Critical care medicine · 1996
Closed-loop control of airway occlusion pressure at 0.1 second (P0.1) applied to pressure-support ventilation: algorithm and application in intubated patients.
Клиническое исследованиеСтатьяРандомизированное исследованиеПоддержка исследования: вне правительства СШАНазвание и аннотация: Перевод пока не подготовлен
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Iotti G A, Brunner J X, Braschi A, Laubscher T, Olivei M C, Palo A, Galbusera C, Comelli A
Аннотация
OBJECTIVE: Airway occlusion pressure at 0.1 sec (P0.1) is an index of respiratory center output. During pressure-support ventilation, P0.1 correlates with the mechanical output of the inspiratory muscles and has an inverse relationship with the amount of pressure-support ventilation. Based on these observations, we designed a closed-loop control which, by automatically adjusting pressure-support ventilation, stabilizes P0.1, and hence patient inspiratory activity, at a desired target. The purpose of the study was to demonstrate the feasibility of the method, rather than its efficacy or even its influence on patient outcome.
DESIGN: Prospective, randomized trial.
SETTING: A general intensive care unit of a university hospital in Italy.
PATIENTS: Eight stable patients intubated and ventilated with pressure-support ventilation for acute respiratory failure.
INTERVENTIONS: Patients were transiently connected to a computer-controlled ventilator on which the algorithm for closed-loop control was implemented. The closed-loop control was based on breath by breath measurement of P0.1, and on comparison with a target set by the user. When actual P0.1 proved to be higher than the target value, the P0.1 controller automatically increased pressure-support ventilation, and decreased it when P0.1 proved to be lower than the target value. For safety, a volume controller was also implemented. Four P0.1 targets (1.5, 2.5, 3.5, and 4.5 cm H2O) were applied at random for 15 mins each.
MEASUREMENTS AND MAIN RESULTS: The closed-loop algorithm was able to control P0.1, with a difference from the set targets of 0.59 +/- 0.27 (SD) cm H2O.
CONCLUSIONS: The study shows that P0.1 can be automatically controlled by pressure-support ventilation adjustments with a computer. Inspiratory activity can thus be stabilized at a level prescribed by the physician.
DESIGN: Prospective, randomized trial.
SETTING: A general intensive care unit of a university hospital in Italy.
PATIENTS: Eight stable patients intubated and ventilated with pressure-support ventilation for acute respiratory failure.
INTERVENTIONS: Patients were transiently connected to a computer-controlled ventilator on which the algorithm for closed-loop control was implemented. The closed-loop control was based on breath by breath measurement of P0.1, and on comparison with a target set by the user. When actual P0.1 proved to be higher than the target value, the P0.1 controller automatically increased pressure-support ventilation, and decreased it when P0.1 proved to be lower than the target value. For safety, a volume controller was also implemented. Four P0.1 targets (1.5, 2.5, 3.5, and 4.5 cm H2O) were applied at random for 15 mins each.
MEASUREMENTS AND MAIN RESULTS: The closed-loop algorithm was able to control P0.1, with a difference from the set targets of 0.59 +/- 0.27 (SD) cm H2O.
CONCLUSIONS: The study shows that P0.1 can be automatically controlled by pressure-support ventilation adjustments with a computer. Inspiratory activity can thus be stabilized at a level prescribed by the physician.