| 1. |
- Biancari, Fausto, et al.
(författare)
-
Multicenter study on postcardiotomy venoarterial extracorporeal membrane oxygenation
- 2020
-
Ingår i: Journal of Thoracic and Cardiovascular Surgery. - : Elsevier BV. - 0022-5223 .- 1097-685X. ; 159:5, s. 1844-1854
-
Tidskriftsartikel (refereegranskat)abstract
- Objectives: The aim of this study was to identify the risk factors associated with early mortality after postcardiotomy venoarterial extracorporeal membrane oxygenation. Methods: This is an analysis of the postcardiotomy extracorporeal membrane oxygenation registry, a retrospective multicenter cohort study including 781 patients aged more than 18 years who required venoarterial extracorporeal membrane oxygenation for cardiopulmonary failure after cardiac surgery from 2010 to 2018 at 19 cardiac surgery centers. Results: After a mean venoarterial extracorporeal membrane oxygenation therapy of 6.9 ± 6.2 days, hospital and 1-year mortality were 64.4% and 67.2%, respectively. Hospital mortality after venoarterial extracorporeal membrane oxygenation therapy for more than 7 days was 60.5% (P = .105). Centers that had treated more than 50 patients with postcardiotomy venoarterial extracorporeal membrane oxygenation had a significantly lower hospital mortality than lower-volume centers (60.7% vs 70.7%, adjusted odds ratio, 0.58; 95% confidence interval, 0.41-0.82). The postcardiotomy extracorporeal membrane oxygenation score was derived by assigning a weighted integer to each independent pre–venoarterial extracorporeal membrane oxygenation predictors of hospital mortality as follows: female gender (1 point), advanced age (60-69 years, 2 points; ≥70 years, 4 points), prior cardiac surgery (1 point), arterial lactate 6.0 mmol/L or greater before venoarterial extracorporeal membrane oxygenation (2 points), aortic arch surgery (4 points), and preoperative stroke/unconsciousness (5 points). The hospital mortality rates according to the postcardiotomy extracorporeal membrane oxygenation score was 0 point, 45.6%; 1 point, 40.5%; 2 points, 51.1%; 3 points, 57.8%; 4 points, 70.7%; 5 points, 68.3%; 6 points, 77.5%; and 7 points or more, 89.7% (P < .0001). Conclusions: Age, female gender, prior cardiac surgery, preoperative acute neurologic events, aortic arch surgery, and increased arterial lactate were associated with increased risk of early mortality after postcardiotomy venoarterial extracorporeal membrane oxygenation. Center experience with postcardiotomy venoarterial extracorporeal membrane oxygenation may contribute to improved results.
|
|
| 2. |
- Lampu, Vesa, et al.
(författare)
-
Multilevel Outphasing With Over-the-Air Combining in Large Antenna Arrays
- 2023
-
Ingår i: IEEE Transactions on Communications. - 0090-6778 .- 1558-0857. ; 71:12, s. 7347-7362
-
Tidskriftsartikel (refereegranskat)abstract
- This article investigates the feasibility of combinerless multilevel outphasing transmitter as a potential architecture for large millimeter-wave (mmWave) phased arrays. We consider two distinct ways of distributing the component signals to the antennas and develop a model for the received signal at each radiated spatial direction from a phased array. Based on the received signal model, we derive expressions for the signal-to-distortion ratio as well as total power experienced at each spatial direction. Furthermore, antenna branch mismatches, overload distortion and quantization are considered, and an analytical model for the signal-to-distortion ratio at the intended receiver is derived. We additionally establish a model for comparing the achievable energy efficiency to those of the relevant reference methods. Extensive numerical experiments are carried out to verify the analytical works, and to assess the commonly used metrics of error vector magnitude (EVM) and total radiated power adjacent channel leakage ratio (TRP-ACLR). It is shown that the combinerless architecture is a valid option for mmWave phased arrays, demonstrating favorable EVM results and TRP-ACLR beyond the 28 dBc limit imposed by the 3GPP, even in the presence of the considered distortions. The conducted energy efficiency assessment shows that efficiency of the reference methods can be exceeded with sufficient amount of outphasing levels. The considered architecture is thus an interesting alternative for addressing the linearity vs. energy-efficiency challenge in mmWave phased-array systems.
|
|
