Crowdsourcing hypothesis tests: Making transparent how design choices shape research results

To what extent are research results influenced by subjective decisions that scientists make as they design studies? Fifteen research teams independently designed studies to answer fiveoriginal research questions related to moral judgments, negotiations, and implicit cognition. Participants from two separate large samples (total N > 15,000) were then randomly assigned to complete one version of each study. Effect sizes varied dramatically across different sets of materials designed to test the same hypothesis: materials from different teams renderedstatistically significant effects in opposite directions for four out of five hypotheses, with the narrowest range in estimates being d = -0.37 to +0.26. Meta-analysis and a Bayesian perspective on the results revealed overall support for two hypotheses, and a lack of support for three hypotheses. Overall, practically none of the variability in effect sizes was attributable to the skill of the research team in designing materials, while considerable variability was attributable to the hypothesis being tested. In a forecasting survey, predictions of other scientists were significantly correlated with study results, both across and within hypotheses. Crowdsourced testing of research hypotheses helps reveal the true consistency of empirical support for a scientific claim.</div

Short- and long-term outcomes for the surgical treatment of acute pulmonary embolism

Acute pulmonary embolism can be a life-threatening condition with a high mortality. The treatment choice is a matter of debate. The early and late outcomes of patients treated with surgical pulmonary embolectomy for acute pulmonary embolism in a single center were analyzed

Direct true lumen cannulation in type A acute aortic dissection: A review of an 11 years' experience.

ObjectivesDirect true lumen cannulation (DTLC) of the aorta is an alternative cardiopulmonary bypass cannulation technique in the context of type A acute aortic dissection (A-AAD). DTLC has been reported to be effective in restoring adequate perfusion to jeopardized organs. This study reports and compares operative outcomes with DTLC or alternative cannulation techniques in a large cohort of patients with A-AAD.MethodsAll patients who underwent surgery for A-AAD between January 2006 and January 2017 in Mainz university hospital were reviewed. The choice of cannulation technique was left to the operating surgeon, however DTLC was our preference in patients who were in state of shock or showed signs of tamponade or hypoperfusion, in cases of potential cerebral malperfusion, as well as in patients who were under resuscitation.ResultsA total of 528 patients (63% males, mean age 64±13.8 years) underwent emergency surgery for A-AAD. The DTLC technique was used in 52.4% of patients. The DTLC group of patients had worse clinical status at the time of presentation with more shock, tamponade, true lumen collapse, cerebral and other malperfusion states. New neurologic events were diagnosed in around 8% of patients in each group following surgery, but there was a trend for quicker neurological recovery in the DTLC-group. Early mortality rates, short-term and long-term survival rates did not differ between the two groups.ConclusionsDTLC is a safe cannulation technique that enables effective antegrade true lumen perfusion in complicated A-AAD scenarios, and is an advantageous addition to the aortic surgeons' armamentarium

Postoperative Compensatory Ammonium Excretion Subsequent to Systemic Acidosis in Cardiac Patients

Background. Postoperative acid-base imbalances, usually acidosis, frequently occur after cardiac surgery. In most cases, the human body, not suffering from any severe preexisting illnesses regarding lung, liver, and kidney, is capable of transient compensation and final correction. The aim of this study was to correlate the appearance of postoperatively occurring acidosis with renal ammonium excretion. Materials and Methods. Between 07/2014 and 10/2014, a total of 25 consecutive patients scheduled for elective isolated coronary artery bypass grafting with cardiopulmonary bypass were enrolled in this prospective observational study. During the operative procedure and the first two postoperative days, blood gas analyses were carried out and urine samples collected. Urine samples were analyzed for the absolute amount of ammonium. Results. Of all patients, thirteen patients developed acidosis as an initial disturbance in the postoperative period: five of respiratory and eight of metabolic origin. Four patients with respiratory acidosis but none of those with metabolic acidosis subsequently developed a base excess &gt; +2 mEq/L. Conclusion. Ammonium excretion correlated with the increase in base excess. The acidosis origin seems to have a large influence on renal compensation in terms of ammonium excretion and the possibility of an overcorrection

