Does change in skin perfusion provide a good index to monitor the sympathetic response to a noxious stimulus in preterm newborns?

Is measurement of capillary refill time useful as part of the initial assessment of children?

OBJECTIVE

The purpose of this study was to establish the usefulness of capillary refill time when measured during the initial assessment of children.

METHODS

All children with spontaneous illness attending a paediatric accident and emergency department over a 7-month period were eligible for entry into the study. Capillary refill time was measured at the fingertip, using a standard technique, as part of the initial assessment. Each child was then followed up to ascertain clinical progress, including the need for admission, intravenous fluids, length of stay and diagnosis, as well as the white cell count when this was available. The value of capillary refill time as a predictor of the markers of illness severity was then assessed.

RESULTS

Capillary refill time measurements were recorded on 4878 children. There was no significant association of capillary refill time with meningococcal disease, other significant bacterial illness or the white cell count. A prolonged capillary refill time was associated with a more urgent triage category, the administration of a fluid bolus and the length of hospital stay (P<0.0001). The best performance was obtained when a capillary refill time of 3s or more is taken to be 'prolonged'. However, this gave positive predictive values of only 9% for a triage category of 1 or 2 (negative predictive value 97%), 11% for requiring a fluid bolus (negative predictive value 99%), 55% for hospital admission (negative predictive value 65%) and 22% for stay over 2 days/death (negative predictive value 91%).

CONCLUSION

The prolongation of capillary refill time is a poor predictor of the need for intravenous fluid bolus or hospital admission.

Skin conductance and the stress response from heel stick in preterm infants

AIM

To evaluate whether spontaneous skin conductance activity is an objective method for measuring the stress response to painful stimuli in premature infants. The number and amplitude of the waves and the baseline increase with the activity of the sympathetic nervous system.

METHODS

In 20 preterm infants of gestational age >/= 29 weeks, behavioural state and spontaneous skin conductance activity variables were measured for three minutes before, during, and for three minutes after heel stick.

RESULTS

The number of waves (p < 0.001), the amplitude of the waves (p = 0.001), and the level of the behavioural state (p < 0.001) increased during heel stick, and then decreased to levels found before the procedure. The baseline increased both during (p < 0.001) and after heel stick (p < 0.001), compared with levels before.

CONCLUSION

Spontaneous skin conductance activity reflects the stress response to heel stick in premature infants from at least 29 weeks of gestational age.