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K.K. Diwakar Golam Rosul
From the Neonatal Division, Department of Pediatrics, Kasturba Medical College, Manipal 576119, India.
Reprint requests: Dr. K.K. Diwakar, Head, Neonatal Division, Associate Professor, Department
of Pediatrics, Kasturba Medical College, Manipal576 119, India.
Manuscript received; August 25, 1998; Initial review completed: October 7, 1998;
Revision accepted: January 6, 1999
The micro-ESR is a popular constituent of the screening tests undertaken to
detect neo- natal sepsis and has for long been recognized as a valid
investigative tool(1). A normal micro-ESR had been considered as 'day of life plus 3 mm/hr! to maximum of 15 mmlhr(2,3). Anecdotal observations made by us, had not supported these recommended values. The present study was done to: (a) to reevaluate the normal values of micro-ESR
in term infants during the first week of life, and (b) to
assess the role of the revised values in diagnosing early neonatal sepsis.
Subjects and Methods
The study consisted of two phases. The first phase, was undertaken to
ascertain the normal values of micro-ESR. In the second phase, extending over a 6-month period, these revised values were evaluated in term infants investigated for early neonatal sepsis.
First phase: Term infants delivered at the Kasturba Hospital, Manipal
between August 1996 and January 1997 were considered for this phase of
the study. The micro-ESR of these infants were longitudinally assessed during the first postnatal week. All infants were asymptomatic, roomed in and on ad libitum breast feeds. Infants with
perinatal asphyxia, hemolytic diseases and those receiving antibiotics were excluded from the study. The tests were done after obtaining verbal consent from the mother. Infants who were discharged from hospital before 7 days were not considered for analysis.
The micro-ESR was assessed on postnatal days 1,3,5 and 7. Between 18h to 24 h of post- natal age was considered as Day 1, 66 h to 72 h as Day 3, 114 h to 120 h as day 5 and 162 h to 168 h as day 7. Blood was obtained by heel
prick and collected in a standard 75 mm heparinized microhematocrit tube with internal diameter of 1.1 mm. The height of the plasma column was measured after the first hour, and reported as Micro-ESR in mm/hr. Blood was also collected simultaneously in a second tube and micro hematocrit assessed by centrifuging at 10,000 rpm for 5 minutes. All observations were made by a single investigator to avoid observer variability.
The mean, mode and percentile values for micro-ESR on days 1,3,5 and 7 were
obtained. The 97th percentile value was considered as the upper limit of
normal. The values for micro-ESR thus obtained were called 'revised micro-ESR' to differentiate them from the traditionally accepted values(2,3). Repeated measure analysis of variance was done to evaluate the changes in micro-ESR with postnatal age. Student 't' test was applied where required.
Second Phase: This phase was undertaken between 1st December 1997 and 31st May 1998. Term infants investigated for sepsis during the first week of life were considered for evaluation.
Values above 97th percentile of the 'revised' micro-ESR and traditional micro-ESR in diagnosing blood culture proven neonatal sepsis were compared.
Results
Revised Micro-ESR: Three hundred and sixty seven infants were recruited
for the study. One hundred and seventy seven infants were discharged by
the 5th postnatal day. The remaining 190 infants were evaluated till the 7th postnatal day and considered for analysis. None of the infants had a hematocrit less than 45% (Table I). There were 85 female and 105 male infants. Mean birth weight was 2849 g (range 1665-4010 g) Thirty three infants weighed less than 2500 g.
TABLE 1
Micro-ESR During 1st week of life
Micro ESR
(mm/h) |
Day 1
(n = 190) |
Day 3
(n - 190) |
Day 5
(n=190) |
Day 7
(n=190) |
| Mean (SD) |
1.17(0.4) |
(1.24(0.5) |
1.46 (0.7) |
2.01(0.9) |
| 50th percentile |
1 |
1 |
1 |
2 |
| 97th percentile |
2 |
2 |
3 |
4 |
| Hematocrit (%) |
|
|
|
|
| Mean Hematocrit (SD) |
63(4) |
61 (4) |
59 (4) |
57(4) |
There was no difference in micro-ESR based on sex (p
=
0.8), or birth weight (small for gestational age
=
33, P
=
0.13). The 50th
percentile values were 1 mm/h on the 1st, 3rd and 5th postnatal day and 2 mm/h on the 7th day. The 97th percentile values were 2 mm/hr on the 1st and 3rd postnatal day, and 3 mm/h and 4 mm/h
on the 5th and 7th postnatal days, respectively. Analysis of variance
for repeated measures revealed that the change in micro-ESR was significant (Bonferroni p <0.01) beyond the 3rd post natal day.
Diagnosis of sepsis: One hundred and fourteen term infants admitted to
the Neonatal Intensive care Unit were investigated for early neonatal
sepsis. There were 32 infants with culture proven sepsis. Twenty of them
had elevated micro-ESR based on the revised values. Out of these only 12 would be considered elevated if the analysis was based on the traditional values for micro-ESR was. The sensitivity and specificity of the 'revised' micro-ESR was 62.5% and
60.9%
respectively in diagnosing culture proven sepsis. The 'traditional' micro-ESR showed a sensitivity and specificity of 37.5% and 78% respectively. The positive and negative predictive values of the revised (38.4% and 80.6%) and traditional (40% and 76.2%) micro-ESR were similar.
Discussion
Gerdes(3}has recommended normal value of micro-ESR as "day of life +3"
corresponding to the 95th percentile value reported by Adler and Denton(2). This would imply that 95th percentile values for micro-ESR on postnatal days 1,3,5 and 7 would be 4mm, 6mm, 8mm and 10 mm, respectively. In our study, the 97th percentile value for postnatal days 1,3,5 and 7 were seen to be 2 mm/h, 2 mm/h, 3 mm/ and 4 mm/h respectively. These are lower than the values recommended ear- lier(2,3).
The sensitivity in diagnosing proven sepsis was higher with 'revised' micro-ESR (62.5%)
than with the traditional values of micro-ESR (37.5%). A sepsis screen scored 'negative' on' the basis of the traditionally accepted values for micro-ESR, would be deemed 'positive' when the revised values for micro-ESR are considered. The revised micro-ESR with its increased sensitivity would enhance the importance
given to this simple and inexpensive bed side test, in detecting
neonatal infection. In view of these observations, we feel that further studies must be undertaken to establish the normal value of micro-ESR in the newborn.
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