Are twitches, startles, and body movements pain indicators in extremely low birth weight infants?

OBJECTIVE: The goal of this study was to examine whether body activity such as postural, trunk, and limb movements may be potential pain cues in preterm infants.
DESIGN: Convenience sample.
SETTING: Level III neonatal intensive care unit (NICU). PATIENTS: Extremely low birth weight (< or = 1,000 g) preterm infants (n = 64) undergoing routine NICU medical care. OUTCOME MEASURES: Procedures likely to differ in evoking distress (i.e., endotracheal suctioning, chest physical therapy, diaper change, or nasogastric feed) were observed. Behaviors were recorded at bedside using the Neonatal Individualized Developmental Care and Assessment Program system.
RESULTS: Changes in heart rate and sleep/waking state were related to the procedures, supporting the assumption of differing relative disruption to the infant. Arching, squirming, startles, and twitching were not observed significantly more during procedures than at baseline. After controlling for background variables, finger splay and leg extension were significantly related to ongoing procedures. Facial brow raising was a function of the number of invasive procedures in the past 24 hours; thus, it may be a useful cue of sensitization.
CONCLUSIONS: Some extensor movements seemed to be distress signals, whereas tremors, startles, and twitches were not related to discomfort during the observation period. These behaviors may differ qualitatively during longer lasting tissue invasive events. The results of this study indicate the need for more in-depth study of patterns of motor activity in preterm infants over longer observation periods to evaluate potential signs of stress and pain in babies undergoing NICU medical care.