| 1. |
- Barack, Leor, et al.
(författare)
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Black holes, gravitational waves and fundamental physics : a roadmap
- 2019
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Ingår i: Classical and quantum gravity. - : IOP Publishing. - 0264-9381 .- 1361-6382. ; 36:14
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Forskningsöversikt (refereegranskat)abstract
- The grand challenges of contemporary fundamental physics dark matter, dark energy, vacuum energy, inflation and early universe cosmology, singularities and the hierarchy problem all involve gravity as a key component. And of all gravitational phenomena, black holes stand out in their elegant simplicity, while harbouring some of the most remarkable predictions of General Relativity: event horizons, singularities and ergoregions. The hitherto invisible landscape of the gravitational Universe is being unveiled before our eyes: the historical direct detection of gravitational waves by the LIGO-Virgo collaboration marks the dawn of a new era of scientific exploration. Gravitational-wave astronomy will allow us to test models of black hole formation, growth and evolution, as well as models of gravitational-wave generation and propagation. It will provide evidence for event horizons and ergoregions, test the theory of General Relativity itself, and may reveal the existence of new fundamental fields. The synthesis of these results has the potential to radically reshape our understanding of the cosmos and of the laws of Nature. The purpose of this work is to present a concise, yet comprehensive overview of the state of the art in the relevant fields of research, summarize important open problems, and lay out a roadmap for future progress. This write-up is an initiative taken within the framework of the European Action on 'Black holes, Gravitational waves and Fundamental Physics'.
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| 2. |
- Tusman, Gerardo, et al.
(författare)
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Multimodal non-invasive monitoring to apply an open lung approach strategy in morbidly obese patients during bariatric surgery
- 2020
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Ingår i: Journal of clinical monitoring and computing. - : SPRINGER HEIDELBERG. - 1387-1307 .- 1573-2614. ; 34:5, s. 1015-1024
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Tidskriftsartikel (refereegranskat)abstract
- To evaluate the use of non-invasive variables for monitoring an open-lung approach (OLA) strategy in bariatric surgery. Twelve morbidly obese patients undergoing bariatric surgery received a baseline protective ventilation with 8 cmH(2)O of positive-end expiratory pressure (PEEP). Then, the OLA strategy was applied consisting in lung recruitment followed by a decremental PEEP trial, from 20 to 8 cmH(2)O, in steps of 2 cmH(2)O to find the lung's closing pressure. Baseline ventilation was then resumed setting open lung PEEP (OL-PEEP) at 2 cmH(2)O above this pressure. The multimodal non-invasive variables used for monitoring OLA consisted in pulse oximetry (SpO(2)), respiratory compliance (Crs), end-expiratory lung volume measured by a capnodynamic method (EELVCO2), and esophageal manometry. OL-PEEP was detected at 15.9 +/- 1.7 cmH(2)O corresponding to a positive end-expiratory transpulmonary pressure (P-L,P-ee) of 0.9 +/- 1.1 cmH(2)O. ROC analysis showed that SpO(2) was more accurate (AUC 0.92, IC95% 0.87-0.97) than Crs (AUC 0.76, IC95% 0.87-0.97) and EELVCO2 (AUC 0.73, IC95% 0.64-0.82) to detect the lung's closing pressure according to the change of P-L,P-ee from positive to negative values. Compared to baseline ventilation with 8 cmH(2)O of PEEP, OLA increased EELVCO2 (1309 +/- 517 vs. 2177 +/- 679 mL) and decreased driving pressure (18.3 +/- 2.2 vs. 10.1 +/- 1.7 cmH(2)O), estimated shunt (17.7 +/- 3.4 vs. 4.2 +/- 1.4%), lung strain (0.39 +/- 0.07 vs. 0.22 +/- 0.06) and lung elastance (28.4 +/- 5.8 vs. 15.3 +/- 4.3 cmH(2)O/L), respectively; all p < 0.0001. The OLA strategy can be monitored using noninvasive variables during bariatric surgery. This strategy decreased lung strain, elastance and driving pressure compared with standard protective ventilatory settings. Clinical trial number NTC03694665.
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| 3. |
- Tusman, Gerardo, et al.
(författare)
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Noninvasive Monitoring of Lung Recruitment Maneuvers in Morbidly Obese Patients : The Role of Pulse Oximetry and Volumetric Capnography
- 2014
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Ingår i: Anesthesia and Analgesia. - : Ovid Technologies (Wolters Kluwer Health). - 0003-2999 .- 1526-7598. ; 118:1, s. 137-144
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: We conducted this study to determine whether pulse oximetry and volumetric capnography (VCap) can determine the opening and closing pressures of lungs of anesthetized morbidly obese patients. METHODS: Twenty morbidly obese patients undergoing laparoscopic bariatric surgery with capnoperitoneum were studied. A lung recruitment maneuver was performed in pressure control ventilation as follows: (1) During an ascending limb, the lungs' opening pressure was detected. After increasing positive end-expiratory pressure (PEEP) from 8 to 16 cm H2O, fraction of inspired oxygen (Fio(2)) was decreased until pulse oximetric arterial saturation (Spo(2)) was <92%. Thereafter, end-inspiratory pressure was increased in steps of 2 cm H2O, from 36 to a maximum of 50 cm H2O. The opening pressure was attained when Spo(2) exceeded 97%. (2) During a subsequent decreasing limb, the lungs' closing pressure was identified. PEEP was decreased from 22 to 10 cm H2O in steps of 2 cm H2O. The closing pressure was determined as the PEEP value at which respiratory compliance decreased from its maximum value. We continuously recorded lung mechanics, Spo(2), and VCap. RESULTS: The lungs' opening pressures were detected at 44 (4) cm H2O (median and interquartile range) and the closing pressure at 14 (2) cm H2O. Therefore, the level of PEEP that kept the lungs without collapse was found to be 16 (3) cm H2O. Using respiratory compliance as a reference, receiver operating characteristic analysis showed that Spo(2) (area under the curve [AUC] 0.80 [SE 0.07], sensitivity 0.65, and specificity 0.94), the elimination of CO2 per breath (AUC 0.91 [SE 0.05], sensitivity 0.85, and specificity 0.98), and Bohr's dead space (AUC 0.83 [SE 0.06], sensitivity 0.70, and specificity 0.95] were relatively accurate for detecting lung collapse during the decreasing limb of a recruitment maneuver. CONCLUSIONS: Lung recruitment in morbidly obese patients could be effectively monitored by combining noninvasive pulse oximetry and VCap. Spo(2), the elimination of CO2, and Bohr's dead space detected the individual's opening and closing pressures.
