Changes in the management of severely Rh-immunized patients

Since July 1, 1978, we have instituted the following changes in the management of severely Rh-immunized patients: (1) serial amniotic fluid optical density (delta OD450 ) values and real-time ultrasound scanning beginning at 21 weeks' gestation, (2) fetal transfusions as early as the twenty-third week, (3) ultrasound surveillance during and after intrauterine transfusions, and (4) planned premature delivery with neonatal exchange transfusions for selected cases between 29 to 32 weeks and for all patients after 32 weeks' gestation. The perinatal survival rate (83.8%) in 37 isoimmunized pregnancies managed with this regimen was significantly higher (p less than 0.05) than in 34 such pregnancies (55.9%) managed according to the protocol utilized during the previous four years.     

Effect of calcium therapy in the sick premature infant with early neonatal hypocalcemia

Twenty-seven sick premature infants with serum calcium concentrations less than 6.0 mg/dl during the first day of age were enrolled in a prospective controlled study involving two treatment regimens--calcium given as a bolus or a drip--or no treatment. Mean total calcium concentration was 5.5 +/- 0.8 mg/dl, and ionized calcium was 3.1 +/- .3 mg/dl, with no significant difference between treatment groups. By 24 hours, in all groups total calcium had increased to greater than 6.0 mg/dl (bolus 6.5 +/- 1.1, drip 7.0 +/- 0.4, control 6.6 +/- 0.4) and ionized calcium to greater than 3.5 mg/dl (bolus 3.9 +/- 0.3, drip 3.6 +/- 0.6, control 3.6 +/- 0.3). Ionized and total calcium concentrations were significantly correlated (r = 0.562; P less than 0.001), but total calcium did not predict ionized calcium in any group. These data support the concept that, even in sick infants, early neonatal hypocalcemia is a physiologic phenomenon that may not require treatment.     

The placenta: Immunologic or hemodynamic protector of the fetus?

Complete separation of the maternal and fetal circulation during normal pregnancy has been regarded as an extremely important protective factor from the immunologic standpoint. This hypothesis was tested in outbred rabbits in which a direct maternal-fetal parabiosis was established during the last week of pregnancy by implanting an intact maternal omental pedicle subcutaneously into the fetus. A functional cross-circulation, which developed after 48 hours as evidenced by maternal⁵¹Cr-labeled erythrocytes, led to pathologic changes culminating in fetal death within 70 to 80 hours postoperatively. Hyperacute graft rejection, previously postulated as the etiology of these fetal changes, was ruled out since the same characteristic syndrome occurred in similarly treated inbred fetuses syngeneic with their mothers. This study indicates that the absence of direct vascular intercommunication between mother and fetus at the level of the placenta is clearly necessary for physiologic as well as immunologic reasons.     

Contingent reinforcement for reduced breath carbon monoxide levels: Target-specific effects on cigarette smoking

This study determined the effects on smoking behavior of providing contingent reinforcement for nonsmoking versus reduced smoking afternoon breath carbon monoxide (CO) target levels. Twenty-eight hired chronic smoker volunteers were randomly assigned to one of three experimental conditions during a 10-day intervention: (a) 8 ppm target CO, $5 per day incentive (n = 11); (b) 16 ppm target CO, $4 per day incentive (n = 8); or (c) 8 ppm target CO, no incentive (n = 9). Both payment groups showed significantly lower CO levels and greater amounts of daytime smoking reduction than the no-pay group. A specific effect of CO target was also seen; 45% of subjects in the 8 ppm group compared with 0% of subjects in the 16 ppm target and no-pay groups produced average afternoon CO levels of 8.5 ppm or lower during the intervention. Average levels of CO and smoking reduction did not differ for the two paid groups, however, because some subjects in the 8 ppm group failed to reduce CO sufficiently to contact the reinforcer. Contingent reinforcement based on expired air CO levels can exercise powerful and precise (target-specific) control over smoking behavior, but there may be individual differences in ability to meet reinforcement contingencies if difficult targets are introduced abruptly.