Relationship between central venous pressure and bioimpedance vector analysis in critically ill patients.

OBJECTIVE: To assess the relationship between central venous pressure values and bioelectrical impedance vector analysis (BIVA), which may be used as complementary methods in the bedside monitoring of fluid status. DESIGN: Cross-sectional evaluation of a consecutive sample. SETTING: Intensive care unit of a university hospital. PATIENTS: One hundred and twenty-one consecutive Caucasian, adult patients of either gender, for whom routine central venous pressure measurements were available. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Central venous pressure values and impedance vector components (i.e., resistance and reactance) were determined simultaneously. Total body water predictions were obtained from regression equations according to either conventional bioimpedance analysis or anthropometry (Watson and Hume formulas). Variability of total body water predictions was unacceptable for clinical purposes. Central venous pressure values significantly and inversely correlated with individual impedance vector components (r2 = .28 and r2 = .27 with resistance and reactance, respectively), and with both vector components together (R2 = .31). Patients were classified in three groups according to their central venous pressure value: low (0 to 3 mm Hg); medium (4 to 12 mm Hg); and high (13 to 20 mm Hg). Three BIVA patterns were considered: vectors within the target (reference) 75% tolerance ellipse (normal tissue hydration); long vectors out of the upper pole of the target (dehydration); and short vectors out of the lower pole of the target (fluid overload). The agreement between BIVA and central venous pressure indications was good in the high central venous pressure group (93% short vectors), moderate in the medium central venous pressure group (35% normal vectors), and poor in low central venous pressure group (10% long vectors). CONCLUSIONS: Central venous pressure values correlated with direct impedance measurements more than with total body water predictions. Whereas central venous pressure values >12 mm Hg were associated with shorter impedance vectors in 93% of patients, indicating fluid overload, central venous pressure values <3 mm Hg were associated with long impedance vectors in only 10% of patients, indicating tissue dehydration. The combined evaluation of intensive care unit patients by BIVA and central venous pressure may be useful in therapy planning, particularly in those with low central venous pressure in whom reduced, preserved, or increased tissue fluid content can be detected by BIVA.

Discriminating between body fat and fluid changes in the obese adult using bioimpedance vector analysis.

OBJECTIVE: Conventional body composition methods may produce biased quantification of fat and fat-free mass in obese subjects, due to possible violation of the assumption of constant (73%) tissue hydration. We used an assumption-free, graphical method for interpreting body weight variation in obesity using bioelectrical measurements. DESIGN: 540 obese subjects with body mass index (BMI) > 31 kg/m2 without apparent edema were compared to 726 healthy subjects with BMI < 31 kg/m2 and to 50 renal patients with apparent edema. A subgroup of 48 obese subjects were evaluated again after weight loss (8.6 kg, 3 BMI units) following one-month energy restriction (5 MJ/d, 1200 kcal/d). 32 obese uremic patients were evaluated before and after a dialysis session (3.2 kg fluid removed). Direct measurements obtained from standard 50 kHz frequency bioelectrical impedance analyzer were used as impedance vectors in the Resistance-Reactance Graph. RESULTS: 1) Impedance vectors of obese subjects could be discriminated from those of edematous patients with 91% correct allocation; 2) A significant lengthening of vectors was observed after fluid loss of 3 kg in obese subjects; but 3) A body weight loss of about 9 kg after energy restriction was associated with no vector displacement. CONCLUSION: A different impedance vector pattern was associated with body weight loss in obesity due to fluid removal (vector lengthening) versus an energy-restricted diet (no vector displacement).

Persistent MR contrast enhancement of calcified neurocysticercosis lesions.

PURPOSE: We sought to determine whether cysticercosis lesions in the brain continue to enhance after nodular involution and complete calcification, and to investigate the clinical significance of this finding with respect to seizure recurrence after cysticidal treatment. METHODS: Serial contrast-enhanced MR images were obtained in all patients with neurocysticercosis seen at our hospital over a 6-year period (1991-1997). From this group, all patients with nodular calcified lesions were selected for study. RESULTS: Sixteen of 29 patients with neurocysticercosis had nodular calcified lesions. Six of these 16 had rim enhancement of nodular calcified lesions for at least 1 year after imaging evidence of complete calcification. Three of these six patients with enhancing, calcified lesions continued to experience seizures. Three of the 10 patients without enhancement also continued to have seizures. CONCLUSION: Contrary to the literature, which states that enhancement and disease activity cease with calcification, six (38%) of 16 patients had lesions that continued to enhance after complete calcification. This abnormality may be a risk factor for posttreatment seizures or may suggest eventual resorption of the calcified lesion.

Asymmetry of the total body water prediction bias using the impedance index.

