7 results on '"Merz, Tobias Michael"'
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2. Assessment of endothelial cell function and physiological microcirculatory reserve by video microscopy using a topical acetylcholine and nitroglycerin challenge
- Author
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Hilty, Matthias Peter, Pichler, Jacqueline, Ergin, Bulent, Hefti, Urs, Merz, Tobias Michael, Ince, Can, and Maggiorini, Marco
- Published
- 2017
- Full Text
- View/download PDF
3. New Insights Into Changes in Corneal Thickness in Healthy Mountaineers During a Very-High-Altitude Climb to Mount Muztagh Ata
- Author
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Bosch, Martina Monika, Barthelmes, Daniel, Merz, Tobias Michael, Knecht, Pascal Bruno, Truffer, Frederic, Bloch, Konrad E., Thiel, Michael A., Petrig, Benno L., Turk, Alexander J., Schoch, Otto D., Hefti, Urs, and Landau, Klara
- Published
- 2010
4. Recruitment of non‐perfused sublingual capillaries increases microcirculatory oxygen extraction capacity throughout ascent to 7126 m.
- Author
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Hilty, Matthias Peter, Merz, Tobias Michael, Hefti, Urs, Ince, Can, Maggiorini, Marco, and Pichler Hefti, Jacqueline
- Subjects
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CAPILLARIES , *CARDIAC output , *ARTERIAL pressure , *SEA level , *MICROCIRCULATION - Abstract
Key points: A physiological response to increase microcirculatory oxygen extraction capacity at high altitude is to recruit capillaries.In the present study, we report that high altitude‐induced sublingual capillary recruitment is an intrinsic mechanism of the sublingual microcirculation that is independent of changes in cardiac output, arterial blood pressure or systemic vascular hindrance.Using a topical nitroglycerin challenge to the sublingual microcirculation, we show that high altitude‐related capillary recruitment is a functional response of the sublingual microcirculation as opposed to an anatomical response associated with angiogenesis.The concurrent presence of a low capillary density and high microvascular reactivity to topical nitroglycerin at sea level was found to be associated with a failure to reach the summit, whereas the presence of a high baseline capillary density with the ability to further increase maximum recruitable capillary density upon ascent to an extreme altitude was associated with summit success. A high altitude (HA) stay is associated with an increase in sublingual capillary total vessel density (TVD), suggesting microvascular recruitment. We hypothesized that microvascular recruitment occurs independent of cardiac output changes, that it relies on haemodynamic changes within the microcirculation as opposed to structural changes and that microcirculatory function is related to individual performance at HA. In 41 healthy subjects, sublingual handheld vital microscopy and echocardiography were performed at sea level (SL), as well as at 6022 m (C2) and 7042 m (C3), during ascent to 7126 m within 21 days. Sublingual topical nitroglycerin was applied to measure microvascular reactivity and maximum recruitable TVD (TVDNG). HA exposure decreased resting cardiac output, whereas TVD (mean ± SD) increased from 18.81 ± 3.92 to 20.92 ± 3.66 and 21.25 ± 2.27 mm mm−2 (P < 0.01). The difference between TVD and TVDNG was 2.28 ± 4.59 mm mm−2 at SL (P < 0.01) but remained undetectable at HA. Maximal TVDNG was observed at C3. Those who reached the summit (n = 15) demonstrated higher TVD at SL (P < 0.01), comparable to TVDNG in non‐summiters (n = 21) at SL and in both groups at C2. Recruitment of sublingual capillary TVD to increase microcirculatory oxygen extraction capacity at HA was found to be an intrinsic mechanism of the microcirculation independent of cardiac output changes. Microvascular reactivity to topical nitroglycerin demonstrated that HA‐related capillary recruitment is a functional response as opposed to a structural change. The performance of the vascular microcirculation needed to reach the summit was found to be associated with a higher TVD at SL and the ability to further increase TVDNG upon ascent to extreme altitude. Key points: A physiological response to increase microcirculatory oxygen extraction capacity at high altitude is to recruit capillaries.In the present study, we report that high altitude‐induced sublingual capillary recruitment is an intrinsic mechanism of the sublingual microcirculation that is independent of changes in cardiac output, arterial blood pressure or systemic vascular hindrance.Using a topical nitroglycerin challenge to the sublingual microcirculation, we show that high altitude‐related capillary recruitment is a functional response of the sublingual microcirculation as opposed to an anatomical response associated with angiogenesis.The concurrent presence of a low capillary density and high microvascular reactivity to topical nitroglycerin at sea level was found to be associated with a failure to reach the summit, whereas the presence of a high baseline capillary density with the ability to further increase maximum recruitable capillary density upon ascent to an extreme altitude was associated with summit success. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
