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Biomedical subjects

D K Stevenson

Publications and source records attributed to D K Stevenson.

At least 307 records · Page 17Linked to original sources
PubMed1982

Favorable results of neonatal intensive care for very low-birth-weight infants.

From 1961 to 1976, 229 infants with birth weights ranging from 751 to 1,000 gm were admitted to the Stanford University Hospital Intensive Care Nursery. The overall neonatal mortality for these infants was 63% (144/229), and there were ten late deaths. Before 1967, no infant in this group who required mechanical ventilation survived; thereafter, 30% (34/114) of the ventilated patients survived. Of the 75 long-term survivors 60 participated in a high-risk infant follow-up program; these included 23 infants who had received mechanical ventilation. The mean birth weight of these infants was 928 +/- 67 (SD) gm. Seventeen children (28%) had significant morbidity: seven (12%) with severe handicaps and ten (17%) with moderate handicaps. During this same period, seven infants weighing less than 750 gm at birth were also observed. The three infants who had not required ventilatory support thrived; the other four infants had required respirators and were significantly handicapped. More recently, neonatal mortality for infants with birth weights from 751 to 1,000 gm has improved: for 1977 to 1980, it was 28% (33/118). Furthermore, neonatal mortality for ventilated infants in this weight group was 27% (26/95). These data indicate an improved prognosis for very low-birth-weight infants, even with ventilatory support.

California↗
PubMed1982

Paired determinations of blood carboxyhemoglobin concentration and carbon monoxide excretion rate in term and preterm infants.

Paired determinations of COHb and VeCO were performed on 30 term infants (38 to 42 weeks' gestation) and 26 preterm infants (28 to 37 weeks' gestation) during the first week of life. All subjects were breathing room air at the time of the study. Values of COHb were corrected for RAco by linear regression of COHb (percent saturation) vs RAco (ppm). Regression coefficients for term and preterm infants with no history of pulmonary impairment were nearly identical (COHb = 0.175 RAco + 0.45, r = 0.77, n = 25 for term infants; COHb = 0.168 RAco + 0.51, r = 0.82, n = 9 for preterm infants) and agreed well with theoretical values. For the group of term infants, linear regression of Veco (microliter/kg/hr) vs. COHbc, where COHbc = COHb - 0.17 RAco, resulted in VEco = 23.4 COHbc + 4.02, r = 0.75, n = 30. The corresponding relationship for preterm infants with no history of pulmonary impairment was VEco = 24.7 COHbc + 3.85, r = 0.61, n = 13. For a subpopulation of preterm infants with a history of pulmonary dysfunction, the correlation decreased significantly, with VEco = 4.34 COHbc + 17.6, r = 0.097, n = 11. These results demonstrate that (1) COHbc is a reasonable index of VEco and consequently of the heme catabolic rate in both term and preterm infants with no clinical history of pulmonary dysfunction and (2) inference of VEco from COHbc may be misleading in certain cases without a consideration of the factors relating these two variables.

Carbon Monoxide↗
PubMed1981

Effects of asphyxia and oral gentamicin on intestinal lactase in the suckling rat.

The effect of oral gentamicin on lactase, the major disaccharidase of the neonatal intestine, was studied using the suckling Wistar rat as a model. The jejunal lactase-specific activity of asphyxiated animals given oral gentamicin at a dose of 20 mg/kg/day for two days was significantly decreased compared to that of nonasphyxiated animals given oral saline (P less than 0.01). Although the intestinal lactase-specific activity of nonasphyxiated animals given oral gentamicin at a dose of 20 mg/kg/day for two days was not significantly different from that of animals given oral saline, a high dose of oral gentamicin (160 mg/kg/day) was associated with decreased lactase-specific activity in both the jejunum and ileum. Intramuscular administration of gentamicin was not associated with decreased intestinal lactase-specific activity. More information is needed regarding the mechanism of the biochemical injury associated with the oral use of aminoglycosides and its clinical significance, if any, in the human infant. Until this is known, the potential for such injury should be of special concern where prophylaxis against necrotizing enterocolitis is being considered, particularly in view of the increased tendency for treated infants to become colonized with gram negative organisms resistant to the antibiotic being used.

