Potentially harmful effects of inspiratory synchronization during pressure preset ventilation

Purpose: Pressure preset ventilation (PPV) modes with set inspiratory time can be classified according to their ability to synchronize pressure delivery with patient's inspiratory efforts (i-synchronization). Non-i-synchronized (like airway pressure release ventilation, APRV), partially i-synchronized (like biphasic airway pressure), and fully i-synchronized modes (like assist-pressure control) can be distinguished. Under identical ventilatory settings across PPV modes, the degree of i-synchronization may affect tidal volume (V T), transpulmonary pressure (P TP), and their variability. We performed bench and clinical studies. Methods: In the bench study, all the PPV modes of five ventilators were tested with an active lung simulator. Spontaneous efforts of −10cmH2O at rates of 20 and 30breaths/min were simulated. Ventilator settings were high pressure 30cmH2O, positive end-expiratory pressure (PEEP) 15cmH2O, frequency 15breaths/min, and inspiratory to expiratory ratios (I:E) 1:3 and 3:1. In the clinical studies, data from eight intubated patients suffering from acute respiratory distress syndrome (ARDS) and ventilated with APRV were compared to the bench tests. In four additional ARDS patients, each of the PPV modes was compared. Results: As the degree of i-synchronization among the different PPV modes increased, mean V T and P TP swings markedly increased while breathing variability decreased. This was consistent with clinical comparison in four ARDS patients. Observational results in eight ARDS patients show low V T and a high variability with APRV. Conclusion: Despite identical ventilator settings, the different PPV modes lead to substantial differences in V T, P TP, and breathing variability in the presence spontaneous efforts. Clinicians should be aware of the possible harmful effects of i-synchronization especially when high V T is undesirabl

Year in review in Intensive Care Medicine 2010: III. ARDS and ALI, mechanical ventilation, noninvasive ventilation, weaning, endotracheal intubation, lung ultrasound and paediatrics

SCOPUS: re.jinfo:eu-repo/semantics/publishe

Dynamic Resource Allocation for Cloud-RAN in LTE with Real-Time BBU/RRH Assignment

International audienceCloud-Radio Access Network (C-RAN) is a new emerging technology that holds alluring promises for Mobile network operators regarding capital and operation cost savings. However, many challenges still remain before full commercial deployment of C-RAN solutions. Dynamic resource allocation algorithms are needed to cope with significantly fluctuating traffic loads. Those algorithms must target not only a better quality of service delivery for users, but also less power consumption and better interference management, with the possibility to turn off RRHs that are not transmitting. To this end, we propose in this paper a dynamic two-stage design for downlink OFDMA resource allocation and BBU-RRH assignment in C-RAN. Specifically, we first model the resource and power allocation problem in a mixed integer linear problem for real-time fluctuating traffic of mobile users. Then, we propose a Knapsack formulation to model the BBU-RRH assignment problem. Simulation results show that our proposal achieves not only a high satisfaction rate for mobile users, but also minimal power consumption and significant BBUs savings, compared to state-of-the-art schemes

Kyste hydatique du muscle psoas r&#233v&233l&#233 par une mass abdominale f&#233brile: A propos d'un cas

No Abstract