Postcardiopulmonary bypass hypoxemia: a prospective study on incidence, risk factors, and clinical significance.

OBJECTIVE: To evaluate the clinical significance of low arterial oxygen tension-inspired oxygen concentration (PaO2-FIO2) ratio, as a measure of hypoxemia, in the early period after cardiac surgery with cardiopulmonary bypass (CPB); and to evaluate the preoperative, intraoperative, and postoperative factors contributing to the development of hypoxemia within the first 24 hours after cardiac surgery with CPB. DESIGN: Prospective observational study. SETTING: University hospital. PARTICIPANTS: Patients who underwent elective or emergency cardiac surgery with CPB (n = 466). INTERVENTIONS: Preoperative clinical and laboratory data were recorded, as were intraoperative and postoperative data regarding the PaO2-FIO2 ratio, fluid and drug therapy, and chest radiograph. Data analysis evaluated hypoxemia as depicted by the PaO2-FIO2 ratios at 1, 6, and 12 hours after surgery. Thereafter, the effect of the PaO2-FIO2 ratios on time to extubation, lung injury, and length of hospital stay was evaluated. The risk factors were analyzed in 3 separate periods: preoperative, intraoperative, and postoperative. Univariate and multivariate analyses were performed on each period separately. All data were analyzed in 2 consecutive steps: univariate analysis and multivariate analysis. MEASUREMENTS AND MAIN RESULTS: PaO2-FIO2 ratios after CPB were significantly lower compared with baseline values. Six patients (1.32%) met the clinical criteria compatible with acute lung injury. All 6 patients had prompt recovery. Significant risk factors for hypoxemia were age, obesity, reduced cardiac function, previous myocardial infarction, emergency surgery, baseline chest radiograph with alveolar edema, high creatinine level, prolonged CPB time, decreased baseline PaO2-FIO2, use of dopamine after discontinuation of CPB, coronary artery bypass grafting, use of left internal mammary artery, higher pump flow requirement during CPB, increased level of hemoglobin or total protein content, persistent hypothermia 2 and 6 hours after surgery, requirement for reexploration, event requiring reintubation, and chest radiograph with alveolar edema 1 hour after surgery. Six hours after surgery, a lower PaO2-FIO2 ratio correlated significantly with time to extubation and lung injury. CONCLUSIONS: This study shows that despite improvements in the technique of CPB, hypoxemia depicted by low PaO2-FIO2 ratios is common in patients after CPB. It is short lived, however, and has minimal effect on the postoperative clinical course of these patients.

Prediction of 90Sr body burdens and radiation dose in Anaktuvuk Pass Alaska Eskimos due to fallout.

Strontium-90 concentrations in skeletons of Eskimo residents of Anaktuvuk Pass. Alaska during 1954-79 were predicted from two models based on (1) Sr kinetics in human bond and (2) estimated annual 90Sr ingestion rates via caribou meat. Predicted skeletal burdens of adult Eskimos gradually increased through 1961 and then rapidly achieved maximal values during 1964-66, reflecting fallout 90Sr levels in caribou meat which contributed 80-97% of dietary 90Sr intake. Concentrations of 90Sr in male Eskimo bone samples were similar using either model. Predicted values in vertebrae of adult Eskimo males were slightly lower than values reported in New York City adults until 1980 and subsequently declined by 9% per yr, while samples from adults in New York City and San Francisco declined by 6 and 5%, respectively. Predicted skeletal burdens in Anaktuvuk Pass residents born in 1954 and 1959 achieved maxima in 1971 and 1974, respectively; concentration in children born in 1964 were still increasing in 1979 but had achieved a lower level than older age cohorts. Estimated radiation dose rates to adult skeletons during 1964-66 were 13-15 mrad/yr based on predicted vertebrae 90Sr concentrations. Those dose rates were less than or equal to 1% of recommended ICRP limits for general populations.

137Cs concentrations in northern Alaskan Eskimos, 1962-79: effects of ecological, cultural and political factors.

Concentrations of worldwide fallout 137Cs were measured in the lichen-caribou-Eskimo food chain of northern Alaska during the period 1962-79. Pronounced inputs of fallout occurred after major nuclear weapons tests in the atmosphere and 137Cs was transmitted through the food chain to Eskimos with about a 2-yr delay due to environmental parameters. Caribou (Rangifer tarandus) meat sampled during spring harvest contained 4 times the 137Cs concentration of lichens obtained from their winter range. Calculated caribou meat ingestion rates of Anaktuvuk Pass Eskimos during winter ranged from approximately 1 kg/day in 1964 to 0.16 kg/day in 1977. Several environmental factors affected seasonal patterns and amounts of 137Cs transferred through the food chain. Maximum 137Cs concentrations of approximately 20 nCi/kg body weight in ESkimos occurred in 1964 and have now decreased to approximately 0.5 nCi/kg, largely because of cultural and political factors. Radiation doses from 137Cs body burdens during the study period ranged from 60 mrad/yr in 1962 to approximately 140 mrad/yr during the 1962-64 maxima and decreased to 8 mrad/yr in 1979.

Cesium-137 body burdens in Alaskan Eskimos during the summer of 1965.

Cesium-137 body burdens of Anaktuvuk Pass, Alaska, residents during the summer of 1965 were about 30 percent less than during 1964. Lower amounts of cesium-137 in the people reflected a similar decrease of this isotope in caribou flesh, which serves as the principal food of the natives.