Our purpose was to prove on a geometric basis that the bias of total body water (TBW) prediction equations based on the impedance index is far greater in fluid overloading than in dehydration. We used formal evaluation of conventional bioimpedance regression equations in both normal and abnormal body fluid status. We plotted the hyperboloid function generated from a standard prediction equation for the TBW over the resistance-reactance (RXc) plane containing the bivariate tolerance intervals (ellipses) of the healthy population. The equation estimated 35 L TBW for the average man (both sexes) of 170 cm height. Leaving the center of the tolerance ellipses, over which the function was relatively flat, the predicted TBW rapidly increased to absurd values for the shorter vectors, indicating fluid overloading (e.g., > 100 L for R < 170 ohm). Migration of the longer impedance vectors beyond the upper pole of 95% tolerance ellipse, which is in the dehydration region, produced less biased estimates of TBW (e.g., < 22 L for the extreme R values > 850 ohm). Different formulas produced TBW prediction bias of the same order. Due to the hyperbolic shape, functions of the impedance index are critically dependent on the region of the RXc plane where they are calculated and they produce misleading results in patients with fluid overload.

A new method for monitoring hydration at high altitude by bioimpedance analysis.

Our study evaluated the performance of a graphical method for monitoring the fluid variation at high altitude in seven adult Caucasian male subjects (average age 25 yr, average height 177 cm). The graphical approach is called the Resistance-Reactance (RXc) graph method and is based on standard bioimpedance analysis (tetrapolar, 50 kHz frequency). Measurements were taken at sea level before the expedition, at 5050 m after 1 wk and 3 wk, and again at sea level after descent. Plasma and urine electrolytes, osmolalities, and the free-water clearance were determined by standard methods. All climbers had baseline impedance vectors within the reference 95% tolerance ellipse for the Italian male population. The high altitude dehydration caused a significant lengthening of vectors, which after descent underwent a significant shortening and returned close to the baseline values. Average urine volume increased by 1.4 l.d-1 in the first week and average body weight decreased by 4.4 kg after 3 wk. The RXc graph method could be useful in the planning of the individual climber's appropriate dehydration and fluid intake at altitude since a feedback control of the hydration is allowed without any assumption of body composition.

Body fluid overload and bioelectrical impedance analysis in renal patients.

Using a new bivariate vectorial approach to the standard bioimpedance analysis (tetrapolar, 50-kHz frequency), we evaluated the performance of a graphical method for the identification of patients with fluid overload. Two hundred and seventeen adult Caucasian subjects were divided into four classification groups: 86 healthy control subjects, 55 patients with mild-to-terminal chronic renal failure in conservative treatment (15% with apparent edema), 36 patients with idiopathic nephrotic proteinuria (58% with apparent edema), and 40 obese subjects. We found a bioimpedance threshold for apparent edema on the lower pole of the sex-specific 75% tolerance ellipse (bivariate tolerance interval) of the healthy population. This innovative graphical method allows identification, monitoring and therapy planning of patients with fluid overload using direct bioimpedance measurements without any assumption on body composition.

A decision analysis comparing three dosage regimens of subcutaneous epoetin in continuous ambulatory peritoneal dialysis.

Epoetin (recombinant human erythropoietin; EPO) therapy adds a significant cost to the management of end-stage renal disease, the majority of the extra expense being attributable to its acquisition cost. In a Japanese multicentre, randomised, prospective study, a significant dose-dependent response was documented with epoetin given subcutaneously (SC) once a week or once every 2 weeks to patients receiving continuous ambulatory peritoneal dialysis. Three different dosages were studied over 5 months in patients with a haematocrit (Hct) of 0.28 or less, namely 6000U (107 U/kg), 9000U (167 U/kg) and 12,000U (211 U/kg). Epoetin was given weekly for the first 2 months until the target Hct value of 0.33 was reached. The rates of response were 81, 85 and 100% with the 6000U, 9000U and 12,000U regimens, respectively. Subsequently, responders were maintained at the target Hct for an additional 3 months, with the administration frequency eventually being reduced to fortnightly or 4-weekly. Patients in the epoetin 6000U and 9000U groups who did not respond after 2 months' treatment underwent induction and maintenance with the 12,000U regimen. During the maintenance phase, patients receiving the epoetin 6000U and 9000U dosages required weekly (54 and 64%, respectively) or fortnightly (46 and 36%, respectively) injections. Patients receiving the 12,000U regimen were found to require weekly (9%), fortnightly (73%) or 4-weekly (18%) injections. Using these data, we performed a decision analysis that quantitatively incorporated the probability of attaining and maintaining target Hct levels in all patients (i.e. the effectiveness of epoetin), and direct costs as a function of both cumulative doses and injections required in all 3 strategies over 5 months. Decision analysis indicated that the most cost-effective SC epoetin strategy in patients undergoing peritoneal dialysis is epoetin 6000U weekly for 2 months, followed by maintaining the target Hct with weekly or 2-weekly epoetin 6000U for the next 3 months. Nonresponders should restart epoetin therapy using the 12,000U strategy. The 9000U and 12,000U strategies were associated with similar costs, because the economic advantages associated with the lower administration frequency of the 9000U regimen compared with the 6000U regimen were offset by its higher cumulative acquisition cost. In other words, decision analysis indicated that the most cost-effective strategy was to use the lowest effective dose, reserving the highest dosage for patients who do not respond after 2 months. The superiority of this strategy was confirmed by a sensitivity analysis performed on the cost of drug administration, which was varied from zero to $US60 per dose.(ABSTRACT TRUNCATED AT 400 WORDS)

