Hydration Volumes Research Articles

Analysis of the hemogram and biochemistry parameters of patients with trauma

Aims: Trauma-related deaths remain a significant public health concern, with organ complications in over 30% of multitrauma patients leading to high morbidity and mortality. This study aims to understand the changes and reliability of hemoglobin, hematocrit, AST, and ALT levels in trauma cases and their impact on treatment planning. Methods: A retrospective analysis was conducted on 259 multitrauma patients admitted to Ankara Atatürk Training and Research Hospital between July and December 2012. Data on demographic details, trauma types, laboratory parameters, physical and tomographic examinations, treatment modalities, and outcomes were analyzed using SPSS software. Results: The study group predominantly comprised males (74.9%) with a mean age of 42.15 years. Various trauma types were analyzed, including traffic accidents and falls. Significant fluctuations in hemoglobin and hematocrit levels were observed post-fluid resuscitation, regardless of bleeding status. Notably, AST and ALT levels were reliable indicators of hepatic injury. The study also highlighted the effects of fluid hydration volumes on hemoglobin and hematocrit levels. Conclusion: The findings challenge the conventional understanding that drops in hemoglobin and hematocrit levels primarily indicate bleeding in multitrauma patients. Instead, these changes might also result from fluid resuscitation. The study underscores the importance of considering both bleeding and resuscitation efforts when interpreting these laboratory parameters. This study provides new insights into the interpretation of hemoglobin, hematocrit, AST, and ALT levels in trauma patients. It suggests a more nuanced approach in treatment planning, considering the significant impact of fluid resuscitation on these parameters, alongside bleeding.

Different hydration protocols for the quantification of healthy tissue uptake of half-dose 18F-FDG total-body positron emission tomography-computed tomography: a prospective study.

This study aimed to investigate the effects of the volume and time of hydration on the quantification of healthy tissue uptake for 2-deoxy-2-[18F]-fluoro-D-glucose (18F-FDG) total-body positron emission tomography (PET)-computed tomography (CT) with half-dose activity. This study prospectively enrolled 180 patients who underwent a total-body PET-CT scan 10 min after injection of a half-dose (1.85 MBq/kg) of 18F-FDG. These patients were placed in hydration groups (30 patients in each group) according to different hydration volumes and times: oral hydration with 500 mL of water 20 min before (G1), 5 min after (G2), and 30 min after (G3) the 18F-FDG injection; and oral hydration with 200 mL of water 20 min before (G4), 5 min after (G5), and 30 min after (G6) the 18F-FDG injection. Another 30 patients underwent dynamic imaging without hydration and were used a nonhydration group. The analysis of quantification of healthy tissue uptake included the maximum standardized uptake value (SUVmax) and the mean SUV (SUVmean) of the blood pool and muscle, as well as the SUVmax, SUVmean, and signal-to-noise ratio (SNR) of the liver. The SUVmax of the blood pool (2.33±0.36), liver (3.03±0.42), and muscle (0.81±0.15) was significantly higher in the nonhydration group than in any of the 6 hydrated groups (P<0.05 for all hydration groups vs. nonhydration group). Muscle SUVmax and SUVmean were significantly (P<0.05) lower in G1 and G2 than in G3 and were lower in G4 and G5 than in G6. The SUVmax and SUVmean of the blood pool were significantly (P<0.05) lower in G1 than in G3 and G4 and lower in G3 than in G6. When total-body PET-CT with a half dose of 18F-FDG activity is performed, hydration can significantly affect the quantification of healthy tissue uptake. Oral administration of 500 mL of water 20 min before injection could reduce background radioactivity.

