Spurious assessment of acid-base status due to dilutional effect of heparin.

A patient was encountered in whom clinically significant spurious hypocapnia and hypobicarbonatemia were diagnosed resulting from the dilutional effect of excessive amounts of sodium heparin solution in the blood sample. This report presents the relevant data in this patient, summarizes the effects of heparin on the determination of the acid-base status, and provides suggestions for avoiding this important pitfall in clinical practice.

A transport model with coupled ternary exchange and chemisorption retention for hydrazinium cations.

A numerical model was developed to describe the fate and transport of hydrazinium (N2H5+) and competing Ca2+ and H+ cations applied in acidic solutions to columns of Ca2+/H+-saturated sandy soil during steady saturated flow conditions. Instantaneous ternary H+-Ca2+-N2H5+ cation exchange using the Gaines-Thomas approach was combined with second-order, irreversible, kinetic chemisorption of exchange-phase N2H5+ ions as major retention mechanisms for N2H5+. Exchange-mediated chemisorption is assumed to occur as chemical binding of N2H5+ ions located on carboxyl-group exchange sites to nearby carbonyl groups, consequently decreasing the effective soil cation exchange capacity (CEC). Comparison of simulated and observed breakthrough curves (BTCs) for concentrations of N2H5+ and Ca2+ ions in column effluent was used in model evaluation. The cation transport model with cation exchange coupled with exchange-mediated chemisorption provided a valid first approximation for N2H5+ transport.

Tracking clinical preventive service use: a comparison of the health plan employer data and information set with the behavioral risk factor surveillance system.

BACKGROUND: There is a need for meaningful and accurate ways of tracking preventive service delivery among different sectors of the US population. OBJECTIVES: To compare methodologies of and clinical preventive service use estimates obtained from 2 data sets: the Health Plan Employer Data and Information Set (HEDIS 3.0) and the Behavioral Risk Factor Surveillance System (BRFSS). METHODS: HEDIS used a combination of mailed-survey, administrative, and medical-record data to measure preventive service use among commercial enrollees of 320 HMOs in 42 states during 1996. BRFSS data are from insured respondents (excluding those reporting Medicare or Medicaid coverage) to a random-digit-dialed telephone survey conducted in the same 42 states during 1996. RESULTS: The median state-specific mammography, Papanicolaou smear, and retinal examination rates reported by HEDIS were consistently and substantially lower than those reported by BRFSS. For mammography, the median HEDIS rate was 72.4%, compared with 81.1% for BRFSS. For Papanicolaou smear and retinal examinations, HEDIS rates were 72.7% and 40.8%, respectively, compared with 91.2% and 61.6% for BRFSS. The median state rates of advice to quit smoking reported by HEDIS were similar to those for BRFSS: 62.1% versus 62.2%, respectively. For each measure, the absolute difference between HEDIS and BRFSS rates varied substantially both within a state and between states. CONCLUSIONS: It does not appear that the BRFSS and HEDIS data can be compared directly to accurately track progress toward national preventive health objectives. This study highlights some of the problems with comparing these data and possible means for addressing the discrepancies.