Retinol deficiency assessed by conjunctival impression cytology (CIC) in preterm infants

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Abstracts / Early Human Development 45 (1996) 13.?- 165

transfusion is to ensure adequate tissue oxygenation. Assessing the adequacy of tissue oxygenation may provide a functional assessment of anaemia. When oxygen delivery to the tissues is low a greater proportion of the available oxygen is extracted resulting in a lower venous oxyhaemoglobin saturation (Svo2). Adequacy of oxygenation can therefore be measured from the fractional oxygen extraction (FOE) where FOE = (Sao 2 - S v o 2 ) / S a o 2, where Sao 2 = arterial oxyhaemoglobin saturation.

Aim: The aim of this study was to assess the effect of total haemoglobin concentration ([Hb]) and the haemoglobin F fraction (HbF%) on FOE.

Subjects: Twenty-eight babies who had previously undergone intensive care. Median (range) gestation: 30 ( 2 5 - 4 1 ) weeks.

Methods: Svo z was measured in the forearm using near infrared spectroscopy with venous occlusion. Sao 2 was measured by pulse oximetry. All measurements were made at rest. [Hb] and HbF% were measured on the same day.

Results: There was no relationship between [Hb] and FOE (n = 28, r =

0.057, P - 0.773). There was a significant positive relationship between HbF% and FOE (n - 21, r = 0.63, P = 0.002). Simple linear regression analysis showed that variations in HbF% accounted for 40% of the variation in FOE. Multiple linear regression analysis showed that this proportion was not improved by allowing for variation in [Hb].

Conclusion: Oxygen extraction in the peripheral tissues was greater with higher HbF%. This effect appeared to be more important than the absolute level of [Hb]. Babies who had multiple transfusions may tolerate lower haemoglobin concentrations than babies who have had fewer transfusions because HbF% is lower. We suggest that knowledge of HbF% or the number of transfusions received by a baby may be helpful in deciding whether to transfuse.

Retinol deficiency assessed by conjunctival impression cytology (CIC) in preterm infants N.J. Shaw, A.R Hughes, M. Hero, R Southall, D. Clark (introduced by A.M. Weindling)

Regional Neonatal Intensive Care Unit. Liverpool Women "s Hospital, Liverpool L8 7SS, UK. Preterm infants are known to be deficient in retinol. This may predispose to the development of chronic lung disease. We have used CIC to assess retinol status and aimed to determine the significance of abnormal findings on CIC. Eighty-nine preterm infants at a median age of 36 post menstrual weeks were

Abstracts / Earl}, Human Development 45 (1996) 133-165

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studied. CIC was successfully performed in 74 infants. Abnormalities were correlated with the presence of intraventricular haemorrhage, retinopathy of prematurity, chronic lung disease and days of oxygen requirement. Thirteen CIC specimens were abnormal, 61 were borderline normal or normal. Birth weight was significantly lower in the abnormal group. Four infants (32%) in the abnormal group required treatment for retinopathy of prematurity compared to two (3%) in the normal/borderline group (P < 0.01). Retinol deficiency as assessed by CIC is associated with retinopathy of prematurity requiring treatment. It may be possible to perform CIC immediately after birth to identify an at risk group who may benefit from extra vitamin A supplementation.

Relationship of visceral blood flow velocity to Ponderal Index R.M. Nicholl, H.R. Gamsu Children Nationwide Neonatal Centre, Kings College Hospital, London, UK. Introduction: It has been suggested that growth restriction in fetal life 'programmes' for disease in later life and that this especially so when growth restriction has been disproportionate [1]. Conventionally babies are regarded as 'growth retarded' if they are below an arbitrary weight centile for gestation. This takes no account of linear growth and therefore babies that have disproportionate growth restriction may be missed. The Ponderal Index (wt. X 100/length 3) has been suggested as a measure of poor nutrition [2] with a value below the 10th centile indicating malnourishment [3]. Accurate measurement of length in small, preterm babies is difficult. The neonatal knemometer is a hand-held electronic calliper which measures lower leg length with accuracy to 1/100th mm (FORCE Institutes, Copenhagen, Denmark). We have used this to calculate the Ponderal Index, using lower leg length as a proxy for total length. Outcome measure: Blood flow velocity in the superior mesenteric and anterior cerebral arteries measured by Doppler ultrasound. Methods: Sixty-four VLBW babies were studied over a 12-month period. Median gestation was 28.8 weeks (range, 23-34) and median birth wt. 1174 g (range, 654-1556). Forty-five babies were above 10th wt. centile for gestation ('AGA'), 10 were below 10th centile and nine were below the 3rd centile. Doppler ultrasound studies of the superior mesenteric and anterior cerebral arteries were performed on the first day of life. Time averaged mean of the peak velocity envelope was calculated from four consecutive cardiac cycles by hand planimetry. No baby had received enteral feeds prior to the Doppler study. Results: Median Ponderal Index for all babies studied was 164.1 (range, 82-226) with 10th centile of 140 and 90th centile of 188.6. Of the 45 'AGA' babies, 12 (27%) had abnormal Ponderal Indices, i.e. six were below the 10th centile and six were above the 90th centile. The 10 babies with birth wt. below the 10th centile all had