Venous outflow and inflow resistance in health and venous disease.

PURPOSE: The purpose of this study was to develop a physiologic method to measure outflow and inflow from the lower extremities and thus to quantify the degree of venous valvular insufficiency and venous obstructive disease. METHODS: Calibrated photoplethysmography was used in combination with passive changes in hydrostatic pressure, by leg elevation followed by repositioning of the leg to the original sitting position. With the principle of venous occlusion plethysmography, timed volume changes were then used to calculate the outflow and inflow. The inflow and outflow units were the percentage of optical reflectance (%OR) per minute. The respective resistances were calculated by identifying the hydrostatic pressure distance from the third intercostal space to the probe site that is inducing these site changes. The resistance units were millimeters of Mercury x minutes per %OR. RESULTS: Four groups of subjects were examined: normal individuals, patients with venous valvular insufficiency, deep venous thrombosis, and a combination of both. The most significant differences in outflow values were found between the control group (81.77% OR/min) and the deep venous thrombosis group (28.47% OR/min). In contrast, the most significant differences in inflow values were found between the control group (9. 67% OR/min) and the venous valvular insufficiency group (108.61% OR/min). The resistances changed correspondingly. CONCLUSION: The application of calibrated photoplethysmography in conjunction with induced changes in leg hydrostatic pressure proved to be an effective physiologic method to noninvasively quantify venous hemodynamics in normal control subjects, patients with venous valvular insufficiency, venous obstructive disease, or both.

Effects of pentachlorophenol and other chemical preservatives on the health of wood-treating workers in Hawaii.

The morbidity and mortality of workers occupationally exposed to wood treating chemicals used in Hawaii for the years 1960 to 1981 were evaluated. The specific chemical exposures investigated were CCA (chromated copper-arsenate), TBTO (tributyl tin oxide) and PCP (pentachlorophenol). Results of detailed medical histories, laboratory and physiological tests, and physical examinations of 88 wood treaters were compared with those of 58 matched controls. The occupationally exposed cases had a significantly higher mean level of urinary PCP as compared to the controls (mean of 174 ppb vs. 35 ppb, micrograms/kg). There were no significant differences between the groups for the other urinary pesticide residues. The medical histories and physical examinations revealed no significant variations between the wood treaters and the comparison group. Review of all organ systems and laboratory data showed no clinically significant differences between exposed and nonexposed cohorts, although elevated hepatic enzymes in both groups merit further study. The results indicated no adverse health effects or increased incidence of mortality resulting from exposure to wood preservative chemicals in wood treaters who had worked in the industry for 0.33 to 26.3 years with a median of 6.5 years. Only 6 deaths were reported, 5 of cardiovascular disease, one of cause undetermined and none of cancer. Total number of deaths were less than the 8 anticipated for this age group.