Whole blood viscosity issues VI: Association with blood salicylate level and gastrointestinal bleeding

Blood Viscosity Changes in Diabetes Mellitus: A 20-Year Bibliometric Review and Future Directions

Changes in hematological parameters due to diabetes are reflected in changes in whole blood viscosity (WBV). Understanding the impact of diabetes and its cardiovascular disease (CVD) complications can provide substantiation of how laboratory tests for WBV are useful to monitor the progression and treatment. The review examines research work done in the past 20 years to provide a framework for the present agenda. This was a narrative review that followed the standard Scale for the Assessment of Narrative Review Articles (SANRA) approach. It includes both conceptual and empirical reviews. WBV was appraised in the context of bibliographic research on diabetes and other related factors such as metabolic syndrome (MetS) and oxidative stress. The association of abnormal erythrocytes as well as the relationship between WBV and MetS is established. Changes in diabetes that contribute to the development of diabetic cardiovascular complications occur through the pathway of WBV physiology. However, longitudinal analysis is very limited. There is a dearth of longitudinal study data on WBV in diabetes management. This lack of data justifies a need for further studies, especially prospective and retrospective analysis, to investigate the prevalence of diabetes mellitus about the prevalence of cardiovascular complications indices, especially estimated WBV (eWBV) between periods and within cohorts.

Mechanical Blood-Immersed Bearings in Continuous-Flow Rotary Blood Pumps

Mechanical blood-immersed bearings have been used in many continuous-flow rotary blood pumps to reduce friction between relatively moving parts, but their use has been associated with a significant incidence of pump thrombosis. As newer cardiac assist devices with more advanced bearings become available, the rate of pump thrombosis will likely decrease. Nevertheless, it is important to understand the design limitations of mechanical bearings as pumps utilizing them are still in use as chronic support devices and especially in the acute setting for temporary support devices. A properly designed journal bearing should support the spinning rotor with no surface-to-surface contact between the bearing and journal surfaces. The journal continuously undergoes orbital motion within the bearing, which can be "stable" or "unstable." Unstable orbital motion causes the journal to move progressively off-center until it collides with the bearing, and even minor variations in manufacturing can create off-design operation and dynamic instability of the journal. Since blood is the lubricant in most clinically-used rotary blood pumps, lubricant viscosity can vary abruptly in response to changes in hematocrit or plasma protein concentration. Additionally, shear stress from the high-speed rotor can cause hemolysis and plasma protein denaturation. We reviewed theoretical design and operating principles of mechanical bearings and discuss why the phenomenon of mechanical bearing thrombosis may be an inherent design issue dependent on variables that are beyond the control of clinicians.

Assessment of the potential ototoxicity of high-dose celecoxib, a selective cyclooxygenase-2 inhibitor, in rats

OBJECTIVE

To evaluate the potential ototoxicity of high-dose celecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor.

STUDY DESIGN

Prospective animal study.

SETTING

Laboratory.

METHODS

Twenty adult male Sprague Dawley rats were divided into 2 groups for hearing and tinnitus tests, respectively. The auditory brain-stem response (ABR) and the gap prepulse inhibition of acoustic startle (GPIAS) were used as indicators of hearing loss and tinnitus, respectively, and were measured before and at 2, 4, 6, 8, 12, 24, and 48 hours after administration of celecoxib (2 g/kg) via gavage.

RESULTS

ABR threshold and wave III latencies did not increase significantly at any frequency following celecoxib administration, at any time point (P > .05). GPIAS remained below 30% after celecoxib, from a baseline of 20.03% ± 3.62%; no change was significant.

CONCLUSION

High-dose celecoxib (2 g/kg), a selective COX-2 inhibitor, did not cause hearing loss or tinnitus in Sprague Dawley rats within 48 hours of administration. Further studies are needed to explore the roles played by COX-related mechanisms when nonselective COX inhibitors induce ototoxicity.

Cardiovascular risks in prediabetes: preliminary data on "vasculopathy triad"

Background:

Subclinical cardiovascular disease is inherent in complications of diabetes mellitus. It occurs before the obvert manifestation of cardiovascular disease complication in diabetes, and involves vasculopathy triad or three major vascular events comprising stasis, endothelial dysfunction, and atherothrombosis.

Aim:

This study was to examine evidence of vasculopathy triad in prediabetes, biomarkers of stasis, endothelial dysfunction, and atherothrombosis in prediabetes were compared with apparently healthy group.

Materials and Methods:

Eighty-one participants with results for plasma D-dimer, homocysteine, and whole blood viscosity were selected from a research database. The participants consisted of control (n = 44) and prediabetes (n = 37) based on clinical history and laboratory results.

Results:

Multivariate analysis shows a significantly higher level of vasculopathy in prediabetes than in the control group (P > 0.0001). Blood viscosity (P < 0.04) and homocysteine (P < 0.03) are significantly higher in prediabetes than in controls. Average levels for plasma D-dimer are also higher in prediabetes than in control, but not statistically significant in this particular analysis.

Conclusion:

This study suggests a novel application of known idea, vasculopathy triad that could be used for assessment of subclinical cardiovascular disease in prediabetes.

Whole blood viscosity issue VIII: Comparison of extrapolation method with diagnostic digital viscometer

Background:

The first issue of this series proposed extrapolation chart with conventional reference range and suggested comparison of results with other methods.

Aim:

This work sets out to compare interpretative results from the extrapolation method with those from a digital viscometer method.

Materials and Methods:

Five cases in our archived clinical pathology database that were specifically tested for whole blood viscosity by the digital method, and had results for haematocrit and serum proteins were pooled. The values of haematocrit and serum proteins were used to derive extrapolated values. The interpretative results of the extrapolation method were compared with those of digital viscometer-based clinical reports. Non-Newtonian fluids such as whole blood have different viscosities at different shear rates. Comparative statement can only be based on interpreted outcome.

Results:

Two-fifth absolute concordance and one-fifth discordance is observed between extrapolation and viscometer-based clinical reports. The discordance is a case of hyperviscosity in the presence of neither hyperproteinaemia nor polycythemia.

Conclusion:

The extrapolation method may underestimate whole blood viscosity in some patients when compared with digital viscometer, which in turn may suggest hyperviscosity that cannot be explained by hyperproteinaemia or polycythemia concepts. The impact of oxidative stress is highlighted.

Prevalence of anemia and risk of adverse bleeding effect of drugs: implication for therapy

This study aimed to evaluate the progress in reduction of prevalence of anemia in rural Australia. It also investigates the prevalence of hypoviscosity in anaemia with a view to determine the fraction of anaemic patients at risk of drug-inducible exacerbation of anemia. Archived clinical pathology data (N = 130, 354) for the period of 1999 to 2008 were utilized. The prevalence of anemia and hypoviscosity was evaluated by working out (i) the number that fell within anemia definition as a percentage of the population and (ii) the number that fell within hypoviscosity definition as a percentage of anemic patients. The prevalence in anemic diabetes and dyslipidaemia was further determined. There was progressive reduction in anemia from 6.1% to 3.2% over the ten years period. Prevalence of anemia is statistically significantly higher in males than in females (P < 0.0001), but protein level is lower in anemic females than in anemic males (P < 0.01). The results further show that up to 75% of anemic patients may benefit from NSAID or salicylates. This paper highlights differences between genders. It suggests more concerted effort in men's health and speculates a new factor to investigate in women's health.