Comparison Of Hydration Practices Of Long-distance Runners During Covid-19: A Cross-sectional Study

PURPOSE: To assess and compare the self-reported hydration practices of long-distance runners during an intended long training run and an intended event during COVID-19. Inconsistent hydration practices may lead to overhydration, a primary cause of exercise-associated hyponatremia (EAH). METHODS: Cross-sectional survey design. An online survey utilized both the North Dakota State University online community and a Connecticut running group listserv(s) in October, 2020. A long-distance runner was defined as one who had completed at least one ten-mile run. Survey questions addressed hydration practices, including hydration strategies and volumes consumed before and during an intended long-distance training run (LTR) and an intended race. Demographics, training experience, sources of hydration information, and knowledge of EAH were collected. RESULTS: The comparison of self-reported hydration strategies between an intended LTR and an intended event showed moderate agreement (0.74) among n = 203. The agreement between an intended LTR and an intended event was statistically significant when estimated by the Kappa statistics (K = 0.674; p < 0.0001). When comparing intended volumes during a LTR and an event, there was a correlation of 0.74. In a one-sided paired t-test, the intended volumes during an event were significantly greater than the intended volumes during a LTR (t = 5.99; p < 0.0001). Runners reported “drinking according to thirst” 24% of the time during an intended LTR, compared to 23% of the time for their intended event. Finally, this study found that 59% reported knowledge and awareness of EAH, while 89% felt they had a solid understanding an effective hydration plan for long distance running. CONCLUSIONS: In this study, long-distance runners reported some differences in planned hydration practices when comparing an intended long training run to an intended event. Drinking according to thirst is recommended to prevent EAH in lieu of a personalized hydration plan. If runners mimic appropriate hydration practices, such as drinking according to thirst, during training when running an event, the risk of EAH may be decreased. This indicates a need for ongoing education on hydration practices and EAH. The primary limitation of this study was the self-reported nature of historical data.

Hydration Practices of Long-Distance Trail Runners Competing in Connecticut (CT) During COVID-19

ObjectivesThe purpose of this research is to assess and compare the self-reported hydration practices of long-distance trail runners during an intended long training run (LTR), an intended event, and during an actual event during COVID-19. The hypothesis is that hydration practices are inconsistent between these three scenarios and runners sometimes consume more than intended during an event. Consuming more fluids than intended may lead to exercise-associated hyponatremia (EAH).MethodsCross-sectional pre- and post-survey design. The setting was the Macedonia Trail Race was in Kent, CT and the Angevine Farm Trail Race was in Warren, CT. A total of 26 (of 310 registered) eligible runners from one of the events volunteered to be participants. The pre-race survey assessed intended hydration practices of training and a possible event. The post-race assessed the actual hydration practices of the race. Main outcome measures were hydration practices, including strategies and volumes during a LTR, and intended event, and the actualevent. Awareness and knowledge of EAH, and the understanding of an effective hydration plan were assessed.ResultsThere was a strong correlation (0.91) between intended volumes before the LTR and the intended event. When comparing volumes consumed during the event to the intended event, the correlation was moderate (0.52). Moderate agreement (64–85%) was found when comparing the hydration strategies in the intended and the actual events. The comparisons were statistically significant when measured by the Kappa statistic (P < 0.05). Runners reported drinking according to thirst an average of 30% across the three scenarios. This study found that 50% of runners reported knowledge and awareness of EAH, while 62% felt they had a solid understanding of an effective hydration plan.ConclusionsIn this study, long-distance trail runners reported differences in hydration practices when comparing an intended LTR, an intended trail event, and an actual trail event. Drinking according to thirst is the recommended hydration strategy to prevent EAH, in lieu of a personalized hydration plan. This indicates a need for ongoing education on hydration practices and EAH. The primary limitations of this study are self-reported data and small sample size due to COVID-19.Funding SourcesNone

Mortar pore pressure prediction during the first hours of cement hydration

During cement hydration, solid, fluid, and total volumes vary as water is consumed by chemical reactions. Those volume variations lead to pore water pressure decrease during the first hours of hydration. The deformations induced by early hydration are quantified in order to understand their consequences on the internal stress state within the hardening material.This paper aims to link pore water pressure with autogenous and chemical shrinkage during the first hours of hydration in the bulk of early setting cement mortar. It is demonstrated that specific volume variations are compensated by an increase of air-entrained volume. The variation of the volume of air is used to predict the air pressure. Using the size of a maximum capillary pore diameter filled with water, the capillary pressure is estimated using the Young-Laplace equation. In order to validate the approach, the pore water pressure is measured and compared to the thermodynamic prediction and air content.

