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Introduction: High altitude exposure may lead to high altitude pulmonary hypertension (HAPH) and high altitude pulmonary edema (HAPE). The pathophysiologic processes of both entities have been linked to decreased nitric oxide (NO) availability.Methods: We studied the effect of acute high altitude exposure on the plasma concentrations of asymmetric (ADMA) and symmetric dimethylarginine (SDMA), L-arginine, L-ornithine, and L-citrulline in two independent studies. We further investigated whether these biomarkers involved in NO metabolism were related to HAPH and HAPE, respectively. Fifty (study A) and thirteen (study B) non-acclimatized lowlanders were exposed to 4,559 m for 44 and 67 h, respectively. In contrast to study A, the participants in study B were characterized by a history of at least one episode of HAPE. Arterial blood gases and biomarker concentrations in venous plasma were assessed at low altitude (baseline) and repeatedly at high altitude. HAPE was diagnosed by chest radiography, and HAPH by measuring right ventricular to atrial pressure gradient (RVPG) with transthoracic echocardiography. AMS was evaluated with the Lake Louise Score (LLS) and the AMS-C score.Results: In both studies SDMA concentration significantly increased at high altitude. ADMA baseline concentrations were higher in individuals with HAPE susceptibility (study B) compared to those without (study A). However, upon high altitude exposure ADMA only increased in individuals without HAPE susceptibility, while there was no further increase in those with HAPE susceptibility. We observed an acute and transient decrease of L-ornithine and a more delayed but prolonged reduction of L-citrulline during high altitude exposure. In both studies SDMA positively correlated and L-ornithine negatively correlated with RVPG. ADMA was significantly associated with the occurrence of HAPE (study B). ADMA and SDMA were inversely correlated with alveolar PO2, while L-ornithine was inversely correlated with blood oxygenation and haemoglobin levels, respectively.Discussion: In non-acclimatized individuals ADMA and SDMA, two biomarkers decreasing endothelial NO production, increased after acute exposure to 4,559 m. The observed biomarker changes suggest that both NO synthesis and arginase pathways are involved in the pathophysiology of HAPH and HAPE.

Introduction Previous studies demonstrated that the implementation of the Kidney Disease Improving Global Outcomes (KDIGO) guideline-based bundle, consisting of different supportive measures in patients at high risk for acute kidney injury (AKI), might reduce rate and severity of AKI after surgery. However, the effects of the care bundle in broader population of patients undergoing surgery require confirmation.Methods and analysis The BigpAK-2 trial is an international, randomised, controlled, multicentre trial. The trial aims to enrol 1302 patients undergoing major surgery who are subsequently admitted to the intensive care or high dependency unit and are at high-risk for postoperative AKI as identified by urinary biomarkers (tissue inhibitor of metalloproteinases 2*insulin like growth factor binding protein 7 (TIMP-2)*IGFBP7)). Eligible patients will be randomised to receive either standard of care (control) or a KDIGO-based AKI care bundle (intervention). The primary endpoint is the incidence of moderate or severe AKI (stage 2 or 3) within 72 hours after surgery, according to the KDIGO 2012 criteria. Secondary endpoints include adherence to the KDIGO care bundle, occurrence and severity of any stage of AKI, change in biomarker values during 12 hours after initial measurement of (TIMP-2)*(IGFBP7), number of free days of mechanical ventilation and vasopressors, need for renal replacement therapy (RRT), duration of RRT, renal recovery, 30-day and 60-day mortality, intensive care unit length-of-stay and hospital length-of-stay and major adverse kidney events. An add-on study will investigate blood and urine samples from recruited patients for immunological functions and kidney damage.Ethics and dissemination The BigpAK-2 trial was approved by the Ethics Committee of the Medical Faculty of the University of Münster and subsequently by the corresponding Ethics Committee of the participating sites. A study amendment was approved subsequently. In the UK, the trial was adopted as an NIHR portfolio study. Results will be disseminated widely and published in peer-reviewed journals, presented at conferences and will guide patient care and further research.Trial registration number NCT04647396.

Abstract Purpose Assessing scapulothoracic kinematics typically involves visually observing patients during movement, which has limited inter‐ and intraobserver reliability. Dynamic rasterstereography (DRS) records, measures and visualizes surface structures in real time, using a curvature map to colour‐code convex, concave and saddle‐shaped structures on the body surface. This study aimed to evaluate the diagnostic efficacy of DRS‐assisted observation in identifying dyskinetic scapulothoracic patterns. Methods Thirty‐seven healthy participants performed shoulder abduction/adduction and flexion/extension cycles without additional weight, recorded using both DRS and a conventional video camera. A metronome ensured consistent timing, and for DRS a grid of parallel light rays projected onto the back surface was captured using indirect optical measurement techniques. The mean surface curvature was converted into a colour scale. The diagnostic performance of conventional and DRS videos in detecting dyskinetic patterns, including static asymmetries, dynamic asymmetries, motion delays and rapid compensatory movements, were compared. Two investigators independently evaluated the videos twice in a blinded and randomized sequence to assess intra‐ and interrater reproducibility. Results Analysis of 118 videos showed good‐to‐excellent intrarater and interrater reproducibility for both techniques (ICCs 0.727–0.949). Movement delays and dynamic asymmetries were observed more frequently when evaluating DRS videos rather than conventional videos (p = 0.0008 and p = 0.0016). However, no differences were found in static asymmetry and rapid compensatory movement detection. Conclusions DRS can create a real‐time model of the trunk surface and allows observers to evaluate the scapular movements with good‐to‐excellent intrarater and interrater reproducibility; compared to clinical observation, some specific scapular motion alterations can be observed more frequently. Clinical Trial Registration: Part of the DRKS00022334 trial. Level of Evidence Level II, prospective cohort study.