3 conditions: (1) acute pain group: Fetuses undergoing intrauterine surgery were assessed in the preoperative period during the anesthetic injection into the thigh; (2) control group at rest: Facial expressions at rest were recorded during scheduled ultrasound examinations; and (3) control group acoustic startle: Fetal facial expressions were recorded during acoustic stimulus (500–4000 Hz; 60–115 dB).
Results:
Raters blinded to the fetuses’ groups scored 65 pictures of fetal facial expressions based on the presence of 12 items (facial movements). Analyses of redundancy and usefulness excluded 5 items for being of low discrimination capacity (P>0.2). The final version of the pain assessment tool consisted of a total of 7 items: brow lowering/eyes squeezed shut/deepening of the nasolabial furrow/open lips/horizontal mouth stretch/vertical mouth stretch/neck deflection. Odd ratios for a facial expression to be detected in acute pain compared with control conditions ranged from 11 (neck deflection) to 1,400 (horizontal mouth stretch). Using the seven-item final tool, we showed that 5 is the cutoff value discriminating pain from nonpainful startle and rest.
Conclusions:
This study inaugurates the possibility to study pain responses during the intrauterine life, which may have implications for the postoperative management of pain after intrauterine surgical interventions
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