Tobacco waste hydrolysate of stem and root of the tobacco plant for biostimulation in rice and corn seed germination

ABSTRACT: Stimulation of seed germination may be due to acceleration of germination as well as due to seedling growth-promotion during early development. Plant hydrolysate can be applied as a stimulant. Thus, we aimed to verify the influence of the hydrolysates, obtained by alkaline or acid treatment, from tobacco (Nicotiana tabacum L.) crop residues (root and stem) on the seed germination process. Seed germination was studied with Oryza sativa (rice) and Zea mays (corn). Sixteen germination experiments of 50 seeds each were undertaken, with 4 replicates, soaked with hydrolysates diluted at 20 and 80%, in 2 and 3 mL of hydration volumes for 48 h. Germinated seeds were counted, at which point radicular protrusions were observed. Rootlets and aerial parts were collected, dried and weighed. The hydrolysates presented seedling nutrition potential to the corn, with ~50% more mass compared to the results with water at the same conditions, and the germination acceleration was not significant. For the tested rice seeds, the results were reversed, and the germination acceleration was significant with rates up to 94% after 48 h of incubation. Better results of germination were obtained with hydrolysate from acid treatment, and root or stem tobacco can be used for this purpose.

Investigating the application of reactive polymers in fluid loss control

Water reactive polymers are rapid setting fluids that exhibit high viscosity after being exposed to water to control severe fluid loss. In this study, the performance of a water reactive polymer is studied through a series of fluid loss experiments. Various unconsolidated and permeable formations were simulated using different sand size grades, with the change in permeability being recorded after applying the reactive polymer under different operating conditions. The results showed 62–100% permeability reductions depending on the initial value of permeability and operating conditions. In addition, the setting time of the reactive polymer was obtained at different water concentrations and temperatures by monitoring the viscosity of the reactive polymer using a Brookfield viscometer. The results indicate that a hydration time of 30 min is satisfactory to reach an acceptable viscosity for all hydration volumes tested. At lower hydration volumes, the viscosity increased rapidly at the same rate and reached the same maximum viscosity. As hydration volume increased, both the rate of increase and maximum viscosity were reduced.

Optimal hydration volume among high-risk patients with advanced congestive heart failure undergoing coronary angiography.

We investigated the relationship between weight-adjusted hydration volumes and the risk of developing contrast-induced acute kidney injury (CI-AKI) and worsening heart failure (WHF) and explored the relative safety of optimal hydration volumes in patients with advanced congestive heart failure (CHF) undergoing coronary angiography (CAG) or percutaneous coronary intervention. We included 551 patients with advanced CHF (New York Heart Association class > 2 or history of pulmonary edema) undergoing CAG (follow-up period 2.62 ± 0.9 years). There was a significant association between hydration volume-to-weight ratio (HV/W) (quintile Q1, Q2, Q3, Q4, and Q5) and the incidence of CI-AKI (3.7%, 14.6%, 14.3%, 21.1%, and 31.5%, respectively) and WHF (3.6%, 5.4%, 8.3%, 13.6%, and 19.1%, respectively) (all P-trend < 0.001). Receiver operating curve analysis indicated that HV/W = 15 mL/kg and the mean HV/W (60.87% sensitivity and 64.96% specificity) were fair discriminators for CI-AKI (C-statistic 0.696). HV/W >15 mL/kg independently predicted CI-AKI (adjusted odds ratio [OR] 2.33; P = 0.016) and WHF (adjusted OR 2.13; P = 0.018). Moreover, both CI-AKI and WHF were independently associated with increased long-term mortality. Thus, for high-risk patients with advanced CHF undergoing CAG, HV/W > 15 mL/kg might be associated with an increased risk of developing CI-AKI and WHF. The potential benefits of a personalized limitation of hydration volume need further evaluation.

Safe Hydration Volume to Prevent Contrast-induced Acute Kidney Injury and Worsening Heart Failure in Patients With Heart Failure and Preserved Ejection Fraction After Cardiac Catheterization.