5. Short-term recovery pattern of plasma fibrinogen after cardiac surgery: A prospective observational study.
- Author
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Erdoes, Gabor, Dietrich, Wulf, Stucki, Monika Pia, Merz, Tobias Michael, Angelillo-Scherrer, Anne, Nagler, Michael, Carrel, Thierry, and Eberle, Balthasar
- Subjects
FIBRINOGEN ,CARDIAC surgery ,SCIENTIFIC observation ,CARDIOVASCULAR agents ,CARDIOPULMONARY bypass - Abstract
Low plasma fibrinogen level is common after cardiopulmonary bypass (CPB). Current substitution practice with fibrinogen concentrate generally follows a single measurement and cut-off values from the literature, whereas early postoperative endogenous fibrinogen kinetics is incompletely described and widely disregarded. The aim of this study was to determine the short-term recovery pattern of plasma fibrinogen after CPB weaning. Our hypothesis was that in the absence of surgical bleeding, CPB-induced hypofibrinogenemia would resolve spontaneously and predictably within a few hours. In a prospective, observational study of 26 patients undergoing conventional CPB (cCPB) or minimally invasive extracorporeal circulation (MiECC), Clauss fibrinogen level (C-FIB) was determined at 10 closely spaced time points after protamine administration. Primary endpoint was the time to recovery of post-CPB fibrinogen levels to ≥1.5 g/L. C-FIB reached its nadir after protamine administration corresponding to 62 ± 5% (mean ± SD) of the baseline level after cCPB and 68 ± 7% after MiECC (p = 0.027 vs. cCPB). C-FIB recovered spontaneously at a nearly constant rate of approximately 0.08 g/L per hour. In all patients, C-FIB was ≥1.5 g/L at 4 hours and ≥2.0 g/L at 13 hours after CPB weaning. Following cardiac surgery with CPB and in the absence of surgical bleeding, spontaneous recovery of normal endogenous fibrinogen levels can be expected at a rate of 0.08 g/L per hour. Administration of fibrinogen concentrate triggered solely by a single-point measurement of low plasma fibrinogen some time after CPB is not justified. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
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6. Morphological Brain Changes after Climbing to Extreme Altitudes—A Prospective Cohort Study.
- Author
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Kottke, Raimund, Pichler Hefti, Jacqueline, Rummel, Christian, Hauf, Martinus, Hefti, Urs, and Merz, Tobias Michael
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BRAIN physiology ,LONGITUDINAL method ,COHORT analysis ,CEREBRAL cortex ,WHITE matter (Nerve tissue) ,HEMORRHAGE ,WOUNDS & injuries - Abstract
Background: Findings of cerebral cortical atrophy, white matter lesions and microhemorrhages have been reported in high-altitude climbers. The aim of this study was to evaluate structural cerebral changes in a large cohort of climbers after an ascent to extreme altitudes and to correlate these findings with the severity of hypoxia and neurological signs during the climb. Methods: Magnetic resonance imaging (MRI) studies were performed in 38 mountaineers before and after participating in a high altitude (7126m) climbing expedition. The imaging studies were assessed for occurrence of new WM hyperintensities and microhemorrhages. Changes of partial volume estimates of cerebrospinal fluid, grey matter, and white matter were evaluated by voxel-based morphometry. Arterial oxygen saturation and acute mountain sickness scores were recorded daily during the climb. Results: On post-expedition imaging no new white matter hyperintensities were observed. Compared to baseline testing, we observed a significant cerebrospinal fluid fraction increase (0.34% [95% CI 0.10–0.58], p = 0.006) and a white matter fraction reduction (-0.18% [95% CI -0.32–-0.04], p = 0.012), whereas the grey matter fraction remained stable (0.16% [95% CI -0.46–0.13], p = 0.278). Post-expedition imaging revealed new microhemorrhages in 3 of 15 climbers reaching an altitude of over 7000m. Affected climbers had significantly lower oxygen saturation values but not higher acute mountain sickness scores than climbers without microhemorrhages. Conclusions: A single sojourn to extreme altitudes is not associated with development of focal white matter hyperintensities and grey matter atrophy but leads to a decrease in brain white matter fraction. Microhemorrhages indicative of substantial blood-brain barrier disruption occur in a significant number of climbers attaining extreme altitudes. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
7. Intensive care without walls - introduction of a Medical Emergency Team system in a Swiss tertiary care centre.
- Author
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Etter R, Takala J, and Merz TM
- Subjects
- Aged, Female, Hospital Rapid Response Team organization & administration, Humans, Intensive Care Units organization & administration, Male, Middle Aged, Monitoring, Physiologic, Retrospective Studies, Tertiary Care Centers organization & administration, Time Factors, Hospital Mortality, Hospital Rapid Response Team statistics & numerical data, Intensive Care Units statistics & numerical data, Tertiary Care Centers statistics & numerical data
- Abstract
Questions Under Study: To improve the response of deteriorating patients during their hospital stay, the University Hospital Bern has introduced a Medical Emergency Team (MET). Aim of this retrospective cohort study is to review the preceding factors, patient characteristics, process parameters and their correlation to patient outcomes of MET calls since the introduction of the team., Methods: Data on patient characteristics, parameters related to MET activation and intervention and patient outcomes were evaluated. A Vital Sign Score (VSS), which is defined as the sum of the occurrence of each vital sign abnormalities, was calculated for all physiological parameters pre MET event, during event and correlation with hospital outcomes., Results: A total of 1,628 MET calls in 1,317 patients occurred; 262 (19.9%) of patients with MET calls during their hospital stay died. The VSS pre MET event (odds ratio [OR] 1.78, 95% confidence interval [CI] 1.50-2.13; AUROC 0.63; all p <0.0001) and during the MET call (OR 1.60, 95% CI 1.41-1.83; AUROC 0.62; all p <0.0001) were significantly correlated to patient outcomes. A significant increase in MET calls from 5.2 to 16.5 per 1000 hospital admissions (p <0.0001) and a decrease in cardiac arrest calls in the MET perimeter from 1.6 in 2008 to 0.8 per 1000 admissions was observed during the study period (p = 0.014)., Conclusions: The VSS is a significant predictor of mortality in patients assessed by the MET. Increasing MET utilisation coincided with a decrease in cardiac arrest calls in the MET perimeter.
- Published
- 2014
- Full Text
- View/download PDF
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