A case of nondigitalis cardiac glycoside toxicity.

A case is presented of cardiac glycoside poisoning in a 1-year-old patient from the plant Nerium oleander (common oleander). The patient had bradycardia, vomiting, altered level of consciousness, and no history of ingestion. Antibody-based digoxin assays may cross-react with other cardiac glycosides nonquantitatively. Chromatographic techniques can be used in the specific diagnosis.

Accurate micromethod of neonatal blood sampling from peripheral arterial catheters.

Blood sampling from peripheral arterial catheters is an important, but inadequately standardized, technique in neonatal intensive care. In this study two peripheral arterial sampling methods were evaluated in a neonatal animal model. One commonly used method (the drip technique) involves inserting a needle into the hub of the peripheral arterial catheter and discarding up to 10 drops of infusate fluid and blood before the sample is collected. This method was compared with a new micromethod where two needles are used (two-needle technique). Blood gas values in the peripheral samples were compared with control values drawn from a femoral artery catheter. Accuracy of peripheral arterial PCO2 and total blood loss constituted the final study variables. The results demonstrated that the two needle technique was more accurate, yielding peripheral arterial PCO2 values that were 98% of control values. Withdrawal of fewer than six drops of infusate fluid and blood with the drip technique resulted in spuriously low PCO2 values. The new technique also resulted in significantly less total blood loss per sample compared with the drip technique (189 +/- 3 microliters vs 398 +/- 3.8 microliters, mean +/- SEM, p < 0.01). We conclude that the two-needle micromethod is an accurate technique for blood sampling from peripheral arterial catheters and is particularly appropriate for low-birth-weight infants in whom minimization of blood loss is desirable.

Similar gastric emptying rates for casein- and whey-predominant formulas in preterm infants.

Casein-predominant infant milk formulas have been speculated to predispose to lactobezoar formation in preterm infants due to delayed gastric emptying. There have been, however, no prospective studies to prove this possibility. In a randomized, double-blinded, prospective study, we tested the hypothesis that preterm infants fed casein-predominant milk formula have slower gastric emptying than infants fed whey-predominant formulas. Twenty preterm infants within the first 4 d of life were randomized to receive either the whey-predominant formula Similac Special Care (whey:casein ratio 60:40) or an experimental casein-predominant formula (whey:casein ratio 18:82). Only the protein composition differed between the two formulas. The infants were fed the assigned study formula until they reached approximately 2200 g body weight when a gastric emptying scan was performed, using the designated study formula mixed with 25 microCi of technetium-99 sulfur colloid. Gastric emptying was followed continuously for 2 h. Gastric emptying at 30, 60, 90, and 120 min was similar between the two study groups. The time for 50% gastric emptying was 64.9 +/- 12.3 min for the infants fed the whey-predominant formula and 56.5 +/- 14.8 min for those fed the casein-predominant formula (p = 0.75). We conclude that the rate of gastric emptying in preterm infants fed casein-predominant formulas is similar to that in those fed whey-predominant formulas.

Measurement of transcutaneous carbon dioxide in low birthweight infants during the first two weeks of life.

With the advent of pulse oximetry, there has been a general decrease in the use of transcutaneous (Tc) blood gas monitoring in intensive care environments. The available data, however, suggest that arterial carbon dioxide pressure (PCO2) levels are best estimated by Tc methods. In this study, we report our experience using routine Tc PCO2 monitoring in 32 consecutive infants less than 2 weeks of age with birthweights less than 1500 g. A total of 644 simultaneous pairs (Tc PCO2 versus arterial PCO2) were obtained. Pairs were categorized according to a 2 x 2 matrix design based on sensor temperature (40 degrees or 43 degrees C) versus site of arterial sampling (umbilical [UAC] or peripheral artery catheter [PAC]). Sampling via the UAC resulted in excellent correlation between sample pairs at both sensor temperatures with similar regressions between groups. Sampling via the PAC, however, yielded poor correlation between sample pairs and a significantly different regression from both UAC groups. Based on these findings, we advocate the use of a sensor temperature of 40 degrees C in very low birthweight infants for tracking Tc PCO2 values. In addition, we suggest that inaccuracies in PAC sampling may lead to erroneous PCO2 determinations. We conclude that routine monitoring of Tc PCO2 is accurate and serves a useful and continuing role in the neonatal intensive care environment.

Lectin activity of the major surfactant protein (SP-A) may participate in, but is not required for, binding to rat type II cells.

Pulmonary surfactant is a complex mixture of lipids and proteins, of which surfactant protein A (SP-A) is the most abundant glycoprotein. The SP-A molecule has several distinct structural features that include a lectin-like domain, sharing structural features with other mammalian lectins. We have tested the hypothesis that lectin activity of the SP-A molecule is required for the binding to its receptor on the surface of alveolar Type II cells. By using colloidal gold immunocytochemistry in conjunction with electron microscopy, we evaluated the ability of mannosylated proteins to inhibit canine SP-A binding to rat Type II cells in vitro. After preincubation of SP-A with the mannosylated protein horse-radish peroxidase (HRP), SP-A was incubated with isolated filter-grown Type II cells. HRP did not alter the binding of SP-A to the Type II cell surface. Evidence that SP-A did bind to HRP was shown by coincident observation of gold-labeled SP-A and HRP precipitates. These results provide visual evidence that the lectin activity associated with SP-A is not required for its binding to receptor on rat alveolar Type II epithelial cells.

Long-term subcutaneous terbutaline tocolysis: report of possible neonatal toxicity.

Terbutaline is a beta-sympathomimetic agent that has gained wide use in obstetrics as a tocolytic agent. In addition to inhibiting uterine contractions, terbutaline can cause other clinically significant beta-mediated effects. Terbutaline readily crosses the placenta, and both fetal and neonatal toxicity have been reported. We report possible cardiovascular toxicity secondary to long-term prenatal terbutaline exposure involving three preterm infants of a quadruplet pregnancy. The infants developed cardiovascular decompensation with bradycardia, metabolic acidosis, poor tissue perfusion, and decreased urine output. The infants' conditions were resistant to all routine interventions but responded well to dobutamine infusion. We theorize that long-term prenatal beta-mimetic exposure led to downregulation of fetal beta-receptors. This resulted in impaired myocardial function, increased peripheral vascular resistance, and poor cardiac output. We suggest that neonates with a history of prenatal exposure to terbutaline should be observed closely after birth for any evidence of cardiovascular deterioration.