Few studies have investigated the efficacy and safety of hydration to prevent contrast-induced acute kidney injury (CI-AKI) and worsening heart failure (WHF) after cardiac catheterization in heart failure and preserved ejection fraction (HFpEF; HF and EF ≥50%) patients. We recruited 1206 patients with HFpEF undergoing cardiac catheterization with periprocedural hydration volume/weight (HV/W) ratio data and investigated the relationship between hydration volumes and risk of CI-AKI and WHF. Incidence of CI-AKI was not significantly reduced in individuals with higher HV/W [quartile (Q) 1, Q2, Q3, and Q4: 9.7%, 10.2%, 12.7%, and 12.2%, respectively; P = 0.219]. Multivariate analysis indicated that higher HV/W ratios were not associated with decreased CI-AKI risks [Q2 vs. Q1: odds ratio (OR), 0.95; Q3 vs. Q1: OR, 1.07; Q4 vs. Q1: OR, 0.92; all P > 0.05]. According to multivariate analysis, higher HV/W significantly increased the WHF risk (Q4 vs. Q1: adjusted OR, 8.13 and 95% confidence interval, 1.03-64.02; P = 0.047). CI-AKI and WHF were associated with a significantly increased risk of long-term mortality (mean follow-up, 2.33 years). For HFpEF patients, an excessively high hydration volume might not be associated with lower risk of CI-AKI but may increase the risk of postprocedure WHF.

Evaluation of individual ionic partial molar volumes in aqueous solutions

In a recent H 2O–D 2O molar volume isotope effect study on the alkali metal halide solutions, individual ionic standard partial molar volume contributions ( V ¯ ion ∘ ( H 2 O ) - V ¯ ion ∘ ( D 2 O ) = Δ V ¯ ion ∘ ( H–D ) ) have been derived, dependent only on the chosen (Pauling) ionic radii, r ion. It has been concluded that the isotope effect of the cations (except for Li +) and that of the chloride anion exhibit a linear function of 1/ r ion, with Δ V ¯ ion ∘ ( H − D ) vanishing when 1/ r ion approaches zero. On the other hand, the directly measurable hydrodynamic “cosphere” volumes of the ions, V ¯ cosph ∘ , derived from the kinetic ionic (Stokes) radii, show a similar pattern, here also the cationic and anionic r ion relations cross or meet at V ¯ cosph ∘ ( Cs + ) ≅ V ¯ cosph ∘ ( Cl - ) . Because both Δ V ¯ ion ∘ ( H–D ) and V ¯ cosph ∘ originate in the hydration volumes of the ions, ( V ¯ hydr ∘ = V ¯ ion ∘ - V ¯ intr ∘ ) determined by electrostriction, this r ion pattern of the V ¯ hydr ∘ (ion) provides an “extra-thermodynamic” assumption to evaluate the individual cationic and anionic molar volume contributions in normal water solution. As a basis for the evaluation, this r ion pattern is applied to the conventional cationic and anionic V ¯ hydr ∘ (ion) values (related to V ¯ ion ∘ ( H + ,aq . ) = 0 cm 3 · mol - 1 ) , calculated from literature V ¯ ion ∘ data, assuming that the V ¯ intr ∘ (ion) = V ¯ cryst ∘ (ion). To adjust the V ¯ hydr ∘ ( Cl - ) to the V ¯ hydr ∘ ( Na + , K + , Rb + , Cs + ) versus r ion relation at T = 298.15 K, the conventional anionic V ¯ hydr ∘ (ion) data have to be increased, the cations have to be decreased by 4.2 cm 3 · mol −1. Similar adjustments at five different temperatures between T = (273 and 323) K, result in V ¯ ion ∘ ( H + ,aq . ) = - ( 4.2 ± 0.2 ) cm 3 · mol - 1 at T = 298.15 K, with an increment of −0.02 cm 3 · K −1 · mol −1. Related to these parameters, relations of V ¯ ion ∘ versus temperature for the alkali metal and halide ions were calculated. The cationic and anionic V ¯ hydr ∘ (ion) values, when related to V ¯ ion ∘ ( H + ,aq . ) = - 4.2 cm 3 · mol - 1 , show strong r ion correlation with V ¯ cosph ∘ , their ratio versus r ion offers a linear equation to compare the influence of the ions on the solvent structure on a well defined “quantitative” scale. The value of the derived V ¯ ion ∘ ( H + ,aq . ) , while being consistent with that widely accepted ca. − (5 ± 2) cm 3 · mol −1, has a higher precision with a reasonable basis of the applied “extra-thermodynamic” assumption. It can serve to verify other partitioning procedures used in non-aqueous solvents.