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| 4. |
- Tusman, Gerardo, et al.
(författare)
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Photoplethysmographic characterization of vascular tone mediated changes in arterial pressure : an observational study
- 2019
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Ingår i: Journal of clinical monitoring and computing. - : SPRINGER HEIDELBERG. - 1387-1307 .- 1573-2614. ; 33:5, s. 815-824
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Tidskriftsartikel (refereegranskat)abstract
- To determine whether a classification based on the contour of the photoplethysmography signal (PPGc) can detect changes in systolic arterial blood pressure (SAP) and vascular tone. Episodes of normotension (SAP 90-140 mmHg), hypertension (SAP > 140 mmHg) and hypotension (SAP < 90 mmHg) were analyzed in 15 cardiac surgery patients. SAP and two surrogates of the vascular tone, systemic vascular resistance (SVR) and vascular compliance (Cvasc = stroke volume/pulse pressure) were compared with PPGc. Changes in PPG amplitude (foot-to-peak distance) and dicrotic notch position were used to define 6 classes taking class III as a normal vascular tone with a notch placed between 20 and 50% of the PPG amplitude. Class I-to-II represented vasoconstriction with notch placed > 50% in a small PPG, while class IV-to-VI described vasodilation with a notch placed < 20% in a tall PPG wave. 190 datasets were analyzed including 61 episodes of hypertension [SAP = 159 (151-170) mmHg (median 1st-3rd quartiles)], 84 of normotension, SAP = 124 (113-131) mmHg and 45 of hypotension SAP = 85(80-87) mmHg. SAP were well correlated with SVR (r = 0.78, p < 0.0001) and Cvasc (r = 0.84, p < 0.0001). The PPG-based classification correlated well with SAP (r = - 0.90, p < 0.0001), SVR (r = - 0.72, p < 0.0001) and Cvasc (r = 0.82, p < 0.0001). The PPGc misclassified 7 out of the 190 episodes, presenting good accuracy (98.4% and 97.8%), sensitivity (100% and 94.9%) and specificity (97.9% and 99.2%) for detecting episodes of hypotension and hypertension, respectively. Changes in arterial pressure and vascular tone were closely related to the proposed classification based on PPG waveform. Clinical Trial Registration NTC02854852.
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| 5. |
- Tusman, Gerardo, et al.
(författare)
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The Sensitivity and Specificity of Pulmonary Carbon Dioxide Elimination for Noninvasive Assessment of Fluid Responsiveness
- 2016
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Ingår i: Anesthesia and Analgesia. - 0003-2999 .- 1526-7598. ; 122:5, s. 1404-1411
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: We sought to determine whether the response of pulmonary elimination of CO2 (Vco(2)) to a sudden increase in positive end-expiratory pressure (PEEP) could predict fluid responsiveness and serve as a noninvasive surrogate for cardiac index (CI). METHODS: Fifty-two patients undergoing cardiovascular surgery were included in this study. By using a constant-flow ventilation mode, we performed a PEEP challenge of 1-minute increase in PEEP from 5 to 10 cm H2O. At PEEP of 5 cm H2O, patients were preloaded with 500 mL IV saline solution after which a second PEEP challenge was performed. Patients in whom fluid administration increased CI by >= 15% from the individual baseline value were defined as volume responders. Beat-by-beat CI was derived from arterial pulse contour analysis, and breath-by-breath Vco(2) data were collected during the protocol. The sensitivity and specificity of Vco(2) for detecting the fluid responders according to CI was performed by the receiver operating characteristic curves. RESULTS: Twenty-one of 52 patients were identified as fluid responders (40%). The PEEP maneuver before fluid administration decreased CI from 2.65 +/- 0.34 to 2.21 +/- 0.32 L/min/m(2) (P = 0.0011) and Vco(2) from 150 +/- 23 to 123 +/- 23 mL/min (P = 0.0036) in responders, whereas the changes in CI and Vco(2) were not significant in nonresponders. The PEEP challenge after fluid administration induced no significant changes in CI and Vco(2), in neither responders nor nonresponders. PEEP-induced decreases in CI and Vco(2) before fluid administration were well correlated (r(2) = 0.75, P < 0.0001) but not thereafter. The area under the receiver operating characteristic curves for a PEEP-induced decrease in Delta CI and Delta Vco(2) was 0.99, with a 95% confidence interval from 0.96 to 0.99 for Delta CI and from 0.97 to 0.99 for Delta Vco(2). During the PEEP challenge, a decrease in Vco(2) by 11% predicted fluid responsiveness with a sensitivity of 0.90 (95% confidence interval, 0.87-0.93) and a specificity of 0.95 (95% confidence interval, 0.92-0.98). CONCLUSIONS: PEEP-induced changes in Vco(2) predicted fluid responsiveness with accuracy in patients undergoing cardiac surgery.
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