Determination of fostriecin pharmacokinetics in plasma using high-pressure liquid chromatography assay.

Fostriecin is an antitumor antibiotic with marked activity against ovarian, breast, and lung cancer cell lines in the human tumor clonogenic assay. The mechanism of cytotoxicity in vivo is unknown; in vitro it has been shown to inhibit macromolecular synthesis, interact with the reduced folate carrier system, and inhibit topoisomerase II. Phase I testing of fostriecin in a daily for 5 days schedule has begun in cancer patients. A high-pressure liquid chromatographic method to measure fostriecin in plasma samples was developed using sulfaquinoxaline as an internal standard and ultraviolet detection (268 nm). The extraction efficiency is 70% and the sensitivity limit is 100 ng/ml. The pharmacokinetics of fostriecin were determined in six rabbits following intravenous injection of 12 mg/m2. The mean distribution space was 4.44 L/m2 and the mean plasma clearance was 302 ml/min/m2. The elimination half-life was 11.95 +/- 8.55 min. All rabbits exhibited a 10-60-fold increase in aspartate aminotransferase (AST) and alanine aminotransferase (ALT) that resolved within 48 h of drug administration.

Therapy for idiopathic membranous nephropathy: tailoring the choice by decision analysis.

Two Italian controlled trials demonstrated that the difference in remission rates obtained with six months of methylprednisolone and chlorambucil (MP+Ch) compared to MP was smaller than MP+Ch versus symptomatic therapy in the treatment of idiopathic membranous nephropathy nephrotic syndrome (NS). A decision analysis was used to compare the three treatment strategies, assuming triple probabilities and costs for MP+Ch complications compared to MP, with no risk for supportive therapy, referring to an average 40-year-old patient and using the quality-adjusted life expectancy year (QALY) as the utility scale. With MP+Ch the difference in expected QALY was 7.2 years compared to supportive therapy, and 2.6 years compared to MP. To offset the longer survival obtained with MP+Ch versus MP, it was assumed that all patients treated with MP+Ch would undergo either fatal (5% vs. 0.3% with MP) or non-fatal complications (95% vs. 15% with MP). This threshold denotes a great stability of the inequality in the expected QALY. Consequently, treatment with MP or with MP+Ch is justified if their side effects are considered to be a suitable trade-off for a five or seven QALY, respectively, longer survival. Only an absurd increase in the death rate with MP+Ch could offset the difference.

An 11-year evaluation of a Living With Cancer program.

Although many attempts are made at starting cancer support groups, few groups ever stand the test of time. Using a successful, long-standing program as a model is an important first step to establishing a new group. The intricacies of staffing, obtaining resources, and marketing are important factors in maintaining a program for any extended length of time. No matter how much a group is wanted or needed, pitfalls that threaten its existence are bound to occur. Overcoming these pitfalls is the key to a lasting support program.

Cyclosporine: a nursing focus on immunosuppressive therapy.

The clinical and psychosocial ramifications of immunosuppressive therapy are important aspects of nursing assessment and intervention. The active role of the critical care nurse in immunosuppressive therapy is critical to reduce serious complications of this drug.

[A survey on the use of pesticides in the province of Treviso]. / Indagine conoscitiva sull'utilizzo di presidi sanitari nella provincia di Treviso.

The results of a study on a sample of 301 farms of the province of Treviso are here presented. The aim of our study was the evaluation of the quantity of pesticides, considered as active principle, spread over this territory in 1987. Our data stress that arboreal cultivations need the major quantity of fungicides, insecticides and acaricides while the use of herbicides and soil insecticides is almost exclusive to grassy cultures. The fungicides result the most widely used pesticides followed by herbicides and, to a less degree, the other products. In our case they are used nearly exclusively in vine growing. We underline that, although the consumption of pesticides fell within correct agronomic standards, this quantity could be considerably reduced by modern technology.