Efficacy and tolerability of a weekly schedule of docetaxel-cisplatin as first-line treatment for advanced non-small cell lung cancer (NSCLC)

18159 Background: Docetaxel-cisplatin, administered every 3 weeks, is an effective first-line chemotherapy for locally advanced or metastatic NSCLC. However, this regimen is commonly associated with neutropenia and neutropenic infections. Moreover, the extensive hydration required with cisplatin given every 3 or 4 weeks makes outpatient treatment difficult. We assessed the efficacy and tolerability of weekly docetaxel-cisplatin, which may be better tolerated than the standard regimen. Methods: Patients (pts) with histologically confirmed stage UICC IIIB (malignant effusion) or IV NSCLC were treated with docetaxel (35 mg/m2, 30 min. infusion) and cisplatin (25 mg/m2, 30-min. infusion) on Days 1, 8, and 15, every 4 weeks for 4–6 cycles. Pts received ondansetron 8 mg iv and dexamethasone 8 mg iv preceding every day of chemotherapy and oral dexamethasone 2 x 4 mg daily from the day before until the day after chemotherapy. NK1-antagonists were given at the investigator’s discretion. On each day of therapy, 2750 mL of fluid was infused over 3.5 h. Most pts were treated in an outpatient department. Safety was assessed using CTCAE v3.0. The primary endpoint was response rate (RECIST). Results: 45 pts were enrolled; efficacy and tolerability data were available for 43 pts. 12/45 pts achieved an objective response (11 partial; 1 complete; ITT response rate 27%). Median time to progression was 3.9 months. Pts received a median of 3 full cycles. 4 pts (9%) required dose reductions. No cases of neutropenic fever/infections or grade 2–4 thrombocytopenia were observed. Only 2 pts (5%) had grade 3 neutropenia. One pt (2%) experienced grade 3–4 nausea/vomiting. 5 pts died during therapy for reasons not unequivocally attributable to tumor progression (bacterial meningitis with normal neutrophil counts [n=1], pneumonia with normal neutrophil counts [n=1], pulmonary arterial embolism [n=1], unknown [n=2]). Conclusions: Docetaxel-cisplatin administered weekly was well tolerated. Hematologic toxicity and neutropenic fever were uncommon. Docetaxel-cisplatin can be safely administered with relatively low hydration volumes in an outpatient setting. Survival data will be presented. No significant financial relationships to disclose.

Raman Spectroscopic Study on the Hydration Structures of Tetraethylammonium Cation in Water

Conformational changes of tetraethylammonium ion (Et4N+) in aqueous solution have been studied by Raman spectroscopy as functions of pressure and concentration. The difference in the partial molar volume (Delta V(tg x tg-->tt x tt)) between the trans-gauche x trans-gauche (tg x tg) and trans-trans x trans-trans (tt x tt) conformers of Et4N+ ion has been calculated from the pressure dependence of the relative Raman intensity ratio between the conformers. We discuss about the Delta V(tg x tg-->tt x tt) with two contributions from the molecular and hydration volumes. Delta V(tg x tg-->tt x tt) is found to be negative, and this is mainly due to the large molecular volume contribution. The value of Delta V(tg x tg-->tt x tt) becomes smaller with increasing R probably due to the hydration volume contribution. In view of the pressure and concentration dependences, the water molecules around Et4N+ ions at R = 19 (R= moles of water/moles of salt) mainly form the hydrophobic hydration. The hydrophobic hydration may prefer the tt x tt conformer to the tg x tg conformer. On the other hand, the hydration structure at R = 4 no longer forms the hydrophobic hydration and changes to another type of hydration, where the medium H-bond component is the dominant species. The increase of the ion-ion interactions with decreasing R induces large fractions of the tg x tg conformer.

