The effect of touch, pain stimulus, and stroking during pain stimulus on heart rate, blood pressure, and transcutaneous arterial oxygen tension in premature infants

This study was undertaken to determine the effects of touch, pain stimulus, and stroking at the time of application of a pain stimulus to premature infants. Data were collected on heart rate, blood pressure, and transcutaneous oxygen readings during each of the three procedures.

There were eight subjects in the study. The population was selected from an intensive care nursery serving as a regional referral center in East Tennessee. All infants included in the study were 32 to 34 weeks gestational age with a mean birth weight of 1,304.75 grams. The participants were nonasphyxiated as assessed by an Apgar score of 7 or higher at 5 minutes. Each infant had an umbilical artery catheter, cardiac monitor, and a transcutaneous oxygen monitor in place. The study included one set of twins.

Each infant in the study received the three treatments of touch, pain stimulus, and stroking during a pain stimulus in a random order. Treatment A was touch only. This treatment consisted of picking up the right foot of the infant, wiping it one time with a prepackaged alcohol wipe, and touching the heel with the blunt end of the lancet. Treatment B was the painful stimulus. This procedure involved picking up the right foot of the infant, wiping one time with a prepackaged alcohol wipe, and sticking the medial aspect of the heel with the lancet to obtain .10 cc of blood. Treatment C involved stroking at the time of application of a pain stimulus. This treatment involved picking up the right foot of the infant, wiping one time with a prepackaged alcohol wipe, sticking the medial aspect of the heel with the lancet while a research assistant stroked the medial aspect of the leg using moderate pressure. Each infant was in sleep state 2 at the beginning of the baseline and treatment periods.

Heart rate, blood pressure, and transcutaneous oxygen pressures were recorded at 1-minute intervals for a 5-minute baseline prior to each treatment. Measures of each parameter were recorded every 30 seconds for the first 2 minutes after each treatment and then at 1-minute intervals for 8 minutes. The infants' sleep states were recorded each minute.

It was concluded that stroking the leg during the heel stick was more aversive than the heel stick alone. The results suggest that premature infants respond to pain with an increase in heart rate and blood pressure as well as a decrease in transcutaneous arterial oxygen tension. These findings suggest that there is a need to identify interventions to decrease this pain response.