The 1996 New York blizzard: impact on noninjury emergency visits.

The purpose of this study was to investigate the impact of the January 1996 New York blizzard on emergency visits to 12 Suffolk County hospitals for 10 noninjury health conditions. Emergency charts from the blizzard week (January 7-11) and a nonblizzard week (January 21-25) were reviewed and information was abstracted from the records meeting the criteria. Blizzard conditions were associated with increased visits for myocardial infarction/angina, primarily shoveling-related, and with decreased visits for asthma. Diagnoses for the other noninjury conditions did not differ significantly between time periods. The decrease in asthma visits possibly resulted from asthmatics avoiding exposure to blizzard conditions. An unexpected finding was that most patients with shoveling-related myocardial infarction/angina did not report pre-existing heart disease. Also of interest was that one quarter of myocardial infarction/angina visits by women were reportedly shoveling-related. This suggests that health warnings may be less effective at decreasing shoveling-induced myocardial infarction if they are directed primarily at men and at people with heart disease.

Peritoneal solvent drag reflection coefficients are within the physiological range.

Previous estimates of the peritoneal solvent drag reflection coefficient (sigma) are widely disparate; some are outside the range expected for a semipermeable membrane (i.e., between 0 and 1). We have evaluated a novel method for determining sigma in a rabbit model of peritoneal dialysis. Test solute was infused intravenously, and sequential 2-hour isotonic and hypertonic exchanges (40 ml/kg) were performed in random order. Test solute was also added to the instilled hypertonic dialysis solution to inhibit transperitoneal solute diffusion during this exchange. Eight experiments were performed with creatinine as test solute and glucose as osmotic solute, and six experiments were performed with glucose as test solute and mannitol as osmotic solute. When using isotonic dialysis solution, the dialysate/plasma concentration ratio (D/P) for both test solutes increased throughout the exchange (p < 0.001). When using hypertonic dialysis solution, D/P creatinine was initially near 1 and decreased during the 1st hour of the exchange (p < 0.05); D/P glucose (as test solute) was initially 0.82 +/- (SEM) 0.07 and did not change during the exchange. The peritoneal diffusive permeability-area product (PA) was determined by fitting a mathematical model to the time dependence of the dialysate test solute concentration during the isotonic exchange using PA as an adjustable parameter, and sigma was determined in like manner during the hypertonic exchange using sigma as an adjustable parameter (and assuming a PA value equal to that during the isotonic exchange). The creatinine PA (1.37 +/- 0.28 ml/min) was higher than that for glucose (0.62 +/- 0.07 ml/min) as expected based on their solution diffusion coefficients. Creatinine and glucose sigma values were 0.38 +/- 0.06 and 0.43 +/- 0.05, respectively. We conclude that peritoneal sigma values for creatinine and glucose are within the physiological range.

Age and smoking-adjusted lung cancer incidence in a Utah county with a steel mill.

In a recent study of urban air pollution, a Utah county with a steel mill was compared with a county without a steel mill. The result was that 38% of respiratory cancer deaths could be attributed to the air pollution emanating from the mill. Rates for smoking in this previous study were not adjusted, but assumed rats were similar in both counties. We used smoking information obtained from an ongoing radon and lung cancer case-control study to adjust for smoking, and no difference was found in incidence rates of respiratory cancer in the county with the steel mill, compared with the other urban counties and the rural counties among male and female nonsmokers and male smokers. There was a slight excess of lung cancer among female smokers in the county with the steel mill when compared with the other urban counties (rate ratio [RR] = 1.3, 95% confidence interval [95% CI] = 1.0-1.6), but there was no effect in nonsmoking women. We conclude that the findings of the previous study can be explained by differences in smoking rates between the county with the steel mill and the other counties.

Convection does not govern plasma to dialysate transport of protein.

The dependence of protein clearance on molecular size during peritoneal dialysis can be explained by assuming that either convection or diffusion is the major mechanism governing plasma to dialysate transport of protein. If convection is the predominant transport mechanism, then plasma-to-dialysate transport rates for protein should not decrease when the protein concentration in the instilled dialysis solution is increased. In the present study, plasma-to-dialysate transport rates for fluorescein-labeled protein tracers, alpha-lactalbumin and immunoglobulin G (IgG), were determined during a six hour isotonic exchange (25 ml/kg) in New Zealand White rabbits. The protein tracers were continuously infused into the bloodstream to keep plasma concentrations relatively constant, and transperitoneal transport rates were determined either with or without tracer protein added to the instilled dialysis solution. Plasma-to-dialysate transport rates were greater for alpha-lactalbumin than for IgG as expected based on the molecular size of these proteins. Transport rates for both alpha-lactalbumin and IgG decreased when tracer protein was added to the instilled dialysis solution. The present observations do not support convection as the major mechanism governing plasma to dialysate transport of protein during peritoneal dialysis.

Macromolecule adsorption to hemodialysis membranes depends on molecular size.

Adsorption to hemodialysis membranes was studied by determining the binding kinetics of model macromolecules, polydisperse DEAE dextran (molecular radii 10-70 A), to an acrylonitrile-methallyl sulfonate copolymer membrane. Hemodialyzers were studied in a postdilution hemofiltration circuit where both blood path output and ultrafiltrate streams were returned to the reservoir. Changes in the reservoir concentration of and sieving coefficients for DEAE dextran were monitored over 24 h. Decreases (or increases) in reservoir concentration were assumed to result from adsorption to (or desorption from) the membrane. Small macromolecules adsorbed rapidly to the membrane but later desorbed. This rapid adsorption resulted in low initial sieving coefficients. Large macromolecules adsorbed slowly over the entire 24-hour study period. Additional experiments suggested that desorption of small macromolecules was due to displacement by large macromolecules. Adsorption and desorption of macromolecules to hemodialysis membranes are dynamic processes and depend on molecular size.