Exploring the association between pain intensity and facial display in term newborns

Pediatricians' focus of sight at pain assessment during a neonatal heel puncture

OBJECTIVE

To evaluate the focus of pediatricians' gaze during the heel prick of neonates.

METHODS

Prospective study in which pediatricians wearing eye tracker glasses evaluated neonatal pain before/after a heel prtick. Pediatricians scored the pain they perceived in the neonate in a verbal analogue numerical scale (0=no pain; 10=maximum pain). The outcomes measured were number and time of visual fixations in upper face, lower face, and hands, in two 10-second periods, before (pre) and after the puncture (post). These outcomes were compared between the periods, and according to pediatricians' pain perception: absent/mild (score: 0-5) and moderate/intense (score: 6-10).

RESULTS

24 pediatricians (31 years old, 92% female) evaluated 24 neonates. The median score attributed to neonatal pain during the heel prick was 7.0 (Interquartile range: 5-8). Compared to pre-, in the post-periods, more pediatricians fixed their gaze on the lower face (63 vs. 92%; p=0.036) and the number of visual fixations was greater on the lower face (2.0 vs. 5.0; p=0.018). There was no difference in the number and time of visual fixations according to the intensity of pain.

CONCLUSIONS

At bedside, pediatricians change their focus of attention on the neonatal face after a painful procedure, focusing mainly on the lower part of the face.

Looking at neonatal facial features of pain: do health and non-health professionals differ?

OBJECTIVE

To analyze the regions that trigger the attention of adults' gaze when assessing pain in newborn infants' pictures and to verify if there are differences between health and non-health professionals.

METHOD

Experimental study with 84 health professionals and 59 non-health professionals, who evaluated two images of 10 neonates, one at rest and the other during a painful procedure. Each image was shown for 7 seconds on a computer screen, while eye movements were tracked by the Tobii TX300 EyeTracker. After evaluating each image, participants gave a score from 0 (absent pain) to 10 (maximum pain), according to their perception of neonatal pain. For each image, the number and total time of gaze fixations in the forehead, eyes, nasolabial furrow, and mouth were studied. Comparisons between both groups of adults were made by an intraclass correlation coefficient, Student's t-test, and Bland Altman graphic.

RESULTS

Health professionals (93% female; 34 ± 9 years old), compared to non-health professionals (64% female; 35 ± 11 years old), gave lower scores for images at rest (0.81 ± 0.50 vs. 1.59 ± 0.76; p = 0.010), with no difference for those obtained during the painful procedure (6.98 ± 1.08 vs. 6.73 ± 0.82). There was a strong or almost perfect correlation for the number of fixations in the mouth, eyes, forehead, and for the total fixation time in the eyes and forehead.

CONCLUSIONS

Adults, irrespective of their profession, showed a homogeneous gaze pattern when evaluating pictures of neonates at rest or during a painful procedures.

Identification of pain in neonates: the adults' visual perception of neonatal facial features

OBJECTIVE

To verify the visual attention of adults when assessing neonatal pain.

STUDY DESIGN

143 adults (59% health professionals) evaluated 20 pictures (2 pictures of 10 neonates' faces: at rest; during a painful procedure). Tobii-TX300 tracked the participants' eyes movement. For each picture, adults scored pain intensity (0 = no pain; 10 = maximum). Latent classes analysis was applied by cognitive diagnosis models-GDINA with two attributes (knowledge of pain presence/absence). Variables associated with belonging to the class of adults that correctly identified pictures of newborns with/without pain were identified by logistic regression.

RESULTS

To identify neonatal pain, adults look at the mouth, eyes, and forehead in facial pictures. The latent class analysis identified four classes of adults: those that identify painful/painless neonates (YY-Class; n = 80); only painful neonates (n = 28); only painless neonates (n = 34) and none (n = 1). Being a health professional (OR: 2.29; 95% CI: 1.16-4.51), and each look at the nasolabial furrow (2.07; 1.19-3.62) increased the chance of belonging to the YY-class.

CONCLUSIONS

Being a health professional and the visual fixation at the nasolabial furrow helped to identify the presence/absence of neonatal pain.

What Facial Features Does the Pediatrician Look to Decide That a Newborn Is Feeling Pain?

OBJECTIVE

 The study aimed to analyze the gaze fixation of pediatricians during the decision process regarding the presence/absence of pain in pictures of newborn infants.

STUDY DESIGN

 Experimental study, involving 38 pediatricians (92% females, 34.6 ± 9.0 years, 22 neonatologists) who evaluated 20 pictures (two pictures of each newborn: one at rest and one during a painful procedure), presented in random order for each participant. The Tobii-TX300 equipment tracked eye movements in four areas of interest of each picture (AOI): mouth, eyes, forehead, and nasolabial furrow. Pediatricians evaluated the intensity of pain with a verbal analogue score from 0 to 10 (0 = no pain; 10 = maximum pain). The number of pictures in which pediatricians fixed their gaze, the number of gaze fixations, and the total and average time of gaze fixations were compared among the AOI by analysis of variance (ANOVA). The visual-tracking parameters of the pictures' evaluations were also compared by ANOVA according to the pediatricians' perception of pain presence: moderate/severe (score = 6-10), mild (score = 3-5), and absent (score = 0-2). The association between the total time of gaze fixations in the AOI and pain perception was assessed by logistic regression.

RESULTS

 In the 20 newborn pictures, the mean number of gaze fixations was greater in the mouth, eyes, and forehead than in the nasolabial furrow. Also, the average total time of gaze fixations was greater in the mouth and forehead than in the nasolabial furrow. Controlling for the time of gaze fixation in the AOI, each additional second in the time of gaze fixation in the mouth (odds ratio [OR]: 1.26; 95% confidence interval [CI]: 1.08-1.46) and forehead (OR: 1.16; 95% CI: 1.02-1.33) was associated with an increase in the chance of moderate/severe pain presence in the neonatal facial picture.

CONCLUSION

 When challenged to say whether pain is present in pictures of newborn infants' faces, pediatricians fix their gaze preferably in the mouth. The longer duration of gaze fixation in the mouth and forehead is associated with an increase perception that moderate/severe pain is present.

KEY POINTS

· Neonatal pain assessment is intrinsically subjective.. · Visual tracking identifies the focus of attention of individuals.. · Adults' gaze in neonates' mouth and forehead is associated with pain perception..

Pain assessment in human fetus and infants

In humans, painful stimuli can arrive to the brain at 20-22 weeks of gestation. Therefore several researchers have devoted their efforts to study fetal analgesia during prenatal surgery, and during painful procedures in premature babies. Aim of this paper is to gather from scientific literature the available data on the signals that the human fetus and newborns produce, and that can be interpreted as signals of pain. Several signs can be interpreted as signals of pain. We will describe them in the text. In infants, these signs can be combined to create specific and sensible pain assessment tools, called pain scales, used to rate the level of pain.