Safety and economic considerations of argatroban use in critically ill patients: a retrospective analysis

Background

Heparin-induced thrombocytopenia (HIT) causes thromboembolic complications which threaten life and limb. Heparin is administered to virtually every critically ill patient as a protective measure against thromboembolism. Argatroban is a promising alternative anticoagulant agent. However, a safe dose which still provides effective thromboembolic prophylaxis without major bleeding still needs to be identified.

Methods

Critically ill patients (n = 42) diagnosed with HIT at a tertiary medical center intensive care unit from 2005 to 2010 were included in this retrospective analysis. Patient records were perused for preexisting history of HIT, heparin dosage before HIT, argatroban dosage, number of transfusions required, thromboembolic complications and length of ICU stay (ICU LOS). Patients were allocated to Simplified Acute Physiology Scores above and below 30 (SAPS >30, SAPS <30), respectively. For calculations, patients (n = 19) without previous history of HIT were compared to patients (n = 23) with a history of HIT before initiation of argatroban.

Results

The mean initial argatroban dosage was below 0.4 mcg/kg/min regardless of SAPS score. Maintenance dosage had to be increased in patients with SAPS <30 to 0.54 ± 0.248 mcg/kg/min (p >0.05) to achieve effective anticoagulation. No thromboembolic complications were encountered. Argatroban had to be discontinued temporarily in 16 patients for a total of 57 times due to diagnostic or surgical procedures, supratherapeutic aPTT and bleeding without increasing the number of transfusions. A history of HIT was associated with a shorter ICU LOS and significantly reduced transfusion need when compared to patients with no history of HIT. Cost calculation favour argatroban due to increased transfusion needs during heparin administration and increase ICU LOS.

Conclusion

Argatroban can be used at doses < 0.4 mcg/kg/min without an increase in transfusion requirements and at a reduced overall treatment cost compared to heparin.

HOI versus HOIO selectivity of a molten-type AgI electrode

AgI electrode is often applied not only to determine iodine concentration but also to follow oscillations in the weakly acidic medium of the Bray-Liebhafsky and Briggs-Rauscher reactions where it partly follows the hypoiodous acid (HOI) concentration. It is known that HOI attacks its matrix in the corrosion reaction: AgI + HOI + H(+) ⇆ Ag(+) + I2 + H2O and the AgI electrode measures the silver ion concentration produced in that reaction. The signal of the electrode can be the basis of sensitive and selective HOI concentration measurements only supposing that an analogous corrosive reaction between AgI and iodous acid (HOIO) can be neglected. To prove that assumption, the authors calibrated a molten-type AgI electrode for I(-), Ag(+), HOI, and HOIO in 1 M sulfuric acid and measured the electrode potential in the disproportionation of HOIO, which is relatively slow in that medium. Measured and simulated electrode potential versus time diagrams showed good agreement, assuming that the electrode potential is determined by the HOI concentration exclusively and the contribution of HOIO is negligible. An independent and more direct experiment was also performed giving the same result. HOIO was produced with a new improved recipe.

CONCLUSION

an AgI electrode can be applied to measure the HOI concentration selectively above the so-called solubility limit potential.

Direct effects of morphine but not of fentanyl-type opioids on human 5-HT3A receptors in outside-out patch-clamp studies

BACKGROUND

The alkaloid morphine is historically the oldest opiate, yet still today it has clinically important uses in analgesic therapies. The main analgesic effect of opioids, including synthetic opioids belonging to the family of 4-anilidopiperidines, is mediated via activation of opioid receptors spread throughout the peripheral and central nervous system. However, morphine acting as a 'dirty' drug also exhibits effects on other receptor systems, e.g., the serotonergic system and its 5-HT3 receptor. Therefore, this study focuses on the interaction of morphine and fentanyl-type opioids (alfentanil, remifentanil and sufentanil) with 5-HT3A receptors.

METHODS

Excised outside-out patches from human embryonic kidney-293 cells, stably transfected with the human 5-HT3A receptor cDNA, were used to determine the opioid effects using the patch-clamp technique.

RESULTS

Within clinical concentrations, the effects of morphine are concentration-dependent. Morphine reduced current amplitudes, as well as activation and decay time constants. These effects were not competitive. Contrary to these results, all fentanyl-type opioids only exerted effects far above their clinical concentration ranges. These effects were not homogenous but varying.

CONCLUSIONS

Morphine is an opioid compound exhibiting special antagonistic interaction with 5-HT3A receptors. This interaction is not shared by the newer synthetic derivatives of the fentanyl-type opioids in the clinical relevant concentration range.

Classification of exacerbation episodes in chronic obstructive pulmonary disease patients

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a progressive disease affecting the airways, which constitutes a major cause of chronic morbidity and a significant economic and social burden throughout the world. Despite the fact that in COPD patients exacerbations are common acute events causing significant and often fatal worsening of symptoms, an accurate prognostication continues to be difficult.

OBJECTIVES

To build computational models capable of distinguishing between normal life days from exacerbation days in COPD patients, based on physical activity measured by accelerometers.

METHODS

We recruited 58 patients suffering from COPD and measured their physical activity with accelerometers for 10 days or more, from August 2009 to March 2010. During this period we recorded six exacerbation episodes in the patients, accounting for 37 days. We were able to analyse data for 52 patients (369 patient days), and extracted three distinct sets of features from the data, one set of basic features such as average, one set based on the frequency domain and the last exploring the cross-information among sensors pairs. These were used by three machine-learning techniques (logarithmic regression, neural networks, support vector machines) to distinguish days with exacerbation events from normal days.

RESULTS

The support vector machine classifier achieved an AUC of 90% ± 9, when supplied with a set of features resulting from sequential feature selection method. Neu- ral networks achieved an AUC of 83% ± 16 and the logarithmic regression an AUC of 67% ± 15.

CONCLUSIONS

None of the individual feature sets provided robust for reasonable classification of PA recording days. Our results indicate that this approach has the potential to extract useful information for, but are not robust enough for medical application of the system.

Chlorine dioxide is a size-selective antimicrobial agent

Background / Aims

ClO₂, the so-called “ideal biocide”, could also be applied as an antiseptic if it was understood why the solution killing microbes rapidly does not cause any harm to humans or to animals. Our aim was to find the source of that selectivity by studying its reaction-diffusion mechanism both theoretically and experimentally.

Methods

ClO₂ permeation measurements through protein membranes were performed and the time delay of ClO₂ transport due to reaction and diffusion was determined. To calculate ClO₂ penetration depths and estimate bacterial killing times, approximate solutions of the reaction-diffusion equation were derived. In these calculations evaporation rates of ClO₂ were also measured and taken into account.

Results

The rate law of the reaction-diffusion model predicts that the killing time is proportional to the square of the characteristic size (e.g. diameter) of a body, thus, small ones will be killed extremely fast. For example, the killing time for a bacterium is on the order of milliseconds in a 300 ppm ClO₂ solution. Thus, a few minutes of contact time (limited by the volatility of ClO₂) is quite enough to kill all bacteria, but short enough to keep ClO₂ penetration into the living tissues of a greater organism safely below 0.1 mm, minimizing cytotoxic effects when applying it as an antiseptic. Additional properties of ClO₂, advantageous for an antiseptic, are also discussed. Most importantly, that bacteria are not able to develop resistance against ClO₂ as it reacts with biological thiols which play a vital role in all living organisms.

Conclusion

Selectivity of ClO₂ between humans and bacteria is based not on their different biochemistry, but on their different size. We hope initiating clinical applications of this promising local antiseptic.