Prophylaxis Strategies for Contrast-Induced Nephropathy

Contrast-induced nephropathy is associated with significant economic and clinical consequences, including prolonged hospitalization, the requirement for dialysis, and an increased risk of death. To summarize the current state of evidence for prophylaxis of contrast-induced nephropathy, provide evidence-based recommendations regarding management of high-risk patients undergoing angiographic procedures, and identify new avenues for research. Systematic searches of peer-reviewed publications were performed in MEDLINE, EMBASE, and the Cochrane database from 1966 to January 2006. Search terms included radio contrast nephropathy, contrast media, acetylcysteine, theophylline, sodium bicarbonate, HMG Co-A reductase inhibitors, ascorbic acid, kidney diseases, renal insufficiency, kidney failure, nephropathy, fenoldopam, diuretics, and saline or half saline. Observational studies of risk factors and randomized controlled trials of prophylaxis strategies for contrast-induced nephropathy that specified a definition of contrast-induced nephropathy or postprocedure creatinine level as an outcome measure. Evidence Synthesis Important patient-related risk factors for contrast-induced nephropathy include chronic kidney disease, diabetes mellitus, heart failure, older age, anemia, and left ventricular systolic dysfunction. Non-patient-related risk factors include high-osmolar contrast, ionic contrast, contrast viscosity, and contrast volume. Practice guidelines recommend obtaining preprocedural serum creatinine levels among patients with renal disease, diabetes, proteinuria, hypertension, gout, or congestive heart failure. Available evidence, largely based on small- to medium-sized trials, supports the use of hydration, bicarbonate, and low volumes of iso- or low-osmolar contrast in patients at risk. N-acetylcysteine or ascorbic acid may be of value in very high-risk patients. While several risk factors for contrast-induced nephropathy have been identified, the development of an effective prophylaxis strategy for contrast-induced nephropathy has been limited by our poor understanding of the pathophysiology and the clinical significance of this condition. Future research should focus on correctly identifying higher-risk patients and testing therapies in the setting of large well-powered clinical trials.

Tolerability of a weekly schedule of docetaxel-cisplatin as first-line treatment in patients with stage IIIB/IV non-small cell lung cancer (NSCLC)

17112 Background: Recent trials have shown that the combination docetaxel-cisplatin is an effective first-line treatment in locally advanced or metastatic NSCLC. However, the regimen can be associated with a marked rate of neutropenia. The present study tests the efficacy and tolerability of a weekly schedule of docetaxel and cisplatin. Methods: Patients (pts) with histologically confirmed NSCLC stages UICC IIIB (malignant effusion) or IV were treated with docetaxel (35 mg/m2, 30 min. infusion) and cisplatin (25 mg/m2, 30 min. infusion) on days 1, 8 and 15 repeated every 4 weeks for 4 to 6 cycles. This phase II study is scheduled to include 50 pts and primary endpoint is tumour response rate. Pts received 8 mg of ondansetron and 8 mg of dexamethasone i.v. preceding every day of therapy and oral dexamethasone 2 × 4 mg from the day before until the day after chemotherapy. NK1-antagonists were given at discretion of the investigator. In total, 2750 ml of volume were infused on each day of therapy. Most of the pts were treated in an outpatient department. Safety was assessed via common terminology criteria for adverse events v3.0 (CTCAE 3.0). Interim tolerability data is presented. Results: Currently, 28 pts were evaluable for this interim tolerability analysis. Pts received a median of 3 full cycles. There were no treatment-related deaths. Dose reductions of docetaxel and cisplatin due to poor tolerability were necessary in 3 pts (11%). No pts suffered from neutropenic fever while grade 3 neutropenia occurred in only 2 pts (7%). There was no grade 2/3/4 thrombocytopenia. 5 pts (18%) had grade 2 anemia, and 2 pts (7%) had an elevation of the plasma creatinine (both grade 1). Other toxicities were non-neutropenic infections (5/1/1 pts with grade 2, 3, 4, respectively), diarrhea (3 pts [11%] with grade 3), constipation (5 pts [18%] with grade 2) and mucositis (4 pts [14%] with grade 2/3). There was no grade 3/4 nausea or vomiting; 3 pts [11%] had grade 2 nausea/vomiting. Conclusions: In the present study, the combination of docetaxel and cisplatin appears well tolerated. It was associated with a very low frequency of severe hematologic toxicity or neutropenic fever. With relatively low hydration volumes it can be safely administered in an outpatient setting. [Table: see text]

