Clinical Evaluation of a Vancomycin Dosage Strategy Based on a Serum Trough Concentration Model in Elderly Patients with Severe Pneumonia

Objective This study aimed to evaluate the clinical benefits of a vancomycin dosage strategy based on a serum trough concentration model in elderly patients.Methods This prospective single-center, open-label, randomized controlled trial categorized 66 elderly patients with severe pneumonia into study and control groups. The control group received vancomycin using a regimen decided by the attending physician. Meanwhile, the study group received individualized vancomycin therapy with a dosing strategy based on a serum trough concentration model. The primary endpoint was the proportion of patients with serum trough concentrations reaching the target values.The secondary endpoints were clinical response, vancomycin treatment duration, and vancomycinassociated acute kidney injury(VA-AKI) occurrence.Results All patients were at least 60 years old(median age = 81 years). The proportion of patients with target trough concentration achievement(≥ 15 mg/L) with the initial vancomycin regimen was significantly higher in the study group compared to the control group(75.8% vs. 42.4%, P = 0.006).Forty-five patients(68.2%) achieved clinical success, the median duration of vancomycin therapy was10.0 days, and VA-AKI occurred in eight patients(12.1%). However, there were no significant differences in these parameters between the two groups. The model for predicting vancomycin trough concentrations was upgraded to: serum trough concentration(mg/L) = 17.194-0.104 × creatinine clearance rate(mL/min) + 0.313 × vancomycin daily dose [mg/(kg·d)].Conclusion A vancomycin dosage strategy based on a serum trough concentration model can improve the proportion of patients achieving target trough concentrations in elderly patients with severe pneumonia.

Remission of hepatotoxicity in chronic pulmonary aspergillosis patients after lowering trough concentration of voriconazole

BACKGROUND Chronic pulmonary aspergillosis(CPA)is a rare syndrome that is often accompanied by gradual lung tissue destruction.Voriconazole is usually employed as the first-line agent for CPA treatment.However,some patients can develop hepatotoxicity and often were forced to stop voriconazole treatment.AIM To record the improving trend of liver function and the therapeutic effects in patients after lowering the trough concentration of voriconazole.METHODS This study retrospectively analyzed 12 adult CPA patients who developed hepatotoxicity during the voriconazole treatment.In these patients,the oral dose was reduced to 3/4 or 1/2 of the standard dose(4 mg/kg,twice daily),and the lower limit of voriconazole trough concentration was maintained more than 0.5μg/m L.The trend of remission of liver toxicity after drug reduction in 12 patients was recorded.During the same period,25 patients who received standard doses served as the control group.Data from the two groups were collected and analyzed for different parameters such as demographic characteristics,underlying pulmonary disorders,laboratory tests,and therapeutic effect.The differences between the two groups were statistically compared.RESULTS Hepatotoxicity occurred in 12 patients within 28-65 d after oral voriconazole treatment.Hepatotoxicity was mainly manifested by the significantly increased level of gamma-glutamyltransferase and a slight increase of alanine aminotransferase and aspartate aminotransferase.The oral dose of voriconazole was reduced to approximately 3 mg/kg in seven patients and approximately 2 mg/kg in five patients.The average trough concentrations for the 12 patients before and after voriconazole oral dose reduction were 3.17±1.47μg/m L(1.5-6.0μg/m L)and 1.70±0.78μg/m L(0.6-3.3μg/m L),respectively(P=0.02).After lowering the trough concentrations,the hepatotoxicity was alleviated in all the patients.However,gamma-glutamyltransferase levels declined slowly.After 4 mo of treatment,7 of the 12 patients were successfully treated in the low trough concentrations group(41.7%).Similarly,8 of the 25 patients in the standard treatment dose group(32.0%)were effectively treated.There was no statistical difference between the groups(P=0.72).CONCLUSION Reducing the lower limit of the voriconazole trough concentration to 0.5μg/m L can alleviate the hepatotoxicity and maintained certain clinical efficacy in CPA patients;however,patients should be closely monitored.

Design of a new static solar concentrator with a high concentration ratio and a large acceptance angle based on bifacial solar cells

Solar concentrators are used in solar photovoltaic systems to lower the cost of producing electricity.In this situation,fewer solar cells can be used,lowering the overall cost of the system.The purpose of this article is to design,construct,install and test a stationary(non-tracking)concentrating system in Irbid,Jordan.Bifacial solar cells are used in the design.Two concentrator designs(with the same concentration ratio)are experimentally tested.Conc-A has a parabolic shape in the lower part but flat reflecting walls,whereas Conc-B has a standard compound parabolic shape in all parts.The receiving solar cells are arranged in three distinct positions in each concentrator.The results reveal that the output power from both concentrators is affected by the placement of the receiving solar cells within the concentrator.It has also been found that concentrators with flat reflecting walls perform better than those with parabolic reflecting walls.Conc-A’s power collection is~198%greater than that of a non-concentrating device.When Conc-B is used,the increase in power is~181%.

Target serum concentration of vancomycin may be reached earlier with a loading dose

Background:Vancomycin treatment failure against vancomycin-susceptible gram-positive cocci is not rare in the intensive care unit(ICU).One of the reasons for this is the substandard drug trough concentration.We aimed to examine the hypothesis that the target serum concentration could be reached earlier with a loading dose of vancomycin.Methods:This retrospective cohort study was conducted at our ICU between June 2018 and June 2020 and involved patients who were suspected of having,or confirmed to have,gram-positive cocci infection and treated with vancomycin.One group of the patients was administered a loading dose of vancomycin(loading group)and compared with the group that did not receive a loading dose(control group).The baseline characteristics,vancomycin serum concentrations,and clinical outcomes were collected and analyzed.Results:Fifty-five patients were finally included,of which 29 received a loading dose of vancomycin.The serum concentration of vancomycin before the second dose was significantly higher for the loading group than for the control group(10.3±6.1 mg/Lvs.5.7±4.4 mg/L,P=0.002).The results for both groups were similar before the fifth dose(12.4±7.3 mg/Lvs.10.3±6.3 mg/L in the loading and the control groups,respectively;P=0.251).The 28-day mortality was lower for the loading group than for the control group(6.7%vs.34.6%in the loading and control groups,respectively;P=0.026).No significant differences were observed in serum creatinine(Cr)concentrations of the two groups.Conclusion:With the loading dose of vancomycin,the target serum concentration of vancomycin may be reached earlier without increasing the risk of acute kidney injury.

Performance analysis of solar cell arrays in concentrating light intensity

Performance of concentrating photovoltaic/thermal system is researched by experiment and simulation calculation. The results show that the I-V curve of the GaAs cell array is better than that of crystal silicon solar cell arrays and the exergy produced by 9.51% electrical efficiency of the GaAs solar cell array can reach 68.93% of the photovoltaic/thermal system. So improving the efficiency of solar cell arrays can introduce more exergy and the system value can be upgraded. At the same time, affecting factors of solar cell arrays such as series resistance, temperature and solar irradiance also have been analyzed. The output performance of a solar cell array with lower series resistance is better and the working temperature has a negative impact on the voltage in concentrating light intensity. The output power has a -20 W/V coefficient and so cooling fluid must be used. Both heat energy and electrical power are then obtained with a solar trough concentrating photovoltaic/thermal system.