Jean Hewitt

Umbilical blood flow response to embolization of the uterine circulation

The uterine and umbilical blood flow response to uteroplacental insufficiency, produced by microsphere embolization of the uteroplacental circulation, was examined by means of electromagnetic flow transducers in 12 pregnant ewes. No acute changes were observed in either circulation immediately after embolization of the uterine vasculature. Significant morphometric fetal growth retardation, in terms of weight, length, and ponderal index, was not associated with early changes in fetal pH, PO2, or PCO2. However, the incremental increases in both flows that were observed in control animals did not occur either during or after embolization because of an increase in vascular resistance. During and after embolization the incremental increase in uterine blood flow was blunted or decreased in most, but not all, animals. A rapid, progressive, and persistent decrease in umbilical flow occurred in the growth-retarded group. The significance of these findings relative to intrauterine growth is discussed.

Fetal metabolic response to experimental placental vascular damage

The fetal metabolic response to repetitive placental damage, produced by microsphere embolization of the uteroplacental circulation, was examined longitudinally in eight singleton fetal lambs and compared with similar data from seven controls. Significant morphometric fetal growth retardation was associated with an abrupt cessation of the normal increases in oxygen, glucose, and lactate uptake observed in the control animals. However, fetal blood levels and umbilical substrate quotients did not change. At the time of sacrifice, fetal oxidative metabolic rate was reduced significantly. The significance of these findings relative to intact fetal survival is discussed.

Disposition of methadone in the ovine maternal-fetal unit.

Abstract The distribution of methadone between mother and fetus after a single dose and at steady state was determined using the chronic pregnant ewe preparation. Chronic indwelling catheters were placed in the maternal aorta and vena cava, umbilical vein and fetal aorta. Following a single i.v. dose (0.5 mg/kg) to the mother, methadone was rapidly distributed to the fetus, with peak concentration in the umbilical vein occurring within two min. An umbilical venous-arterial gradient existed for 10–15 min after drug administration, indicating uptake of methadone by fetal tissues. Methadone concentration in the fetus was 2–5 times lower than those in the mother even in the post-distribution phase. The terminal half-life of methadone in 4 animals was 57±7.6 (S.E.) min in the mother, and 58.5±10.0 (S.E.) min in the fetus. When methadone was infused at a constant rate to the mother (0.01 mg/kg/min), steady state was achieved in both mother and fetus by 4–5 hrs. In 5 animals, maternal steady state was found to be 203±18.8 (S.E.) ng/ml, and fetal steady state was found to be 29.7±2.9 (S.E.) ng/ml. These studies show that methadone is rapidly distributed to the fetus, but fetal concentration remain lower than maternal concentration at all times.

EARLY DIAGNOSIS OF NEONATAL INFECTION WITH A SCORING SYSTEM

A need exists for a rapid method of identifying neonatal sepsis. Of 444 babies admitted to our ICN, 140 were clinically suspected of having sepsis. A two phase evaluation score was used. A “rapid” score was obtained (within 1 hour) with WBC and Dlff., mini-ESR, and latex determinations of haptoglobin (Hp), C-reactive protein and IgM. A “complete” score (within 24 hours) added α1-acid glycoprotein, Hp by hemoglobin binding capacity, and IgM by electrophoresis. Table I shows the scoring:In Table II, none, clin+ and cult+ represent no apparent infection, infection strongly suspected clinically and blood culture positive, respectively.All cases with documented infection had elevated scores. There were 16 other elevated scores which would have indicated a need for antibiotic treatment, while 102 babies may not have required antibiotics. This rapid assessment was superior to using any one test alone.