Strategies to reduce the risk of contrast nephropathy: an evidence-based approach

Contrast nephropathy is a common complication associated with angiographic procedures that carries significant morbidity and mortality. Recent clinical trials of prophylactic strategies have reported contradictory results. This review presents recent insights into the pathophysiology of contrast nephropathy and reviews trial results in this context. A prediction rule has been developed to better identify patients at risk of developing contrast nephropathy. Factors other than osmolality play a significant role in the pathogenesis of contrast nephropathy, at least for agents with osmolalities of 800 mOsm/kg or less. New randomized trial data do not support a role for N-acetylcysteine in contrast nephropathy prophylaxis and there is additional evidence that fenoldopam is ineffective. Pooled analyses of theophylline prophylaxis trials are inconclusive. Theoretical and clinical data suggest that ascorbic acid may be renoprotective, but this requires further study. The overall incidence of contrast nephropathy remains low. Available evidence supports the use of hydration and low volumes of iso-osmolar or low-osmolar contrast in patients at risk of developing contrast nephropathy. Heterogeneity has affected interpretability of interventional trials of N-acetylcysteine or theophylline prophylaxis strategies. Future clinical trials must identify and target moderate-risk to high-risk patients and ensure that proven therapies are included in trial protocols.

Effect of Added Pharmatose DCL11 on the Sustained-Release of Metronidazole From Methocel K4M and Carbopol 971P NF Floating Matrices

ABSTRACTIn vitro dissolution of metronidazole from sustained release floating tablets was studied with varied proportions of sodium bicarbonate (SB) and Pharmatose DCL 11. Two polymers with different hydration characteristics, Methocel K4M and Carbopol 971P NF, were used to formulate the matrices. The variables studied include the matrices' release profile, hydration volume, and floating behavior. All Methocel matrices floated more than 8 h with SB proportions up to 24%, while Carbopol matrices floated more than 8 h with SB proportions only up to 12%. Matrices' hydration increased with time until reaching a peak and declining thereafter. Methocel matrices showed greater hydration volumes and greater drug dissolution compared to Carbopol matrices. After adding increasing quantities of Pharmatose to matrices containing 12% SB, hydration volume decreased while dissolution increased. These results were attributed to water-filled pores that formed following the Pharmatose dissolution and to reduced polymer proportions. Carbopol matrices showed greater susceptibility to the added Pharmatose, becoming more erodible and releasing higher quantities of metronidazole. The greater Carbopol susceptibility to added Pharmatose was attributed to its faster hydration. Methocel matrices hydrate rapidly only at the surface, delaying hydration and Pharmatose dissolution.

N-acetylcysteine for radiocontrast-induced nephropathy: Potential role in the emergency department?

To systematically review the efficacy and safety of N-acetylcysteine (NAC) for the prevention of radiocontrast-induced nephropathy (RIN), and to discuss its potential role in the emergency department. We conducted a search of MEDLINE (from 1966 to December 2003), PubMed (1966 to December 2003) and EMBASE (1988 to December 2003) for English-language, prospective, randomized, controlled trials in humans using the search terms N-acetylcysteine, acetylcysteine, radiopharmaceuticals, contrast media, and kidney failure (acute). Five trials support and 4 trials refute the hypothesis that NAC helps prevent RIN. In 7 of 9 trials, oral NAC was administered twice daily for 2 days, on the day before and on the day of the radiocontrast study--a regime not feasible for emergent situations. More recent trials suggest that adequate hydration and lower volumes of radiocontrast, rather than NAC, are more effective ways to prevent RIN. Although further study may be indicated, current evidence does not suggest that NAC has a role in the emergency prevention of RIN.

Hydration management at the end of life.

