Impaired parasympathetic response to feeding in
ventilated preterm babies
Sandra L Smith 1*, Alexa K Doig 1 and William N Dudley 1
1 University of Utah, United States
* To whom correspondence should be addressed. E-mail: sandra.smith{at}nurs.utah.edu.
Accepted 20 May 2005
 | Abstract |
|---|
Background:Premature very-low-birth-weight (VLBW)
infants are born with an underdeveloped parasympathetic
nervous system which may limit their ability to respond
adequately to feeding, and may limit their capacities
for extrauterine growth and development.
Objectives:To describe the patterns of autonomic
response to feeding and identify relationships between
change in heart period variability measures over time
with selected infant characteristics.
Methods:Individual growth curve analysis
techniques were used to describe the patterns of change
over time in sympathetic and parasympathetic tone as
measured by low- and high-frequency heart period power.
Results:Sixteen mechanically ventilated VLBW
infants with a mean corrected gestational age of 30.4
weeks participated. The LF power slope was -17.67
(p=0.0002) and the HF power slope was -0.92 (0.0003).
There was a significant relationship between HF slope
and birth gestational age (r = -0.49, p = 0.05).
Conclusions:HF power, representing primarily
parasympathetic activity, did not increase with enteral
feeding as anticipated. LF power, an indicator of
sympathetic tone, decreased during and after feeding,
suggesting the anticipated effect of inhibition of the
sympathetic nervous system in response to the gut
stimulus. Critically ill VLBW infants possess an
overriding sympathetic response, but may not have
adequate PNS tone development.
Keywords:
growth curve analysis, heart period variability, high-frequency power, low-frequency power, ventilated infant
