Remifentanil for analgesia-based sedation in the intensive care unit

Providing effective analgesia and adequate sedation is a generally accepted goal of intensive care medicine. Due to its rapid, organ independent and predictable metabolism the short acting opioid remifentanil might be particularly useful for analgesia-based sedation in the intensive care unit (ICU). This hypothesis was tested by two studies in this issue of Critical Care. The study by Breen et al. shows that remifentanil does not exert prolonged clinical effects when continuously infused in renal failure patients, although the weak acting metabolite remifentanil acid accumulates. The study by Muellejans et al. reports a multicenter trial comparing a remifentanil versus a fentanyl based regimen in ICU patients. With both substances a target analgesia and sedation level was reached, and no major differences were found when frequent assessments of the sedation level and according readjustments of doses were performed. These results are in accordance with other studies suggesting that the adherence to a clear analgesia-based sedation protocol might be more important then the choice of medications itself

Extracorporeal gas exchange in acute lung injury: step by step towards expanded indications?

Extracorporeal membrane oxygenation (ECMO) is widely accepted as a rescue therapy in patients with acute life-threatening hypoxemia in the course of severe acute respiratory distress syndrome (ARDS). However, possible side effects and complications are considered to limit beneficial outcome effects. Therefore, widening indications with the aim of reducing ventilator induced lung injury (VILI) is still controversial. Consequently, technological progress is an important strategy. Miniaturized ECMO systems are believed to simplify handling and reduce side effects and complications. Mueller and co-workers evaluated such a small-sized device in 60 patients with severe ARDS. They accomplished both the treatment of severe hypoxemia and reduction of VILI, demonstrating feasibility, a moderate rate of severe complications, and a 45% intensive care survival rate. Although neither randomized nor controlled, this study should encourage others to implement such systems in clinical practice. From a strategic perspective, this is another small but useful step towards implementing extracorporeal gas exchange for the prevention of VILI. It is already common sense that the prevention of acute life-threatening hypoxemia usually outweighs the risks of this technique. The next step should be to prove that prevention of life-threatening VILI balances the risks too

Time-dependency of improvements in arterial oxygenation during partial liquid ventilation in experimental acute respiratory distress syndrome

BACKGROUND: The mechanisms by which partial liquid ventilation (PLV) can improve gas exchange in acute lung injury are still unclear. Therefore, we examined the time- and dose-dependency of the improvements in arterial oxygen tension (PaO(2)) due to PLV in eight pigs with experimental lung injury, in order to discriminate increases due to oxygen dissolved in perfluorocarbon before its intrapulmonary instillation from a persistent diffusion of the respiratory gas through the liquid column. RESULTS: Application of four sequential doses of perfluorocarbon resulted in a dose-dependent increase in PaO(2). Comparison of measurements 5 and 30 min after instillation of each dose revealed a time-dependent decrease in PaO(2) for doses that approximated the functional residual capacity of the animals. CONCLUSION: Although oxygen dissolved in perfluorocarbon at the onset of PLV can cause a short-term improvement in arterial oxygenation, diffusion of oxygen through the liquid may not be sufficient to maintain the initially observed increase in PaO(2)

Minimal instructions improve the performance of laypersons in the use of semiautomatic and automatic external defibrillators

INTRODUCTION: There is evidence that use of automated external defibrillators (AEDs) by laypersons improves rates of survival from cardiac arrest, but there is no consensus on the optimal content and duration of training for this purpose. In this study we examined the use of semiautomatic or automatic AEDs by laypersons who had received no training (intuitive use) and the effects of minimal general theoretical instructions on their performance. METHODS: In a mock cardiac arrest scenario, 236 first year medical students who had not previously attended any preclinical courses were evaluated in their first study week, before and after receiving prespecified instructions (15 min) once. The primary end-point was the time to first shock for each time point; secondary end-points were correct electrode pad positioning, safety of the procedure and the subjective feelings of the students. RESULTS: The mean time to shock for both AED types was 81.2 ± 19.2 s (range 45–178 s). Correct pad placement was observed in 85.6% and adequate safety in 94.1%. The time to shock after instruction decreased significantly to 56.8 ± 9.9 s (range 35–95 s; P ≤ 0.01), with correct electrode placement in 92.8% and adequate safety in 97%. The students were significantly quicker at both evaluations using the semiautomatic device than with the automatic AED (first evaluation: 77.5 ± 20.5 s versus 85.2 ± 17 s, P ≤ 0.01; second evaluation: 55 ± 10.3 s versus 59.6 ± 9.6 s, P ≤ 0.01). CONCLUSION: Untrained laypersons can use semiautomatic and automatic AEDs sufficiently quickly and without instruction. After one use and minimal instructions, improvements in practical performance were significant. All tested laypersons were able to deliver the first shock in under 1 min

Method of calculation of electrical properties of materials based on the results of quantum-chemical calculations

The work is devoted to a literary analysis of methods for interpreting the results of quantum-chemical calculations of the electronic structure. The concept of calculating the density of electronic states on the basis of the results obtained by the Hartree-Fock method is given. The structural scheme of the software based on the constructed concept is presented

Fluctuations of inspired concentrations of nitric oxide and nitrogen dioxide during mechanical ventilation

BACKGROUND: Nitric oxide (NO) is a very reactive agent with potentially toxic oxidation products such as nitrogen dioxide (NO(2)). Therefore, during NO inhalation a constant inspired concentration and accurate measurement of NO and NO(2) concentrations are essential. The objective of this study was to test the NO concentrations at various positions along the inspiratory limb of the breathing circuit using a recently developed system to administer NO in phase with inspiratory flow during mechanical ventilation (Servo 300 NO-A, Siemens, Sweden). Furthermore, we tested whether an active heating system would interfere with inspired NO concentrations. RESULTS: A sharp decline in the NO concentration was found between the respirator's inspiratory outlet and more distal points along the inspiratory limb of the circuit. This finding was most evident when an active heating system was mounted between those points. CONCLUSIONS: The concentrations of NO and NO(2) should be measured as near to the patient as possible, as significant fluctuations of these concentrations might be found along the inspiratory limb of the respiratory circuit especially when an active heating system is used

Analysis of aberrantly methylated sequnces in circulating DNA from blood of patients with lung cancer

Malignant cell transformation is accompanied by two processes of DNA methylation changes: promoter hypermethylation of specific genes and hypomethylation of retrotransposons. The composition of circulating DNA (cirDNA) from plasma and cell-surface-bound circulating DNA (csb-cirDNA) was shown earlier to be altered in the blood of cancer patients due to accumulation of tumor-specific aberrantly methylated DNA fragments, which are currently considered valuable cancer markers. The present study compares LINE-1 retrotransposon methylation patterns in plasma cirDNA and csb-cirDNA from untreated lung cancer patients (LC) and healthy donors. Concentrations of methylated LINE-1 region 1 copies (LINE-1met) were assayed by real-time methylation-specific PCR. In order to normalize the LINE-1 methylation level, the LINE-1 region 2 concentration was evaluated, which was independent of the methylation status (LINE-1Ind). We recorded an statistically significant increase of the LINE-1 methylation index determined as (LINE-1met/LINE-1Ind) due to the profound LINE-1Ind decrease (Mann-Whitney test, p = 0.005). Plasma cirDNA demonstrated no difference in the ratio LINE-1met/LINE-1Ind between LC patients and healthy donors (p = 0.40). The data obtained agree with our earlier results, which showed that csb-cirDNA was a highly informative material for lung cancer diagnostics