The management of parenteral hydration at the end of life remains controversial. The debate centers on whether and/or how often patients should be hydrated, the volume of hydration received, and the benefit verses side effects of parenteral hydration. In order to clarify the routine practice of physicians involved in the end-of-life care in Edmonton, Alberta, Canada, we investigated the routine management of hydration by attending physicians caring for patients dying in a palliative care unit (PCU) at Norwood Capital Care, and in acute care wards at the Royal Alexandra Hospital (RAH) both while receiving and while not receiving consult advice from the Palliative Care Program. We conducted a retrospective chart review of 50 consecutive patients who died in each of the 3 sites included in the study. Data from the last 7 days prior to and including the date of death (day 0) was recorded. The majority of patients at all sites received hydration. The volume of hydration ordered in the Norwood PCU site was significantly different compared to both RAH groups on all days studied (p < 0.005). The RAH palliative care group showed a trend for lower hydration volumes compared to the RAH acute care group with significant differences on days 1 and 2 (p < 0.05). Throughout the week, for all of the hydrated patients in the Norwood PCU site, hypodermoclysis (HDC) was ordered; for nearly all of the hydrated patients in the RAH acute care group, intravenous (IV) hydration was ordered; and for approximately one third of the hydrated RAH palliative care consult group HDC was ordered, and for the remainder IV hydration was ordered. The RAH acute care group represented the largest percentage of hydrated patients receiving diuretics while the Norwood hospice site represented the lowest. The data raise the possibility that more patients in the RAH acute care group were overhydrated and may have developed symptoms such as edema, ascites, and respiratory distress. This study suggests that hydration at the end of life is managed differently in different settings of care and highlights areas for education to improve management.

Regulation of Glycosaminoglycan Function by Osmotic Potentials: MEASUREMENT OF WATER TRANSFER DURING ANTITHROMBIN ACTIVATION BY HEPARIN

The sulfated glycosaminoglycan heparin is an important anticoagulant, widely used to treat and to prevent arterial thrombosis. Heparin triggers conformational changes in, and the functional activation of, the serine proteinase inhibitor antithrombin. We investigated water-transfer reactions during the activation process to explore the possibility that functional interaction between antithrombin and sulfated glycosaminoglycans can be regulated by osmotic potentials. Volume of water transferred upon heparin binding was measured from differences in free energy change, Delta(Delta G), with osmotic stress, pi. Osmotic stress was induced with chemically inert probes that are geometrically excluded from the water-permeable spaces of antithrombin and from intermolecular spaces formed during the association reaction. The free energy change, Delta G, for the antithrombin/heparin interaction was calculated from the dissociation constant, determined by functional titrations of heparin with antithrombin at fixed concentrations of the coagulation protease factor Xa. The effect of osmotic stress was independent of the chemical nature of osmotic probes but correlated with their radius up to radius >17 A. In mixtures including a large and a small probe, the effect of the large probe was not modified by the small probe added at a large molar excess. With an osmotic probe of 4-A radius, the Delta(Delta G)/pi slope corresponds to a transfer of 119 +/- 25 water molecules to bulk solution on formation of the complex. Analytical characterization of water-permeable volumes in x-ray-derived bound and free antithrombin structures revealed complex surfaces with smaller hydration volumes in the bound relative to the free conformation. The residue distribution in, and atomic composition of, the pockets containing atoms from residues implicated in heparin binding were distinct in the bound versus free conformer. The results demonstrate that the heparin/antithrombin interaction is linked to net water transfer and, therefore, can be regulated in biological gels by osmotic potentials.

Effective Ionic Radii and Hydration Volumes for Evaluation of Solution Properties and Ionic Adsorption

Evaluation of effective ionic radii and corresponding individual hydrated-ion volumes provides data required for interpretation of various ion-specific solution properties and for understanding of specificity of ion adsorption at electrode and colloid interfaces. Principles involved in assignment of intrinsic ionic radii and hydrated-ion volumes are comparatively reviewed and examined as a basis for discussion of electrostriction volume changes. Three examples are given of applications of procedures for evaluation of individual hydrated-ion radii and volumes: (a) partial molal volumes and isentropic compressibilities of a series of oxyanions of various structures; (b) steric effects in hydration of alkylammonium and pyridinium cations; and (c) role of ion-hydration effects in specificity of chemisorption of electron donative anions at electrode surfaces.