Limitations of the Countershock Dose Response: A Study of Transthoracic Current

Dose response assessment of Countershock efficacy has been widely determined with respect to energy but not current. The purpose of this study was to examine the utility of the dose response method in a current-based model of trunsthoracic defibrillalion (penlobarbital anesthetized dogs, n = 8). Ventricular fibrillation induction lasting 15 seconds was separated by 5-minute intervals. Current defibrillation threshold (DFT: the lowest current that successfully defibrillated) was determined by decreasing current on successive trials. Energy DFT equaled the energy value of the corresponding current DFT. Subsequent data were expressed in normalized terms with each DFT assigned a normalized value of 1.00. Three shocks were delivered in random order at each of seven normalized current nodes (total of 21 shocks); 0.55, 0.70, 0.85, 1.00, 1.15, 1.30, and 2.00 × DFT (early testing). Randomization was repeated, and a second set of 21 trials were performed (late testing). Composite plots were made relating normalized current and energy to the percent successful defibrillation. The dose response expressed in normalized energy demonstrated an overall shift to the left compared to current. The difference was significant at every node value below the estimated DFT. Ninety percent of successful trials with respect to current and energy occurred at or above 0.85 DFT and 0.55 DFT, respectively. Significant changes in impedance occurred between early testing (60 ± 6 ohms) and late testing (47 ± 5 ohms), n = 8, mean ± SD. Current, compared to energy, is a more accurate parameter in the dose response assessment of transfhoracic defibrillation. This phenomenon is largely secondary to a time-dependent fall in impedance that results in lower delivered voltage and energy for a fixed delivered current. Energy should not be used as a parameter of Countershock efficacy.     

Antepartal Nursing Management of Grave''s Disease

The signs and symptoms of Grave's disease may be difficult to distinguish from the normal thyroid changes that occur in pregnancy. A brief review of thyroid physiology, thyroid changes during pregnancy, the effect of Grave's disease during pregnancy on the woman and fetus, and an assessment tool for use during the antepartal period is presented. Recommendations of specific areas of need seen in the pregnant Grave's patient during the antepartal period are also outlined.     

Observations Questioning a Protective Role for Breast-feeding in Severe Rotavirus Diarrhea

ABSTRACT. To investigate whether breast-feeding protects children against rotavirus diarrhea (RVD), we compared rates of breast-feeding by age and enteric pathogens among 2 276 children with diarrhea 0-4 years of age who attended a diarrhea hospital in Bangladesh. Infants 0-5 months were less likely to be breast-fed than children 6-11 months of age suggesting that some protection against diarrhea with all agents was associated with early breast-feeding. In every age group studied, breast-feeding was more common among children with RVD than among children with non-RYD whereas it was less common among children with cholera and shigellosis. Twenty percent of breast milks consumed by infants less than 1 year of age had high levels of neutralizing activity (>320) to the Wa strain of rotavirus but this activity did not appear to be protective since the 30 infants with RVD consumed milk which had titers that did not differ significantly from those consumed by 44 infants with diarrhea of other cause. Despite the prolonged breast-feeding which is common in Bangladesh, the mean age of hospitalization with RYD is approximately the same as in countries where the duration of breastfeeding is quite short. None of these 3 independent observations support a protective role for breast-feeding against rotavirus diarrhea after the first months of life.