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Biomedical subjects

P MacMahon

Publications and source records attributed to P MacMahon.

9 recordsLinked to original sources
PubMed1990

Routine lumbar punctures in the newborn--are they justified?

The records of 62,107 neonates cared for at three neonatal referral units between 1979 and 1985 were analysed with regard to the number of lumbar punctures (LP) performed and the results obtained. The mean perinatal mortality rate was 9.3/1000 live births and the neonatal mortality rate was 5.9/1000. The units were comparible in this respect. Two hundred and sixty three (0.4%) babies weighed less than 1.0 kg at birth and 510 (0.8%) babies weighed 1.0-1.5 kg. A total of 1554 LPs were performed on 1084 babies, 1.7% of the whole population. Seventeen babies were diagnosed as having meningitis following CSF examination; 5 weighed less than 1.5 kg (VLBW) (incidence of meningitis 6.5/1000 births) and 12 weighed more than 1.5 kg (incidence 0.2/1000 live births). An LP was performed on 44% of VLBW babies and 1.2% of babies weighing more than 1.5 kg. In both groups approximately 1.5% of CSF samples were positive. Eight of the 17 positive results were obtained during the first 3 postnatal days. Only one VLBW baby had meningitis on the 1st day of life (1.3/1000). In view of the low incidence of meningitis and the risk factors associated with an LP it is questionable whether this procedure should be a routine investigation in the VLBW newborn.

Humans↗
PubMed1990

Calcium and phosphorus solubility in neonatal intravenous feeding solutions.

The limited solubility of calcium and phosphorus in standard parenteral nutrition formulations has restricted the ability to provide sufficient minerals to preterm infants to prevent substrate deficient metabolic bone disease. We determined the solubility limits of calcium and phosphorus in a total of 160 formulations under carefully controlled conditions. By increasing the concentrations of dextrose, amino acids, and by using Addiphos instead of 8.7% dipotassium hydrogen phosphate as the phosphorus source, higher concentrations of both calcium and phosphorus were held in solution. This should permit the delivery of increased concentrations of these minerals at rates which approximate fetal accretion.

Amino Acids↗
PubMed1990

Acid-base state of the preterm infant and the formulation of intravenous feeding solutions.

An acidic intravenous source of phosphorus (Addiphos) was compared with dipotassium hydrogen phosphate in 25 preterm infants to study acid-base state. Eight infants were given either Addiphos or dipotassium hydrogen phosphate alternately for 48 hour periods and similar amounts of calcium and phosphorus were delivered. There were no significant differences in calcium and phosphorus intake, calcium and phosphate plasma concentrations, or acid-base state between study periods on the two solutions. Seventeen infants were given the two solutions alternately for 72 hour periods; Addiphos was used to increase the amounts of calcium and phosphorus being delivered. Calcium and phosphorus intake was decreased on dipotassium hydrogen phosphate, but Addiphos significantly increased calcium and phosphorus intake and plasma calcium and phosphate concentrations. It also lowered the pH of the urine and raised the titratable acidity. Acid-base state, however, was not significantly different. It is therefore possible to increase intake of calcium and phosphorus in preterm infants without causing a significant metabolic acidosis.

Acid-Base Equilibrium↗
PubMed1990

A further family with congenital renal proximal tubular dysgenesis.

A new syndrome of oligohydramnios, Potter's syndrome, and anuric renal failure leading to stillbirth or neonatal death from respiratory failure has recently been described. Histologically, there is renal tubular dysgenesis, especially of the proximal tubules, and apparent glomerular crowding. To date, five families have been reported, in four of which there have been affected sibs and in two parental consanguinity. The disorder is, therefore, thought to be inherited in an autosomal recessive manner.

Adult↗
PubMed1989

Early parenteral feeding of amino acids.

Serial 24 hour balance studies of nitrogen and energy were carried out over 10 days in two groups of ventilator dependent preterm infants, of comparable weight and gestational age. In one group (n = 10) a parenteral amino acid source (Vamin 9) was started within 24 hours of birth, and in the other group (n = 11) it was not started until 72 hours. The feeding protocol was otherwise identical. The nitrogen intake (286 compared with 21 mg/kg/day), energy intake (188 compared with 151 kJ), and nitrogen retention (120 compared with -133 mg/kg/day), were all significantly higher during the first three days of life in the group in which the amino acid solution was started early. There were no differences by 7-10 days. The early introduction of amino acids improves the early nutritional state of sick preterm infants.

Amino Acids↗
PubMed1989

Association of mineral composition of neonatal intravenous feeding solutions and metabolic bone disease of prematurity.

To assess the effects of increasing the mineral content of parenteral nutrition solutions on the biochemical and radiological indicators of metabolic bone disease of prematurity 27 neonates who required parenteral nutrition were sequentially allocated to receive either a standard solution (group 1) or one with an increased mineral content (group 2). The 13 patients in group 1 received 0.68 mmol/kg/day of calcium and 0.61 mmol/kg/day of phosphorus, and the 14 in group 2 received 1.25 and 1.20 mmol/kg/day, respectively. The two groups did not differ significantly in the severity of their illness measured by birth weight, gestational age, duration of parenteral nutrition or ventilation, or the amount of supplementary oxygen required. In patients in group 2 the median plasma phosphate concentration was higher, the plasma alkaline phosphatase activity was lower, and there was less radiological evidence of rickets. There were no complications caused by excess calcium and phosphorus, and the rate of growth was similar in both groups. We conclude that an increased mineral content in parenteral nutrition solutions reduces the severity of metabolic bone disease in sick infants who require this form of nutrition.

Alkaline Phosphatase↗