Transient dilutional acidosis but no lactic acidosis upon cardiopulmonary bypass in patients undergoing coronary artery bypass grafting

Introduction : Dilutional acidosis may result from the introduction of a large fluid volume into the patients’ systemic circulation, resulting in a considerable dilution of endogenous bicarbonate in the presence of a constant carbon dioxide partial pressure. Its significance or even existence, however, has been strongly questioned. Blood gas samples of patients operated on with standard cardiopulmonary bypass (CPB) were analyzed in order to provide further evidence for the existence of dilutional acidosis. Material and methods : Between 07/2014 and 10/2014, a total of 25 consecutive patients scheduled for elective isolated coronary artery bypass grafting with CPB were enrolled in this prospective observational study. Blood gas samples taken regularly after CPB initiation were analyzed for dilutional effects and acid-base changes. Results : After CPB initiation, hemoglobin concentration dropped from an average initial value of 12.8 g/dl to 8.8 g/dl. Before the beginning of CPB, the mean value of the patients’ pH and base excess (BE) value averaged 7.41 and 0.5 mEq/l, respectively. After the onset of CPB, pH and BE values significantly dropped to a mean value of 7.33 and –3.3 mEq/l, respectively, within the first 20 min. In the following period during CPB they recovered to 7.38 and –0.5 mEq/l, respectively, on average. Patients did not show overt lactic acidosis. Conclusions : The present data underline the general existence of dilutional acidosis, albeit very limited in its duration. In patients undergoing coronary artery bypass grafting it seems to be the only obvious disturbance in acid-­base homeostasis during CPB

Serum markers for early detection of patients with mesenteric ischemia after cardiac surgery

Mesenteric ischemia (MESI) is a rare but often fatal complication in patients after cardiac surgery. Non-specific clinical symptoms and lack of specific laboratory parameters complicate the diagnosis. We evaluated potential serum markers for MESI in cardiac surgery patients

Aortic remodelling after thoracic endovascular aortic repair in acute and chronic type B aortic dissections.

OBJECTIVES: Type B aortic dissections are routinely treated with thoracic endovascular aortic repair (TEVAR). The timing for TEVAR remains controversial and might have an impact on the remodelling capacity of the aorta. This study analyses and compares aortic remodelling in acute (ABD) and chronic (CBD) type B aortic dissections after TEVAR. METHODS: This retrospective study analysed the preoperative, postoperative and at least 1-year follow-up computed tomography of 53 TEVAR patients (36 ABD, 17 CBD) at a single institution between May 2005 and May 2016. The volumes of aortic lumen (AL), true lumen, false lumen (FL) and perfused FL were measured at the stent graft level (A), from the stent graft to the coeliac trunk (B) and from the coeliac trunk to the bifurcation (C). The absolute volumes, normalized volume changes and FL thrombosis rate of ABD and CBD patients were compared. RESULTS: Absolute AL and FL of segment A were significantly larger in CBD patients compared to ABD patients preoperatively (AL: 354 ± 68 vs 255 ± 51 ml, P = 0.023, FL: 253 ± 56 vs 183 ± 35 ml, P = 0.028) until last follow-up (AL: 462 ± 52 vs 246 ± 52 ml, P = 0.003, FL: 268 ± 202 vs 91 ± 31 ml, P = 0.004). The true lumen in segment A increased more in ABD than in CBD patients preoperatively to postoperatively (112% vs 36% P \u3c 0.001) and within the first year postoperatively (171% vs 80% P \u3c 0.001). FL in segment A decreased more in ABD compared to CBD patients within the first year (-42% vs -13% P \u3c 0.001) and thereafter (-50% vs +6% P = 0.002). In segments B and C, the FL thrombosis rate was higher in ABD than in CBD patients at all time points and significantly higher in segment A after the first year (91% vs 98% P = 0.035). CONCLUSIONS: Aortic remodelling after TEVAR is significantly different in acute and chronic dissection patients. TEVAR promotes aortic remodelling in both acute and chronic dissections in terms of true lumen increase at stent graft level. Nevertheless, significant AL reduction by FL shrinkage is primarily found in ABD