Effect of dietary protein on hepatic mitochondrial function and cardiac muscle protein turnover in uremic rats

Abstract To define the metabolic consequences of diets low in protein in chronic renal failure, young uremic and sham operated rats were fed isoenergetic diets for three weeks varying in protein content from 22% to 8% casein at the expense of carbohydrate. The results indicate that reducing casein content from 22% (control) to either 16%, 12% or 8% in uremic rats did not result in gross differences in renal function or decreases in liver weight, mitochondrial content or respiration. Atrial muscle protein synthesis was increased 26% while degradation was slightly, but not significantly, decreased in uremic and sham-operated rats fed the 8% casein diet compared to control. In both uremic and sham-operated rats fed the 8% casein diet, serum triiodothyronine (T 3 ) concentrations and hepatic mitochondrial glycerolphosphate (GP) shuttle activity were significantly increased while malate-aspartate shuttle activity was decreased compared to all other diet groups. The increased serum T 3 level and GP shuttle activity produced by feeding the 8% casein diet suggests a diet induced alteration in hepatic mitochondrial intermediary metabolism which may be of benefit in protecting against the potentially serious consequences of lowered thyroid hormone levels in chronic renal insufficiency.

802 CAN NEONATAL SEPSIS BE DIAGNOSED EARLY

Currently, many babies receive antibiotics unnecessarily for “phantom” infections. One-third of babies (258/800) admitted to our intensive care nursery in approximately 2 years had bacterial cultures of blood, urine and CSF, and received antibiotics.Several tests which can be rapidly and easily performed were combined to predict neonatal infection. These included WBC and diff., “mini”-sed. rate, latex C-reactive protein, haptoglobin and IgM. The scoring system previously described (Pediatr. Res. 11:504, 1977) was used. Of 20 cases of proven infection, 17 (85%) had elevated scores (the other 3 babies died very rapidly). In 32 babies with possible or probable infection (antibiotics given for 5 or more days without positive blood culture), 23 (72%) had an elevated score. In 206 babies without infection (antibiotics for 3 or less days), only 8 (4%) had an elevated score.Individual tests were predictive in 33% or less of proven cases of infection. Substituting buffy-coat smears for latex-IgM could improve the predictive value of this scoring system.These easily performed tests require no special laboratory facilities and provide an accurate diagnostic indication of neonatal sepsis within 1 hour. This could save physicians time and decrease antibiotic use, length of hospital stay and nosocomial infection.

RAPID PETERMINATION OF IgM USING LATEX REAGENT IN NEONATES

Chronic intrauterine infection commonly results in increased levels of immunoglobulin M (IgM). It is recognized that elevated levels of IgM are non-specific, but useful as a screening test. This is particularly true in infants with intrauterine growth retardation. In many hospitals IgM testing is done infrequently (e.g., twice weekly). The use of a rapid method for determination was tested for reliability by doing paired determinations of IgM by a latex method and an immunoelectrophoretic method. Samples were obtained from babies being investigated for possible bacterial or viral infection. The “positive” on the latex method is currently set at 30 mg% or more. The results were:When the false negatives (5) and false positives (3) were examined, only 1 false positive fell outside the ± 5 mg% range and was within 10 mg%. Introduction of another reagent set at 20 mg% could eliminate this error, in conjunction with the present reagent. The latex IgM method is easily performed, rapid (within 10 minutes) and inexpensive. A positive test could influence further investigatipns (e.g., viral cultures, long-bone x-rays, etc.).

59 Prevention of Hyperbilirubinemia of Prematurity by Phototherapy

The ideal treatment for hyperbilirubinemia of prematurity would be a safe and simple method for preventing its occurrence. CREMER et al. (1958) first demonstrated that serum bilirubin concentrations of newborn infants can be reduced by exposure to light. This treatment has not been widely used because of doubts as to its effectiveness and concern for the possible toxicity of the photochemical decomposition products of bilirubin. Recent experimental evidence indicated that these products are non-toxic. A controlled clinical trial has been carried out among 59 premature infants to test the effectiveness of artificial blue light in preventing hyperbilirubinemia of prematurity. Treated infants were placed in light from 12 to 144 hours of age and serial bilirubin determinations were carried out. The control and treated groups were comparable with respect to birth weight, gestational age, fluid intake and weight loss. The results are summarized below and indicate a statistically significant difference between the groups. Additional observations on the effect of phototherapy on serum albumin. H.A.B.A. dye binding capacity, free fatty acids and uric acid will be presented. (APS)