Variability in pain expression characteristics in former preterm infants

textabstractObjectives: To document pain expression characteristics in former preterm infants in the first year of life in whom systematic evaluation and treatment of pain was provided. Methods: Data on the Modified Behavioral Pain Scale (MBPS), Visual Analogue Scale (VAS, crying time and heart rate were collected during immunization. The effect of clinical characteristics {postconception and gestational age [PCA], surgery, ventilation, fentanyl, length of stay (LOS)} on bio-behavioral parameters was evaluated. Results: 121 procedures were recorded in 49 infants. GA was 28 (25-32) weeks. PCA was 60 (34-90) weeks. Median MBPS was 8 (2-10), median crying time 44 (0-112) s. Median pre-procedural heart rate was 144 (103-201) and increased to 184 (147-220) afterwards, resulting in a relative increase of 29 (5-99)%. Median VAS score was 7 (1-10). Significant correlations of PCA with pre-procedural heart rate (r=-0.36) and with relative increase in heart rate (r=0.33) were identified. A correlation of LOS on crying time (r=0.37) was observed. Conclusions: Correlations of PCA with pre-procedural and relative increase in heart rate reflect the maturational decrease in heart rate. LOS had an effect on pain expression, potentially reflecting the impact of cumulative 'minor' procedural pain. Copyright