Aortic volume determines global end-diastolic volume measured by transpulmonary thermodilution

BACKGROUND: Global end-diastolic volume (GEDV) measured by transpulmonary thermodilution is regarded as indicator of cardiac preload. A bolus of cold saline injected in a central vein travels through the heart and lung, but also the aorta until detection in a femoral artery. While it is well accepted that injection in the inferior vena cava results in higher values, the impact of the aortic volume on GEDV is unknown. In this study, we hypothesized that a larger aortic volume directly translates to a numerically higher GEDV measurement. METHODS: We retrospectively analyzed data from 88 critically ill patients with thermodilution monitoring and who did require a contrast-enhanced thoraco-abdominal computed tomography scan. Aortic volumes derived from imaging were compared with GEDV measurements in temporal proximity. RESULTS: Median aortic volume was 194 ml (interquartile range 147 to 249 ml). Per milliliter increase of the aortic volume, we found a GEDV increase by 3.0 ml (95% CI 2.0 to 4.1 ml, p < 0.001). In case a femoral central venous line was used for saline bolus injection, GEDV raised additionally by 2.1 ml (95% CI 0.5 to 3.7 ml, p = 0.01) per ml volume of the vena cava inferior. Aortic volume explained 59.3% of the variance of thermodilution-derived GEDV. When aortic volume was included in multivariate regression, GEDV variance was unaffected by sex, age, body height, and weight. CONCLUSIONS: Our results suggest that the aortic volume is a substantial confounding variable for GEDV measurements performed with transpulmonary thermodilution. As the aorta is anatomically located after the heart, GEDV should not be considered to reflect cardiac preload. Guiding volume management by raw or indexed reference ranges of GEDV may be misleading

Investigation of the Porosity of Poly(sodium methacrylate) Hydrogels by ¹H‐NMR T₂‐Relaxation and Inverse Size‐Exclusion Chromatography

A series of poly(sodium methacrylate) hydrogels, also called superabsorbents, having a theoretical degree of neutralization of 100 mol%, and degree of crosslinking varying from 0.6 to 20 mol%, are synthesized via conventional free radical polymerization. The networks are characterized in detail by inverse size-exclusion chromatography and 1H-NMR relaxometry in order to place particular emphasis on the investigation of the pore size distribution (PSD) and the chain mobility, respectively. The two previously mentioned parameters are compared to understand the correlation between the elastic chain mobilities and the average pore size of the hydrogel. From the resulting data, a new empirical equation is proposed, which is valid under the given experimental conditions and permits a rough estimation of the average PSD from the relaxation data. Thus, the equation permits to reduce the number of analytical techniques needed for the characterization of complex systems such as polymer networks.</p

4D Printing at the Microscale

3D printing of adaptive and dynamic structures, also known as 4D printing, is one of the key challenges in contemporary materials science. The additional dimension refers to the ability of 3D printed structures to change their properties—for example, shape—over time in a controlled fashion as the result of external stimulation. Within the last years, significant efforts have been undertaken in the development of new responsive materials for printing at the macroscale. However, 4D printing at the microscale is still in its early stages. Thus, this progress report will focus on emerging materials for 4D printing at the microscale as well as their challenges and potential applications. Hydrogels and liquid crystalline and composite materials have been identified as the main classes of materials representing the state of the art of the growing field. For each type of material, the challenges and critical barriers in the material design and their performance in 4D microprinting are discussed. Importantly, further necessary strategies are proposed to overcome the limitations of the current approaches and move toward their application in fields such as biomedicine, microrobotics, or optics

Fully independent photochemical reactivity in one molecule

We introduce a chemically λ-orthogonal bichromophore triggered simply by different colours of light, enabling two different photochemical reactions in one molecule. Uniquely, the short wavelength (λ = 314 nm) does not trigger the red-shifted reaction system (λ = 416 nm), opening possibilities for the light controlled gating of specific molecular sites independent of wavelength.</p

Effectiveness of Lumbar Cerebrospinal Fluid Drain Among Patients With Aneurysmal Subarachnoid Hemorrhage: A Randomized Clinical Trial.

