Related Experiment Video
Updated: Jul 19, 2026
A Preterm Rat Model for Pain Studies
Published on: February 9, 2024
Behavioral responses to pain are heightened after clustered care in preterm infants born between 30 and 32 weeks
Liisa Holsti1, Ruth E Grunau, Michael F Whifield
1Centre for Community Child Health Research, Child and Family Research Institute, Vancouver, Canada. lholsti@cw.bc.ca
Insights
Preterm infants’ pain responses differ by gestational age. Earlier born infants show heightened arousal, while later born infants exhibit sensitized responses to routine nursing care before procedures.
Area of Science:
- Neonatal care
- Pediatric pain research
- Biobehavioral responses
Background:
- Preterm infants experience frequent painful procedures.
- Gestational age influences pain response development.
- Routine nursing care can impact pain sensitivity.
Purpose of the Study:
- To compare biobehavioral pain responses in preterm infants based on gestational age.
- To investigate the effect of preceding rest versus routine nursing interventions on pain responses.
Main Methods:
- Randomized, within-subjects, cross-over design.
- 43 preterm infants (GA 25-32 weeks) assessed.
- Facial, sleep/wake, and heart rate responses measured during blood collection.
Main Results:
- Infants <30 weeks GA showed consistent facial responses.
- Infants ≥30 weeks GA had heightened facial responses after clustered care (P=0.05).
- Later born infants showed reduced facial and heart rate reactivity during recovery post-clustered care (P=0.05, P=0.04).
Conclusions:
- Earlier born infants exhibit heightened arousal and poor heart rate modulation post-procedure.
- Later born infants display sensitized responses when procedures follow clustered care.
- Individualized, cue-based care is crucial for preterm infants.
Objective:
To compare biobehavioral pain responses of preterm infants born at differing gestational ages (GAs) when pain was preceded by a rest period or by a series of routine nursing interventions.
Methods:
In a randomized, within subjects, cross-over design, facial (Neonatal Facial Coding System), sleep/wake state and heart rate (HR) responses of 43 preterm infants [mean birth weight: 1303 g (range 590 g to 2345 g); mean GA at birth: 30 weeks (range 25 to 32)] were examined across 3 phases of blood collection (Baseline, Lance, and Recovery) under 2 conditions: pain after a 30-minute rest period versus pain after a series of routine nursing interventions (clustered care). Infant behavioral responses were coded from continuous bedside videotapes. HR was analyzed using custom physiologic signal processing software.
Results:
Infants born at earlier GA (<30 wk) had equally intense facial responses during the Lance phase regardless of condition. However, later born infants (> or =30 wk GA) showed heightened facial responses indicative of sensitized responses during blood collection when it was preceded by clustered care (P=0.05). Moreover, later born infants had significantly lower facial (P=0.05) and HR (P=0.04) reactivity during Recovery when blood collection followed clustered care.
Discussion:
Earlier born preterm infants showed heightened states of arousal and poor ability to modulate HR during Recovery when an invasive procedure was preceded by routine tactile nursing procedures. Alternatively, later born infants exhibited sensitized responses when clustered care preceded blood collection. Our findings support the importance of cue based individualized approaches to care.
