FACTORS THAT INFLUENCE THE BEHAVIORAL PAIN RESPONSES OF PREMATURE-INFANTS

The responses of preterm neonates to acute tissue-damaging stimuli hav e been described. However, factors which influence these responses hav e received little attention. In this study, we observed 124 premature infants before, during and after a routine heel lance and determined h ow two contextual variables (severity of illness and behavioral state) influenced their behavioral responses. Significant changes in facial actions occurred between baseline and the most invasive phase of the h eel lance procedure, stick. The fundamental frequency, harmonic struct ure and peak spectral energy of the infant's cry were also significant ly increased during the stick phase. Behavioral state was found to inf luence the facial action variables and severity of illness modified th e acoustic cry variables. Accurate identification of pain in premature infants requires consideration of factors that influence their respon se.