IMPORTANCE After aneurysmal subarachnoid hemorrhage, the use of lumbar drains has been suggested to decrease the incidence of delayed cerebral ischemia and improve long-term outcome. OBJECTIVE To determine the effectiveness of early lumbar cerebrospinal fluid drainage added to standard of care in patients after aneurysmal subarachnoid hemorrhage. DESIGN, SETTING, AND PARTICIPANTS The EARLYDRAIN trial was a pragmatic, multicenter, parallel-group, open-label randomized clinical trial with blinded end point evaluation conducted at 19 centers in Germany, Switzerland, and Canada. The first patient entered January 31, 2011, and the last on January 24, 2016, after 307 randomizations. Follow-up was completed July 2016. Query and retrieval of data on missing items in the case report forms was completed in September 2020. A total of 20 randomizations were invalid, the main reason being lack of informed consent. No participants meeting all inclusion and exclusion criteria were excluded from the intention-to-treat analysis. Exclusion of patients was only performed in per-protocol sensitivity analysis. A total of 287 adult patients with acute aneurysmal subarachnoid hemorrhage of all clinical grades were analyzable. Aneurysm treatment with clipping or coiling was performed within 48 hours. INTERVENTION A total of 144 patients were randomized to receive an additional lumbar drain after aneurysm treatment and 143 patients to standard of care only. Early lumbar drainage with 5 mL per hour was started within 72 hours of the subarachnoid hemorrhage. MAIN OUTCOMES AND MEASURES Primary outcome was the rate of unfavorable outcome, defined as modified Rankin Scale score of 3 to 6 (range, 0 to 6), obtained by masked assessors 6 months after hemorrhage. RESULTS Of 287 included patients, 197 (68.6%) were female, and the median (IQR) age was 55 (48-63) years. Lumbar drainage started at a median (IQR) of day 2 (1-2) after aneurysmal subarachnoid hemorrhage. At 6 months, 47 patients (32.6%) in the lumbar drain group and 64 patients (44.8%) in the standard of care group had an unfavorable neurological outcome (risk ratio, 0.73; 95% CI, 0.52 to 0.98; absolute risk difference, -0.12; 95% CI, -0.23 to -0.01; P = .04). Patients treated with a lumbar drain had fewer secondary infarctions at discharge (41 patients [28.5%] vs 57 patients [39.9%]; risk ratio, 0.71; 95% CI, 0.49 to 0.99; absolute risk difference, -0.11; 95% CI, -0.22 to 0; P = .04). CONCLUSION AND RELEVANCE In this trial, prophylactic lumbar drainage after aneurysmal subarachnoid hemorrhage lessened the burden of secondary infarction and decreased the rate of unfavorable outcome at 6 months. These findings support the use of lumbar drains after aneurysmal subarachnoid hemorrhage. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT01258257

technical prerequisites, development of a new method to evaluate the quality of pain treatment, study of gender-specific, age-dependent pain scores