Animals↗
PubMed1980

Component concentrations and activation of the complement system in neonatal illness: a preliminary study of necrotizing enterocolitis.

Determinations of C3, C4, and C5 concentrations by radial immunodiffusion, and assays for the activation products of C3, C3c and C3d by counterimmunoelectrophoresis, were performed on 80 infants. Seven nonbacteremic preterm infants with necrotizing enterocolitis (NEC) or probable NEC (PNEC) were found at the time of diagnosis to have a significantly lower mean concentration of C3 (P less than 0.05, 1-tailed) without C3 activation when compared to other noninfected preterm infants. Ten full-term and 63 preterm infants were studied prospectively during the first days of life, and were then followed for the postnatal development of localized or systemic infection. Assays for the detection of C3 activation products were negative in all these infants. Four preterm infants who developed PNEC after 5 or more days without clinical illness had low original concentrations of complement components. The pathogenesis of NEC may not involve primarily complement activation, and susceptibility to this condition may be related to pre-existing deficiencies in complement component concentrations relative to gestational age, or to defective activation of C3 in the presence of certain bacterial species and strains.

Complement Activation↗
PubMed1980

Cerebro-costo-mandibular syndrome.

The cerebro-costo-mandibular syndrome is characterized by cerebral maldevelopment or malfunction or both, costal deficiencies, and micrognathia. Cleft palate and glossoptosis are frequently present and contribute to the common presenting sign, neonatal respiratory distress. Intrauterine and postnatal growth retardation are common. Familial cases are rare and the mode of transmission is uncertain. The deficiencies in the posterior portion of affected ribs are the sine qua non for diagnosis; roentgenographic confirmation is required. Since the first description of this pattern of prenatal growth defect in 1966, 19 patients who fulfill the criteria for diagnosis have been reported. We present three additional cases, one of which includes roentgenographic-pathologic correlations, and summarize the combinations of features present in previously described cases. Pulmonary complications incident to lack of thoracic cage support result in poor prognosis for survival.

Abnormalities, Multiple↗
PubMed1980

Pulmonary excretion of carbon monoxide in the human infant as an index of bilirubin production. IV. Effects of breast-feeding and caloric intake in the first postnatal week.

Measurements of the pulmonary excretion rate of carbon monoxide (VEco) as an index of bilirubin production in the first several days of life were taken from 64 breast-fed or bottle-fed infants. Twenty-one infants (greater than or equal to 37 weeks of gestation) were breast-fed; 43 infants (28 to 42 weeks of gestation) were bottle-fed a commercially prepared formula. Information pertaining to their caloric intake during the 24-hour period preceding VEco determination was taken from 38 of the 43 infants who were bottle-fed and they were placed into three groups based on their caloric intake: (1) less than or equal to 60 kcal/kg/day (19 infants); (2) 61 to 100 kcal/kg/day (7 infants); and (3) greater than 100 kcal/kg/day (12 infants). There was no significant difference in bilirubin production between bottle-fed and breast-fed infants. No effect of caloric deprivation on bilirubin production was demonstrated. The mean VEco values were 18.5 +/- 0.9 (SE) for group 1, 17.7 +/- 1.8 (SE) for group 2, and 16.2 +/- 1.1 (SE) microliter/kg/hr for group 3.

Bilirubin↗
PubMed1980

Late morbidity among survivors of necrotizing enterocolitis.

Of 40 survivors of necrotizing enterocolitis 19 were completely normal children at the time of follow-up, one to three years later. Among the other 21 children, only six had moderate to severe neurologic impairment, representing 15% of all survivors. Despite the fact that intestinal injury is the main feature of the neonatal disease, only four children were symptomatic from gastrointestinal sequelae, and none of these suffered failure to thrive. Thus, 81% (17) of the children with late morbidity had problems unrelated to the gastrointestinal tract. The nongastrointestinal morbidity was associated with prematurity and the degree of perinatal stress.

