The pupils of neonates often need to be dilated to examine the retina for retinopathy of prematurity and other disorders. It is known that low-weight infants (less than 1600 grams) are susceptible to systemic hypertension when 10% or 2.5% phenylephrine eye drops are used. To find the safest and best commercially available mydriatic agent in neonates, 30 low-weight infants were divided evenly into three groups. The drops tested were cyclopentolate 0.5% alone, cyclopentolate 0.5% plus mydriacyl 0.5%, and a combination drop of phenylephrine 1% and cyclopentolate 0.2%. There was no clinically significant effect of any of the drops on systolic blood pressure or pulse rate. The cyclopentolate and phenylephrine combination dilated the pupils by a mean of 2.8 mm which was statistically greater than the other groups (P less than 0.01) and had a longer duration of maximal dilation than the other drops (P less than 0.05).

D R U G S T H A T A R E I N N O C U O U S IN A D U L T S and safe in children may be dangerous when administered to small infants. Phenylephrine 10% ophthalmic solution has caused adverse reactions in adults and children,' including blood pressure elevation and blanching of skin (particularly the eyelid). Mydriatic eyedrops are used in low-birth-weight infants primarily to dilate their pupils to facilitate retinal examination for the presence of retinopathy of prematurity, and also to examine the fundus in cases of suspected glaucoma or neonatal infection, such as toxoplasmosis or cytomegatovirus. This study was conducted to investigate the systemic influence of mydriatic eyedrops when administered to LBW infants.

Basal acid output and meal-stimulated acid output were measured in newborn infants after nasogastric infusion of 5% glucose and elemental formula, respectively. In six older infants (age range 6 to 31 months), basal acid output was 0.067 +/- 0.017 mmol/kg/hr and maximal acid output was 0.200 +/- 0.028 mmol/kg/hr. Meal-stimulated acid output in four of six older infants was 0.149 +/- 0.038 mmol/kg/hr. In eight healthy newborn infants basal acid output was 0.038 +/- 0.008 mmol/kg/hr; meal-stimulated acid output was 0.064 +/- 0.011 mmol/kg/hr (P less than 0.01). The time course of the secretory response to the elemental formula was as described previously after a protein meal in adults: the rate of acid secretion increased after 20 minutes and remained greater than the basal rate through the remainder of the 90 minute test period. These results demonstrate that in human newborn infants a mixed meal containing protein hydrolysate induces an acid secretory response that is qualitatively similar to but weaker than the response in older infants and adults.

Cross-sectional and limited sequential studies of neutrophil and monocyte chemotaxis were done using cells isolated from cord blood and peripheral blood of 2- to 6-day-old neonates and infants at 4 and 6 months of age. These studies show that cord blood phagocyte chemotaxis is comparable to adult values, whereas phagocyte chemotaxis at 2–6 days of age is significantly lower than adult (P<0.01) or cord (P<0.01) chemotaxis values. At 6 months of age, phagocyte chemotaxis is still low compared to adult values (P<0.01).