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Organic light-emitting diodes (OLEDs) currently suffer mostly from only moderate outcoupling efficiencies, calling for many different photonic strategies to increase the share of extracted photons. The quantification of concepts relying on scattering based on periodic or random structures proves complicated and often deserves more attention. To evaluate light extraction methods of OLEDs, we define a procedure leading to a quantifiable extraction efficiency η EE which can be calculated for top- or bottom-emitting OLEDs comprising external as well as internal outcoupling structures. Hence, the extraction efficiency allows to evaluate scattering approaches independently from the employed OLED system. A systematic study of 1D periodically corrugated red top-emitting OLEDs reveals the origin of a moderate enhancement due to an extraction efficiency of η EE = 14 %. Furthermore, our work provides recommendations how OLEDs with periodic corrugations should be characterized.

Many aquatic invertebrates alter their behaviour in response to chemical stimuli from predators. Less is known about how finely prey can discriminate between stimuli from predatory and related nonpredatory species, even in well-studied hermit crabs. We tested the time to emerge from the shell after disturbance (hiding time) of a common intertidal hermit crab. Pagurus granosimanus was exposed to effluent from two large-bodied brachyuran crabs: the durophagous, predatory red rock crab, Cancer productus, and the herbivorous kelp crab, Pugettia producta, in a controlled laboratory setting. Hiding times were a dramatic 41% shorter in the presence of Cancer effluent than when exposed to Pugettia effluent, which did not differ from a sea water control. Therefore hermit crabs can distinguish between chemical effluent from predatory and nonpredatory brachyuran crabs, which could include crab-specific compounds or metabolites from recently consumed prey, and adjust their behaviour accordingly. Shorter hiding times probably decrease the risk of being eaten by a shell-breaking predator because hermit crabs may be better able to elude them, either by running rapidly away or by abandoning their shell before it is crushed. Individual tests with three video stimuli (control, predatory crab, herbivorous crab), and combined tests with video and chemical stimuli, revealed a consistent generalized response to the presence of video but no differences among video treatments.

Objective Extracorporeal circulation is considered the gold standard in the treatment of hypothermic cardiocirculatory arrest; however, few centers use extracorporeal membrane oxygenation instead of standard extracorporeal circulation for this indication. The aim of this study was to evaluate whether extracorporeal membrane oxygenation-assisted resuscitation improves survival in patients with hypothermic cardiac arrest. Methods A consecutive series of 59 patients with accidental hypothermia in cardiocirculatory arrest between 1987 and 2006 were included. Thirty-four patients (57.6%) were resuscitated by standard extracorporeal circulation, and 25 patients (42.4%) were resuscitated by extracorporeal membrane oxygenation. Accidental hypothermia was caused by avalanche in 22 patients (37.3%), drowning in 22 patients (37.3%), exposure to cold in 8 patients (13.5%), and falling into a crevasse in 7 patients (11.9%). Multivariate logistic regression analysis was used to compare extracorporeal membrane oxygenation with extracorporeal circulation resuscitation, with adjustment for relevant parameters. Results Restoration of spontaneous circulation was achieved in 32 patients (54.2%). A total of 12 patients (20.3%) survived hypothermia. In the extracorporeal circulation group, 64% of the nonsurviving patients who underwent restoration of spontaneous circulation died of severe pulmonary edema, but none died in the extracorporeal membrane oxygenation group. In multivariate analysis, extracorporeal membrane oxygenation-assisted resuscitation showed a 6.6-fold higher chance for survival (relative risk: 6.6, 95% confidence interval: 1.2–49.3, P = .042). Asphyxia-related hypothermia (avalanche or drowning) was the most predictive adverse factor for survival (relative risk: 0.09, 95% confidence interval: 0.01–0.60, P = .013). Potassium and pH failed to show statistical significance in the multivariate analysis. Conclusions Extracorporeal rewarming with an extracorporeal membrane oxygenation system allows prolonged cardiorespiratory support after initial resuscitation. Our data indicate that prolonged extracorporeal membrane oxygenation support reduces the risk of intractable cardiorespiratory failure commonly observed after rewarming.