Eine adäquate Schmerztherapie ist für das „Outcome“ und Wohlbefinden der Patienten unerlässlich. Als unabdingbar hat sich die Messung von Schmerzen - üblicherweise an Hand von NRS/VRS/VAS-Werten - erwiesen, deren Validität und Empfindlichkeit im klinischen Alltag für den Aufwachraum wenig geklärt ist (NRS: „numeric rating scale“, VRS: „verbal rating scale“, VAS: “visual analog scale”). Daher wird die ‚Test – Retest’ Validität der erhobenen NRS/VRS, sowie die Empfindlichkeit des NRS anhand der Alters- und Geschlechtsabhängigkeit untersucht. Eine Qualitätskontrolle setzt ein Maß, das den Erfolg verschiedener Therapiestrategien vergleichbar macht, voraus. Da absolute Schmerzscores bei Entlassung stark von der initialen Schmerzintensität bei Aufnahme in den Aufwachraum abhängen, wurden auch relative, intraindividuelle Maße zur Messung des Therapieerfolgs vorgeschlagen. Die Abhängigkeit solcher relativen Maße von der initialen Schmerzintensität und damit ihre Eignung für den Vergleich verschiedener schmerztherapeutischer Maßnahmen ist bisher nicht untersucht. Methodik: Von insgesamt 47.599 Patienten wurden 24.946 mit validen Daten eingeschlossen. Die Studie wurde von der Ethikkommission der Charité — Universitätsmedizin Berlin — genehmigt und unter der Nummmer ISRCTN86489071 registriert. 1) Zur Untersuchung der interindividuellen Test-Retest- Reliabilität wurden bei einer Untergruppe von 3.571 Patienten sowohl von Pflegekräften zur Routineversorgung im Aufwachraum als auch von Studienpersonal prospektiv Schmerzscores erhoben. 2) Die alters – und geschlechtsabhängigen Schmerzempfindlichkeit wurde an Hand des von Pflegekräften erhobenen NRS bei Aufnahme in den Aufwachraum (NRSAufnahme) von 5.797 Patienten mit Schmerzen untersucht. 3) Als Ergebnisparameter für die Schmerztherapie im Aufwachraum wurden der NRS bei Entlassung aus dem Aufwachraum (NRSEntlassung) mit dem Quotienten für die relativen Schmerzlinderung (NRSAufnahme, - NRSEntlassung )/ NRSAufnahme verglichen. Statistik: Ein p < 0.05 wurde als signifikant betrachtet. Nichparametrische Regressionen wurden mit lokalen 95% Konfidenzintervallen berechnet. Ergebnisse: 1\. Der überwiegende Teil der dokumentierten Schmerzscores NRS/VRS wies – abgesehen vom NRSAufnahme - mit Abweichungen von ± 2 Punkten auch in der Routine eine hinreichende Genauigkeit auf. 2\. Für Frauen liegt das Maximum der altersabhängigen Schmerzwahrnehmung, gemessen am NRSAufnahme bei 22,5 Jahren (KI: 18,5 - 26,5), bei Männern in einem deutlich höheren Alter bei 44,4 Jahren (KI: 38,6 - 50,1). 3\. Der Quotient der relativen Schmerzlinderung (NRSAufnahme, - NRSEntlassung )/ NRSAufnahme stellte sich im Vergleich zum absoluten NRSEntlassung als deutlich robuster im Hinblick auf Einflüsse des initialen Schmerzscores (NRSAufnahme) heraus. Schlussfolgerung: Die Test- Retest Validität des NRS in der klinischen Routine entspricht im Wesentlichen der an kleineren Gruppen gewonnen Angaben der Literatur. Die Schmerzempfindlichkeit ist sowohl bei Frauen als auch bei Männern stärker vom Lebensalter abhängig als bisher vermutet. Die Planung von Studien sollte das frühe und sehr hohe Maximum der Schmerzempfindlichkeit von Frauen um 22 Jahre genauso wie das spätere Maximum der Schmerzempfindlichkeit von Männern um 44 Jahre berücksichtigen. Die relativen Schmerzlinderung (NRSAufnahme, - NRSEntlassung )/ NRSAufnahme erwies sich als geeigneter Ergebnisparameter für die Qualität der postoperativen Schmerztherapie und als solcher dem NRSEntlassung überlegen.Effective pain treatment has been shown to be pivotal for an improved postoperative „outcome“ and well being of surgical patients. Pain measurements – usually employing scoring system such as the NRS („numeric rating scale“), VRS („verbal rating scale“) or VAS (“visual analog scale”) - are the basis for measuring any successful pain treatment. Nervertheless, validity and sensitivity of these scores - although routinely used in the recovery room - is not well established, yet. We therefore validated the test-retest reliability of the NRS and tested the susceptability of the NRS towards age and gender when applied to postsurgical patients on admission to the recovery room. In addition, since absolute pain scores (e.g., NRS) depend on the pain intensity on admission to the recovery room, a relative, intraindividual score is proposed. To prove the feasibility of this score to measure the quality of postoperative pain treatment, its independence from the initial pain intensity needed to be shown. Methods: A total of 47.599 patients was screened. 24.946 patients with validated data sets were finally included. The study was approved by the institutional review board of the Charité — Universitätsmedizin Berlin and registered for the trial number ISRCTN86489071. 1) In 3.571 patients pain scores on admission to recovery room and at discharge were collected twice: First for ‚routine’ pain treatment by the recovery room nurses and a little later by study personnel. This enabled us to test the test/retest reliability of the NRS. 2) Of the 24.946 patients included, 5.797 had pain on admission to the recovery room (indicated by an NRSadmission > 0 collected by nurses). These data were used to examine the susceptability of the NRS towards age and gender, as well as to prove applicability of the NRS for this purpose in roune clinical use. 3) To show the usefulness of relative pain reduction we compared the NRS at discharge from the recovery room (NRSdischarge) with the relative pain reduction as (NRSadmission - NRSdischarge) / NRSadmission Statistics: A p < 0.05 was considered to be significant for parametric tests. Nonparametric regression was calculated with local 95% confidence limits. Results: 1\. Most of the documented pain scores NRS/VRS showed – with exception of NRSadmission - a deviation of ± 2 points and proved acceptable precision for routine clinical use. 2\. Female subjects showed the maximum of the age dependent pain sensitivity as measured by NRSadmission at the age of 22.5 years (CI: 18.5 – 26.5), male subjects at a definitely higher age of 44.4 years (CI: 38.6 – 50.1). 3\. Relative pain reduction as calculated by (NRSadmission - NRSdischarge) / NRSadmission proved to be almost independent of initial pain score (NRSadmission), whereas the absolute values of NRS at discharge showed a strong dependence on the NRS at admission. Conclusions: 1) Test-retest validity of the NRS in daily clinical routine proved essentially the same as for smaller groups in literature. 2) Pain sensitivity depends on age, especially in female but also in male subjects to a greater extent as presently known. Studies in pain research have to attach importance to this fact. 3) Relative pain reduction as calculated by (NRSadmission - NRSdischarge ) / NRSadmission proved almost independent of the initial pain level and seems to be much more suitable for the quality assessment in pain treatment than the NRS at discharge