Placement of Umbilical Artery Catheters High vs. Low

Placement of umbilical artery catheters was retrospectively reviewed in 181 newborns to evaluate random placement of catheter tip in the "high" position between T₇ and T₉ in the thoracic aorta of 127 infants and in the "low" position below 4 in the abdominal aorta of 54 infants. Group differences in gestational age, asphyxia, hypotension, respiratory disease, duration of catheterization, or infusate type were not significant. Cyanosis or blanching in the low extremities occurred in 67% of the "low" group and 21% of the "high" group ( P < .001). Hematuria occurred in 39% of the "low" group and 21% of the "high" group ( P < .05). High placement appears to have fewer complications. Prompt intervention by neonatal nurse practitioners can help reverse complications that occur during umbilical artery catheterizations.     

Effects of variations in temperature on impulse conduction along nonmyelinated axons in the mammalian brain

The effects of changes in brain temperature on conduction velocity and minimal interspike interval were examined in nonmyelinated callosal axons in awake and in barbiturate-anesthetized rabbits. These two parameters exhibited different sensitivities to brain temperature. For a range of 4.0°C, increases in brain temperature resulted in a decrease of approximately 2.5%/°C in antidromic latency and in a decrease of approximately 10%/°C in minimal interspike interval. Significant variations in conduction velocity and interspike interval can therefore be expected to occur with normally occurring changes in brain temperature. These variations may have implications for mechanisms of neural coding.