Objective: The aim of the current study was to assess the effects of epinephrine in a pig model of hypothermic cardiac arrest followed by closed-chest cardiopulmonary resuscitation combined with active rewarming, simulating the clinical management of an arrested hypothermic patient in a hospital without cardiopulmonary bypass facilities. Design: Prospective, randomized animal study. Setting: University research laboratory. Subjects: Twelve 12- to 16-week-old domestic pigs. Interventions: Pigs were surface cooled to a body core temperature of 28°C. After 4 min of untreated cardiac arrest, manual closed-chest CPR and thoracic lavage with 40°C warmed fluid were started. After 3 min of external chest compression animals were randomly assigned to receive epinephrine (45, 45 and 200 μg/kg) or saline placebo in 5-min intervals. Measurements and main results: Coronary perfusion pressure was about 15 mmHg in placebo group pigs. Coronary perfusion pressure was significantly higher after epinephrine, but restoration of spontaneous circulation was not more frequent (one of six epinephrine versus three of six saline placebo pigs, P =0.34). After 45 μg/kg epinephrine the arterial P o 2 was significantly lower when compared to the saline placebo. The third 200 μg/kg epinephrine dose resulted in a significantly enhanced mixed venous hypercarbic acidosis. Conclusions: After a short 4-min period of hypothermic cardiac arrest, epinephrine may not be necessary to maintain coronary perfusion pressure around the threshold usually correlating with successful defibrillation, even during prolonged closed-chest CPR combined with active rewarming. The enhanced mixed venous hypercarbic acidosis in epinephrine-treated animals may support the argument against repeated or high dose epinephrine administration during hypothermic CPR.

Objective : To study reactive hyperemia (PH) using a transcutaneous PO2/PCO2 combination electrode heated to 37°C and tissue reflectance spectrophotometry in patients before and after cardiopulmonary bypass (CPB) to determine whether microcirculatory function of skin is altered. Design : Prospective study. Setting : Anesthesiology and critical care unit of a university hospital. Participants : Eight patients undergoing elective CPB under mild hypothermia. Interventions : To produce RH, blood flow to the forearm was prevented by inflation of a cuff to 300 mmHg for an interval of 5 minutes. Measurements and Main Results : Measurements were obtained on the day prior to surgery (DPS), on the day of surgery (DOS) rewarmed to 37°C in the intensive care unit (ICU), and on the first (POD 1) and the third postoperative days (POD 3). The following parameters were recorded: preocclusive baseline cutaneous PO2, and PCO2 (B-PtcO2, B-PtcCO2), and microvascular hemoglobin saturation (B-HbO2); postischemic peak of PtcO2, PtcCO2, and HbO2; and 10 minutes after release of the cuff occlusion posthyperemic PtcO2, PtcCO2, and HbO2. B-PtcO2 was 3.5 ± 1.2 mmHg, on DPS, 2.6 ± 0.7 mmHg on DOS, 1.5 ± 0.3 mmHg on POD 1, and 3.5 ± 3.5 mmHg on POD 3. B-PtcCO2 increased significantly from 40.1 ± 2.5 mmHg to 52.2 ± 2.0 mmHg on DOS (p = 0.01) and to 48.9 ± 3.6 mmHg on POD 1 (p = 0.02). On POD 3, B-PtcCO2 was 40.6 ± 2.6 mmHg. B-HbO2 declined from a preoperative value of 42.4% ± 8.6% to 37.1% ± 14.7% on DOS and further to 21.7% ± 4.8% on POD 1, which was significantly different (p = 0.03). On POD 3, B-HbO2 still remained lower (30.7% ± 6.2%) compared with the preoperative value. RH (ΔPtcO2, ΔHBO2) was quantified as the differences between peak PtcO2, HBO2 and B-PtcO2, B-HBO2. ΔPtcO2 was 13.0 ± 2.3 on DPS, 11.3 ± 2.9 on DOS, 12.6 ± 2.6 on POD 1, and 11.5 ± 3.5 on POD 3. ΔHBO2 was 42.0 ± 5.6 on DPS, 40.0 ± 7.1 on DOS, 49.9 ± 2.5 on POD 1, and 52.9 ± 6.4 on POD 3. The elimination rate of carbon dioxide from skin (ECO2) was calculated as difference between peak PtcCO2 and PtcCO2 after 3 minutes of reperfusion divided by the difference between peak PtcCO2 and B-PtcCO2. ECO2 was 1.0 ± 0.2 kPa/min on DPS, 0.7 ± 0.1 kPa/min on DOS, and 0.8 ± 0.1 kPa/min on POD 1 and POD 3. Conclusion : Cutaneous microcirculation assessed by RH is well preserved during the immediate postoperative period in patients undergoing uncomplicated coronary artery surgery with CPB.