Child, Preschool↗
PubMed1979

Unusual roentgenographic presentation of a congenital cystic malformation of the lung.

We describe here an infant with a large, solitary, fluid-filled lung cyst and hyperinflation of adjacent lung tissue in the same lobe. The combination of a fluid-filled cyst and ectatic emphysema in the same lobe suggests bronchial collapse and airway obstruction as a contributory mechanism for this unusual roentgenographic presentation of a congenital cystic malformation of the lung.

Female↗
PubMed1979

Pulmonary excretion of carbon monoxide in the human infant as an index of bilirubin production. I. Effects of gestational and postnatal age and some common neonatal abnormalities.

Using a single pass, flow-through system, the pulmonary excretion rate of endogenously produced carbon monoxide was measured as an index of bilirubin production in human infants with varying gestational and postnatal ages and with a variety of clinical abnormalities. No significant difference in VECO was found related to sex or gestational age. The mean VECO for a small group of Oriental infants was significantly increased. VECO decreased with increasing postnatal age. As expected, infants with hemolytic disease of the newborn had a markedly increased mean VECO. Infants with jaundice of unknown etiology also had an elevated mean VECO, implying that increased bilirubin production may be a factor contributing to the "nonphysiologic" bilirubinemias of these infants.

Bilirubin↗
PubMed1979

Refractory hypoxemia associated with neonatal pulmonary disease: the use and limitations of tolazoline.

Thirty-nine critically ill infants with pulmonary disease received tolazoline because of severe hypoxemia refractory to administration of 100% O2 and mechanical ventilation. Twenty-seven (69%) of the infants responded with an increase in PaO2 greater than or equal to 20 torr in the first umbilical arterial gas after completion of the initial ten-minute infusion (1 to 2 mg/kg) of the drug. A response was not correlated with survival. The overall survival was 46%, essentially unchanged from our previous report (44%). Infants with hyaline membrane disease had the poorest survival rate (33%). Complications associated with the use of tolazoline occurred in 82% of the infants. A hypotensive reaction, defined as a 25% decrease in mean arterial pressure from the pre-tolazoline level, occurred in 67% of the infants, and more commonly in the infants with RDS (87%). In 11 infants who did not respond to the initial dose of tolazoline, the dose was increased up to 10 mg/kg/hour; only one infant responded, and eight (73%) had a hypotensive reaction.

Carbon Dioxide↗
PubMed1979

The white cell ratio in the very low birth weight infant.

The purpose of this study was to assess the usefulness of the white cell ratio of immature neutrophils (PMNs) to total (immature plus mature) PMNs as an indication of infection in the very small premature infant. We retrospectively reviewed the charts of 59 premature infants less than or equal to 1,250 g admitted to our Newborn Intensive Care Unit over a one-year period who had at least one white count determined. Twenty-three were born after rupture of membranes for greater than or equal to 24 hours (PROM), 47 had a one-minute Apgar score less than or equal to 6 and 31 had a five-minute Apgar scores less than or equal to 6, 38 had respiratory distress syndrome (RDS), and 4 had confirmed infection. Thirty-one of the infants had a ratio greater than or equal to .15 in the first day of life, a value which has been suggested in the literature as being abnormal and an indication to suspect sepsis. This ratio bore no statistical relationship to PROM, low Apgar scores, or RDS. We analyzed these same relationships using a ratio greater than or equal to .25, another ratio derived from data in the literature which has been said to suggest infection. No statistical correlation was found for low Apgars or RDS, but there was a significant relationship between PROM and attainment of a ratio greater than or equal to .25 (p less than .005). It is notable that 2 out of the 4 infants with infection had a ratio less than .15. We wish to cast doubt on the applicability of the currently defined WBC ratios in the literature as they apply to the infant with birth weight less than 1,250 g and emphasize the apparent effect of PROM as a factor upon these ratios.

Asphyxia Neonatorum↗