Dear Sir,
We read this paper with interest and would like to comment. The
authors have concluded that there is little evidence that early postnatal
hypotension indicators are associated with developmental delay at 24
months corrected in their large cohort of extremely low gestational age
newborns.
We agree with their conclusion as our recent study in 11 asphyxiated
term infants demonstrated the similar results (1): there were no
significant differences in mean arterial blood pressure (ABP) nor mean
cerebral blood flow (CBF) during the first 4 days of life between 5
infants with delayed development and 6 infants with normal development at
20 months of age. Interestingly enough, however, significant difference
(p=0.04) was found in an average stability index during the first 48 hours
of life (SI), arbitrarily defined as a coefficient of variation of CBF
monitored by a newly developed laser doppler flowmeter system (CDF Trend,
LIBMECH Inc. Tokyo, Japan) (2).
Cerebral blood passivity develops when changes in blood pressure
exceed the capacity of the intact cerebral autoregulatory system or the
system is impaired by illness such as HIE. In such a situation, ABP may
directly affect and are expected to correlate with CBF. Contrary to our
expectation, however, there was no significant relationship between the
mean ABP and CBF even in the 5 infants with HIE in the present study.
Thus, function of cerebral autoregulatory system, which is expected
to be a good predictor for neurological prognosis, cannot be assessed by
simple measurements of ABP. Serial monitoring of CBF stability during
early neonatal period assessed as SI by a novel laser doppler flowmeter
can be sensitive indicator for cerebral autoregulatory system as it
reflects instability of CBF in the vulnerable period. Further study will
be worthwhile.
References
1. Ohashi A, Kuroyanagi Y, Kitamura N, Kinoshita Y, Kaneko K, Yabuta K.
Cerebral blood flow monitoring using a novel laser Doppler flowmeter in
asphyxiated infants. Pediatr Int. 2009; 51: 715-719
2. Niwayama J, Sanaka Y. Development of a new method for monitoring blood
purification: the blood flow analysis of the head and foot by laser
Doppler blood flowmeter during hemodialysis. Hemodial Int. 2005; 9: 56-62
Conflict of Interest:
None declared
Dear Sir,
We read this paper with interest and would like to comment. The authors have concluded that there is little evidence that early postnatal hypotension indicators are associated with developmental delay at 24 months corrected in their large cohort of extremely low gestational age newborns.
We agree with their conclusion as our recent study in 11 asphyxiated term infants demonstrated the similar results (1): there were no significant differences in mean arterial blood pressure (ABP) nor mean cerebral blood flow (CBF) during the first 4 days of life between 5 infants with delayed development and 6 infants with normal development at 20 months of age. Interestingly enough, however, significant difference (p=0.04) was found in an average stability index during the first 48 hours of life (SI), arbitrarily defined as a coefficient of variation of CBF monitored by a newly developed laser doppler flowmeter system (CDF Trend, LIBMECH Inc. Tokyo, Japan) (2).
Cerebral blood passivity develops when changes in blood pressure exceed the capacity of the intact cerebral autoregulatory system or the system is impaired by illness such as HIE. In such a situation, ABP may directly affect and are expected to correlate with CBF. Contrary to our expectation, however, there was no significant relationship between the mean ABP and CBF even in the 5 infants with HIE in the present study.
Thus, function of cerebral autoregulatory system, which is expected to be a good predictor for neurological prognosis, cannot be assessed by simple measurements of ABP. Serial monitoring of CBF stability during early neonatal period assessed as SI by a novel laser doppler flowmeter can be sensitive indicator for cerebral autoregulatory system as it reflects instability of CBF in the vulnerable period. Further study will be worthwhile.
References 1. Ohashi A, Kuroyanagi Y, Kitamura N, Kinoshita Y, Kaneko K, Yabuta K. Cerebral blood flow monitoring using a novel laser Doppler flowmeter in asphyxiated infants. Pediatr Int. 2009; 51: 715-719 2. Niwayama J, Sanaka Y. Development of a new method for monitoring blood purification: the blood flow analysis of the head and foot by laser Doppler blood flowmeter during hemodialysis. Hemodial Int. 2005; 9: 56-62
Conflict of Interest:
None declared